Spectrum biology august 2016 by Alberto Arevalo

Dr. Anamika Tripathi

E Bryophytes are small, non-vascular land plants encompassing the liverworts, the hornworts and the mosses. They are the most simple and primitive group of land plants including approximately 25000 species. They are considered as amphibians of plant world. Bryophytes are non-vascular terrestrial plants of moist habitats. They possess a multicellular diploid sporophyte, which lives as a parasite on an independent multicellular haploid gametophyte. This gametophyte develops multicellular jacketed sex organs. These plants are very small and cosmopolitan. They are classified as â&#x20AC;&#x2DC;Atracheataâ&#x20AC;&#x2122; as they lack a vascular tissue. They must rely on slow diffusion or poorly developed conducting tissues to distribute water and other nutrients. Primarily they are terrestrial, grow in moist and shady places, such as damp walls, damp soil, on banks of river and pond, etc. Fertilisation is zooidogamic and water is necessary for it.

General Characteristics l

The bryophytes are a small group of primitive land dwellers. They possess a leafy or thalloid green plant body. None of the bryophyte have true Hydroids Leptoids Parenchyma vascular (i.e. xylem and phloem) and lignified tissue. Many mosses have special water conducting cells called hydroids in the centre of the stem and few have food conducting cells called leptoids surrounding the hydroids. Most water is absorbed directly through the surface. TS of a Moss thallus

The plant body lacks the true roots, stems and leaves. It grows prostrate on the ground. It is attached to the substratum by delicate, unbranched, unicellular, hair like structures, called rhizoids. Higher bryophytes have erect body. It consists of a central axis which bears leaf-like expansions. It is attached to the substratum by branched multicellular rhizoids. The plants are small. They seldom attain great length or height. The maximum height is 60 cm for a moss species growing in New Zealand.

Bryophytes : Terrestrial Amphibians Bryophytes are known as terrestrial amphibians as they require an external layer of water on the soil surface for their existence. The external water is required for the dehiscence of antheridia and archegonia. Male gametes swim to archegonia through water. Water protects them from transpiration and hence desiccation as the plant body is not covered by cuticle. The external water is necessary for supply of water to all parts through capillarity in the absence of vascular tissues.

Habitat l

Bryophytes grow on moist walls, wet soil, on tree trunks, near river banks, on rocks and their crevices, etc. Few species like Riccia fluitans, Ricciocarpons natans and Riella are aquatic. There are no marine bryophytes, but some such as dune mosses grow near the sea shore. Epiphylium or Follicolous Grow on surface of living leaves of higher plants e.g. Ephemeropsis, Crossomitrium

Why bryophytes do not attain great heights?

Desert Bryophyte Able to tolerate great heat and drought e.g. Barbula torquata, Tortula princes

Bryophytes seldom achieve great heights. They are small sized because they lack a well developed root system. Further, the absence of vascular tissue also restricts their growth. They lack mechanical tissue and require an external sheet of water for the transport of male gametes. l

Sexual reproduction is highly oogamous. Male reproductive organs are club-shaped antheridia, while female reproductive organs are flask-shaped archegonia. Zygote or oospore starts its germination immediately after fertilisation and forms the sporophyte generation called sporogonium. Sporophyte may be very simple and represented by a spore sac only as in Riccia or differentiated into foot, seta and capsule as in moss. The sporophyte of bryophytes never separates from the gametophyte. It is more or less completely dependent on the gametophyte for nutrition and water. The sporogonium is concerned with the production of wind disseminated, non-motile, cutinised spores which belong to the category of gonospores or meiospores. On falling, each spore germinates to give rise to the gametophyte plant either directly or indirectly as a lateral bud from the protonema.

Terrestrial Grow on soil surface, e.g. Riccia discolor, Riccia billardieri

Aquatic Grow in water, e.g. Riccia fluitans, Riella affinis, Scapania undulata

Bryophytes

Lignicolous Grow on wood such as old logs, e.g. Nowillia, Zoopsis, Cephalozia

Saxicolous or Epilithic Grow on rock surface. e.g. Porella thuja, Bryum capillare

Epiphytic or Corticolous Grow on other plants e.g. Tortula laevipila, Zygodon conoidens

Resemblance between Bryophytes and Algae Branchlets Sex organs

Node l

Internode Shara (Thallus)

Oogonium (nucule)

Bracteoles Bracts

Antheridium (globule)

Chara (Sex organs)

Midrib

Thalloid plant body. Lack of roots. Absence of complete vascular tissues. Autotrophic mode of nutrition. Both need water during fertilisation due to swimming habit of gametes. Chlorophyll pigments present. Reserved food material is true starch. Cell wall is consist of cellulose surrounded by a peptic layer containing galactouronic acid.

Sporogonium

Riccia (Female plant)

Riccia (Male plant)

Differences between Bryophytes and Algae Characters

Bryophytes

Habitat Tissue differentiation Sexual reproduction

Grow in moist shady places and in water Well developed Only oogamous

Sex organs Female sex organ Zygote Dominant phase

Covered by a sterile jacket Archegonium Remains enclosed in the archegonium Gametophytic phase Sporophyte is dependent upon gametophyte Produced from zygote Differentiated into foot, seta and capsule Absent

Embryo Sporophyte Mitospores

Algae Usually aquatic Found only in higher forms Isogamous, anisogamous and oogamous Not covered by sterile jacket Oogonium Liberated from the plant Sporophytic phase Sporophyte is independent of gametophyte Never produced No such differentiation Usually present

Resemblance in Bryophytes and Pteridophytes It is often said that bryophytes are probably descendents of pteridophytes. This statement is based on the certain similari ties between the two groups. These similarities are as follows : l

l l

l l l l

The simple, rootless and leafless sporophytes of the primitive pteridophytes (e.g., Rhynia) can be compared with the sporophytes of bryophytes. Like bryophytes, the sporophytes of primitive pteridophytes, viz., Rhynia possesses rhizoids in tufts instead of roots. The structure of archegonium is fundamentally similar in both the groups. The antheridium in both the groups consists of androcytes enclosed in a single layer of sterile jacket. Antherozoids are flagellated in both the groups. In both, presence of water is essential for fertilisation. In both groups, the zygote germinats to give rise to embryo. Both groups exhibit heteromorphic type of alternation of generations.

Cyanobacteria : Bryophyte Symbiosis Only few bryophytes are able to form epiphytic or endophytic associations with cyanobacteria. In the case of mosses, the cyanobacteria grow mostly epiphytically. The exception being two Sphagnum species in which the cyanobacteria occupy water filled, hyaline cells. They are thought to provide some protection from the acidic bog environment. These nitrogen fixing cyanobacterial associations with mosses often supply most of the combined N2 to the local ecosystems of the Arctic, the Antarctic and boreal forest regions. Cyanobacterial associations with liverworts are rare. By contrast, in the hornworts, endophytic associations are ubiquitous.

Differences between Bryophytes and Pteridophytes Character Dominant phase Plant body Ploidy level Vascular tissue Sporophytic phase

Bryophytes

Pteridophytes

Gametophytic phase Usually leafy or thalloid Main plant body haploid Xylem-phloem absent Dependent on gametophytic phase

Sporophytic phase Usually differentiated into root, stem and leaf Main plant body diploid Xylem-phloem present Independent and autotrophic

Calyptra

Bryokinin

Sporangioferous spike

Capsule l

Bryokinin is an endogenous cytokinin. It can replace kinetin as a growth factor in tissue culture of some plants like Nicotiana tobacum. In mosses bryokinin is physiologically active at several stages of development. At the caulonema stage it promotes bud formation. In the phase immediately before sexual maturation, it supports apogamous sporogonium formations as in Splachnum ovatum. In the phase of sexual maturation it promotes archegonium differentiation is Splachnum ovatum.

Seta Lateral bigger leaves Dorsal small leaves Leaflets or pinnules

Leaf

Stem

Stem A

Rhizophore

Male branch

Female branch B

Rhizoids

Adventitious roots

Funaria hygrometrica Selaginella

A. A female branch of leafy gametophore with sprophyte B. A leafy gametophore with a male branch and a female branch with young sporophyte Capsule Pseudopodium Commal tufa

Branch tuft

Sporophyll

Sori Rachis

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Leaflets or pinnules

Main axis Ramenta

Sterile branches

Circinate leaf Rhizome Roots

Sphagnum Dryopteris

Adaptations in Bryophytes Bryophytes are the simplest land plants. They grow on land but water is very important for their survival. They show adaptations for the terrestrial and water habitats. Therefore, they are considered as â&#x20AC;&#x2DC;amphibians of plant kingdomâ&#x20AC;&#x2122;. Rhizoids for attachment and absorption of water

Compact plant structure

Adaptation to Land Conditions

Reproductive structures protected by sterile jacket

Retention of zygote in the archegonium

Production of large number of spores for increasing the chances of survival Effective wide dispersal of spores Development of embryo

Desiccation Tolerance in Bryophytes Desiccation tolerance is a primitive trait. They are the mechanisms by which the first land plants achieved tolerance. It may be reflected in how extant desiccation - tolerant bryophytes survive drying. Cellular structures appear intact in the desiccated state but are disrupted by rapid uptake of water upon rehydration. However, cellular integrity is rapidly regained. The photosynthetic machinery appears to be protected such that photosynthetic activity recovers quickly. Gene expression responds following rehydration and not during drying. Gene expression is translationally controlled and results in the synthesis of a number of proteins, collectively called rehydrins. The basic mechanisms of tolerance seen in modern day bryophytes have changed little from the earliest manifestations of desiccation-tolerance in land plants. Adaptation to Water Dependent on water for reproduction because sperms must swin to archegonia. Adapted to release their sperms when H2O is available. No special supportive structures, so the plants are restricted in upward growth. Dependent on availability of water and mineral salts close to or at the surface of the soil, because they have no roots to penetrate the substrate.

Bryophytes : The Ignored Medicinal Plants Bryophytes are source of many incredibly interesting and useful bioactive compounds. The majority of the compounds reported in bryophytes are lipophilic terpenoids and fragrant compounds. In the last few decades the medicinal value of bryophytes has received interest to a great extent. Many chemicals and secondary metabolites have been isolated from them. The medicinal uses of bryophytes are mostly explored by Native North Americans (28%), followed by Chinese (27%). However, in India this figure is not very encouraging. Three plants are very significant for their medicinal importance viz. Marchantia polymorpha (pulmonary tuberculosis and liver related ailments), Riccia (ringworm treatment) and Polytrichum commune (tea prepared by it helps in liquefying kidney and gall bladder stones).

Reproductive Bodies of Bryophytes Bryophytes reproduce vegetatively as well as sexually. Reproduction by vegetative methods is the common mode of reproduction and propagation in bryophytes. Air chamber Gemma cup

Gemma cup

Gemma

Gemmae Air pore

Mucilage hair

Adventitious branches By adventitious branches

Thallus Scale Rhizoid Gemma cup with a part. of the thallus tissue By branch tips

By gemma

Vegetative Reproduction

By death and decay of older parts

By bulbil, rhizoids and protonema

By cladia

By tubers Tubers

Gametophore Bud

Secondary protonema

Rhizoids

Bulbil

Alternation of Generation Bryophytes show alternation of generation. Two types of organisms, a haploid gametophyte generation and a diploid sporophyte generation, alternate in the life cycle. Haploid generation undergoes sexual reproduction and produces gametes. Therefore, it is known as gametophyte. Gametes are formed through mitosis, so they are also haploid. The gametes fuse to form a diploid zygote which grows into the diploid sporophyte generation. It is called sporophyte because it undergoes asexual reproduction to produce spores. Production of spores involves meiosis, so that there is a return to the haploid condition. The haploid spores give rise to the gametophyte generation.

Sexual Reproduction Bryophytes show oogamous type of sexual reproduction. The gametes are produced in complex, multicellular, jacketed sex organs. Each sex organ consists of an outer, protective wall of sterile cells which surround the gamete producing cells. Male sex organ is known as antheridium while female sex organ is known as archegonium.

Antheridium It is a multicellular ellipsoidal or club-shaped structure. The body of antheridium is made up of jacket layer. It encloses a central mass of squarish or cubical cells called androcytes. The androcytes produce the biflagellate male gemetes, known as antherozoids or sperms.

Involucral leaves

Fertilisation

Paraphyses Antheridium Androgonial mass

The mature antheridium ruptures at its apex liberating the sperms. At the same time the axial row of neck canal cells including the venter canal cell in the mature archegonium disorganise. The tip of archegonium opens and a narrow canal opening to the exterior is formed.

Cap cells

Body

Androcyte

Jacket

The liberated sperms swimming in a thin film of water reach the archegonia. They enter through the neck and swin down the canals of the archegonia. Reaching the venter, one of them penetrates the ovum. It fuses with the nucleus of the ovum to accomplish fertilisation.

Zygote The fertilised egg or ovum secrets a cellulose wall around it and is called the zygote.

Stalk Stem LS of an antheridium (young stage) Male Sex Organs of Funaria

LS of antheridial head

Economic Importance of Bryophytes l

Archegonium

It is a flask-shaped structure with tubular neck and a swollen venter. The single layered wall of neck has 5-6 rows of cells. Internally it encloses a few sterile neck canal cells. The wall of venter is 1-2 layered. It encloses a venter cavity which possesses a sterile venter canal cell and a fertile egg or oosphere.

Bryophytes in Carbon and Nitrogen Cycling Bryophytes generally fix C and N from atmospheric pools, reduce N availability for vascular plants and microbes. They release dissolved compounds that are immobilised by soil microbes or lost via runoff and transform C and N into recalcitrant organic matter. Bryophytes influence the apportionment of C and N ecosystem inputs and indirectly influence the rate at which these elements are lost from ecosystems through litter decay, fire and herbivory.

Paraphyses Cover cells

Archegonia

Bryophytes, especially mosses, form dense mats over the soil and prevent soil erosion by running water. Mosses are an important link in plant succession on rocky areas. They take part in building soil in rock crevices formed by lichens. Dry Sphagnum can absorb 18-26 times its weight of water. This characteristic is employed by gardeners to keep seedlings and cut plants moist during transportation and propagation. Some bryophytes are used as fodder for herbivorous animals.

Sphagnum is used as fuel also. Peat-tar known as sphagnol has been effectively used in the treatment of skin diseases. They are used as experimental material, e.g. the mechanism of sex-determination in plants was discovered for the first time in a liverwort Sphaerocarpos. Bryophytes, especially Sphagnum is useful as atmospheric and aquatic pollution indicator. Mosses are used as stuffing in furniture, for fuels as an absorbent in oil spills or for cushioning. Thus, it can be concluded that bryophytes are very important for the ecological balance. These tiny plants are important for the evolutionary point of view as they gave rise to present terrestrial, vascular plants.

l l

Neck

Venter canal cell Oosphere

Stem

Neck canal cells

Venter LS of archegonial head

An archegonium

Female sex organs of Funaria

Occurrence of the primary cell wall polysaccharide rhamnogalacturonan II in bryophytes : Implications for the evolution of vascular plants The first plants that colonised the land approximately 480 million years ago are believed to be related to extant bryophytes. These early land plants subsequently gave rise to the trachaeophytes that now dominate the terrestrial environment. One of the most important biochemical changes that allowed plants to adapt to life on land is borate ester cross-linking of the cell wall, pectic polysaccharide rhamnogalacturonan II (RG II). Recent studies have shown that boron has a major role in maintaining wall structure. Boron requirements of flowering plants are correlated with the amounts of pectin in their primary walls. Boron exits in primary walls predominantly as 1:2 borate diol ester that covalently cross-links two chains of the pectic polysaccharides RG II. Plants carrying mutations, result in abnormally low amounts of this cross-link. Such plants are dwarfed or exhibit reduced intercellular attachment. The gametophytic generation of members of the avascular bryophytes (Bryopsida, Hepaticopsida and Anthocerotopsida) have primary cell walls that contain small amount of an RG II like polysaccharide. The amount of RG II incorporated into the walls of plants increased during evloution of vascular plants from their bryophyte like ancestors. Thus, it can be concluded that during evolution bryophytes gave rise to higher plants.

Classification of Bryophyta Classes Anthocerotopsida (Hornworts) Gametophyte dorsiventral (never foliose)

Bryopsida (Mosses) After short protonema phase, gametophyte develops erect shoots of radial symmetry with leafy appendages on a stem-like structure

Gametophytic tissue usually differentiated and heteromerous

Homogenous gametophytic tissue

Gametophytic tissue is differentiated

Gametophytes monomorphic and monophasic

Gametophytes dimorphic and diphasic

Sporophyte simple or differentiated into foot, seta and capsule

Sporophyte differentiated into foot and capsule

Sporophyte well differentiated into foot, seta and capsule

Sporogenous cells of endothecial origin and capsule without any columella

Sporogenous cells of amphithecial origin (except Notothylas), sterile columella present

Sporogenous cells of endothecial origin but always surrounding a sterile columella

Order

Hepaticopsida (Liverworts) Usually dorsiventral gametophyte, thallose, sometime with leaf-like appendages

Sphaerocarples e.g. Sphaerocarpus

Marchantiales e.g. Riccia, Marchantia, Pellia

Jungermanniales e.g. Porella, Lejeunea

Calobryales e.g. Calobryum

Order

Bryales e.g. Funaria, Polytrichum

Anthocerotales e.g. Anthoceros

Riccia (Liverwort)

Sphagnales e.g. Sphagnum

Hypnum curvifolium (Moss)

Phaeoceros laevis (Hornwort)

Marchantia It is a small dorsiventral flattened dichotomously branched thalloid plant. Each lobe has an apical notch, a midrib and a dorsal groove. Ventral surface bears two types of unicellular rhizoids, i.e. smooth walled and tuberculate. Vegetative reproduction occurs by fragmentation, progressive death of older parts, gemmae and adventitious branches. Marchantia is dioecious with sex organs borne on stalked upright receptacles or gametophores (maleantheridiophore and female-archegoniophore).

Apical notch

Midrib

Rhizoids Microscopic view of thallus of Marchantia

Rays

8 Lobed receptacle Stalk Gemma cup

Thallus Antheridia

Stalk

Thallus

Apical notch

Archegoniophore Thallus

Thallus

Midrib

Antheridiophore

Midrib

Rhizoids

Gemmae cup Gemmae

Rhizoids

Thallus Rhizoids

Sex organs of Marchantia

Vegetative thallus of Marchantia showing gemmae cup

Marchantia A. Vegetative thallus; B. Male thallus; C. Female thallus Antheridiophore Archegoniophore Male thallus Female thallus

Germination of spores and development of young gametophyte

Spores released

Gemmae cup Male and female gametophyte plants

Meiosis

Sperm cell Haploid (n) gametophyte generation

Diploid (2n) sporophyte Foot generation Seta Tissue derives from archegonium

Antheridia with sperm cells

Capsule

Archegonia with eggs Fertilisation

Zygote Embryo

Sporogenous cells that undergo meiosis

Marchantia in Medicines Marchantia polymorpha has been used to cure pulmonary tuberculosis and affictions of the liver. The extracts of Marchantia polymorpha and Marchantia stellata have anti-tumour properties. Marchantia polymorpha and Marchantia palmata are used as medicines for boils and abscesses by Himalyan Indians. Marchantin-A, obtained from Marchantia polymorpha shows anti-leuckemic activity.

Sporophyte

Life cycle of Marchantia

Funaria

It is a common moss of 3-5 cm in height that forms dense patches during rainy season. The plant has a radial symmetry. It possesses a number of spirally arranged leaves. Rhizoids are multicellular, colourless and possess oblique septa. Main axis functions as male shoot while its branch which is extra axillary in origin, is female shoot. It multiplies vegetatively through fragmentation, formation of secondary protonema, gemmae and tubers. They are monoecious and autoecious. Sporophyte has an embedded foot, an elongated curved seta and a terminal pyriform asymmetrical capsule. Haploid (n) Diploid (2n)

Meiosis

Spores (n)

Mature sporophyte (2n)

Funaria Operculum Peristome Annulus Rim Columella

Protonema (young gametophyte) (n)

Outer wall of spore sac Spores

Male Female gametophyte gametophyte

Inner wall of spore sac Hypodermal layer Spongy layer

Capsule (sporangium)

Antheridia Stomata

Sperm (n) Archegonia Young sporophyte (2n)

Gametophyte (n)

Zygote (2n) Gametophyte (n)

Air space

Apophysis Sperm (n)

Conducting strand

Egg (n)

Seta

Life cycle of Funaria

LS of mature capsule (Moss)

Anthoceros It is terrestrial and grows on moist, shady places. Its thallus is dorsiventral, green, non-leafy, deeply lobed and dichotomously branched. Tuberculated rhizoids are absent. Some species of Anthoceros are monoecious and some are dioecious. Sex organs are antheridia (male) and archegonia (female). The antheridia are endogenous in origin, while archegonia are exogenous. Sporophyte is differentiated into a foot, a constriction -like intermediate zone and a capsule. There is no seta.

Anthoceros

Spores (1n) Protonema (1n)

Pseudoelater Stoma

Sperm (1n)

Antheridium

Within the sporophyte, meiosis produces 1n spores. Each spore grows into a 1n gametophyte plant

Egg (1n) Sperm swim into the archegonium and fertilise the egg, producing a 2n embryo.

Archegonium Meristem Sporophyte (2n)

Foot

Gametophyte plant (1n) The embryo develops into a slender sporophyte Thallus

Rhizoids

Life cycle of Anthoceros

Anthoceros and Cynobacteria Anthoceros housing nitrogenfixing cynobacteria enable them to colonise bare rock surfaces. They are of biological significance as they show exhibit probable lines of biological progress.

Smart Practice 1. Choose the correct statement.

Codes

(a) Bryophytes can live in soil, but are dependent on water for sexual reporduction (b) The sex organs in bryophytes are unicellular (c) In bryophyte the main plant body is a gametophyte wihch is differentiated into true root, stem and leaves (d) Common example of liverwort is Polytrichum

2. Identify the wrong combination (a) Dryopteris (b) Cycas (c) Volvox (d) Marchantia

— — — —

Rhizome Coralloid roots Colonial form Pseudoelaters

3. Bryophytes resemble algae in one of the following aspect. (a) Filamentous body, presence of vascular tissue and autotrophic nutrition (b) Differentiation of plant body into root, stem and leaves (c) Thallus-like plant body, presence of root and autotropic nutrition (d) Thallus-like plant body, lack of vascular tissue and autotropic nutrition

4. In bryophytes, the sporophytic phase is represented by (a) spores (c) spore mother cell

(b) antheridium (d) egg

5. Moss spore germinate to form (a) sporophyte (c) seta

(b) protonema (d) capsule

6. Which of the following statements is incorrect about bryophytes? (a) Fertilisation takes place in the presence of water (b) Gametophytic phase is dominant in life cycle (c) Sporophyte is physiologically dependent on gametophyte (d) Zygote undergoes meiosis to produce sporophyte

7. Calyptra develops from (a) venter wall of archegonium (b) outgrowth of gametophyte (c) neck wall of archegonium (d) paraphysis of the archegonial branch

8. Match the following columns. Column I A.

Coleorhiza

Apogamy

Indusium

Caudex

(a) (b) (c) (d)

A 5 4 3 2

B 2 1 5 3

C 4 5 2 1

D 1 3 4 5

9. Choose the wrong pair. (a) Hepaticopsida (b) Lycopsida (c) Bryopsida (d) Pteropsida (e) Sphenopsida

— — — — —

Marchantia Selaginella Anthoceros Dryopteris Equisetum

10. Spore dissemination in some liverworts is aided by (a) elaters (c) calyptra

(b) indusium (d) peristome teeth

11. Bryophytes are called amphibians of plant kingdom because (a) their reproductive phase requires water (b) their sex organs are multicellular and jacketed (c) they have tracheids (d) All of the above

12. Chloroplasts, with pyrenoid-like structures are found in the leaves of (a) Funaria (c) Selaginella

(b) Cycas (d) Zea mays

13. In a moss, the sporophyte (a) is partially parasitic on the gametophyte (b) produces gametes that give rise to the gametophyte (c) arises from a spore produced from the gametophyte (d) manufactures food for itself, as well as for the gametophyte

14. At the base of seta of capusule of moss, there is a haploid brownish growth called (a) calyptra (c) vaginula

(b) perigonium (d) perichaetial

15. Which of the following in moss capsule is haploid/gametophytic tissue? (a) Annulus and peristome (c) Columella and theca

(b) Calyptra and spore (d) Operculum, foot and seta

16. Which of these is mismatched? Column II

1. Development of sporophyte directly from gametophyte without intervention of gametes. 2. Development of gametophyte directly from sporophyte without the involvement of reduction division. 3. An unbranched columnar stem with a crown of leaves 4. Protective covering of radicle. 5. Protective structure of a sorus.

(a) Phaneros (b) Kryptos (c) Gymno (d) Bryon (e) Trachea

— — — — —

Visible Concealed Naked Liverworts Windpipe

17. Which type of the rhizoids are present in Riccia? (a) Unicellular smooth (b) Multicellular smooth (c) Unicellular smooth and tuberculated (d) Multicellular smooth and tuberculated

18. Mosses occur in moist place because they (a) cannot grow on land (c) lack vascular tissue

(b) gamete fuses in water (d) lack root and stomata

19. During development of embryo in archegonium of Bryophyta, its posterior part forms a protective embryo cover, which is called (a) calyptra

(b) paraphysis (c) apophysis

(d) hypophysis

20. Which of the following part of Funaria sporophyte is involved in the dispersal of spores? (a) Calyptra (c) Peristome

(b) Operculum (d) Annulus

21. Number of peristomial teeth in moss is (a) 16 + 16

(b) 16 + 32

(d) 32 + 32

22. In Funaria, the stomata are found on (a) foot

(b) seta

24. Read

the following statements regarding bryophytes. I. Bryophytes possess a multicellular haploid gametophyte which lives as a parasite on an independent multicellular diploid sporophyte. II. They are classified as 'Atracheataâ&#x20AC;&#x2122; as they lack vascular tissue. III. Some mosses have food conducting cells, leptoids in the centre of the stem and water conducting cells, hydroids surrounding it. IV. Few species of bryophytes like Riccia fluitens and Riella are aquatic. Choose the incorrect statements. (a) I and IV

(b) I and III

Statement I Bryophytes are amphibians of plant kingdom.

considered

Statement II They reproduce through gemmae, secondary protonema, tubers etc. Choose the correct option from the codes given below. (a) Statement I and II both are corrrect and statement II is the correct explanation of statement I. (b) Statement I and II both are correct but statement II is not the correct explanation of Statement I. (c) Statement I is correct but statement II is incorrect. (d) Both statement I and II are incorrect.

28. Match the classes of bryophytes given in column I with their examples given in column II and choose the correct option from the codes given below.

(d) All of these

23. Dominant generation in bryophytes is (a) capsule (c) gametophyte

27. Read the two statements regarding bryophytes

Column I

Column II

A. Hepaticopsida

1. Funaria

B. Bryopsida

2. Marchantia

C. Anthocerotopsida

3. Anthoceros

Codes A (a) 1 (c) 2

B 2 1

C 3 3

A (b) 3 (d) 2

B 2 3

C 1 1

29. Refer to the given figure of gemma cup of Marchantia and choose the correct option for the parts labelled as A, B, C and D from the codes given beow. Gemma cup B D

A C

(d) II and IV

25. Match the column I with column II and choose the correct option from the codes given below. A. B. C. D.

Column I Marchantia Funaria Riccia Anthoceros

1. 2. 3. 4.

Column II Ringworm treatment Unicellular rhizoids The absence of seta Curved seta

26. Refer to the following table regarding differences in pteridophytes and bryophytes. Byophytes I. Gametophytic phase is dominant. II. Sporophyte is independent and autotrophic. III. They are classified as tracheota.

Pteridophytes Sprophytic phase is dominant. Sporophyte is dependent on gametophyte. They are classified as atracheota.

From the codes given below choose the option stating incorrect differences. (a) I and II

(b) II and III

(d) Only I

Thallus

A (a) Thallus

Scale

Rhizoid

Gemmae

Air chamber

Air pore

(b) Mucilage hair Air chamber

Gemmae

Air pore

Mucilage hair

Air chamber

(d) Gemmae

Air Chamber

Mucilage hair

Air pore

30. Read the given statement regarding bryophytes and choose the correct option from the codes given below. I. In liverworts the sporogenous cells are of endothecial origin and capsule lacks columella. II. In hornworts, the sporophyte remains differentiated into foot, seta and capsule. To be Continued at Page 23

EAMCET (AP) 2016 SOLVED PAPER Medical Entrance Examination

Held on : 29.04.2016

INSTRUCTION l

All questions are compulsory. The question paper consists of 80 questions. There is no overall choice. However, internal choices has been provided. You have to attempt only one of the atternatives in all such questions. Use of calculator is not permitted.

EXAM CRUX ■

■

In Biology paper, 33 questions were asked from class XII and 48 questions from Class XI. According to topicwise distribution, the number of questions were asked from Class XI–Diversity in the Living World (11), Structural Organisation in Plants and Animals (8), Structure and Function (7), Plant Physiology (8), Human Physiology (14). As per topicwise distribution in Class XII–Reproduction (6), Genetics and Evolution (11), Biology in Human Welfare (6), Biotechnology (5), Ecology (5). As per the difficulty level around 20% questions are easy, 52.5 are relative moderate and rest 26.25% are tough. by Arihant Team

List I

List II Assemblage of virions

List III

A. Absorption phase

(i)

(I)

Complementary receptor sites

B. Lytic phase

(ii) Tail core is driven (II) Eclipse period in through the bacterial cell wall

C. Maturation phase

(iii) Contact between (III) Lysozyme phase particle and bacteria

D. Penetration phase

(iv) Cell wall dissolution

(IV) Tail sheath

The correct answer is

Botany 1.

Match the following.

A B C D (a) i,III ii, IV iv, II iii, I (c) iii, I iv, III i, II ii, IV

Match the following. List I

List II

A. Climax community (i)

Prolonged periods of drought

A B C D (b) iii, II i, II ii, III iv, IV (d) iv, IV, iii, I i, III ii, II

Match the following. List I

List II

B. Victoria regia

(ii) Photosynthesis by flattened stem

A. Tracheids

C. Opuntia

(iii) Final plants which are near equilibrium with the environment

(i) Cells possess highly thickened walls with obliterated central lumen

B. Vessels

D. Casuarina

(iv) Roots fixed to substratum and epistomatous

(ii) Elongated tube-like cells with thick lignified walls and tapering ends

The correct answer is A (a) iii (c) i

B iv ii

C D ii i iii iv

A (b) iii (d) II

B iv I

C i iv

D ii iii

C. Xylem (iii) Individual members are parenchyma interconnected through perforations in their common walls D. Xylem fibres (iv) Cells are living with thin cellulosic cell walls

The correct answer is A B C D (a) ii iii iv i (c) iii ii iv i

A B C D (b) ii iv i iii (d) ii iii i iv

(a) (b) (c) (d)

In a series of reactions during carbon fixation,‘A’, a six carbon (6C) compound reacts with a three carbon (3C) compound to give rise, ‘B’, a four carbon (4C) compound and ‘C’, five carbon (5C) compound ‘B’ reacts with a three carbon (3C) compound to form ‘D’, a seven carbon (7C) compound ‘D’ reacts with a triose to form two molecules of ‘E’, five carbon (5C) compound. Identify the reactant with ‘B’ and enzyme involved in the formation of ‘D’ respectively. (a) G-3P; aldolase (b) DHAP; aldolase (c) Erythrose; transketolase (d) Erythrose; aldolase

List I

10.

List II

List III

(i)

Supernatant as effluent

(I)

Useful aerobic microbes

B. FLOCS (ii)

Measure of organic matter

(II)

All settled solids

C. Primary (iii) Masses of sludge bacteria associated with fungus

(III)

Methane, hydrogen sulphide and carbon dioxide

D. Biogas (iv) Anaerobic sludge digester

(IV) Polluting water has more BOD

A B C D (a) ii, IV iii,I i, II iv, III (b) ii, I i, III iv, II iii, IV (c) i, IV, iii, II iv, I ii, III (d) iii, III ii, IV iii, I i, II

Assertion (A) Sugar beet, cabbage, carrot like plants are monocarpic. Reason (R) Both vernalisation and photoperiodism are related to flowering. (a) (b) (c) (d)

Identify the wrong statements. I. The substrate binds to the active site of the enzyme and does not fit into the active site. II. The binding of the substrate induces the enzyme to alter its shape. III. Chemical bonds of the substrate break down not to form new enzyme-product complex. IV. The enzyme releases the products of the reaction and runs through the catalytic cycle once again. (a) I and III (c) II and III

A is true and R is the correct explanation of A A and R are true, but R is not the correct explanation of A A is true, but R is false A is false, but R is true

(b) II and IV (d) I and IV

Identify the wrong statements. I. Genetic modifications in plants help to reduce post harvest losses. II. In tobacco plants ‘cry’ genes are introduced against nematodes. III. Gene therapy must to be under taken for infectious diseases, where genes are inserted into person’s cells and tissues to treat diseases. IV. Injustice, inadequate compensation and benefit sharing are related to molecular diagnosis. The correct answer is (a) I, II, III

11.

(b) II, III, IV

(d) I, III, IV

Assertion (A) Acidic pH of the insect gut converts inactive Bt toxin into active form. Reason (R) Most of the Bt toxins are insect group specific.

The correct answer is

A and R are true and R is the correct explanation of A A and R are true, but R is not the correct explanation of A A is true, but R is false A is false, but R is true

The correct answer is

Match the microbes with the commercial industrial products.

A. BOD

Assertion (A) Virus free plants can be produced from virus infected plant by means of meristem culture. Reason (R) Virus fails to grow during the growth of host tissue in the artificial medium.

TACAAAGGGTTTCAACCC – If it is the sequence of nucleotides in a DNA strand, then predict the sequence of amino acids found in a protein formed from it. (a) Proline, phenylalanine, lysine, methionine, glycine, valine (b) Methionine, phenylalanine, glycine, valine, lysine, proline (c) Valine, glycine, proline, lysine, phenylalanine, methionine (d) Methionine, phenylalanine, proline, lysine, valine, glycine

(a) A and R are true and R is the correct explanation of A (b) A and R are true, but R is not the correct explanation of A (c) A is true, but R is false (d) A is false, but R is true

12.

The correct sequence in the tissue culture technique is (a) Inoculation — Explant incubation — Callus formation — Organogensis — Preparation of medium — Transferred to field (b) Preparation of medium — Inoculation — Explant incubation — Callus formation — Organogenesis — Transferred to field (c) Explant incubation — Preparation of medium — Inoculation — Organogenesis — Callus formation — Transferred to field (d) Preparation of medium — Inoculation — Explant incubation — Organogenesis — Callus formation — Transferred to field

13.

A pea plant with round-shaped seeds with yellow colour seed (RRYY) was crossed with another pea plant showing wrinkled shape with green cotyledons (rryy). The results of progeny in F2 -generation are produced in the following number. I. Heterozygous for both shape and colour of seeds .......... number. II. Dominant for colour , but recessive for shape .......... number. III. Homozygous for both shape and colour of seeds .......... number. IV. Heterozygous for seed-shape only .......... number. The correct answer is I (a) 2 (c) 3

14.

II 4 4

III IV 3 8 8 2

I (b) 4 (d) 4

II 2 3

III 3 2

17.

(a) I, III

18.

IV 8 8

List II List III (i) Specific base (I) Taq sequence polymerase B. Downstream (ii) Inheritable gene (II) Ampicillin resisprocessing tance gene C. Restriction (iii) Amplification of (III) E. coli endonuclease DNA D. Selectable (iv) Transformation marker and non(IV) Quality control transformation (v) Product (v) Ori separation and purification

19.

15.

A (b) i, IV (d) iii, I

(b) II, III and IV (c) III and IV

(d) II and IV

Plasmid can be considered as a suitable cloning vector. I. It can be readily isolated from bacterial cells. II. It possesses a single recognition site for one restriction enzymes. III. It should have a high molecular weight. IV. Plasmids and bacteriophages have the ability to replicate within bacterial cells. Choose the correct answer. (a) I, II, IV

(b) I, II, III, IV

(d) I, II, III

What did Engelmann experiments?

(d) III, IV

observe

from

his

prism

Pick the reactions from the following where a water molecule is removed and reduction of NAD+ does not occur in the reactions of respiration. I. Succinic acid ® Fumaric acid II. Malic acid ® Oxaloacetic acid III. 2-phosphoglycerate ® Phosphoenol pyruvic acid IV. Pyruvic acid ® Acetyl Co-A (a) I, IV

20.

B C D iv, I ii, V iii, I iv, I i, III ii, V

Which of the following is true with reference to transformation in bacteria? I. Transfer of genetic material is mediated by F-factor. II. Uptake of naked DNA fragments from the surrounding environment and the expression of that genetic information in the recipient cell. III. Transformation experiments were the basis to propose chromosomal theory of inheritance. IV. Transformation was discovered by Frederick Griffith in Streptococcus pneumoniae. (a) I and IV

16.

D i, III iv, II

The correct answer is

The correct answer is A B C (a) iii, I v, IV ii, V (c) iii, I v, IV i, III

(b) II, III

(a) Bacteria could not detect the sites of O 2 evolution (b) Bacteria released excess carbon dioxide in red and blue light (c) Bacteria accumulated due to the increase in temperature caused by increase in oxygen concentration (d) Bacteria get accumulated towards red and blue light

Identify wrong statements. List I A. PCR

Select the correct statements. I. H1 histone molecule lies inside the nucleosome core and seals the two turns of DNA. II. Acrocentric chromosome has one extremely short and one very long arm. III. The association between positively charged DNA and negatively charged histones allows for meaningful DNA packaging inside the nucleus. IV. A few chromosomes have non-staining secondary constrictions at a constant location and give the appearance of a small fragment called the satellite

(b) I, II

(d) I, III

Study the following statements. I. F1 -progeny is the first hybrid generation and progeny resembles either of the two parents. II. F2 -progeny is a resultant hybrid generation of cross pollination among F1 -progeny and progeny shows retain as such both dwarf and tall plants. III. F2 -progeny is second hybrid generation, produced by selfing F1 -hybrids and progeny contained both dwarf and tall plants. IV. The proportion of probability of plants that were dwarf were 1/4th of the F2 -plants while 3/4th of the F2 -plants were tall. The correct statements are (a) I, II, III, IV (c) I, II, IV

21.

(b) I, III, IV (d) III, IV

The transcription unit is represented by the following diagram. Select the correct answer based on this. A 3′ 5′

(a) (b) (c) (d)

B C

A Promoter Promoter Terminator Promoter

B Terminator Coding strand Coding strand Structural gene

C Coding strand Terminator Structural gene Coding strand

5′ 3′ D Structural gene Structural gene Promoter Terminator

22.

23.

Identify the correct sequence of taxonomic hierarchial arrangement in ascending order of the following.

IV. Aerial roots of Taenliophyllum help in vegetative propagation.

(a) Spermatophyta, Sapindales, Dicotyledons, Anacardiaceae, Mangifera (b) Mangifera, Dicotyledons, Anacardiaceae, Spermatophyta, Sapindales (c) Mangifera, Anacardiaceae, Sapindales, Dicotyledons, Spermatophyta (d) Dicotyledons, Anacardiaceae, Sapindales, Spermatophyte, Mangifera

The correct answer is

27.

A student observed a water drop under microscope. He found a photosynthetic organism. Its cell walls form two thin overlapping shells, which fit together as in a soap box. Which of the following organism is it? (a) Euglenoid (c) Sporozoan

24.

(a) I and IV (c) III and IV

(b) Dinoflagellate (d) Diatom

Study the major pigments and storage products in the following lists and match correctly.

A. B. C. D.

List I Chlorophylls-a and c, fucoxanthin and mannitol. Chlorophylls-a and d, phycoerythrin and floridian starch. Chlorophylls-a and b, pyrenoids with starch and proteins. Chlorophylls-a and b, carotene and xanthophylls, leucoplasts store carbohydrates, fats and proteins

25.

B iv i

C ii iv

D iii v

A (b) iv (d) iv

The micropyle of the ovule lies close to the funiculus as a result of 180Â° curvature.

(ii) Volvox

The micropyle, chalaza and (ii) Loranthus funiculus of the ovules are on the same vertical line.

(iii) Hibiscus (iv) Dictyota (v) Anabaena B i iii

C ii v

D iii i

Arachis Ginkgo Cycas Laminaria

26.

A v ii iv iv

B iv iv iii iii

C i i ii i

C. The body of the ovule is placed at right angles to the funiculus and bends in such a away that micropyle comes towards the funiculus.

(iii) Helianthus

D. The ovules are without integuments

(iv) Polygonum

The correct answer is A (a) iii (c) v

29.

B iv iv

C D ii v iii ii

A (b) iv (d) iii

B v iv

C i i

D iii ii

Assertion (A) Tageticula and Amorphophallus cannot complete their life cycle without each other. Reason (R) The moth deposits its eggs in the locule of the ovary and the flowers, which are on a many feet height inturn gets pollinated by moth. The larvae comes out of the egg as the seeds start developing.

D ii iii i ii

Identify the pair of wrong statements from the following. I. Branches of limited growth in Asparagus perform photosynthesis. II. Petiole of Australian Acacia helps in climbing. III. Floral bud of Agave stores food materials.

(i) Dolichos

(v) Sphagnum

The correct answer is (a) (b) (c) (d)

List II

List II (i) Amphibians of plant kingdom (ii) (iii) (iv) (v)

Study the types of ovules in list I and match correctly with their occurrence with list II. List I

Study the following lists and match correctly. List I A. Siphonogamy and zooidogamy B. Living fossil C. Liverworts D. Double fertilisation

A and R is true and R is the correct explanation of A A and R is true, but R is not the correct explanation of A A is true, but R is false A is false, but R is true

List II (i) Porphyra

The correct answer is A (a) v (c) ii

Assertion (A) All the fruits that we eat are not real fruits. Reason (R) In few plants floral parts like thalamus or pedicel also contribute to the fruit formation. Such, fruits are called false fruits. (a) (b) (c) (d)

28.

(b) I and II (d) II and IV

(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true, but R is not the correct explanation of A (c) A is true, but R is false (d) A is false, but R is true

30.

A plant produced 50 flowers. Ovary of each flower has 50 ovules. How many fruits and seeds are produced by that plant, respectively? (a) 50, 50 (c) 50, 2500

(b) 50, 100 (d) 2500, 2500

31.

Select the correct statement from the following regarding asexual reproduction. I. It is slower than sexual reproduction. II. It involves a single parent. III. It produces progeny that are genetically identical with the parent. IV. Clones are the progeny of asexual reproduction. (a) I, II, III, IV (b) I, II, IV (c) I, II, III (d) II, III, IV

32.

33.

36.

37.

List I (Element)

List II (Deficiency symptom)

(i)

(ii) Mottled leaf in citrus

(a) zygomorphic flower, epipetalous, epiphyllous, superior ovary (b) actinomorphic flower, epiphyllous, epipetalous, inferior ovary (c) zygomorphic flower, epiphyllous, epipetalous, superior ovary (d) actinomorphic flower, epipetalous, epiphyllous, superior ovary

(iii) Whiptail in cauliflower

(iv) Mouse ear in pecan

Asseration (A) Eukaryotic cell shows extensive compartmentalisation of cytoplasm.

Arrange the following compounds in descending order on the basis of number of carbon atoms present in them. (A) Palmitic acid (B) Serine (C) Ribose (D) Arachidonic acid (E) Glucose (a) DCABE (c) DAECB

A (a) ii (c) ii

38.

(a) BDCA (b) ACDB (c) ADCB (d) DCBA

B i iii

C iv iv

D iii i

A (b) iv (d) i

B i ii

C iii iii

D ii iv

Summarise the differences between a dicot and monocot root from the following table and pick up the wrong differences. No.

Characters

A. Activity of pericycle

Dicot root Lateral root production

Monocot root Secondary growth and cambium

B. Vascular bundle Diarch to tetrarch Polyarch C. Cambium

Later developed

Absent

D. Pith

Well developed

Poorly develped

(a) B, D (c) A, D

39.

(b) BCEAD (d) CBADE

Arrange the following in descending order. (A) Number of bivalents are formed during meiosis of a spore mother cell of Ophioglossum. (B) Number of chromatids seen on equatorial at metaphase-I in pollen mother cell of Haplopappus gracilis during meiosis. (C) Number of chromosomes found at one pole after anaphase-II during meiosis in butterfly. (D) The total number of chromosomes found in all daughter cells formed during meiosis from one megaspore mother cell in potato.

Bronzing in legume

The correct match is

(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true, but R is not the correct explanation of A (c) A is true, but R is false (d) A is false, but R is true

35.

Match the following.

The given symbols of floral parts indicate the condition of % or Â C A, P A, G

Reason (R) The presence of membrane bound organelles is an important character in prokaryotes.

34.

Identify the wrong statement. (a) The degree of decrease of chemical potential of water depends on concentration of solute (b) Bacteria and fungal spores are killed when they enter into pickles and jams due to the plasmolysis (c) The process of water exudaton is called transpiration (d) Reverse plasmolysis will occur when flaccid cells are placed in hypotonic solution

Arrange the following in descending order based on their numbers. I. Number of central microtubules in a cilium. II. Number of radial spokes in a flagellum. III. Number of nuclei found in a mature sieve tube cell. IV. Number of peripheral microtubes in a flagellum. (a) IV, II, III, I (c) III, I, II, IV

40.

(b) A, C (d) A, B

(b) IV, II, I, III (d) I, III, IV, II

Arrange the following compounds formed in respiration based on their C-atoms in ascending order. I. Pyruvic acid II. a-ketoglutaric acid III. Citric acid IV. Malic acid The correct answer is (a) IV, I, II, III (b) I, IV, II, III (c) I, II, IV, III (d) I, IV, III, II

Zoology 41.

(a) Both A and R are true and R is the correct explanation for A (b) Both A and R are true, but R is not the correct explanation for A (c) A is true, but R is false (d) A is false, but R is true

Match the following. List I Stomochord Botryoidal tissue Captacula Rhabdites

A. B. C. D.

(i) (ii) (iii) (iv)

List II Hirudinaria Dentalium Balanoglossus Dugesia

44.

The aquatic weed which is popularly called terror of Bengal is (a) Erythroxylum (b) Eichhornia (c) Echinus (d) Echidna

(v) Pinctada

The correct answer is A (a) iii (c) iii

42.

C D v i ii iv

A (b) i (d) i

B ii iii

C iv ii

D iii v

45.

The following organs appeared for the first time in amphibians (a) (b) (c) (d)

43.

B ii i

syrinx, urinary bladder and cloaca tympanum, sternum and lacrimal glands harderian glands, sebaceous glands and lacrimal glands furcula, four chambered heart and palate

Rhabditiform larva performs extraintestinal migration through different organs in the body of man. Arrange them in the correct sequence. I. Liver II. Hepatic portal vein III. Heart IV. Postcaval vein V. Lungs VI. Pulmonary arteries VII. Alveoli VIII. Intestine The correct sequence is

Assertion (A) In sidewise-lash movement, a flagellate moves forward due to effective stroke of flagellum.

(a) IV, I, II, V, VI, III, VIII, VII (b) V, VI, I, III, II, IV, VII, VII (c) I, II, IV, VI, III, VII, V, VIII (d) II, I, IV, III, VI, V, VII, VIII

Reason (R) Flagellum becomes comparatively soft so as to offer least resistance to water in propulsive stroke.

46.

Study the following events related to Na and K voltage-gated channels and find the incorrect combination. S. No Channel

Gate

Activation gate

Inactivation gate

Resting phase

Depolarised

Closed

Open

Closed

Fast

Open

Closed

Slow

Closed

Open

Slow

Activation gate

Repolarised Hyperpolarised The speed of response

Incorrect combination is (a) A

47.

(b) B

In the female cockroach the anterior wall, roof and floor of genital pouch are formed respectively by the following abdominal sterna of

50.

(a) 7th, 8th and 9th segments (b) 8th, 7th and 9th segments (c) 9th, 8th, 7th and segments (d) 8th, 9th and 7th segments

48.

Chilomicrons are (a) micelles covered by a protein coat (b) droplets along with triglycerides (c) triglycerides along with monosaccharides (d) glycerol droplets formed in intestine after digestion of fats

49.

Study the following and identify the incorrect statements. I. Muscles of the iris and ciliary body are the smooth muscles of mesodermal origin. II. Slow and sustained involuntary contractions of smooth muscles are called spasms. III. Quiescent mononucleate myogenic cells of skeletal muscles are called pericytes. IV. The skeletal muscle fibre is multinucleate and is a synctium. (a) I, IV

(b) II, IV

(d) I, III

(d) A, C

Identify the incorrect statements. I. Members of gastropoda exhibit ‘torsion’. II. Aristotle lantern is present in heart urchins. III. Anthozoans are polyploid forms. IV. Diplopoda includes centipedes. (a) II, III (c) II, IV

51.

(b) III, IV (d) I, II

Read the following statements. I. Adam’s apple in man is formed by thyroid cartilage. II. The maximum volume of air a person can breath in after forced expiration is vital capacity. III. About 20-25% of CO2 is transported as carbaminohaemoglobin. IV. Pneumotaxic centre lies in pons. The correct statement(s) is (a) Only I (c) I, II, III

(b) I, II (d) I, II, III, IV

52.

Study the following statements with reference to drugs and choose the incorrect one. I. Barbiturates cause sleeplessness. II. Opioids are obtained from the leaves of Erythroxylum coca. III. Morphine is a very effective sedative and pain killer. IV. Cocaine is obtained from Indian hemp plant. (a) I, II, III

53.

(b) II, III, IV

(d) I, II, IV

Study the following statements with reference to nervous system in Periplanata. I. The brain is mainly a sensory and an endocrine centre. II. All thoracic ganglia supply nerves to the parts of their respective segments only. III. Sixth abdominal ganglion is the largest of all the abdominal ganglia. IV. Frontal ganglion is connected to the ingluvial ganglion by a recurrent nerve. (a) II, IV

(b) II, III

Population – Density

Natality

56.

In renal tubules aldosterone increases (a) Absorption of K + , H+ and elimination of Na + , H 2 O (b) Absorption of Na + , H 2 O and elimination of K + , PO 24 (c) Absorption of Na + , H 2 O, K + , PO 24 (d) Elimination of Na + , H 2 O , K+ , PO 24

57.

Read the following about pollution and identify the correct matching combinations. List I

List II

Chernobyl

Accidental leakage

Radioactive wastes

II. El nino effect

Global warming

Causing climatic changes

III. Chloroflouro carbons

Ozone degradation

Fluorine atoms released

58.

Population + Density

A (a) iii (c) iii

Immigration

59.

–

Interferons Paratope Interleukins Histamine

Natality

60.

+ Population Density

Mortality

– Emigration Mortality – (c) Emigration

Population Density +

B i iv

C D ii iv v ii

(i) (ii) (iii) (iv) (v)

Fab Inflammatory mediators Antiviral proteins White blood cells Anticoagulant

Natality

A (b) iii (d) iii

B i ii

C iv iv

D ii v

During fertilisation, zona pellucida is dissolved by (a) hyaluronidase (c) renin

Emigration

–

(d) II, IV

The correct answer is

(b) Immigration

Match the following. A. B. C. D.

(d) I, IV

(b) I, IV

Mortality +

List III

IV. Snow blindness UV-B radiation Inflammation of cornea (a) I, III

Which of the following is correct with reference to population growth?

(a) Natality

Emigration

From the above identify the correct statements

55.

–

(d) Mortality

Assertion (A) Monkey acts as a reservoir host for the parasite that causes African sleeping sickness. Reason (R) Reservoir host lodges the infective stages of the parasite, when the primary host is not available. (a) Both A and R are true and R is the correct explanation for A. (b) Both A and R are true, but R is not the correct explanation for A. (c) A is true, but R is false. (d) A is false but R is true.

54.

Immigration

(b) hyaluronic acid (d) acrosin

Choose the correct statements with regard to human respiration. I. Inspiration is facilitated by the contraction of phrenic and internal intercostal muscles. II. Healthy human can inhale or exhale about 2000 to 3000 mL of air per minute. III. Functional residual capacity represent the volume of left out air in lungs after expiration. IV. Total lung capacity is the total volume of air that can be accomodated in the lungs after forced inspiration. The correct answer is (a) I, III (c) III, IV

(b) II, IV (d) I, II

Immigration

61.

9% of Hardy-Weinberg population of 800 individual are recessive. How many of this population are heterozygous? (a) 336

62.

(b) 392

Assertion (A) In dialiser, the plasma proteins of the blood cannot be filtered, but molecules like urea, uric acid, creatinine and ions can be filtered. Reason (R) The cellophane membrane, used in the dialiser is permeable to micromolecules, but impermeable to macromolecules.

64.

Identify the correct sequence of blood coagulation I. Activation of prothrombin. II. Formation of prothrombin activator. III. Formation of blood clot. IV. Conversion of fibrinogen to fibrin. The correct answer is (a) II, IV, I, III

65.

(b) II, I, IV, III

(d) I, II, III, IV

Read the following and find the correct statements. I. Midbrain, pons varoli and medulla oblongata are together called the brain stem. II. Paracoels are connected to the diacoel through the iter. III. The regulation centres of heartbeat, respiration, swallowing, cough, etc., are located in medulla oblongata. IV. Cerebellum is also called the gyroscope of the body. The correct answer is (a) I, II, III

66.

(d) I, II, IV

Choose the correctly paired sets from the following. I. II. III. IV.

Set I Sphenoid bone Acromion process Xiphoid process Odontoid process

(a) I, IV

(b) I, III, IV

(b) II, IV

Set II Key-stone bone Collar bone Breast bone Atlas (c) II, III

Set III Cranium Scapula Thorax Cervical vertebra (d) I, III

List II Myxedema Addison’s disease

(iii) Increased metabolic rate (iv) Cushing’s syndrome Kidney stones

The correct answer is A (a) iii (c) i

68.

B ii vi

C i iii

D v ii

A (b) iii (d) i

B iv ii

C i iii

D ii v

Study the following with regard to spermatogenesis. I. Spermatogonia II. Secondary spermatocyte III. Spermatogonial stem cells IV. Primary spermatocyte V. Spermatid Arrange them in the correct sequence.

Reason (R) The descending limb of the loop of Henle water is reabsorbed; the ascending limb is impermeable to water, but salts are absorbed. Both A and R are true and R is the correct explanation for A Both A and R are true, but R is not the correct explanation for A A is true, but R is false A is false, but R is true

(i) (ii)

(v)

Assertion (A) The renal fluid becomes increasingly concentrated when it flows down in the descending limb of loop of Henle towards inner medulla, but its concentration decreases in the ascending limb when it flows towards the cortex.

(a) (b) (c) (d)

Match the following. List I A. Hyperthyroidism B. Hyposecretion of glucocorticoids C. Hypothyroidism-I D. Hyperparathyroidism

(d) 362

(a) Both A and R are true and R is the correct explanation for A (b) Both A and R are true, but R is not the correct explanation for A (c) A is true, but R is false (d) A is false, but R is true

63.

67.

(a) III, IV, II, I, V (c) I, II, III, IV, V

69.

Choose the correct statements regarding genetic disorders. I. Turner ’s female is result of aneuploidy. II. Tritanopia is a sex-linked recessive disorder. III. Haemophilia-C follows criss-cross pattern of inheritance. IV. Sickle cell anaemia is due to mutation of alleles in chromosome 11. (a) I, IV

70.

(b) III, I, IV, II, V (d) III, IV, I, II, V

(b) II, III

(d) II, III

Assertion (A) According to Genic Balance Theory, the karyotype with AA-XO in Drosophila is sterile female. Reason (R) Y-chromosome in Drosophila lacks male determining factor. (a Both A and R are true and R is the correct explanation for A (b) Both A and R are true, but R is not the correct explanation for A (c) A is true, but R is false (d) A is false, but R is true

71.

Choose the correct combination among the following. S.No.

List I

Thomas Malthus

Principles of populations

Phenomenon of gradualism

II.

Paul Kammarer

Proteus anguinus

Inheritance of somatic character

III.

Hugo de Vries

Oenothera lamarckiana

Synthetic theory of evolution

IV.

Bernard Kettlewell Biston betularia Industrial melanism

List II

List III

The correct answer is (a) I and IV

(b) II and IV

(d) II and III

72.

Assertion (A) The milk of transgenic cow, Rosie, was nutritionally more balanced than normal cow milk.

76.

Reason (R) a-1 antitrypsin is a biological product produced by transgenic animals. (a) (b) (c) (d)

73.

A. B. C. D.

Both A and R are true and R is the correct explanation for A Both A and R are true but R is not the correct explanation for A A is true, but R is false A is false, but R is true

List I List II (Wave/interval of ECG) (Clinical Interference) A. Prolonged Q-T interval (i) Fast breathing of the heart B. Tall T-wave (ii) Block of conduction through bundle of His C. Shortened P-R interval (iii) Hypothyroidism D. Variation (iv) Enlarged atria

A (a) ii (c) iv

77.

The correct answer is

74.

C D ii i ii i

A (b) ii (d) iii

B iv v

C D v i i ii

78. 79.

(d) d -diversity

Assertion (A) In situ conservation is an ideal conservation strategy for biodiversity.

(a) Both A and R are true and R is the correct explanation to A (b) Both A and R are true, but R is not correct explanation to A (c) A is true, but R is false (d) A is false but R is true

Continued from Page 14 III. In mosses the sporogenous cells of endothecial origin always surround a sterile columella. IV. The gametophyte of hornworts is always foliose while liverworts' gametophyte is thallose. (a) Statements I and III are correct, but statements II and IV are incorrect. (b) Statements I and IV are correct, but statements II and III are incorrect. (c) Only statement I is correct and statements II, III and IV are incorrect. (d) Only statement IV is correct and statements I, II and III are incorrect.

1. 11. 21. 31.

(a) (a) (a) (a)

(b) Pogonatum (c) Porella 2. 12. 22. 32.

(d) (a) (c) (b)

3. 13. 23. 33.

(d) (a) (c) (a)

4. 14. 24. 34.

(d) Sphagnum (c) (c) (b) (c)

C D iv i ii I

A (b) v (d) v

5. 15. 25. 35.

(b) (b) (b) (a)

B ii ii

C i iii

D iv iv

Both A and R are true and R is the true explanation to A Both A and R are true, but R is not the true explanation to A A is true, but R is false A is not true, but R is true (b) placoid scales (d) anadromous migration

Study the following and identify the correct match. Scientific name Draco Bungarus Ptyas Vipera russelli

Common name Flying lizard Pond snake Rat snake Chain viper

Character Cleidoic egg Poisonous Non-poisonous Non-poisonous

The correct match is (a) II, III

80.

(b) III, IV

32.

(d) Nucleolus

(b) it is hygroscopic (d) it serves as a disinfectant

In capsule of moss, shock absorbers are (a) trabeculae (c) seta

34.

Moss peat is used as a packing material for sending flowers and live plants to distant places because (a) it is easily available (c) it reduces transpiration

33.

(d) I, IV

The modified cell organelle involved in the formation of cilia and flagellum is (a) Golgi complex (b) Centriole

(b) peristome teeth (d) annulus

Have capacity of absorbing water used to replace cotton and used as a fuel is (a) Marchantia (c) Sphagnum

35.

Retort cells occur in (a) Funaria

List II Ruminants Wrist bone Intervertebral discs Larynx Pinna

Parents of ammocoete larva show

I. II. III. IV.

Reason (R) It maintains recovering populations in the surrounding where they have developed their distinctive properties.

31.

B iii iii

(a) paired fins (c) catadromous migration

The number of taxa present within a particular area or an ecosystem is (a) a -diversity (b) b -diversity (c) g -diversity

75.

(i) (ii) (iii) (iv) (v)

Assertion (A) White adipose tissue is predominant in infants and has several small lipid droplets and numerous mitochondria. Reason (R) White fat is metabolically less active. (a) (b) (c) (d)

(v) Hyperkalemia B iv v

List I Pisifrom bone Fibrous cartilage Hyaline cartilage OS-cardis

The correct answer is

Match the following lists.

A (a) v (c) iii

Match the following.

(b) Riccia (d) Funaria

Elaters are absent in (a) Funaria

6. (d) 16. (d) 26. (b)

(b) Marchantia (c) Pellia 7. (a) 17. (c) 27. (b)

8. (b) 18. (b) 28. (c)

9. (c) 19. (a) 29. (d)

(d) Porella 10. (a) 20. (c) 30. (c)

Answers with Explanation 1. (a) The correct matching is

7. (b) Monocarpic plants flower only once in their life. These plants

Climax community Final plants which are near equilibrium with the environment Victoria regia Roots fixed to substratum and epistomatous Opuntia Photosynthesis by flattened stem Casuarina Prolonged period of drought

2. (c) The correct matching is Complementary receptor sites Lysozyme Eclipse period Tail sheath

3. (c) The correct matching is Tracheids

Elongated tube-like cells with thick lignified walls and tapering ends Vessels Individual members are interconnected through perforations in their common walls Xylem parenchyma Cells are living with thin cellulosic cell walls Xylem fibres Cells possess highly thickened walls with obliterated central lumen Key Note Tracheids are elongated narrow tube-like cells with hard thick and lignified walls with large cell cavity with tapering or pointed ends.

4. (d) Sequence on DNA strand is TAC AAA GGG TTT CAA CCC Therefore, sequence on mRNA will be AUG UUU CCC AAA GUU GGG Sequence of amino acids on protein will be methionine —phenylalanine—proline—lysine —valine—glycine Methionine always attaches to initiation codon.

5. (d) The reactions given in the question are: A

B+

¾®

(3 carbon compound)

(4 carbon (5 carbon compound) compound)

Aldolase

¾ ¾¾¾ ¾®

(4 carbon compound compounds)[DHAP]

(7C carbon compound)

D + Glyceraldehyde -3 -phosphate or DHAP (3C) ¾® 2 E ( 5 carbon compounds) B is a 4C compound-Erythrose Erythrose react with 3-carbon compound DHAP or glyceraldehyde-3-phosphate which is catalysed by aldolase.

6. (a) The correct matching is BOD

Measure of organic matter Polluting water has more BOD

FLOCS Masses of bacteria associated with fungus

Useful aerobic microbes

Primary Supernatant as effluent sludge

All settled solids

Biogas Anaerobic sludge digester Methane, hydrogen sulphide and carbon dioxide Key Note FLOCS are masses of bacteria associated with fungal filaments form mesh like structures.

Vernalisation is the process of inducing flowering by cold treatment and photoperiodism is the time period required for flowering. Thus, both the terms are related to flowering, but do not explain the assertion.

8. (a) Virus free plants can be grown by means of meristem culture.

Absorption phase Contact between phase particle and bacteria Lytic phase Cell wall dissolution Maturation phase Assemblage of virions Penetration phase Tail core is driven in through bacterial cell wall

(6 carbon compound)

are generally annual or biennial. They die after flowering and fruiting, e.g. sugar beet, cabbage, carrot, etc.

The reasons for the escape of the meristem from virus invasion are (i) Viruses readily move in a plant body through the vascular system which is absent in the meristem. (ii) High metabolic activity in the actively dividing meristem cells does not allow virus replication. Microbes such as virus may be present in the medium from beginning or with cultured tissue. So, instruments as well as explants are sterilised before culture.

9. (a) I and III are wrong statements. The correct form of these statements are (I) Active site of enzyme is not exactly complementary to the substrate, but it is induced to assume the complementary shapes as soon as substrate binds to it. (III) Chemical bonds of substrate breakdown and new enzyme-product complex is formed E+S

-ES ¾® EP ¾® E + P (Enzyme product complex)

10. (b) The correct form of II, III and IV are (II) Tobacco plants are genetically modified to express cry genes in corn and potato, but not in tobacco. (III) Gene therapy involves putting engineered genes into people to cure genetic diseases. Thus, correct form of this statement is gene therapy is to be under taken for genetic diseases, where gene are inserted into person cells and tissues to treat diseases. (IV) Molecular diagnostics is a collection of techniques. This technique is used to diagnose and monitor disease, defect risk.

11. (d) Bt toxin gets dissolved in the high pH of insect gut and becomes active . It attacks the cells of gut of insects creating a hole in it which finally leads to death of insects. Bt toxins show insect growth specificity.

12. (b) The tissue culture technique involves the following steps (i) Preparation of culture medium containing essential macro and micronutrients, organic nutrients for energy, growth hormones (auxins, etc) and agar/gelatin to make the medium solid. (ii) Explant is a group of plant cells or plant part selected for tissue culture. It is inoculated on the sterile medium. (iii) Next step is incubation, i.e. set up of aseptic conditions with optimum conditions for growth of explant. (iv) In the culture medium cells of explant start dividing and form an unorganised mass of cells, called callus. (v) Under the influence of various hormones in different concentrations in medium, the undifferentiated cells of callus differentiate to form shoots and roots, leading to organogenesis. (vi) The miniature plantlets are then transfered to fields.

18. (d) Engelmann prism experiment showed effect of light on

13. (d) Pea plant × Wrinkled and green coloured seeds (rryy)

Round and yellow coloured seed (RRYY) RRYY

rryy

Parents

photosynthesis. He illuminated an alga Spirogyra with different colour of light using a prism. He found that blue and red light is most effective in the photosynthesis and bacterium (Rhodospirillum) accumulate on alga in red and blue light.

19. (d) I and III reactions in which water is removed, but NAD+ is not Gametes

reduced. The II and IV reaction occur the following way (II) Malic acid ¾® Oxaloacetic acid + H2O + NADH +

NAD +

(IV) Pyruvic acid ¾® Acetyl Co -A +

Gametes will be of four types RY, Ry, rY and ry RY Ry rY ry Female RY RRYY

RRYy

RrYY

RrYy

Ry RRYy

RRyy

RrYy

Rryy

RrYY

RrYy

rrYY

rrYy

RrYy

Rryy

rrYy

rryy

FAD +

20. (b) The correct form of III statement is In F2-generation self-pollination is done, not the cross pollination between F1-hybrids.

Tt F1-generation Self-pollination ×

T t

Taq polymerase Quality control TT

(Tall plants)

E. coli

F2-generation

(Dwarf plant)

21. (d) Ampicillin resistance gene

Key Note Restriction endonucleases are one of the essential tools for genetic engineering which recognise and cleave off (cut open) specific sequences of nucleotide bases in DNA molecule. They are also called molecular scissors.

15. (d) II, IV are true statements, correct form of I and III are as follows

16.

tt (Dwarf)

TT (Tall)

14. (c) The correct matching is Amplification of DNA Product separation and purification Specific base sequences Transformation and non-transformation

FADH + H 2O

(III) 2 phosphoglycerate ¾® 2 phosphoenol pyruvic acid +H2O

(I) Heterozygous for both shape and colour of seed ...4... number. (II) Dominant for colour but recessive for shape ..3.. number. (III) Homozygous for both shape and colour of seeds ..2.. number. (IV) Heterozygous for seed shape only ..8.. in number. PCR Downstream processing Restriction endonuclease Selectable marker

NAD + + CO 2 + H 2

I and III reaction occur as follows: (I) Succinic acid ¾® Fumaric acid

Selfing

Male

NAD +

F1-generation

RrYy

Located upstream of initiation codon of structural gene. TATA box in prokaryotes and pribnonow box in eukaryotes. Highly conserved sequences. Structural gene Sequences involved in actual protein synthesis and are the functional unit of inheritance. Coding strand 5 - 3 ¢ polarity, sequence same as in mRNA except thymine. Terminator This region is downstream of structural gene at the 3¢-end of coding strand. It defines end of transcription process.

22. (a) The correct sequence of taxonomic hierarchial arrangement in ascending order is Mangifera > Anacardiaceae > Sapindales (Genus)

(Family)

Dicotyledons (Class)

17. (c) II and IV are correct statements, correct form of I and III are as follows (I) H1 is a histone protein which is called linker histone or plugging and act as marker proteins. Nucleosome core is made up of H2A, H2 B, H3 and H4 in pair thus forming an octamer called Nu-body or proteosome. The nucleosomes are linked together by linker DNA. (III) The association between negatively charged phosphate groups of DNA and positively charged histones allow for meaningfully DNA packaging inside the nucleus providing stability and flexibility to DNA.

(Order) >

(I) Transfer of genetic material is through small part of DNA not by F-factor. F-factor is involved in conjugation in bacteria. (III) Transformation experiments were the basis to propose that DNA is a genetic material. (a) Plasmids and bacteriophage act as vectors for cloning DNA. Plasmid should have low molecular weight so, that it can easily enter into bacterial cell. Plasmid replicates autonomously along with the foreign DNA having some marker gene. Key Note Plasmids are small DNA molecules within a cell that are physically separated from the cheomosomal DNA and can replicate independently.

Promoter

Spermatophyta (Division)

The above classification is of mango or Mangifera indica.

23. (d) Diatoms belong to class–Bacillariophyceae of phylum–Algae. Their cell wall is made up of silica. They are non-motile. Two thin overlapping shells are formed by cell wall. They also carryout photosynthesis and take part in the formation of diatomous earth.

24. (b) The correct matching is

34. (c) Number of atoms in the given compounds are

Chlorophyll-a and c, fucoxanthin and mannitol.

Dictyota

Chlorophyll-a and d, phycoerythrin and floridian starch. Porphyra Chlorophyll-a and b, pyrenoids with starch and proteins. Volvox Chlorophyll-a and b, carotene and xanthophylls, leucoplasts store carbohydrates, fat and proteins.

Hibiscus

Living fossil

Ginkgo

Liverworts

Amphibians of plant kingdom

Double fertilisation

Arachis

26. (a) (I) In Asparagus leaves are modified into cladode and flat green stems are found. (IV) Aerial roots of Taenliophyllum help in photosynthesis because they are green and adventitious, so called as photosynthetic or assimilatory root.

27. (a) True fruits are developed from ovary, but false fruits develop from other parts of flower except ovary. In apple and pear fleshy thalamus is eaten. These fruits are not real fruits.

28. (d) The correct matching is The micropyle of the ovule lies close to funiculus Helianthus as a result of 180° curvature. The micropyle, chalaza and funiculus of the ovules are on some vertical line.

Polygonum

The ovules are without integuments.

(A) Number of chromosomes in Ophioglossum is 1260 (2n). (B) Number of chromosomes in Haplopappus gracilis is = 2 (2n). (C) Number of chromosomes in butterfly = 380. (D) Total number of chromosomes in potato = 48. So, correct descending order is A > C > D > B.

36. (c) Guttation is the process of excudation of xylem sap on the edges of leaves. Hydathodes are structures by which this process occur. Whereas transpiration is the process of loss of water vapours from plant body surface.

37. (a) The correct matching is Zn Cl Ni Mo

Mottled leaves of cirtus Bronzing in legumes Mouse ear in pecan Whiptail in cauliflower

38. (c) Answer A and D. In monocot root no secondary growth occurs and cambium is absent. In monocot roots pith is well developed, but in dicots roots is absent.

39. (b) The correct descending order is as given below IV > II > I > III

The body of the ovule is placed at a right angle to Dolichos the funiculus and bends in such a way that micropyle comes towards funiculus. Loranthus

29. (a) Flower of Amorphophallus is 6 feet tall. There is process of coevolution in them. Tageticula and Amorphophallus can not complete life cycle without each other. So, both of them depend on each other.

30. (a) 50 flowers have 50 ovules. 50 fruits from 50 ovaries will be obtained and 50 seeds from 50 ovules will be obtained. So, 50 fruits and 50 seeds will be produced by 50 flowers.

31. (d) II, III and IV statements are correct. Asexual reproduction is a rapid mode of reproduction involving single parent. Since, no meiosis and gametic fusion occur, genetic variation is not observed in offspring. These are clones of their parent and are genetically identical. Key note Asexual reproduction is a uniparental phenomenon. The organisms increase their mass and maturity until at a critical point. They reproduce by simple division of their substance. Each successive organism has the same physico-chemical constitution as the parent. Zygomorphic flower (can’t cut into two equal parts) Epipetalous condition androecium attached to corolla Epiphyllous condition Superior ovary

33. (c) In eukaryotes cytoplasm is divided into many compartments by formation of membrane found organelles such as mitochondria and chloroplast, which are specialised for various functions of the cell. In prokaryotes membrane bound organelles are not present and only ribosomes of (70 S) type are present.

16 C 3C 5C 20 C 6C

35. (b)

Siphonogamy and zooidogamy Cycas

% CA PA G

Palmitic acid Serine Ribose Arachidonic acid Glucose

So, correct descending order is D > A > E > C > B.

25. (d) The correct matching is

32. (a)

A. B. C. D. E.

In (IV) Number of peripheral microtubules in a flagellum is—18. (II) Number of radial spokes in a flagellum—9. (I) Number of central microtubules in a cilium—2. (III) Number of nuclei found in a mature sieve tube cell is—zero

40. (b) I. II. III. IV.

Pyruvic acid a- ketoglutaric acid Citric acid Malic acid

3C 5C 6C 4C

I < IV < II < III. Pyruvic acid (3C) < Malic acid (4C) < a-ketoglutaric acid (5C) < 6C (citric acid).

41. (c) The correct matching of list I with list II are Stomochord Botryoidal tissue Captacula Rhabdites

Balanoglossus Hirudinaria Dentalium Dugesia

Key Note Rhabdites are rod-like structures in the cells of the epidermis or underlying parenchyma in certain turbellarians and in the epidermis of nemerteans. They are discharged in mucous secretion.

42. (b) Tympanum, sternum and lacrimal glands first appeared in amphibians.

43. (c) Assertion is true, but reason is false because, the flagellar movement of many organisms is a sidewise- lash, which consists of two ‘strokes’ namely the effective or propulsive stroke and the recovery stroke. (i) In effective stroke, flagellum becomes rigid and starts binding to one side beating against the water. This beating against water is at right angles to the body axis and the organisms move forward. (ii) Recovery stroke, flagellum becomes comparatively soft as to offer least resistance to water and moves backwards to its original position. It is called ‘recovery stroke’.

44. (b) Eichhornia is an aquatic weed, which is known as terror of

52. (d) Only statement III is correct as morphine is a very effective

Bengal. It is a fast growing weed in rivers and lakes. It is also known as water hyacinth. It takes up O 2 rapidly making the, aquatic life deprived of oxygen, which eventually causes death of river organisms by a phenomenon known as eutrophication.

sedative and pain killer useful in patients who have undergone surgery. Other statements can be corrected as II. Opioids are obtained from dried latex of unripe capsular fruits of poppy plant, (Papaver somniferum). IV. Cocaine is obtained from (Erythroxylon coca). I. Barbiturates reduce anxiety and causes sleep.

45. (d) The correct path of migration of Rhabdiform larva of Ascaris through different parts of body is II ® I ® IV ®III® VI ® V ® VII ® VIII Hepatic portal vein ¾® Liver ¾® Post caval vein ½ ¯ ¾ Lungs ¬¾ Pulmonary arteries ¬¾ Heart ½ ¯ Alveoli ¾® Intestine

53. (a) When primary host is not available then reservoir host perpetuates the infective stages of parasite. In case of African sleeping sickness, which spreads by Glossine palpalis, monkey acts as reservoir host.

54. (b) The statements II and III are correct. Other statements can be corrected as I. The brain is the chief sensory organ in Periplanata. IV. A frontal ganglion on the dorsal wall of the pharynx is present, which is connected to the hypocerebral ganglion by a recurrent nerve.

46. (d) The incorrect combination is B. The correct sequence of events in action potential taking place in Na-K voltage gated channels is: (i) Resting state all voltage gated Na + and K + channels are closed. (ii) Depolarising phase depolarisation to threshold open Na + channel activation gates. Na + inflow further depolarises the membrane, opening more Na + channel activation gates. (iii) Repolarising phase Na + channel inactivation causes K + channel to open. (iv) Hyperpolarisation gated Na + channels are reset to close and membrane remains hyperpolarised until K + channels close, causing the relative refractory period. The speed of response of Na + channel is faster than K + channels.

55. (d) Population density is increased by immigration and natality (maximum birth rate) and decreased by mortality (death rate) and emigration (outward migration) of organisms.

56. (b) Aldosterone acts mainly at renal tubule, it stimulates

reabsorption of Na + and water and excretion of K + and PO 24 ions. Thus, aldosterone helps in maintenance of electrolytes balance, body fluid volume, osmotic pressure and blood pressure.

57. (c) I, II and IV are correct. III is incorrect because Chloroflourocarbon (CFC) causes ozone degradation with release of chlorine atoms. Even one molecule can degrade 10000 molecules of O 3 . Cl + O 3 ¾® ClO + O 2 ClO + O 3 ¾® Cl + O 2 CFC molecules move to stratosphere and release chlorine atom which it can react again with another ozone molecule creating huge destruction of O 3 layer by a very low concentration of CFC.

47. (a) In female cockroach 7th sternum is boat-shaped. It becomes fused with 8th and 9th segments and forms broad genital pouch whose anterior part contains female gonophore, spermathecal pores and collateral glands.

48. (b) Chilomicrons are lipoprotein droplets that consist of triglycerides, phospholipids, cholesterol and proteins. Key note Chylomicrons are lipoprotein molecules/particles that consist of triglycerides (85-92%), phospholipids (6-12%), cholesterol (1-3%) and proteins (1-2%). They transport dietary lipids from the intestines to other locations in the body.

58. (b) The correct matching is A. B. C. D.

49. (d) Statement I, II and III are incorrect. (But this is not given in

50.

51.

option). These statements can be corrected as (I) Muscles of the iris and ciliary body are ectodermal in origin. (II) A sudden involuntary contraction of muscle is called spasm. Slow, involuntary and sustained muscle contraction of hand, toes and feet is called dystonia. (III) Pericytes are contractile cells surrounding endothelial cells of capillaries also known as mural cells or rouget cells. (c) Statement II and IV are incorrect. (II) Aristotle lantern is a complex arrangement of muscles and calcareous teeth forming a eversible organ in most echinoderms, functioning in mastication. (IV) Class–Diplopoda includes millipedes (d) All statements are correct. Adam’s apple is a projection in front of neck formed by thyroid cartilage of the larynx, more prominent in man. Vital capacity is the maximum volume of air that person breathes out after forceful inspiration. VC =ERV + TV + IRV CO 2 is carried by haemoglobin in the form of carbamino haemoglobin, partial pressure of O 2 affects this binding. Pons varolli of brain act as a pneumotaxic centre which regulates rhythm of breathing mechanism.

59. 60.

61.

Interferon Paratope Interleukins Histamine

(iii) (i) (iv) (ii)

Antiviral proteins Fab White blood cells Inflammatory mediators

Key Note Interlecekins are a subset of a large group of cellular messenger molecules called cytokines which are modulators of cellular behaviour. Like other cytokines, interleukins are not stored with cells but are secreted rapidly and briefly in response to a stimulus, such as an infectious agent. (d) Acrosin digests the zona pellucida and the membrane of the oocyte. (c) III and IV are correct. The correct forms of I and II are: I. Inspiration is facilitated by the contraction of diaphragm and contraction of external intercostal muscles. II. Healthy humans can inhale 6000 to 8000 ml of air per minute. (a) Hardy-Weinberg equation is [where, p + q = 1 ] p2 + 2 pq + q 2 = 1 out of 800 individuals, 9% are recessive thus q 2 = 0.9. So, 72 individuals are recessive If q 2 = 0.9, then q = 0.3 If p + q = 1 then p + 0.3 = 1, leaves p = 1 - 0.3 = 0.7 So, p2 = 0.49, so 49% organisms are dominant, that is = 392. 2 pq leaves the heterozygotes, so 2 ( 0.3 )( 0.7 ) = 42% are heterozygous or 336 individuals are heterozygous.

62. (c) The cellophane tube is surrounded by a fluid having same

63.

composition as plasma except nitrogenous wastes. The porous cellophane membrane of the tube allows the passage of molecule based on concentration gradient. It is impermeable to large molecule but permeable to micromolecules. (a) Descending loop of Henle is permeable to water but impermeable to electrolytes whereas ascending limb is impermeable to water, but allows transport of electrolyte. In descending limb of Henle concentration is increased because of reabsorption of water but in ascending limb concentration of filrate is decreased due to reabsorption of electrolytes.

64. (b) Steps of blood coagulation

65.

66. (d) The correct pair are

67.

List I

List II

List III

Sphenoid bone Acromion process Xiphoid process Odontoid process

Key-stone bone Shoulder joint Breast bone Axis

Cranium Scapula Thorax Second cervical vertebra

(a) The correct matching is A. B. C. D.

Hyperthyroidism Hyposecretion of glucocorticoids Hypothyroidism- I Hyperparathyroidism

(iii) (ii) (i) (v)

Increased metabolic rate Addison’s disease Myxedema Kidney stones

Key Note Hyperparathyroidism is caused due to the overactivity of the parathyroid glands resulting in parathyroid hormone (PTH) levels in the blood which are in excess of what a normally functioning plasma ionized calcium regulators as homeostat or negative feedback mechanism would produce.

68. (b) The correct sequence is Spermatogonial stem cells (III) ¯ Spermatogonia (I) ¯ Primary spermatocytes (IV) ¯ Secondary spermatocytes (II) ¯ Spermatids (V) ¯ Finally spermatozoa develop by spermiogenesis.

69. (a) I and IV are correct. Other statements are corrected as : (III) Haemophilia-C is a mild form of haemophilia affecting both sexes. (II) Tritanopia is a colour blindness for blue-yellow colour. It is a rare colour vision disturbance. It is caused by heterozygous mutation. Key Note Haemophilia-C (also known as plasma thromboplastin antecedent (PTA) deficiency). Rosenthal syndrome is a mild form of haemophilia affecting both sexes, due to factor XI deficiency. It is the fourth most common coagulation disorder after Von Willebiard’s disease and heaemophilia A and B.

According to Genic Balance theory karyotype with AA-XO is male in Drosophila. It is the ratio of X-chromosome and somatic chromosome which decides sex of chromosome.

71. (b) II and IV are correct. Correct I and III combinations are (I) Thomas Malthus — Principles of population — Evolution theory (III) Hugo de Vries — Oenothera lamarckiana — Mutation theory

72. (b) Both assertion and reason are true but reason is not the correct

Step Formation of prothrombin activation (II) ¯ Activation of prothrombin into thrombin (I) ¯ Thrombin convert fibrinogen protein into fibrin (IV) ¯ Formation of blood clot occur (III) (b) Only statement II is incorrect, because cavity of diencephalon or diocoel or 3rd ventricle is connected to the 4th ventricle through a narrow passage called the iter. Paracoel is called the 2nd ventricle or lateral ventricle.

I. II. III. IV.

70. (a) A is false but R is true.

explanation of assertion. In 1997, the first transgenic cow, Rosie, who had been injected with a human milk protein gene, (a)- lactalbumin was produced. a-lactalbumin is an important nutritional protein. It is produced in human breast milk at a much higher concentration than in cow’s milk. Thus, the milk of Rosie was more nutritionally balanced. a-I-antitrypsin is a human protein produced by transgenic animals to treat emphysema.

73. (d) The correct matching is A. B. C. D.

Prolonged Q-T interval Tall T-wave Shortened P-R interval Variation

(iii) (v) (i) (ii)

Hypothyroidism Hyperkalemia Fast breathing of the heart Blockage of conduction through bundle of His

74. (a) The number of taxa present within a particular area or an ecosystem is a-diversity.

75. (a) Both assertion and reason are true and reason is the correct explanation of assertion. In situ conservation is a type of conservation strategy for biodiversity in the natural habitat. National parks, sanctuaries and biosphere reserves are means of in situ conservation.

76. (a) The correct match are A. B. C. D.

Pisiform bone Fibrous cartilage Hyaline cartilage OS-cardis

(ii) (iii) (iv) (i)

Wrist bone Intervertebral discs Larynx Ruminants

77. (d) Assertion is incorrect, but reason is correct. Brown Adipose Tissue (BAT) or brown fat makes up the adipose organ in newborns and in hibernating mammals. It is metabolically more active than white adipose tissue. Its primary function is thermoregulation. BAT adipocytes contain numerous smaller droplets and a much higher number of iron containing mitochondria which give BAT its brown appearance.

78. (c) Ammocaete larva belongs to Petromyzon. It shows movement from ocean to freshwater and vice-versa for feeding and reproduction. Petromyzon is also known as sea lamprey. It shows catadromous migration. Its reproductive phase occurs in freshwater and vegetative phase occurs in ocean.

79. (c) I and III are correctly matched. The correct combination for II and IV are (II) Bungarus — Banded krait (IV) Vipera russelli — Russell’s viper

— —

Poisonous Poisonous

80. (b) Centriole is a modified cell organelles which forms basal body of flagella and cilia. Thus, centriole is required for cilia and flagella formation.

GENETIC CLASSROOM

Exception to LAW OF DOMINANCE In this section, we will try to infer and apply some ‘Laws of Genetics’. Here, we will be discussing ‘Exception to Law of Dominance’. There are some exceptions to the law of dominance. These are

Connectivity with the Laws

(i) Incomplete Dominance (Intermediate Inheritance) It is the phenomenon where none of the two contrasting alleles or factors is dominant. The expression of the character in a hybrid individual is intermediate or a fine mixture of the expression of the two factors.

 F1 -progeny ↓ BW (Blue) When F1 -progeny fowls were self crossed,

species with RR (Red flower)

WW (White flower)

  F1 -progeny ↓ RW (Pink flower)

The F1 -progeny plants when crossed among themselves, produces offsprings (F2 -generation) represented by the following cross. Parents–RW × RW Gametes

RR (Red)

RW (Pink)

WW (White)

Phenotypic ratio

1: 2 : 1 Red : Pink : White

32 AUGUST 2016

BIOLOGY SPECTRUM

Gametes

WW (White)

WR (Roan)

RR (Red)

Phenotypic ratio

1 : 2 : 1 White : Roan : Red

Connectivity with the Laws On cross-breeding the individuals of F1 -generation are found to have roan colour. The effect is produced due to juxtaposition of small patches of red and white colour. It is known as mosaic inheritance. As both the alleles form small patches side by side, they are codominant.

Parents–BW × BW

Problems

Sol. If we consider a cross between plant

When Andalusian fowls of two pure forms, i.e., black and white are crossed, they show deviation from the law of dominance. Give explanation and predict phenotypic ratio as well as genotypic ratio of F2 -progeny. Andalusian fowls, i.e., black and white can be shown as follows: BB × WW (Black) (White)

The phenomenon of expression of both the alleles in a heterozygote is called codominance. The heterozygous condition has a phenotype different from either of homozygous genotypes.

Mirabilis jalapa has two types of flower colour in pure state, red and white. When the two types of plants were crossed they showed deviation from the Mendel’s law of dominance and in F1-generation pink coloured flowers were obtained instead of red flowers. In F2 -generation again Red and white coloured flowers were observed with pink flowers in 1 : 2 : 1 (red : pink : white) ratio. How would you justify the disappearance of red flowers in F1 -generation and its reappearance in F2 -generation?

Parents – WR × WR

Sol. The cross between two pure forms of

(ii) Codominance

The proportion of F2 -progeny can be explained as follows :

The absence of red colour flower in F1 -generation and its reappearance in F2 -generation can be explained on the basis of law of incomplete dominance.

Gametes

BB (Black)

BW (Blue)

WW (White)

Phenotypic ratio Genotypic ratio

1 : 2 : 1 1 : 2 : 1 Black : Blue : White

Connectivity with the Laws In F1-generation, blue coloured fowls were obtained. Thus, an intermediate or a fine mixture of the expression of the two factors was observed. However, in F2-generation black and white colours reappeared with blue colour. It can be explained on the basis of law of incomplete dominance. n

There are two types of pure short horned cattle, red and white. On cross-breeding, the individuals of the F1 -generation are found to have roan colour. Explain and also predict the phenotype of F2 -progeny and their ratios with the help of Punnett square.

Sol. If we consider a cross between pure short horned cattle with red and white hair colour, i.e., WW × RR (White) (Red)  F1 - progeny ↓ WR (Roan)

A homozygous man of ‘A’ blood group marries with the homozygous women of ‘B’ blood group. What would be the blood group of their progeny and why? Explain with the help of Punnett square.

Sol. From the facts given in the problem, we can conclude following result Genotype of homozygous man of ‘A’ blood group– I AI A Genotype of homozygous woman of ‘B’ blood group– IB IB Parents— I A I A × IB IB Gametes

I A IB (AB blood group)

Thus, they will give birth to the child of ‘AB’ blood group.

Connectivity with the Laws It can be explained with the help of law of incomplete dominance. Alleles for blood group A (I A ) and blood group B (I B) are codominant, so that when they come together in an individual they produce blood group ‘AB’.

Anatomy of Flowering Plants Chapterwise Collection of Best Assertion-Reason Problems for AIIMS Directions (Q. Nos. 1-50) These questions consist of two statements, each printed as Assertion and Reason. While answering these questions you are required to choose any one of the following five responses. (a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion. (b) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion. (c) Assertion is true, but Reason is false. (d) Both Assertion and Reason are false. (e) Assertion is false, but Reason is True. 1. Assertion Quiescent centre is found in the centre of root apex. Reason It consists of actively dividing cells.

2. Assertion Intercalary meristem increases length of the plant like apical meristems. Reason Intercalary meristem originates from the apical meristems.

3. Assertion Sclerenchyma cells do not have plasmodesmata. Reason The cell walls of some permanent tissues are heavily lignified.

4. Assertion All tissues lying inside vascular cambium are called as bark. Reason Bark is made up of phellogen, phellem and phelloderm lying inside secondary phloem.

5. Assertion In collateral vascular bundles, phloem is situated towards innerside. Reason In monocot stem, cambium is present.

6. Assertion Apical and intercalary meristems contribute to the growth in length, while the lateral meristems bring increase in girth in maize. Reason Apical and intercalary meristems always increase the height of plants.

7. Assertion Stomata are absent in submerged hydrophytes.

Reason Respiration occurs by means of air chambers in submerged plants.

8. Assertion Higher plants have meristematic regions for indefinite growth. Reason Higher plants have root and shoot apices.

9. Assertion Cambium is a lateral meristem and causes growth in width. Reason Cambium is made up of fusiform and ray initials in stem.

10. Assertion Xylem and phloem are also called as leptome and hadrome, respectively. Reason Xylem and phloem form conducting tissue of the plant.

11. Assertion Thick cuticle is mostly present in disease resistant plants. Reason Disease causing agents cannot grow on cuticle and cannot invade the cuticle.

12. Assertion The upper surface of leaf is darker than the lower surface. Reason Spongy mesophyll cells contain less chloroplasts than palisade mesophyll cells.

13. Assertion Idioblasts are derived from parenchyma. Reason Secretory cells are modified parenchyma.

14. Assertion Tyloses plug the tracheids and vessels. Reason Tyloses are ingrowth of xylem cells.

15. Assertion In grasses intercalary meristems are not

28. Assertion Loosely arranged areas in periderm are

present. Reason Intercalary meristems form permanent tissues.

called lenticels. Reason Lenticels are characteristic of woody stems.

16. Assertion Bulliform cells are useful in the

29. Assertion Apical meristem is responsible for

unrolling of leaf. Reason Bulliform cells store water.

17. Assertion Sapwood is less durable than the heartwood. Reason Hollow tree trunks are due to the disappearance of sapwood.

18. Assertion Growth rings are also called as annual rings. Reason Generally a single growth ring is formed in a year.

19. Assertion Cuticle is also present in lower epidermal region of leaf. Reason The lower epidermis contains a large number of stomata.

20. Assertion Xerophytic leaves may contain stomatal crypts or sunken stomata. Reason Spongy parenchyma is more in xerophytic leaves.

21. Assertion Tunica and corpus are two portions in the shoot apex. Reason Tunica divides only anticlinally while corpus divides both anticlinally as well as periclinally.

22. Assertion Fusiform initials are elongated cells with pointed ends. Reason Fusiform initials are made up of ray initials.

23. Assertion In dicot stem, the vascular bundles are open. Reason Cambium is present between xylem and phloem of vascular bundle in dicot stem.

24. Assertion Cork cells are dead and buoyant. Reason Cork cells are suberised.

25. Assertion Xylem is a complex permanent tissue. Reason Four types of cellsâ&#x20AC;&#x201C;vessels, tracheids, xylem parenchyma and xylem fibres form xylem.

26. Assertion Collenchyma is a thick walled dead tissue. Reason Collenchyma is thickened deposition of cellulose and pectin.

due to the

27. Assertion Group of continuously dividing cells is called meristem. Reason Cells of meristem are isodiametric and thin walled.

increase in length. Reason Vascular cambium and cork cambium are examples of apical meristem.

30. Assertion When phloem and xylem lie together on the same radius with phloem towards the innerside and xylem towards the outerside, the vascular bundle is said to be collateral. Reason Collateral vascular bundles characteristically occur in monocot roots.

31. Assertion The extensions of peripheral layers of the pith to the pericycle between the vascular bundles are called pith rays or medullary rays. Reason Pith rays or medullary rays occur in most of the dicots and in some gymnosperms.

32. Assertion In a tetracytic stoma, mature stoma is surrounded by four subsidiary cells. Reason These four subsidiary cells are arranged in a narrow ring around the stoma.

33. Assertion Sieve tubes continue to live even in the absence of nuclei. Reason Nucleus of companion cell associated with sieve tube helps in this matter.

34. Assertion Xylem vesseles are much elongated tubes. Reason Xylem vesseles are formed by the union of several short, wide and thickened cells called vessel elements.

35. Assertion Secondary thickenings are absent in protoxylem while they are present in metaxylem and secondary xylem. Reason Secondary wall thickenings of metaxylem and secondary xylem are known as scalariform and reticulate.

36. Assertion In mass meristem, cell division takes place in all planes resulting in the formation of a massive plant body or organ. Reason Plate meristem occurs in leaves and increases surface area without an increase in the number of mesophyll layers.

37. Assertion Apical meristems of both root and shoot are terminal in position. Reason Root cap cells covering the root apex are meristematic in nature.

38. Assertion Each stoma may be interpreted as an intercellular space between two highly specialised epidermal cells called guard cells. 35

Reason Guard cells are living and possess chloroplasts.

39. Assertion Lateral meristems are responsible for increase in diameter of plant. Reason Lateral meristems are only primary meristem.

40. Assertion The irregularly arranged collenchyma cells are present with thickenings at angles in Vitis. Reason It provides mechanical support to plant.

41. Assertion

Cotton is obtained from long unicellular, epidermal hairs present on Gossypium seeds. Reason These hairs are called lint.

45. Assertion All cells of endodermis bear Casparian strips to control the movement of substances in the root. Reason It is a characteristic feature of dicot roots only.

46. Assertion Only secondary xylem consists of wood parenchyma. Reason Wood parenchyma consists of lignified dead cells.

47. Assertion The histogen theory is applicable only for roots. Reason In dicot roots, the median initial forms periblem and innermost one forms plerome.

48. Assertion

Reason Stone cells are present in seed coats of some fruits.

Tamarix aphylla possesses dead sclerenchymatous fibres. Reason Fibres are usually dead with thick lignified secondary walls.

43. Assertion Prickles are outgrowths of epidermal

49. Assertion Exudation of water takes place through

42. Assertion Endocarp of coconut is hard in texture.

tissues. Reason They lack vascular supply.

44. Assertion Parenchyma cells become long and tapering at both ends in pericycle of some plants. Reason The main function of parenchyma is storage of food.

hydathodes. Reason Hydathodes are enlarged stomata whose guard cells have lost the ability to control the opening and closing. 50. Assertion Endoxylic vascular bundles are found in some aquatic angiospermic plants. Reason Ectoxylic vascular bundles are found in monocots like Yucca.

Answers with Explanation 1. (c) Quiescent centre is found in the centre of the root apex. Cell divisions are very few in the quiescent centre as there is very little synthesis of new proteins, RNAs and DNA. Quiescent centre functions as reserve meristem and may supply the active initials when the former active cells are damaged.

2. (a) Intercalary meristems are intercalated in between the permanent tissues.The activities of these meristems also add to the length of the plant or its organs. They originate from apical meristems when their portions get detached due to the growth of organs. Some cells at the base of nodes or above the nodes retain their meristematic activity and function as intercalary meristems.

3. (a) Sclerenchyma is a widely distributed mechanical tissue composed of dead cells which are highly thickened and have lignified cell walls. As a result there are no intercellular spaces between them. Since, they are purely mechanical in function there is no connection between cytoplasm of adjacent cells (dead) and so they do not have plasmodesmata.

4. (d) All tissues present outside the vascular cambium constitute the bark. Phellem, phellogen and phelloderm constitute periderm.

5. (d) In collateral vascular bundles phloem is situated towards outerside and xylem towards innerside and both are found on

same radius. In monocot stem vascular bundles are closed which indicates absence of cambium.

6. (e) Apical and intercalary meristems always increase the height of plants, while lateral meristem is responsible for secondary growth (increase in girth), but secondary growth doesnâ&#x20AC;&#x2122;t occur in monocots. Therefore, lateral meristems cannot contribute to increase in girth in maize, a monocot plant.

7. (b) Both the statements are correct, but the reason does not explain the assertion statement. Stomata are absent in submerged hydrophytes as there is no need for transpiration. Air chambers help in gaseous exchange. The oxygen liberated during photosynthesis is stored in these chambers and used in respiration. CO 2 released during respiration also remain in these chambers, which is utilised in the process of photosynthesis.

8. (a) Higher plants have root and shoot apices where cells are in continuous state of division, i.e. meristematic regions. Due to this meristematic activity these regions can grow indefinitely contributing to the height of the plant. Such regions are absent in lower plant groups and even in animals.

9. (b) Both the statements are correct, but reason does not provide an explanation for the assertion. Cambium is a lateral meristem, whose activity causes increase in width. It is composed of fusiform and ray initials.

10. (e) Haberlandt used the term leptome for phloem and hadrome

20. (c) Spongy parenchyma is reduced in xerophytic leaves.

for xylem. Phloem transports the food synthesised in leaves to the rest parts of plant while xylem transports water and minerals or sap in upward direction to plant parts. Thus, they form the conducting tissues of the plant.

Palisade parenchyma may occur on both upper and lower sides with spongy parenchyma sandwiched between the two. The lower surface bears deep depressions called crypts (stomatal crypts). The crypts possess a number of cutinised hair and stomata. In some xerophytic plants, stomata are sunken below the surface.

11. (a) Disease resistant plants possess thick cuticle. Infectious organisms cannot grow or invade cuticle and therefore are unable to cause disease or infection in the plant.

12. (a) The palisade mesophyll lies below the upper epidermis. The spongy parenchyma or spongy mesophyll lies between the lower epidermis and the palisade parenchyma. The spongy mesophyll cells have fewer chloroplasts in comparison to palisade parenchyma cells. The presence of abundant chloroplasts in compactly arranged palisade mesophyll cells, imparts a deep green colour to the upper surface. Lower surface is of light colour owing to few chloroplasts in loosely arranged mesophyll cells.

13. (b) Both the statements are correct, but reason does not explain

21. (b) The tunica-corpus concept of shoot organisation was given by Schmidt (1924). According to him the shoot apex is divided into two portions-tunica and corpus. The outer single layer is tunica which divides only anticlinally while inner mass of cells is called corpus. It divides both periclinally as well as anticlinally.

22. (c) Fusiform initials are elongated cells which give rise to vertical elements, e.g., vessels, tracheids, etc. These fusiform initials arise from cambial cells. These meristematic cambial cells also give rise to ray initials. Ray initials are horizontal in position and give rise to radial system of secondary vascular tissue.

the assertion. The secretory cells are specialised parenchyma cells that produce nectar, oil, etc. Idioblasts are specialised non-green large sized parenchyma cells, which possess inclusions or ingredients like tannins, oils, crystals, etc.

23. (a) When cambium is present between xylem and phloem, the

14. (a) The tracheids and vessels of the heartwood get plugged by

fatty substance. This makes the cork cells impervious to water and thus they float. So, the cork cells are dead and buoyant.

ingrowth of adjacent parenchymatous cells into their cavities through the pits. Such, ingrowths are called tyloses. These parenchyma cells are dead and lignified.

15. (e) Intercalary meristems are intercalated in between the permanent tissues and unlike other meristems they ultimately get fully used up in the formation of permanent tissues. In grasses they are present above the nodes of the stems. They may also be present at the base of leaf as in Pinus or at the base of node, e.g., mint.

16. (b) The upper epidermis of isobilateral leaves contains

vascular bundles are said to be open. In dicot stem, the vascular bundles are conjoint, collateral and open.

24. (a) The cork cells or phellem have depositions of suberin, a

25. (a) Complex tissues are formed from a group of different types of cells that perform common function. Since, xylem is composed of four types of cells or elementsâ&#x20AC;&#x201C;tracheids, vessels, xylem parenchyma and xylem fibres that together help in the conduction of water, it is a complex permanent tissue.

26. (e) Collenchyma is made up of thick walled and living cells. The cells have thickenings due to the deposition of cellulose and pectin. Intercellular spaces are therefore absent in collenchymatous tissues.

specialised cells, i.e., bulliform or motor cells, which are highly vacuolate and can store water. During water scarcity, these cells lose water and become flaccid . Due to this, the leaf gets rolled up to reduce the exposed surface. These bulliform cells are also useful in the unrolling of leaf during its development.

27. (b) In plants, some regions have capacity to grow and divide

17. (c) The secondary wood in old trees is differentiated into a

28. (b) Lenticels are loosely arranged areas in periderm, formed

darker and harder wood called heartwood or duramen which is physiologically inactive and dead. The outer lighter zone is called sapwood. The latter is physiologically active, but less durable as it is susceptible to infections by pathogens and insects. On the other hand, heartwood cells and cavities have depositions of tannins, resins, gums, essential oils, etc. Therefore, it is much stronger and durable. However it is susceptible to wood rotting fungi which attacks on it and makes the tree trunk hollow.

due to more activity of certain phellogen cells. As a result, the phellem cells are cutoff very rapidly and hence are loosely arranged with large intercellular spaces. These are characteristic of woody stems. The lenticels help in gaseous exchange and transpiration.

18. (a) The activity of cambium is not uniform in plants growing in temperate regions. They become more active and form greater number of vessels with wider cavities. The activity of cambium is periodic and thus produces a growth layer. Since, it forms autumn wood and spring wood in distinct concentric circles, they are known as annual rings. 19. (b) A distinct layer of cuticle is present in lower epidermis, but it is less developed as compared to upper epidermis. The lower epidermis contains a large number of stomata which lead internally to substomatal cavities.

indefinitely. This is due to the presence of group of continuously dividing cells called meristem. These cells are isodiametric, have thin cellulosic walls and have no intercellular spaces and reserve food.

29. (c) Apical meristems are present at apices of root and shoot. These cells divide in various planes and are responsible for increase in length. Lateral meristems are present on lateral sides of plant axis and are responsible for increase in girth or diameter, e.g., vascular cambium and cork cambium.

30. (d) When the phloem and xylem are present on the same radius, such vascular bundles are known as conjoint. When phloem is present on the outer side of xylem, the vascular bundle is called collateral. However, radial vascular bundles in which xylem and phloem are present at different radii are characteristic feature of roots.

31. (b) In most of the dicotyledonous plants, the peripheral layers of the pith extend between the vascular bundles and make

contact with pericycle. Such extensions are known as medullary rays or pith rays. The cells of medullary rays are smaller, densely packed parenchyma. It is also found in some gymnosperms.

41. (b) Long unicellular hairs present on Gossypium seeds are

32. (c) In tetracytic stomata, the opening is guarded by four

42. (a) Stone cells or sclereids are isodiametric cells with extremely

subsidiary cells, e.g., tomato. Of these four guard cells, two are parallel and two are at right angles to the long axis of guard cells.

thick wall of lignin. It is present in seed coats of some fruits like endocarp of coconut or pulp of fruits like pear. The hardness of seed coat is thus due to stone cells.

33. (a) Sieve tubes are formed by the fusion of sieve cells. Though the younger sieve tubes have nucleus, it disappears in mature ones. They are associated with the companion cells through pits both of them being related ontogenetically. The companion cells are living and posses distinct nucleus and cytoplasmic contents. Hence, the nucleus of companion cell helps in the transport of food along the sieve tubes.

34. (a) Vesseles are formed by the union of several short, wide and thickened cells called vessel elements or members. Therefore, they are much elongated. They take part in the conduction of water or sap and provide mechanical support.

35. (e) The xylem that develops first and is derived from procambial strand is called protoxylem. While the xylem that develops in later stage and is derived from vascular cambium is called secondary xylem and metaxylem. Metaxylem consists of bigger tracheids and vessels possessing scalariform, reticulate or pitted thickenings. The wall thickenings of the protoxylem are of simple and primitive type (annular or spiral).

36. (b) On the basis of plane of cell division, three types of meristems, i.e., rib, plate and mass meristems are recognised. In mass meristems, cell division takes place in all planes resulting information of massive plant body or organ. It is involved in early development of embryo, endosperm, etc. Plate meristem consists of parallel layers of cells which divide anticlinally and bring about intercalary growth resulting in an increase in the area of the organ like a plate. It occurs in leaves and increases the surface area without an increase in number of mesophyll cells.

37. (d) Shoot apical meristems are terminal in position as present at

elongation of epidermal cells. These hairs in cotton seeds are referred to as lint.

43. (a) Prickles are examples of emergences, i.e., multicellular outgrowths comprising of epidermal and subepidermal tissues. They are sharp, complex in structure and lack vascular supply. They protect the plant from grazing animals, help plant in climbing and even check excessive transpiration in some plants.

44. (b) Parenchyma cells are thin walled with well developed intercellular spaces. In pericycle of some plants these cells become long and tapering at both ends, known as prosenchyma. However, the main function of parenchyma is storage of food. Such cells develop thick walls and provide rigidity and strength.

45. (d) The radial and transverse walls of endodermal cells become thick walled due to deposition of lignin and suberin, which is called Casparian strip. It controls the movement of substances in the roots. But, certain endodermal cells, present opposite to protoxylem remain thin walled and are devoid of Casparian strips. These cells are called passage cells as they indirectly allow water and dissolved salts to move from cortex to xylem. This anatomical feature is a characteristic of both dicot and monocot roots.

46. (d) The parenchyma associated with xylem is called wood parenchyma. These are thick lignified secondary cells but living cells. They form the only living component of xylem tissues. Both protoxylem a primary xylem and secondary xylem consists of wood parenchyma. It helps in storage of food and lateral conduction.

apices but root apical meristems are subterminal in position due to the presence of root cap. The root apical meristem is partly enclosed within a fully differentiated mature root cap. Thus, root cap is is not meristematic.

47. (b) The histogen theory is applicable only for root meristems.

38. (b) Stomata are minute openings or apertures in the epidermis

48. (e) Fibres are usually dead and empty cells with narrow lumen

of leaves or aerial parts of plants. The opening is guarded by highly specialised bean-shaped guard cells (dumbbell shaped in monocots). The guard cells are living, have chloroplast and expand or contract in response to turgidity. Thus, they open or close the stomatal aperture.

49. (a) Exudation of water takes place through hydathodes. These

39. (c) Lateral meristems are present along the side of stem and are called so due to their lateral position. These are responsible for increase in diameter of plant. Since, these meristems are formed after some growth in primary permanent tissues and give rise to secondary permanent tissues, they are referred to as secondary meristems, e.g., cambium.

40. (b) When the collenchyma cells are irregularly arranged and thickenings are present at angles, it is of angular type. It is the most common type of collenchyma found in plants, e.g, Vitis, Ficus, Polygonum, etc., It provides mechanical support to plant and its organs.

According to this theory, the dicotyledonous plants possess three groups of initials, of which the outer forms the cap, the median forms periblem and innermost forms plerome. and thick lignified secondary walls at maturity. But the fibres in Tamarix aphylla possess nucleated protoplasts, hence are living. are internal glands that are considered to be permanently open enlarged stomata. It consists of an epithem, chamber and a pore that opens to outside. The pore is lined by guard cells that have lost the power of controlling the size of pore, hence water is discharged through the pore.

50. (b) Endoxylic or ectophloic or amphicribal vascular bundles consisting of phloem surrounding the xylem, which forms a central core. It is found in ferns, leaves of dicots and some aquatic angiosperms. Endophloic or ectoxylic or amphivasal type of vascular bundle comprises of xylem completely surrounding the phloem that forms a core. It is found in some monocot plants like Yucca and Draceana.

Usually bacteria show harmful effects and cause many diseases. However, some bacteria are beneficial also, like colon bacilli. They are present even normally in the absorbing colon. They are capable of digesting small amounts of cellulose. In this way, they provide a few calories of extra nutrition for the body. In herbivorous animals, this source of energy is significant, although it is of negligible importance in human beings. Other substances formed as a result of bacterial activity are vitamin-K, vitamin-B12 , thiamine, riboflavin and various gases. The bacteria-formed vitamin-K is especially important because the amount of this vitamin in the daily ingested foods is normally insufficient to maintain adequate blood coagulation.

Do you known, where do proteins go to die? Nothing in nature is permanent. Just as cells and organisms eventually die, proteins stop functioning. In most cases, a cell outlives its proteins. So, when the proteins stop functioning, the cell can recycle many of the amino acids in the polypeptide(s) making up the protein. Proteins stop functioning often by folding into one or more stable, but useless shapes. An important method for recycling misfolded or unused proteins, called protein degradation, reduces proteins to individual amino acids for use in building new proteins. Cells use three different mechanisms to degrade proteins, each confined to a specific compartment of the cell. Proteosomes degrade proteins in the cytoplasm and in the nucleus. These proteins are tagged for destruction by the covalent attachment of many copies of a small protein called ubiquitin. Lysosomes degrade proteins in the endomembrane system, including those captured by endocytosis. Metalloproteinases degrade proteins in the extracellular space, allowing remodelling of this space in multicellular organisms.

Do you know, during World War II, urine of some patients was used to isolate penicillin? In 1928, Alexander Fleming discovered a substance in the bread mold Penicillium that retarded the growth of bacteria. However, the antibiotic was difficult to isolate. So, it did not become available for clinical use until the late 1930s. During World War II, penicillin made a major difference in the number of deaths and amputations caused by infected wounds. The only means of producing penicillin, was to isolate it from bread mold and supplies were limited. Demand for the drug was heightened by the fact that kidney tubules secrete penicillin. Renal secretion is so efficient at clearing foreign molecules from the blood that within 3-4 hrs after a dose of penicillin has been administered, about 80% has been excreted in urine. During the war, the drug was in such short supply that it was common procedure to collect the urine from patients being treated with penicillin, so that the antibiotic could be isolated and reused. However, this solution was not satisfactory, so researches looked for a way to slow penicillin secretion. They find a synthetic molecule probenecid, that competes with penicillin for the organic anion transporter

Do you know, why all living cells are enclosed by at least one membrane? Membranes are essential to all living cells because they create the boundary that permits cells to establish chemical equilibrium and thereby store energy. Life is not possible without this energy. Cytosolic structures that are surrounded by at least one distinct membrane are called organelles. The presence of these membranes allows the cell to create specialised compartments in the cytosol that are devoted to perform a subset of cellular tasks under optimised conditions. These membranes are selectively permeable. They help to create a unique internal environment optinally suited to the molecules contained inside.

Do you know, a virus can infect another virus also? A new type of virus, a mimivirus (mimicking microbe virus), that infects amoebae was discovered in 2003 and named Acanthamoeba polyphaga Mimivirus (APMV). It is the largest virus known and has the largest viral genome known (900 protein coding genes). A second small virus with 21 genes is associated with the mimivirus in the amoebae, but it infects the mimivirus, not the Amoeba. Although APMV is the only known such virus till date. A virus infecting a virus opens up a new window on the link between life and non-life.

responsible for secretion. When probenecid is administered concurrently with penicillin, the transporter removes probenecid preferentially, prolonging the activity of penicillin in the body. Once mass-produced synthetic penicillin became available and supply was no longer a problem, the medical use of probenecid declined.

Do you know, some bacteria present in our absorbing colon provide a few calories of extra nutrition to the body?

Do you know, our stomach and intestine can sense the composition of a meal? Our stomach and intestine have the ability to sense the composition of a meal and secrete appropriate hormones and enzymes. Gut chemoreception is mediated by the same receptors and signal transduction mechanisms that occur in taste buds on the tongue. Studies have proved the presence of T1R receptor proteins for sweet and umami tastes as well as the G-protein, gustducin in various cells of rodent and human intestine.

BIOLOGY SPECTRUM

AUGUST 2016

Animals which lack backbone or vertebral column are referred to as ‘invertebrates’. All such animals are included in a group–Invertebrata. The invertebrates represent a heterogenous assemblage which includes such diverse forms as sponges, corals, worms and butterflies. Here we will discuss about lower invertebrates.

u PHYLUM–PORIFERA

•

THE SPONGES (PORE BEARING ANIMALS) (Gk. Porus–pore; ferre –to bear)

•

A HABITAT

•

All the sponges are aquatic, mostly marine, rarely freshwater (e.g., Spongilla), solitary or colonial, sessile. They like warm water.

B GENERAL CHARACTERISTICS • • •

•

The body of sponges is provided with pores : inhalent pores, ostia and exhalent pores, oscula. Most of the sponges are asymmetrial. However, some show radial symmetry. The sponges are first multicellular diploblastic animals. They are derived from two embryonic germ layers, viz., ectoderm and endoderm. The sponges have cellular level of organisation. Its body wall consists following layers:

a Pinacoderm (Dermal Layer) •

Outer cellular layer contains (i) flattened pinacocytes and (ii) oval porocytes. Flagellum

•

Inner cellular layer consists of highly specialised, flagellated choanocytes (collar cells). Both pinacoderm and choanoderm lack basement membrane.

Sycon, Euplectella (The Venus’ flower basket), Hyalonema (The glass rope sponge), Euspongia (The bath sponge), Spongilla (freshwater sponge), Cliona (The boring sponge), Chalina (The deadman’s fingers or the Mermaid’s gloves).

•

To outside

Incurrent canals

Osculum

Come out of snail

Excretory

B GENERAL CHARACTERISTICS •

Cercariae (4th larva b

Many cnidarians show polymorphism like Obelia is trimorphic. It has three kinds of zooids–polyps, blastostyles and medusae.

Cnidarians show radial symmetry. They are diploblastic animals, derived from two embryonic germ layers, viz., ectoderm and endoderm. These are the first multicellular animals which show tissue level of organisation. Body wall consists of outer epidermis and inner gastrodermis. A non-cellular gelatinous layer, mesogloea is found between epidermis and gastrodermis.

Operculum

Stylet Spines

Life cycle of Tapewor Develops into young tapeworm in human gut Reaches to human gut Develops into cysticerci (larvae)

Adult tapeworm Scolex Neck

Blade

Mature proglottides

In muscles of pig Immature proglottides

Gravid proglottides

•

• •

Excurrent canals

•

The central cavity of sponge is called spongocoel or paragastric cavity.

•

Most of the sponges possess an internal skeleton of calcareous or siliceous spicules or fine spongin fibres or both. Digestion is intracellular.

•

Hexacanths penetrate the gut of pig

Each onchosphere con Young worms

Cytoplasm Nucleus Lasso

Nucleus

A B Cnidoblasts : A. Undischarged, B. Discharged

• • Flagellated chamber Apopyle

Thread tube Operculum

Supporting fibrils

Cell membrane

Spongocoel

Prosopyles

Spines Stylet Shaft

Refractile rods

Thread tube

•

Radial canals Apopyles

Shaft Cnidocil Capsule

Cnidocil

To outside

Leucon Type Canal System Dermal ostia

Metacercariae (5th larvae)

All are aquatic and are mostly marine, except a few like Hydra , are freshwater.

Choanocyte

Sycon Type Canal System Dermal Prosopyles Ingressing Incurrent ostia water canals

Ingressing water

Or Go Aceta

In blood of pig

Ascon Type Canal System Through Through Ingressing Spongocoel ostia osculum water

To outside

Oral cone Gonopore Acetabulum

Weeds with metacercariae are eaten by sheep or goat

Get attached to water weeds

A HABITAT

•

A non-cellular layer found in between pinacoderm and choanoderm. Three types of canal systems are found in sponges : (i) Asconoid canal system (simplest type, e.g., Leucosolenia), (ii) Syconoid canal system (relatively more complex system, e.g., Sycon), (iii) Leuconoid canal system (most complex system, e.g., Spongilla).

Osculum

Oral or ante

Mouth

Gk. Knide–nettle or sting cells

Connections

c Mesenchyme (Mesohyl Layer) •

Life Cycle of Liver fluke Young fluke

Ora

COELENTERATA

•

Basal granule Rhizoplast Blepharoplast Nucleus Cytoplasm Protoplasmic processes

INVERTEBR

v PHYLUM–CNIDARIA OR

• • Collar

your Revi

EXAMPLES

b Choanoderm (Gastral Layer) •

During respiration, exchange of gases occurs by diffusion through the plasma membrane of the cells. Both asexual and sexual reproduction (by budding and gemmules) occur. Sponges are hermaphrodite and fertilisation is internal. Zygote undergoes holoblastic cleavage. The development includes a free swimming larva, the amphiblastula (in Sycon) or parenchymula (in Leucosolenia).

CONCEP

Life cycle of

Intestine (4th mould) Stomach Oesophagus

Cnidoblasts (stinging cells) present in epidermis are their characteristic feature. A cnidoblast has a nematocyst (stinging organ) which consists of capsule, shaft and thread tube. They have an incomplete digestive tract. They possess a central gastrovascular cavity (coelenteron) with a mouth, which also acts as anus. Digestion is of both, intracellular and extracellular type. Respiration and excretion are carried out through body surface by diffusion. Ammonia is chief excretory waste. They have a primitive nervous system. Statocyst is a sense organ for balance. Reproduction is both by asexual and sexual methods. The power of regeneration is also developed.

Bronchioles (4th stage juvenile)

The cleavage is holoblastic. Direct or indirect development (Obelia–planula larva and Aurelia– planula, scyphistoma and ephyra larvae) occurs. Obelia shows metagenesis (polyps reproduce medusae asexually and medusae form the polyps sexually).

Lung capillaries

Pharynx Trachea Bronchi

4th stage juvenile in lung alveoli

Mouth

Amphid Lateral Excretory papilla pore Female genital Lateral aperture line cloacal aperture

Lip

(3rd mould) 3rd stage juvenile in lung alveoli (2nd mould) Lung alveoli

Pineal setae (spicules) Male Female

Pha

Ascaris

Pulmonary artery

Heart

PT MAP

ision Tool

RATE WORLD (Fasciola hepatica)

EXAMPLES Hydra, Obelia (the sea fur), Physalia (The Portugeseman of war), Velella (the soil by the wind), Aurelia (the jelly fish), Adamsia (the sea anemone), Astraea (the star coral), Meandrina sinuosa (the brain coral), Pennatula (the sea pen or sea feather), Gorgonia (the sea fan).

w PHYLUM–CTENOPHORA A HABITAT

• •

m or posterior sucker

al sucker

Mouth

Miracidium (1st larva)

ral cone onopore abulum

• •

Snail •

dult fluck

Sporocyst (2nd larva)

pore

•

rm (Taenia solium) Zygotes in mature proglottides Handle guard

•

Capsule containing zygotes in gravid proglottides

Hook Rostellum

•

Redial (3rd larva by pedogenesis)

by pedogenesis)

Hooks in two rows

Onchospheres (larvae)

Suckers (4)

Outside the body through faeces

Scolex

Faeces with onchospheres is eaten by pig

Proglottides budding off

ntains a hexacanth

Out with host faeces

tio

tili

Sperms Ova

Fertilised eggs

r Fe

Ascaris

1st stage juvenile in egg—also called Rhabditiform larva (1st mould)

Dorsal lip 2nd stage juvenile—also called embryonated egg Double papilla (infective juvenile in egg) Denticulate margin of lips Embryonated egg swallowed Double papilla by man with food Ventro lateral lip

Tail asmids

2nd stage juvenile free in human intestine

Gland of phasmid Duct of phasmid

They show power of regeneration. Bioluminescence is their characteristic feature. They show biradial (radial + bilateral) symmetry. They are diploblastic with ectoderm and endoderm. They show tissue level of organisation. Body wall consists of outer epidermis, inner gastrodermis and middle mesogloea. Special adhevise cells, colloblasts (lasso cells), present in epidermis of tentacles, help in food capture. The cilia present on the comb-like eight ciliary plates, called comb plates, help in swimming. Digestive tract is complete with mouth, pharynx or stomodaeum, stomach, (infundibulum), anal canals and two anal pores. Digestion is both extracellular and intracellular. Anal pore The arboral end bears a Lateral pit sense organ, called Ciliated statocyst for equilibrium. comb plates They are monoecious Mouth (bisexual). Fertilisations is usually external. Asexual reproduction is lacking. Tentacles Paedogenesis is common. Egg is lecithal. Development is indirect with a ciliated Pleurobrachia spherical cydippid larva.

EXAMPLES

Neck

2nd stage juvenile bores through intestinal wall into blood capillaries

Hormiphora (the sea walnut), Pleurobrachia (the sea gooseberry), Cestum (The Venus’ girdle).

THE FLATWORMS (GK. Platys–broad or flat; helmin–worm)

•

Planaria, Fasciola (the lever fluke), Schistostoma (blood fluke), Taenia solium (the pork tapeworm), Taenia saginata (beef tapeworm), Echinococcus granulosus (the dog tapeworm).

y PHYLUM–ASCHELMINTHES OR NEMATHELMINTHES THE ROUNDWORM (GK. Nema–thread, helmin–worm)

A HABITAT Many roundworms live as parasites in plants and animals. Some are free-living and occur in freshwater, sea water and soil.

B GENERAL CHARACTERISTICS • • •

• •

•

• •

A HABITAT B GENERAL CHARACTERISTICS • • • •

•

• •

The body is dorsoventrally flattened and is without true segments. They show bilateral symmetry. The flatworms have organ level of organisation. The body covering is soft, may or may not be ciliated. Rod-shaped bodies, the rhabdites, present in epidermal cells, are protective and used in food capture. Flatworms are acoelomates. The space between the body wall and organs is filled with a peculiar connective tissue, parenchyma. The digestive tract, if present, is incomplete. In tapeworms, digestive tract is absent. Skeletal, respiratory and circulatory systems are absent. The hydroskeleton maintains, the body shape. Gaseous exchange occurs by diffusion through body surface.

Excretory system consists of peculiar flame cells (solenocytes/protonephridia) for excretion and osmoregulation. Ammonia is chief excretory waste. The nervous system is ladder-like. It consists of the brain and two longitudinal nerve cords connected at intervals by transverse commisure. They are hermaphrodite and fertilisation is cross and internal. Tapeworms show self-fertilisation. Development is indirect with one or more larval stages, (liverfluke–miracidium, sporocyst, redia, cercaria and metacercaria larvae and tapewormonchosphere, hexacanth and cysticercus larvae). Regeneration is well marked in some flatworms like Planaria.

EXAMPLES

The flatworms are mostly parasite but some are free living (terrestrial, freshwater or marine).

Liver

Posterior vena-cava

•

x PHYLUM–PLATYHELMINTHES

Hepatic portal vein

Hepatic vein

•

All ctenophores are exclusively marine.

B GENERAL CHARACTERISTICS

Capsules containing zygotes

•

THE COMB JELLIES OR SEA WALNUTS (Gk. Ktene–comb, phors–to bearing)

•

erior sucker

•

They are called roundworms because they appear circular in cross-reactions . They are unsegmented. Body wall consists of cuticle, syncytial epidermis and muscle layer. They are pseudocoelomates. Mesoderm is found scattared as pouches in between the ectoderm and endoderm. Digestive tract is complete with muscular pharynx. Skeletal, respiratory and circulatory systems are absent. Pseudocoelomic fluid maintains body shape and forms hydroskeleton. The excretory system consists of gland cells or of canals or of both. In Ascaris H-shaped system of canals and complicated ‘giant cells’, called renette cells are present. Ammonia is main excretory matter (Ascaris excretes urea). Nervous system consists of a circumpharyngeal ring. Sense Organs (i) papillae (raised structures) on lips, side of anterior end of both male and female as well as in front and behind the cloacal apperture, tactile (ii) amphids (pits) on the lips and are chemoreceptors (iii) phasmids unicellular glands on lateral sides of posterior end are glandulosensory. They usually show sexual dimorphism. Often females are longer than males. Fertilisation is internal. Asexual reproduction is absent. Development may be direct or indirect. Ancyclostoma (filariform larva), Wuchereria (microfilaria larva), Ascaris and Enterobius (rhabditiform larva).

EXAMPLES

Ascaris lumbricoides (the giant intestinal roundworm, causes ascariasis disease), Ancylostoma duodenale (the hook worm, causes ancylostomiasis disease), Wuchereria bancrofti (the filarial worm, causes filariasis, viviparous, digentic life cycle in man and Culex mosquito), Enterobius vermicularis (the pin worm), Trichinella medinensis (the Trichina worm, causes trichinellosis disease), Loa-loa (the eye worm, causes laiosis disease).

REPRODUCTIVE STRUCTURES OF MAMMALS : MATCHLESS MODELS Reproduction is one of the fundamental characteristics of living organisms. It involves the transmission of genetic material from one generation to the next, ensuring that the species survives over long periods of time. Thus, it is necessary for the continuity of life. Maintenance of the self and perpetuation of the species are the two cardinal concerns of organisms. However, since the self is mortal, perpetuation of the species qualifies as the ‘‘very essence (sin qua non)of life”. It occurs through reproduction. It is a biological process in which an organism produces young ones of the same species.

Purpose of Reproduction Purpose of reproduction are as follows: Continuity of species Variations Population organisation Life

Mammals show sexual dimorphism. It is the phenomenon in which male and female individuals are differentiated externally.

Insemination Transfer of sperms by male into the genital tract of the female

Fertilisation Fusion of male and female gametes to form zygote

Types of Reproduction

Asexual Reproduction (Offspring is produced by a single parent with or without the involvement of gamete formation) l

Sexual Reproduction (It occurs through the formation and fusion of male and female gametes)

Asexual reproduction occurs in lower organisms. Mammals usually show sexual reproduction.

42 AUGUST 2016

BIOLOGY SPECTRUM

Gametogenesis Formation of gametes Parturition Expelling of baby from the mother’s womb

Major Reproductive Events

Organogenesis Formation of specific tissues, organs and organ-systems from three primary germ layers

Cleavage Rapid mitotic division of zygote to form a multicellular blastocyst Implantation Attachment of blastocyst to the uterine wall Placentation Formation of placenta Gastrulation The process by which blastocyst is changed into gastrula with three primary germ layers

METICULOUS ANALYSIS Pubic symphysis

Mammals are the most highly evolved and the most important group in the animal kingdom. They belong to class–Mammalia (L., mamma–breast). It includes all the forms in which the female possesses mammary glands for the production of milk with which they nourish their young. They are worm blooded and possess a hairy covering on their body.

Sexual precocity is generally defined by the appearance of secondary sexual characteristics in females before eight years of age and in males before nine years of age. Precocious puberty might occur as a result of premature activation of the hypothalamic- pituitary-gonadal axis or more rarely because of inappropriate androgen or oestrogen exposure. Most cases of central precocious puberty are reported in females, the majority of which have no identifiable cause (termed idiopathic central precocious puberty). Few cases are due to a variety of cerebral lesions. The major clinical concerns related to premature puberty are the psycho-social environment of early maturation in relation to peers. It is also responsible for reduced final height due to earlier fusion of the epiphyses.

Bulbourethral gland Urethra

Prostate gland Urinary bladder

Glans penis

Rectum Inguinal gland Ureter

Anus

Vas deferens

Rectal gland

Here we will discuss about reproductive structures of placental mammals (man and rabbit) in detail, followed by the differences among egg-laying mammals, pouched mammals and placental mammals.

Precocious and Early Onset Puberty

Penis

Corpus cavernosa

Gubernaculum Cauda epididymis

Testis B

Corpus epididymis

Uterus masculinus Caput epididymis

Urinogenital System of Rabbit A. Ventral dissection, B. Side view

Scrotum A pouch of deeply pigmented skin divided into two separate sacs. Each sac contains one testis. Temperature of testes in the scrotum is 2-2.5°C lower than the internal body temperature which is ideal for developing sperms. n

In mammals with relatively a lower body temperature (e.g. Insectivora, Tubulidentata, Chiroptera, most Rodentia), formation of scrotal sacs and descent of testes are seasonal activities and occur during breeding season. Mammals with still lower body temperature (e.g., Monotremata, Proboscidea, Hyracoidea, Sirenia and Cetacea), testes do not need cooling, hence always remain in abdominal cavity.

Testes

Male Reproductive System

These are primary sex organs. During foetal life the testes develop in the abdominal cavity then they descend into the scrotum. It performs two functions– production of sperms and secretion of male sex hormones.

It consits of following parts:

Histology of Mammalian Testis Tunica albuginea Tunica vaginalis Tunica vasculosa Dorsal blood vessels Corpora cavernosa Central artery Corpus spongiosum Urethra

Reproductive anatomy of the human male

Tunicae (Protective coverings) Testis is surrounded by three layers

Head of epididymis Vasa efferentia

Capillary

Rete testis Sertoli cell Seminiferous tubule Leydig celll Epididymis Vas deferens

Spermatogonium

Scrotal cavity

Left kidney

Right kidney

Lumen of seminiferous tubule

Each testis has about 250 testicular lobules (a) Spermatids

Ureter

Spermatic cord Vas deferens

Urinary bladder Uterus masculinus Prostate glands

Urethra

Bulbourethral or Cowper’s glands

Caput epididymis Corpus epididymis Testis

Inguinal or perineal gland

Scrotal sac Cauda epididymis Penis Glans penis

Perineal pouch Prepuce A

Gubernaculum

Secondary spermatocyte Primary spermatocyte Spermatogonium Tight junction between Sertoli cells Fibroblast

(b)

Spermatozoa

Basal lamina Capillary Leydig cells

(c)

Interstitial cells or Leydig’s cells present in between the seminiferous tubules, secrete androgens. Sertoli cells or sustentacular cells Support developing germ cells and provide them nutrition, secrete Androgen Binding Protein (ABP) and inhibin (which suppresses FSH synthesis) Anatomy of Human Testis (a) LS of a portion of testis (b) A part of transverse section (c) A part of seminiferous tubule showing Sertoli cell and stages of spermatogenesis

BIOLOGY SPECTRUM

AUGUST 2016

METICULOUS ANALYSIS In rabbit, rat and other rodents, testes descend into the scrotum during breeding season.

Epididymis It is a mass of long narrow closely coiled tubule which lies along the innerside of each testis. It stores sperms and secrete a fluid to nourish them. It consists of three parts Caput epididymis Anterior end in which the vasa efferentia open. Corpus epididymis Middle part of epididymis. Cauda epididymis Posterior end of epididymis.

Prostate Gland It produces a milky, slightly alkaline secretion which forms 25% of the volume of semen. This secretion contains citric acid (a sperm nutrient) and enzymes (acid phosphates, amylase, pepsinogen).

Perineal Gland

It is a pair of dark elongated scent glands lying behind Cowper’s glands. Their odorus secretion gives the rabbit its characteristic smell.

Rectal Gland

Vasa Deferentia It emerges from cauda epididymis on each side. The vas deferens loops over urinary bladder. Here, it is joined by duct from seminal vesicle to form ejaculatory duct. It carries sperms. Rete testis, vasa efferentia, epididymis and vasa differentia are called male sex accessory ducts. These ducts store and transport the sperms to the outside through urethra.

A pair of rectal glands of unknown function are situated dorsally on the rectum.

Hormonal Control of Male Reproductive System l

Ejaculatory Ducts There are two short tubes, formed by the union of the duct from a seminal vesicle and a vas deferens. They carry sperms and secretions of seminal vesicles.

Urethra It is the common passage for both urine and semen. It is called as urinogenital duct.

The growth, maintenance and functions of male reproductive organs are under the hormonal control. GnRH, secreted by the hypothalamus, stimulates the anterior lobe of pituitary gland to secrete LH and FSH. LH (ICSH) stimulates interstitial cells (Leydig’s cells) to secrete androgens. FSH stimulates Sertoli cells to secrete an Androgen Binding Protein (ABP). They also secrete inhibin which suppresses FSH synthesis. Stimulates anterior lobe of the pituitary gland to secrete LH and FSH. It stimulates Sertoli cells of testes to secrete androgen-binding protein (ABP). It concentrates testosterone in the seminiferous tubules.

Penis It is the copulatory organ. It contains three cylindrical masses of erectile tissue-two dorsal, corpora cavernosa and one ventral, corpus spongiosum. It remains enclosed in a sheath of skin which hangs loosely as a fold over its cap-like tip or glans penis as prepuce. It transmits sperms into the vagina of the female during sexual intercourse.

Hypothalamus

GnRH

Anterior pituitary

FSH

Male Reproductive Glands Seminal Vesicles

Fructose, produced by the seminal vesicle, is not present anywhere else in body, provides a forensic test for rape. The presence of fructose in female genital tract confirms sexual intercourse.

Bulbourethral Glands or Cowper’s Glands They contribute mucus for lubrication and buffers to neutralise the usually acidic environment of the vagina. Thus, the secretion of these glands protect spermatozoa.

AUGUST 2016

Inhibin

Testes

They contribute prostaglandins that influence sperm motality and transport in both male and female reproductive tract. Its secretion contains fructose, clotting proteins.

BIOLOGY SPECTRUM

It is called Interstitial Cell Stimulating Hormone (ICSH). It stimulates Leydig’s cells to secrete androgens

Sertoli cell

Spermatogonium

Leydig cells

Spermatocyte

Second messenger

Sertoli cell

Cell products

Androgen-binding protein (ABP)

ABP T

Sertoli cells secrete inhibin (protein hormone) which suppresses FSH synthesis. FSH acts directly on spermatogonia to stimulate sperm production. Hormonal control of male reproductive system

Testosterone (T)

To body for secondary effects

Female Reproductive System

Ovaries

The female reproductive system consists of the ovaries, uterine tubes, uterus, vagina and the external genitalia.

Ovaries are primary sex organs. The ovarian ligament attaches the ovary to the uterus. The broad ligament of uterus attaches to the ovary by a double layered fold of peritoneum called the mesovarium.

Fallopian tube Uterine Uterine Uterine part Broad Infundibulum Isthmus ligament Ovarian fundus cavity Ampulla ligament

Fine Structure of Ovary Surface epithelium Theca Basal lamina

Uterine body Fimbriae

Perimetrium Myometrium Endometrium

Ovary Wall of uterus

Granulosa cells (nourish the developing oocyte and secrete oestrogens) Antral fluid (contains hormones and enzymes needed for ovulation)

Cervix of uterus

Internal OS

Cervical canal

External OS

Mature follicle or Graafian follicle Secondary follicle changes into Graafian follicle It contains an oocyte

Vagina Vaginal opening Hymen Female reproductive system of human

Mesovarium Kidney

Ruptured follicle Storma Graafian follicle ruptures to release egg, i.e., ovulation

Fimbriated funnel

Ureter

Vagina

Urinary bladder

Fine structure of ovary of human (female)

Rectal

gland

Vulva Perineal

Reproductive

system

gland

female (Ventral rabbit

Vein

Primary follicles Oogonia or egg mother cells undergo mitosis to form primary oocyte. Each primary oocyte gets surrounded by a layer of granulosa cells called primary follicle.

Urethra Urinogenital sinus

Regressing Artery corpus luteum

Corpus luteum After ovulation collapsed follicle fills with a partially clotted fluid. The follicular cells enlarge and fill with a yellow pigment lutein. They secrete relaxin, estradiol and progesterone.

Uterus

Bartholin’s gland

Secondary follicle Primary follicles surrounded by more layers of granulosa cells are called secondary follicle

Ovulated oocyte

Ovary

Fallopian tube

Oocyte

view)

Cryptorchidism The failure of one or both testes to descend is known as cryptorchidism [Crypto–hidden; orchis–testicle]. It occurs in 1-3% of newborn males. About 80% of crytorchid testes spontaneously descend later. Those that remain in the abdomen through puberty become sterile and are unable to produce sperm. Although cryptorchid testes lose their sperm producing potential, they can produce androgens. It indicates that hormone production is not as temperature sensitive as sperm production. Undescended testes are prone to become cancerous. It is recommended that they should be moved to the scrotum with testosterone treatment or surgically.

Oviduct In humans it consists of four parts–infundibulum, ampulla, isthmus and uterine part. Oviducts convey the ovum from the ovary to the uterus. It is done by peristalsis. In rabbit, ovary opens into Fallopian or oviducal funnel. Funnel leads into a short, narrow, coiled and internally ciliated duct called Fallopian tube. It opens into uterus.

Uterus It is a hollow, muscular and inverted pear-shaped structure. Its lower part is known as cervix. The walls of the uterus are composed of three layers of tissues–perimetrium, myometrium and endometrium. Endometrium undergoes cyclical changes during menstrual cycle. In rabbit, two utri are found. Fertilised ova or zygotes get implanted on the uterine wall to develop into embryos. Each attached to the placenta by an umbilical cord.

Uterine Types of Eutherian Mammals Basically four uterine types occur on the basis of the relationship of the uterine horns. These are as follows: 1. Duplex uterus It is characterised by two uteri, each with a cervix opening into the vagina, e.g., rodents, lagomorphs. 45

2. Bipartite uterus The horns of uterus are separate but they enter the vagina by a single cervix. e.g., whales, most carnivores. 3. Bicornuate uterus The uterine horns are Y-shaped, being separated medially but fused distally, where they form a common chamber, the body. It opens into the vagina through a single cervix. e.g., elephants, most bats. 4. Simplex uterus They lack all separation between the uterine horns. The single uterus opens into the vagina through one cervix. e.g., higher primates. Oviduct Ovary Uterus Uterus horn Uterus body Cervix Vagina Urethra Urogenital sinus Duplex uterus

Bipartite uterus Oviduct Ovary Uterus Uterus horn Uterus body Cervix Vagina Urethra Urogenital sinus

Bicornuate uterus

Simplex uterus

Types of uterus

Vagina It is a tube-like structure which extends from the cervix to the outside of the body. It serves as the receptacle for sperm during intercourse and forms part of the birth canal during labour. In rabbit the uteri of both sides meet into a long wide, median duct, the vagina. It opens posteriorly into the neck of bladder to join the urethra forming a short narrow common urinogenital canal or vulva.

External Genitalia (Vulva) It consists of mons pubis, clitoris, labia majora, labia minora and perineum. Clitoris is homologous to glans penis of the male.

Accessory Sex Glands Two glands–paraurethral gland (homologous to the male prostate and secrete mucus) and Bartholin’s glands (homologous to Cowper’s glands of male and secrete viscid fluid that supplements lubrication during sexual intercourse). In female rabbit Bartholin’s glands are either reduced in size or absent. The perineal and rectal glands are also found as in the male.

Cyclical Changes during Reproductive Phase In females of placental mammals, there are cyclical changes in ovaries, accessory reproductive ducts and hormones during the reproductive phase. Cyclical Changes Menstrual cycle (It occurs in primates, e.g., monkeys, apes and humans)

Oestrous cycle (It occurs in non-primate mammals, e.g. cows, sheep, rats, due, dogs, tiger, etc.)

Menstrual Cycle 1. It occurs in primates (monkeys, apes and human beings) only. 2. This cycle consists of menstrual phase, proliferative phase and the secretory phase. 3. Blood flows in the last few days of this cycle. 4. The broken endometrium is passed out during menstruation. 5. Sex urge is not increased during menstruation. 6. Female does not permit copulation during menstrual phase of the cycle.

Oestrous Cycle 1. It occurs in non-primates such as cows, dogs, etc. 2. It consists of a short period of oestrous or heat (e.g. 12-24 hours in cow) followed by anoestrous or passive period. 3. Blood does not flow in this cycle. 4. The broken endometrium is reabsorbed. 5. Sex urge is increased during oestrous period. 6. Female permits copulation only during oestrous period.

Phases of Menstrual Cycle The menstrual cycle consists of following four phases: 1. Menstrual Phase (Bleeding phase or Menses) In a 28 day menstrual cycle, it takes place on cycle days 3-5. During this phase, the production of LH is considerable reduced causing degeneration of the corpus luteum. Therefore, progesterone and oestrogens production also decreases. The endometrium of the uterus breaks down and menstruation beings. 2. Follicular Phase (Proliferation phase) This phase usually includes cycle days 6-13 or 14 in a 28 day cycle. The FSH stimulates the ovarian follicles to secrete oestrogens which in turn stimulate the proliferation of the uterine wall. The endometrium becomes thicker. This is accompanied by an increase of uterine glands and blood vessels.

CHROMATIC PROBES

Molecular Basis of Inheritance Figure Based Learning Boosters 1. Carefully observe the structure of given compounds and consider the statements following it O

NH2 CH3

C HN 3

NH2

C N1 6 5C

C 2 1 6 CH N H A

3 4C

CH O

A, B and C. B

C 2 1 6 CH N H C

Statements I. A and C are purines containing single carbon ring. II. B is a pyrimidine containing two carbon-nitrogen rings. III. B is present only in RNA. IV. A and B bases are joined through two hydrogen bonds in the structure of DNA/RNA to provide stability. Choose the incorrect pair of statements. (a) I, III and IV (b) II and IV

3. From the given diagram, identify the structures

N 3 4 5 CH

N H

(a) A−0.34 Å, B−20 Å, C−3.4 Å (b) A−3.4 Å, B−20 Å, C− 34Å (c) A−34 Å, B−20 Å, C−3.4 Å (d) A−34 Å, B−20 Å, C−0.34 Å

(d) All of these

Core of histone molecules

(a) A−DNA, B−H1, histone, C−Histone octamer (b) A−RNA, B−H1, histone, C−Histone octamer (c) A−DNA, B−H1, histone C−Histone tetramer (d) A−RNA, B−H1, histone, C−Histone tetramer

4. In the given diagram of chemical structure of DNA, identify the type of bonding shown by A, B and C. H O H

2. Consider the given diagram showing Watson and Crick model of DNA structure. Identify the correct values for A, B and C. B Guanine

HO 3′ 3

Cytosine

Thymine F

Adenine

T C

H2C

5′

G T

A O

3′

H2C

C T

54 AUGUST 2016

O Cytosine O

CH2 5′

3′

H Deoxyribose

C H

HO—P== O 8

Guanine

CH2

5′

3′

HO Deoxyribose

3′

O== P—OH

H A

Hydrogen bonds

5′

N Adenine

A G

O== P—OH

N O Thymine

5′

H 3C

3′

HO—P== O

BIOLOGY SPECTRUM

(a) A−N-glycosidic bonding, B−Phosphodiester bonding, C−Hydrogen bonding (b) A−N-glycosidic bonding, B−Phosphodiester bonding, C−Covalent bonding

(c) A−N-glycosidic bonding, B−Phosphodiester bonding, C−Coordinate bonding (d) A−N-glycosidic bonding, B−Hydrogen bonding, C−Phosphodiester bonding

8. Consider the given diagrammatic representation of transcription unit and identify the following enlisted sites. Transcription start site

5. Consider the given diagram depicting the

replication of strands of DNA. Identify the strands A, B and C.

5′

5′ 3′

3′

5′ B

3′ 5′

3′

B. Structural gene D. Template strand

A (a) 5 (c) 5

B 1 4

C 4 1

D 2 2

E 3 3

A B (b) 5 1 (d) 5 4

A F B

Transcription of lac mRNA

C A U G U A E

Translation

5′

enzymes A

7. Consider

the given diagrammatic representation of a single nucleotide. Suppose two nucleotides are joined together, than the diagram would look like.

10. Consider the given diagram of protein synthesising machinery and identify the suitable correct options for A, B, C and D.

Phosphate Sugar

Gly Leu Tyr Ser Growing Leu polypeptide chain

Base

Asn Gly

tRNA tRNA

Ser

(b) O

Choose the appropriate structure from given options. (a)

D E mRNA 3′

(a) A−Variable arm, B−D-loop, C−T-loop, D−Anticodon arm, E−Codon on mRNA, F−Variable arm (b) A−Amino acid arm B−T-loop, C−Variable arm, D−Anticodon Arm, E−Codon on mRNA, F−D-loop (c) A−Amino acid arm, B−T-loop, C−Anticodon loop, D−Anticodon, E−Codon on mRNA, F−D-loop (d) A−Amino acid arm, B−T-loop, C−Anticodon loop, D−Anticodon, E−Codon on mRNA, F−Variable arm

(a) A−Galactosidase, B−Permease, C−Transacetylase, D−Repressor protein, E−Inducer (lactose) (b) A−Galactosidase, B−Permease, C−Transacetylase, D−Inducer (lactose), E−Repressor protein (c) A−Galactosidase, B−Transacetylase, C−Permease D-Repressor protein, E−Inducer (lactose) (d) A−Permease, B−Transacetylase, C−Galactosidase, D−Repressor protein, E−Inducer (lactose)

E 2 2

Tyr

mRNA

D 3 3

marked as A−F.

identify its components and enzymes A−E. o

C 4 1

9. From the given figure of tRNA, identify the labels

6. Consider the given diagram of lac operan and p

3′

Choose the correct option from codes given below.

5′

(a) A−Continuous strand, B–Discontinuous strand, C–Templates strand (b) A−Leading strand, B−Lagging strand, C−Parental strand (c) Both (a) and (b) (d) None of the above

5′

A. Promoter site C. Terminator site E. Coding strand

3′

Ala

Vla

tRNA

CGU

CAA

C U C U U G G G U C C G C A G U U A A U U U C U A U C

(c)

mRNA

Ribosome

(d) O

(a) (b) (c) (d)

A−Uncharged t RNA, B−Charged t RNA C–5′-end D–3′-end A−Charged t RNA, B−Uncharged t RNA C–3′-end, D–5 ′-end A−Charged t RNA, B−Uncharged t RNA C–5′-end, D−3′-end A−Charged t RNA, B−Uncharged t RNA C−5′ -end C− 3′-end

11. Observe the given unit of lac operon and identify its components. A

Repressor RNA polymerase operator complex

mRNA

central dogma of molecular biology. Identify the labellings marked in the diagram and choose the correct alternative.

C z

14. The given diagram represents the

Repressor

(a) A−Regulatory gene, B−Promoter, C−Operator, D−Structural gene (b) A−Regulatory gene, B−Promoter, C−Structural gene, D−Operator (c) A−Regulatory gene, B−Structural gene, C−Promoter, D−Operator (d) A−Regulatory gene, B−Structural gene, C−Operator gene, D−Promoter gene 20Å

12. Carefully

observe the given diagram of double helical structure of DNA.

(a) A−Protein, B−RNA, C−DNA, D−Translation, E−Transcription (b) A−RNA, B−DNA, C−Protein, D−Transcription, E−Translation (c) A−Transcription, B−Translation, C−Translation, D−DNA, E−RNA (d) A−DNA, B−mRNA, C−Protein, D−Transcription, E−Translation

DNA DNA polymerase I polymerase III (removing RNA primer and filling gap)

I. A is responsible for synthesis of DNA strands. II. B are topoisomerases that help stabilise the single stranded DNA. III. D are helicases that reduce the tension caused by unwinding of strand. IV. E are ligases that join and seal DNA fragments. Choose the option with correct statements. (a) I and IV

(b) II and III

(d) Only IV

16. Carefully observe the given diagram of tRNA and consider the statements following it. 3′

A-DNA B-DNA 40 min

C-DNA D-DNA

Base pairs

5′

A C C A B

Variable arm

Generation II

15N-DNA

20 min

RNA primer

3′ 5′

Stahl’s experiment wherein they grew E. coli in N medium initially and then transferred it to growth medium containing normal nitrogen 14 N. After 40 minutes, what combinations of isotopic DNA will be obtained in generation-II offsprings. Generation I 15N-DNA 14N-DNA

5′ 3′

Okazaki fragment

13. Given below is a representation of Meselson and

(a) (b) (c) (d)

the action of various enzymes involved. Read the statements describing the function of these enzymes or proteins involved and identify them correct option.

(b) Only III (d) None of these

15. Consider the given replication machinery showing

Choose the correct pair of statements.

3′ 5′

Now read the statements describing the above diagram. I. The above structure 3.4Å shows that DNA comprises of a sugar 34Å phosphate backbone 10Å on the inside and paired bases on the outside. II. The planes of sugars Minor Major groove groove are right angle to the bases. III. The DNA is a double helical structure running antiparallel. IV. The helix is not regular and forms major and minor grooves. (a) II and III (c) III and IV

A− N-DNA, B− N-DNA, C− N-DNA, D− N-DNA A−14 N-DNA, B−15 N-DNA, C−14 N-DNA, D−14 N-DNA A−14 N-DNA, B−15 N-DNA, C−15 N-DNA, D−15 N-DNA A−14 N-DNA, B−15 N-DNA, C−15 N-DNA, D−14 N-DNA

I. A is the point of attachment of amino acid. II. C recognises and binds to codons in mRNA. III. B contains a sequence of TψC . IV. D is binding site for aminoacyl synthetase. Choose the incorrect pair not identifying the appropriate function for each of the labels A−D. (a) I and II (c) Only III

(b) III and IV (d) None of these

17. Identify the nitrogenous base found in nucleotides,

(a) I and III (c) I and IV

from the structures given below O C

C NH

C C N

mRNA

C O

Initiation site C

N CH

C NH2

process of transcription and carefully read the statements describing it.

C C

(a) (b) (c) (d)

C—CH3

(b) II and III (d) I, III and IV

19. Consider the given diagrammatic representation of

N CH

H2N

NH2

Which of the following statements are incorrect?

NH E

A−Uracil, B−Adenine, C−Thymine, D−Guanine, E−Cytosine A−Uracil, B−Guanine, C−Cytosine, D−Adenine, E−Thymine A−Thymine, B−Adenine, C−Cytosine, D−Guanine, E−Uracil A−Uracil, B−Guanine, C−Uracil, D−Adenine, E−Cytosine

18. Given below is diagrammatic representation of Hershey and Chase experiment, in which he cultured bacteriophages in two different mediums as shown below Bacteriophage Radioactive ( 35S) labelled Protein capsule

Radioactive ( 32P) labelled DNA

I. A is formed by joining of core enzyme and sigma factor. II. Sigma factor remain associated with RNA polymerase throughout the process of transcription of DNA. III. A can start transcription by attaching itself to any site on DNA strand. IV. As the RNA chain grows towards completion, the B dissociates from C to bring about termination. Choose the incorrect statements regarding the process described. (a) I and II (c) II, III and IV

(b) II and III (d) I and IV

20. Carefully observe the following diagram and consider the statements in reference to the process depicted through it.

Infection

Amino acid

P A P

P A

AMP

Blending

tRNA Amino acid– t RNA complex Centrifugation No radioactive ( 35S) detected in cells + Radioactive ( 35S) detected in supernatant

( 35P)

Radioactive detected in cells + No radioactivity detected in supernatant

The conclusions derived from this experiment are I. Only protein coat and not DNA entered the bacterial cell. II. DNA is the genetic material, which is passed from virus to bacteria and not protein. III. DNA is structurally more stable than RNA. IV. The first genetic material on earth was DNA not RNA.

Statements I. The process describes the activation of amino acids during translation. II. A high energy ester bond is formed between carboxyl group of amino acid and 3′ hydroxy group of terminal adenosine of tRNA. III. Amino acyl tRNA synthetase has two separate active sites for recognising both tRNA and specific amino acid. IV. As a result of binding, the amino acid tRNA complex is formed. Choose the correct statements. (a) Only I (c) II, III and IV

(b) I and II (d) All of these

Answers 1. (c) 11. (a)

2. (c) 12. (c)

3. (a) 13. (b)

4. (d) 14. (d)

5. (c) 15. (a)

6. (a) 16. (d)

7. (d) 17. (a)

8. (c) 18. (d)

9. (c) 19. (c)

10. (c) 20. (c)

EARTHW RM 1. Consider the following statements regarding earthworm and choose the option with all correct statements. I. Earthworm is a reddish brown terrestrial invertebrate that inhabits the upper layer of the moist soil. II. They make burrows in the soil by boring and swallowing the soil and live in them. III. They are traced by their faecal deposits that are known as earthworm tracings. IV. Pheretima is the only Indian earthworm. Codes (a) I, II, III

(b) II and III

(d) I and II

2. The structure in earthworm that serves as a wedge to force open cracks in the soil is (a) peristomium (b) prostomium (c) clitellum (d) typhlosole

3. Consider the following statements regarding the morphology of earthworm and choose the incorrect statement. (a) The ventral surface of the body is distinguished by the presence of a dark median mid ventral line (b) Prostomium is a lobe present at the anterior end and serves as a covering for the mouth (c) The body of earthworm is divisible into three prominent regions, i.e. preclitellar, clitellar, postclitellar segments (d) The first body segment of earthworm is called the buccal segment

4. Consider the following structure-location match pairs and choose the incorrect pairs. (a) Spermathecal apertures – Ventrolateral sides of intersegmental grooves, i.e, 5-9th segments (b) Female genital pore – Midventral line of 14th segment (c) Nephridiopores – Surface of the body (d) Buccal segment – First body segment at the posterior-end

AUGUST 2016

BIOLOGY SPECTRUM

5. Consider the figure given below which depicts the lateral view of anterior end of Pheretima. E B

D A C

Identify the parts labelled as A, B, C, D and E. A

(a) Prosto Clitellum mium

Metameres Mouth opening

Peristo mium

(b) Peristo Ring of setae mium

Metameres Mouth opening

Prosto mium

Nephridiopore Metameres Genital opening

Prosto mium

(d) Annuli

Female genital Clitellum aperture

Transverse Peristo groove mium

6. In earthworm setae are present in all segments except (a) Only first segment (c) First, last and clitellum

(b) Only last segment (d) 15th and 16th segment

7. The body of earthworm is divided into 100-120 similar short segments. Match the segments of earthworm’s body given by Column I with their respective structures given in Column II. Column I A. B. C. D.

Segment 5-9th Segment 14th Segment 14-16 Segment 18th

Codes A B C D (a) 1 4 3 2 (c) 2 4 3 1

Column II 1. 2. 3. 4.

Spermathecal aperturs Male genital pore Clitellum Female genital pore

A B C (b) 4 3 2 (d) 1 2 3

D 1 4

Codes A B C D E (a) 4 3 2 1 5 (c) 6 5 4 3 2

8. In each body segment of earthworm except the first, last and clitellum, locomotive structure is present, which is called as (a) nephridiopores (c) annuli

(b) setae (d) prostomium

15. The structures present on the 4th, 5th and 6th segments of earthworm which are responsible for the production of blood cells and haemoglobin that remains dissolved in blood plasma, are known as

single layer known as (b) columnar epithelium (d) compound epithelium

(a) blood glands (c) haeme cavities

11. In earthworm, after the 26th segment, there present

(a) Grinding of soil particles and decaying leaves (b) Storing fats (c) Neutralisation of humic acid present in humus (d) Increasing the effective area of absorption

Codes (a) I and II (c) II and IV

(b) haemopores (d) lymph glands

16. Blood cells of earthworm are (a) exocytic

(b) endocytic

(d) osmotic

17. Which of the following statement is/are incorrect in reference to the blood vascular system of the earthworm? I. Blood vascular system is of open type. II. Smaller blood vessels supply the gut, nerve cord and the body wall. III. Blood glands are present on 6th, 7th and 8th segments. IV. Blood cells are phagocytic.

12. Consider the following statements regarding the alimentary canal of Pheretima and choose the option with all incorrect statements. I. The alimentary canal is a straight tube which runs between 1st to 15th segment of the body. II. A terminal mouth opens into a small narrow tube oesophagus (1-3 segments). III. On the 15th segment, a pair of short and conical intestinal caecae project from the intestine. IV. The stomach extends from 9-14 segments.

F 6 6

Codes (a) Statement I is true and statement II is false. (b) Statement II is true and statement I is false. (c) Both the statements are false. (d) Both the statements are true.

10. Epidermis of the earthworm’s body is made up of a

an internal median fold of dorsal wall called typhlosole. Which among the following alternatives represents the function of typhlosole?

D E 4 5 4 1

process of respiration in earthworm. Select the correct alternative. I. Respiratory exchange in earthworm occurs through the moist body surface into their blood stream. II. Earthworms lack specialised breathing devices.

composed of five layers of cells. Which of the following alternatives represents the correct sequence of layers of body wall in earthworm?

(a) cuboidal epithelium (c) squamous epithelium

A B C (b) 1 2 3 (d) 5 3 2

14. Two statements are given below regarding the

9. The body wall of the earthworm is muscular and

(a) Cuticle ® Epidermis ® Coelomic epithelium ® Circular muscle layer ® Longitudinal muscle layer (b) Cuticle ® Epidermis ® Endodermis ® Columnar epithelium ® Coelomic Epithelium (c) Cuticle ® Epidermis ® Circular muscle layer ® Longitudinal muscle layer ® Coelomic epithelium (d) Cuticle ® Epidermis ® Mesodermis ® Endodermis ® Epithelium

F 6 1

(a) Only I

(b) I and IV

(d) II and III

18. Observe the given figure of closed circulatory system of earthworm and identify A, B, C and D.

Lateral oesophageal hearts

Lateral hearts

A 5

(b) I and IV (d) I, II and III

13. Match the following columns. Column I

Column II

Buccal cavity

9-14th segments

Oesophagus

8-9th segments

C. Gizzard

5-7th segments

D. Stomach

1-3rd segments

Intestine

15th-last segment

Typhlosole

26th segment to 23-25 segments in front of anus

Lateral oesophageal vessel D

Anterior loops

(a) A–Ventral vessel, B–Subneural vessel, C–Commissural vessel, D–Dorsal vessel (b) A–Subneural vessel, B–Ventral vessel, C–Dorsal vessel, D–Commissural vessel (c) A–Dorsal vessel, B–Commissural vessel, C–Subneural vessel, D–Ventral vessel (d) A–Commissural vessel, B–Dorsal vessel, C–Ventral vessel, D–Subneural vessel

19. The excretory organs of earthworm occur as segmentally arranged coiled tubules called nephridia. Which of the following statements regarding nephridia is correct? (a) Septal nephridia are present on both the sides of intersegmental septa of segment 15 to the last that open into intestine. (b) Pharyngeal nephridia are found as three paired tufts in 7th, 8th and 9th segments. (c) Integumentary nephridia remain attached to the lining of the body wall of segment 16-26. (d) The structure of all three types of nephridia differs from each other markedly.

20. In earthworm, nephridium collects the excess of fluid from the (a) septal chamber (b) nephridial chamber (c) coelomic chamber (d) gizzard chamber

24. The cocoons which are produced by gland cells of clitellum are a site for (a) the production of eggs by a female (b) the deposition of mature sperms, egg cells and nutritive fluid (c) the process of copulation (d) the production of factors/chemical responsible for the maturation of gonads

25. The process of fertilisation and development of earthworm occurs within the cocoons. Which of the following statements is false regarding cocoon? (a) Development of Pheretima within cocoon is direct, i.e., there is no formation of larva. (b) Cocoons are produced by the gland cells of glandular tissue present in segments 14-16th. (c) After about 3 weeks of fertilisation, each cocoon produces 2-20 body worms. (d) Cocoons are retained by the earthworm for self-fertilisation.

26. Go through the given figure of reproductive system of earthworm and label A to G.

21. Nervous system of earthworm is represented by ganglia arranged on the ventral nerve cord. Consider the following events and choose the option that states all incorrect events in the formation of a nerve ring. I. Bifurcation of nerve cord in the posterior region (30th and 31st segment). II. Pharynx is encircled by the nerve cord laterally. III. Nerve cord gets itself attached to the subpharyngeal ganglia. IV. Nerve cord joins the cerebral ganglia dorsally. Codes (a) I and II (c) I, II and IV

(b) I and III (d) None of these

22. Match the columns. Column I (Reproductive part)

Column II (Relative location)

Testes

1. 12-18th segment

Vasa deferentia

2. 10-11th segment

C. Accessory glands

3. 12-13th segment

D. Ovary

4. 17-19th segment

Codes A (a) 2 (b) 1 (c) 4 (d) 3

6 7

8 9 B

Testes sac with testes

10 11 12

Vasa differentia

Common prostatic and spermatic duct

18 19

B 1 3 1 1

C D 4 3 2 4 2 3 4 2

23. The function of four pairs of spermathecae that are located in 6-9th segments is (a) storage of spermatozoa during copulation (b) providing a site for fertilisation (c) production of spermatozoa (d) to synthesise factors responsible for the maturation of spermatocytes into spermatozoa

2 3

(a) A–Ovary, B–Spermathecae, C–Spermiducal funnels, D–Prostate gland, E–Accessory gland, F–Ovarian funnel G–Seminal vesicles (b) A–Spermathecae, B–Spermiducal funnels, C–Seminal vesicles, D–Ovary, E–Ovarian funnel, F–Accessory gland G–Prostate gland (c) A–Ovarian funnel, B–Ovary, C–Spermathecae, D–Seminal vesicles, E–Prostate gland, F–Spermiducal funnel G–Accessory gland (d) A–Seminal vesicles, B–Ovarian funnel, C–Ovaries, D–Accessory gland, E–Spermiducal funnels, F–Prostate gland, G–Spermathecae

27. Consider the two statements given below

30. Consider the following structures (Column I) found

regarding the economic importance of Pheretima posthuma and choose the most correct option.

in Pheretima and match them to their respective descriptions (Column II).

Statement I Earthworms increase the fertility of soil. This is called vermicomposting.

Column I (Structures)

Column II (Description)

Statement II Earthworms make burrows in the soil and make it porous which helps in penetration of developing plant roots.

Chemoreceptors 1. Regulation of volume and and receptor cells composition of body fluids

Ovarian funnels

Codes (a) Statement I is true and statement II is false. (b) Statement II is true and statement I is false. (c) Both the statements are true. (d) Both the statements are false.

C. Spermatophores

3. Present at intersegmental septum of 13th and 14th segment

D. Gizzard

4. Sensory cells

5. Pouch of sperms exchanged during mating

28. Earthworm is an economically important animal and called as farmer’s friend. Go through the statements given below regarding the morphology and anatomy of earthworm and choose the option that correctly depicts these as true (T) and false (F) statements. I. The blood vascular system of Pheretima consists of blood vessels, capillaries and heart. II. The sensory system of earthworm has two distinctly marked eyes but does not have touch sensitive organs. III. Epidermis consists of columnar epithelial cells which contain secretory gland cells. IV. Development of earthworm embryos proceeds as Egg ® Larva ® Young worm ® Adult worm. Codes I (a) T (b) F (c) F (d) T

II F F T T

III T F F T

IV F T T F

29. Consider the following statements related to Pheretima and select the correct option stating which ones are true and which are false? I. It exhibits open type of vascular system. II. It lacks speacialised breathing device. III. Typhlosole is responsible for the regulation of volume and composition of body fluids. IV. Earthworms show sexual dimorphism, i.e., male and female animal can be distinguished morphologically. Codes I (a) F (b) T (c) F (d) F

II T T T T

III F F T F

IV T F T F

Nephridia

Codes A B C D (a) 4 3 5 2 (c) 4 2 1 3

E 1 5

2. 8-9th segments

A B C D E (b) 1 2 3 5 4 (d) 5 1 3 2 4

Correct Answers along with NCERT Textbook Reference 1. (d) Key-page-106 2. (b) Key-page-106 3. (a) Key-page-106, 107 4. (d) Key-page-106, 107 5. (b) Key-page-107 6. (c) Key-page-107 7. (a) Key-page-107 8. (b) Key-Page-107 9. (c) Key-page-107 10. (b) Key-page-108 11. (d) Key-page-108 12. (d) Key-page-108 13. (a) Key-page-110 14. (d) Key-page-108 15. (a) Key-page-108 16. (c) Key-page-108 17. (c) Key-page-108 18. (c) Key-page-109 19. (a) Key-page-109 20. (c) Key-page-109 21. (b) Key-page-109 22. (a) Key-page-110 23. (a) Key-page-110 24. (b) Key-page-110 25. (d) Key-page-110 26. (b) Key-page-110 27. (c) Key-page-111 28. (a) Key-page-108-110 29. (d) Key-page-108-110 30. (a) Key-page-108-110

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PRODUCTIVE FACT BITES

MYCOTOXINS ■

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Mycotoxins are non-volatile, relatively low-molecular weight, secondary metabolic products of some filamentous fungi or molds. They may affect exposed persons in a variety of ways. Fungi that produce mycotoxins are referred to as toxigenic fungi. Most of the mycotoxins are produced by species of Aspergillus, Fusarium, Myothecium, Penicillium and Stachybotrys. The kind and amount of toxin produced depend on the fungal strain, the growing conditions and the presence or absence of other organisms. The functions of mycotoxins are ⇒ To eliminate other microorganisms ⇒ To help plant parasitic fungi invade the host tissues ⇒ To contaminate crop in the field, after harvest or during storage. ⇒ To cause health effects in human and livestock populations. ⇒ To show insecticidal, antimicrobial and phytotoxic effects. Over 300 mycotoxins have been identified, produced by some 350 fungal species. The agriculturally most important ones are aflatoxins, fumonisins, patulin, ochratoxins, sporidesmins, trichothecenes, zearalenone. The principle mycotoxins that have been shown to occur naturally are tenuazonic acid, alternariol monomethyl ether, alternariol, altenuene and altertoxin I. The study of mycotoxins known as mycotoxicology originated with the discovery of the aflatoxins in the early 1960s after outbreaks of ‘Turkey-x-disease’. Trichothecenes have been implicated in several natural intoxications, e.g., alimentary toxic aleukia in human beings and a variety of mouldy corn toxicoses of domesticated animals. Aflatoxins are the most biologically potent, economically important and scientifically understood mycotoxins. Aflatoxin B is one of the most potent carcinogens. It is produced by Aspergillus flavus and Apergillus parasiticus. The four major aflatoxins are called B1 , B2 , G1 and G2 based on their fluorescence under UV light (blue or green) and relative chromatographic mobility during thin layer chromatography. Aflatoxins are difuranacoumarin derivatives produced by a polyketide pathway by many strains of Aspergillus flavus and Arpergillus parasiticus. The aflatoxins can damage liver, decrease milk and egg production and suppress immunity in animals consuming low dietary concentrations. The young ones of many species are usually most susceptible to these mycotoxins. Citrinin is obtained by Penicillium citrinum and several species of Aspergillus and Penicillium. It causes yellow rice disease in humans. Ergotamine is produced by Claviceps purpurea and related fungi. It causes vasoconstriction, gangrenous necrosis. It is neurotoxic. The ergot alkaloids are among the most fascinating of fungal metabolites. They are classified as indole alkaloids and are derived from a tetracyclic ergoline ring system.

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Fumonisins are produced by Fusarium moniliforme and F. proliferatum. It causes oesophageal cancer and encephalopathy (in horse). Aspergillus ochraceus and several other species of Aspergillus and Penicillium produce ochratoxins. They are responsible for kidney damage neuropathy in pigs and poultry. Patulin is obtained from Penicillium patulum, Penicillium expansum and Aspergillus clavatus. It causes contact edema and haemorrhage. Sterigmatocystin is produced by Aspergillus versicolor and several other species of Apergillus. It is a hepatocarcinogen. Sporidesmin is obtained from Pithomyces chartarum. It causes facial eczema in sheep and cattle. Penicillium cyclopium produces tremorogens. It causes tremors. Zearalenone is produced by Fusarium graminearum and several Fusarium species. It is responsible for gynaecological disturbances. Alternaria is a common genus with a number of species that can invade crops at the pre and post-harvest stage. They cause considerable loss due to rotting of fruits and vegetables. A. alternata is the most important mycotoxin producing species and occurs on cereals, sunflower seeds, oilseed rape, olives, various fruits, etc. The trichothecene mycotoxin are a large group of mycotoxins that suppress the immunity. Three mycotoxins, i.e., aflatoxins, ochratoxins and sterigmatocystin are known to induce tumours. These may show carcinogenic effects on liver, kidney, urinary system, digestive tract and lungs. Fusarium species grow on the grains of standing cereal crops in wet weather and can lead to the formation of mycotoxins before the grains are harvested. It is estimated that one quarter of the worlds food crops are affected by mycotoxins annually. Mycotoxin production is highly dependent on both natural environmental conditions such as rainfall, ambient temperature, soil type, etc., and human agricultural practices; tillage method, irrigation, level of mechanisation, use of insecticides, etc. A few mycotoxins such as those associated with ergotism are produced exclusively in the field. Aflatoxins can be found in the field before harvest and under certain circumstances the cotamination may progressively increase during post-harvest activities, such as crop drying or in stroage.