Set-I: Past Entrance Papers

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(a) Volvox is a fresh water green hollow ball-like colonial alga. Its colony has a fixed number of cells (500-60000). It is called coenobium.

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(d): Pinus is a monoecious plant, i.e., in Pinus the male and female cones or strobili are borne on the same plant.

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(c) : In Chlamydomonas, zygote divides by meiosis. It exhibits haplontic type of life cycle.

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(c) Needle-like leaves with thick cuticle and sunken stomata are xerophytic adaptations of conifers for tolerating extreme environmental conditions.

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(b) Alginic acid is obtained from brown algae whereas carrageenan is obtained from red algae.

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(a) Sequoia sempervirens is the tallest gymnosperm. The leaves of gymnosperms are well adapted to extremes of climate. This is the reason for gymnosperm to flourish in cold areas where instead of rain, snow is the source of water. Gymnosperms are heterosporous i.e., produce two different kinds of spores-microspores and megaspores. Salvinia is an aquatic pteridophyte.

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(b) The sperms of bryophytes and pteridophytes are flagellated and hence require an external supply of water to reach archaegonia.

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(b) Laminarin and mannitol are food reserves of brown algae or Phaeophyceae. Rhodophycean algae store food in the form of floridean starch.

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(b) In gymnosperms (like Pinus), the male and female gametophyte do not have an independent free living existence. They remain within the sporangia retained on the sporophytes i.e., female gametophyte (within megasporangium) and male gametophyte (within microsporangium).

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(a) Selaginella is a heterosporous pteridophyte. Corralloid roots of Cycas harbour blue green algae like Nostoc, Anabaena and are not a type of VAM (vesicular arbuscular mycorrhiza) which is a symbiotic association with fungus.

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(a) Ectocarpus produces biflagellate gametes. Anabaena is a cyanobacteria and does not reproduce sexually. Spirogyra produces non-flagellated male gamete during conjugation, where entire cell content functions as gamete. Polysiphonia also produces nonflagellated spermatia.

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(c) All species of Chara reproduce sexually and show highly advanced oogamy. The sex organs are the most distinctive features of the Order Charales and are the most complicated among the thallophytes. Male and female gametangia are called antheridia and oogonia respectively. Male fructification (cluster of antheridia) is called globule and the female is nucule. They are borne at the nodes of short branches, globule towards the lower side, and nucule (female structure) towards the upper side.

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(d) Among the bryophytes Sphagnum accounts by far the most important place economically. It is popularly called bog moss or peat moss. It is perennial and its growth continues year after year. Older portions undergo death but do not decompose due to secretion of acid that accounts for the antibacterial and antifungal actions. The increasing mass of dead remains accumulate year after year and form a compact dark coloured mass rich in carbon which is called peat. Peat is used as fuel. Paraffin, acetic acid, peat tar, and ammonia are formed as by-products of peat obtained for industrial uses.

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(a) In oomycetes, like other oogamous organisms female gamete is large and non-motile, while male gamete is small and motile.

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(d) Chlamydomonas has flagellated gametes which are similar or dissimilar in size. In Volvox and Fucus, non-motile female gametes and motile male gametes are produced (oogamy). Spirogyra has gametes that are similar in size (isogamous) and are non-flagellated.

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(b) All species of Chara reproduce sexually and show highly advanced oogamy. The sex organs are the most distinctive features of the Order Charales and are the most complicated among the thallophytes. Male and female gametangia are called antheridia and oogonia respectively. Male fructification (cluster of antheridia) is called globule and the female is nucule. They are borne at the nodes of short branches, globule towards lower side and nucule (female structure) towards upper side.

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(a) Statement (i), (ii) and (iii) are correct. In liverworts and ferns gametophytes are free-living while in fern, sporophytes are free living. Gymnosperms and genera like Selaginella and Salvinia are heterosporous. The sporophyte in mosses are more elaborate than that of liverworts, Pinus is monoecious and heterosporous. Marchantia is dioecious.

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(b) Syngamy is the complete and permanent fusion of male and female gametes to form the zygote. When fertilization occurs outside the body of the organism, this type of gametic fusion is called external fertilization or external syngamy. In majority of algae, external fertilization occurs.

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(a) In Funaria (Bryophyta), Dryopteris (Pteridophyta), and Ginkgo (Gymnosperm) female sex organ archaegonium is formed. Funaria lacks independent sporophyte and vascular tissues while independent gametophyte is absent in Ginkgo.

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(a) In Spirogyra, gametes are non-motile and sexual reproduction takes place by conjugation. Sargassum belongs to Phaeophyceae group of algae. They are commonly called as ‘brown algae’ and contain photosynthetic pigments chlorophyll $a$ and c. Puffballs are Basidomycetes with a stalked rounded structure that sends out puffs of spores, e.g., Lycoperdon oblongisporum. Nostoc is a colonial cyanobacterium. It enriches its habitat with nitrogen by fixing atmospheric nitrogen and also causes water bloom.

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(c) Sphagnum and Funaria belong to Class Bryopsida of Division Bryophyta. They are typically mosses. The plant body has radial symmetry and is essentially leafy.
Salvinia belongs to division Pteridophyta. It has a sporophyte plant body with true leaves, stem and roots. Marchantia belongs to Class Hepaticopsida of Division Bryophyta. They are also called liverworts. The plant body is a dorsoventrally flattened thallus.

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(d) Algae and moss are included in plant kingdom while fungi constitute a separate kingdom. Among them, mosses invariably show diplontic life cycle while others may or may not. Algae and moss are autotrophic while fungi are heterotrophs. But they all show multiplication by fragmentation.

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(d) In majority of the pteridophytes all the spores are of similar kinds; such plants are called homosporous. Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous. The megaspores and microspores germinate and give rise to female and male gametophytes, respectively. The female gametophytes in these plants are retained on the parent sporophytes for variable periods. The development of the zygotes into young embryos takes place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution.

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(b) Cycas is a gymnosperm and Adiantum is a pteridophyte. Cambium and seeds are absent in pteridophytes, while vessels are absent in both of these two groups. Both Cycas and Adiantum resemble each other in having multi-ciliated sperms.

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(b) Salvinia is a heterosporous fern where the reproductive structures are born on the fruiting body sporocarps.
They either bear microsporangia or megasporangia i.e., monosporangiate. Thus the reproductive structures are not born on prothallus rather on specialized sporocarp.

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(d) Equisetum is a pteridophyte and in pteridophytes, the main plant body is a sporophyte which is differentiated into true root, stem and leaves. Gametophytes are small or inconspicuous and free living, mostly photosynthetic thalloid called prothallus.
Riccia is a liverwort and Polytrichum is a moss. The sporophyte in mosses is more elaborate than that in liverworts.
Volvox shows oogamous type of sexual reproduction, i.e., fusion between one large, non motile (static) female gamete and a smaller, motile male gamete. During unfavourable conditions, the slime mould differentiates and forms fruiting bodies bearing spores at their tips. The spores possess true walls. They are extremely resistant and survive for many years, even under adverse conditions.

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(c) Autotrophic nutrition involves manufacture of organic materials from inorganic raw materials with the help of energy obtained from outside sources. It is of two types – chemosynthesis and photosynthesis. The organisms which are able to manufacture their organic food from inorganic raw materials with the help of energy derived from exergonic chemical reactions are called chemoautotrophs. Nitrosomonas and Nitrobacter are chemoautotrophic nitrifying bacteria.

Those organisms who can manufacture organic compounds from inorganic raw materials with the help of solar energy in the presence of photosynthetic pigments are called photoautotrophs. E.g., Nostoc, Chara, Porphyra and Wolffia.

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(d) In gymnosperms, (e.g. Pinus, Cycas, etc.) the male and female gametophytes do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes.

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(d) In bryophytes, the dominant phase of life cycle is gametophytic plant body. In contrast, vascular plants have sporophytic plant body in most of their life cycle and reduced, smaller gametophyte which have smaller sex organs.

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(a) Marchantia is a dioecious plant. Male plants bear antheridiophores and female plants bear archegoniophores. Antheridiophores consists of a stalk and a disc-like portion called receptacle. Archegoniophore is composed of a stalk and disc-like receptacle at its distal end.

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(b) Cycas forms facultative symbiotic association with autotrophic nitrogen fixing cyanobacteria. Cycas provides fix carbon and a stable environment to the cyanobacteria in exchange for fixed nitrogen. These cyanobacteria are endosymbionts and live within the roots of Cycas. In addition to normal roots, Cycas develops specialised symbiotic organs at a young age called pre-coralloid roots which transform into coralloid roots upon successful colonisation by cyanobacteria.

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(a) The given figure is of female thallus of Marchantia (bryophyte) in which A, B, C, and D are archegoniophore, female thallus, gemma cup, and rhizoids respectively.

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(d) Selaginella and Salvinia are advanced pteridophytes.

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(b) The sporophyte in mosses is more elaborate than that in liverworts. The male and female cones or strobili is borne on the same tree in (Pinus). In Cycas male cones and megasporophylls are borne on different trees.

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(a) Majority of algae (eukaryotes) possess a definite cell wall containing cellulose and other carbohydrates. In algal cell wall, different chemical components are present which vary widely among different groups (e.g., xylan, mannan, galactan, alginic acid, silica, agar, pectin, carrageenin, etc.). Cell wall of blue-green algae is made up of micro-peptides (proteins). This micro-peptide is not found in eukaryotic algae.

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(d) Sphagnum is a bryophyte in which dominant phase or plant body is independent and free living gametophyte. The sporophyte is parasitic over gametophyte. In Pinus (a gymnosperm), mustard and castor (angiosperms), the main plant body is sporophytic. Gametophyte is highly reduced and is completely dependent on sporophyte.

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(c) Monoecious plants have separate male and female flowers on the same plant. Pinus have both the male and female cones or strobili on the same tree.

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(c)

A -Selaginella
B – Equisetum
C – Salvinia
D – Ginkgo

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(d) Pteridophytes are known as vascular cryptogams (Gk kryptos = hidden + gamos = wedded). They reproduce by spores rather than seeds. They are the first vascular land plant.
The pteridophyte Equisetum belongs to the Class Sphenophtya. All vegetative parts of it possess vascular tissues (i.e. hadrome equivalent to xylem and leptome equivalent to phloem) organised in definite groups of steles.

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(b) Fucus is a brown algae i.e. belongs to Class Phaeophyta. In this alga the accumulation product of photosynthesis is D-mannitol (a sugar alcohol) and the reserve food material is laminarin.

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(a) Heterospory is the production of spores of two different sizes and of two different developmental patterns. It is the most important evolutionary development in the vascular plants because it has ultimately lead to seed development, which is seen in, Selaginella, Salvinia, Azolla, etc.

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(d) Funaria exhibits gametophytic ( n ) as well as sporophytic (2 n) generation in its life cycle. The gametophytic generation is represented by a short-lived protonema which produces spermatozoids in antheridium of male shoot and egg in archegonium of female shoot. Egg and spermatozoids are fused to form zygote. From zygote diploid sporophyte is produced. The capsule of sporophyte produces haploid spores. Then the haploid gametophyte is produced from the haploid spores. So, the zygote is the only diploid stage in the life cycle. Hence, the life cycle is haplontic life cycle.

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(a) Pinus plant is monoecious i.e. both male and female cone are present in same plant but on different branches. Pinus, with over 100 species, is the largest genus of conifers and the most widespread genus of trees in the Northern Hemisphere.

Pinus are also extensively planted in temperate regions of the Southern Hemisphere. Pines have a relatively rich fossil record.

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(d) In gymnosperm except Order Gnetales (Gnetum ) xylem consist of xylem parenchyma and tracheids with bordered pits but lacks vessels. So, Gnetales are the most advanced among gymnosperms. They lack archegonia in female gametophyte thus showing similarity with angiosperm and act as connecting link between the two.

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(b) In gymnosperm (like Cedrus) the male and female gametophyte do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes i.e., female gametophyte with megasporangium and male gametophyte within microsporangium.

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(d) The sporophyte of pteridophyte produces meiospores inside sporangia, which may be homosporous (e.g., Equisetum, Adiantum, Dryopteris, etc.) or heterosporous (e.g., Salvinia, Selaginella, etc.).

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(c) In gymnosperms, pollen chamber represents the microsporangium in which pollen grains develop. The microspore is generally a globular sac like structure having large number of microspores. The microspores are also termed as pollen grains.

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(d) An elater is a cell (or structure attached to a cell) that is hygroscopic, and therefore will change shape in response to changes in moisture in the environment. Elaters come in a variety of forms, but are always associated with plant spores. In plants that do not have seeds, they function in dispersing the spores to a new location. In the liverworts, elaters are cells that develop in the sporophyte alongside the spores. They are complete cells, usually with helcial thickenings at maturity that respond to moisture content. In most liverworts, the elaters are unattached, but in some leafy species (such as Frullania) a few elaters will remain attached to the inside of the sporangium (spore capsule). The elaters by hygroscopic movement help in spore dispersal.

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(c) Flagellated male gametes are mostly seen lower groups of plants like algae, bryophytes, pteridophytes. It is also seen in certain gymnosperms like Cycas. The bryophytes like Riccia have the male gametes which are biflagellate.

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(d) Algae are a group of chlorophyllous, nonvascular plants with thallose plant body. Different algae show different pigments present in the cell-like chlorophyll – a, b, xanthophylls, carotenes, etc. These pigments provide the base for classification of various groups of algae into different classes. Members of Chlorophyceae possess chlorophyll a, b pigments, Bacillariophyceae contains diatomin pigment whereas that of Phaeophyceae has fucoxanthin, Rhodophyceae has r-phycocyanin and r-phycoerythrin and cyanophyceae has phycobilin pigment.

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(c) In prothallus of vascular cryptogams the antherozoids and eggs mature at different times. The spores on germination gives rise to prothallus. The antherozoids are biflagellated or multiflagellated. The egg is produced inside the venter, water is essential for fertilization and it is always crossfertilization. Self fertilization is prevented.

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(c) The partially decomposed Sphagnum mass accumulates to form compressed mass called peat, which after drying is used as coal. So it is also called peat moss. Sphagnum has the capacity to retain water for long periods and thus it is used to cover plant roots during transportation.

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(a) Conifers belong to gymnosperms. They are seed-bearing plants in which the sporophylls are aggregated to form cones and the seeds develop in exposed state over the surface of megasporophylls. Vascular strand consists of tracheids and sieve cells. Female gametophyte forms archegonia, provides nourishment to developing embryo and later gets transformed into food-laden tissue or endosperm inside the seed. This endosperm is formed before fertilization so it is haploid in nature. It provides nourishment for growth of seedlings at the time of seed germination. Grass is an angiospermic plant and endosperm is produced after fertilization.

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(b) In moss, main plant body is gametophyte while sporophyte is meant for spore dispersal mainly. Hence it is called that the sporophyte is partially parasitic on gametophyte.

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(d) Until 1907, auxospore formation was regarded as asexual process but now it is considered as an act of sexual process. The auxospores may be autogamous, isogamous, anisogamous or oogamous. Their pattern of formation differs in pennate and centric diatoms.

Formation of hormogonia is the common method of reproduction in Nostoc which are produced by accidental breaking of trichome into several pieces. It may also be formed by death and decay of ordinary intercalary cells. Soon, the hormogonium escapes from mucilage and grows into a new filament and then into a new colony.

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(a) Stele is a column containing vascular tissues which is surrounded by pericycle and separated from ground tissue by endodermis.
Siphonostele is medullated protostele or protostele with a central non-vascular pith. Leaf gaps are absent. Siphonostele is of two types :
In Ectophloic siphonostele, central pith is surrounded successively by xylem, phloem, pericycle, and endodermis. In amphiphloic siphonostele there is a central pith and xylem is surrounded on either side by phloem, pericycle, and endodermis. It is found in Osmunda and Equisetum.

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(a) Flagellation is the arrangement of flagella over the body surface of a bacterial cell. Peritrichous flagellation has flagella all over the surface of a bacterial cell e.g. E. coli.
Ginkgo belongs to Order Ginkgoales of gymnosperms. It is called living fossil because it is the single living genus in a big fossilized order. Macrocystis belongs to Class Phaeophyceae. It is the largest perennial alga, about $40-60 \mathrm{~m}$ in size. Wolffia is the smallest flowering plant. Rhizophore is a leafless, colourless, positively geotropic elongated structure that grows down from the point of bifurcation of the stem. It occurs in Selaginella.

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(a) Cycas is an evergreen palm-like plant. The plant body is sporophytic differentiated into root, stem, and leaves, sexual reproduction is of oogamous type takes place by the fusion of distinct male and female gametes. The male and female gametes are formed by the germination of microspores and megaspores which are borne on microsporophylls and megasporophylls. These microspores germinate to form male gametophyte that produces male gametes. The male gametes of Cycas are largest $(300 \mu)$ in nature, visible to the naked eye, oval in form, and top-shaped. It is spirally coiled in the anterior half with thousands of small cilia. After fertilization the ovule is connected into a seed. In the endosperm of the seed lies a well-developed embryo having two cotyledons, a plumule, and a radicle.

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(a) Diversification in plant life appeared due to long periods of evolutionary changes. Algae and bryophytes have thalloid plant body with no differentiation into root, stem and leaves. They had no vascular tissues but later in pteridophytes vascular tissues (xylem and phloem) developed and plant body became differentiated into root, stem and leaves. But the vascular tissues lack vessels and companion cells and they reproduce by spores. In gymnosperms seed habit developed but the seeds are not enclosed inside fruit. In angiosperms vessels and companion, cells are present, flowers are present and seeds are enclosed inside fruits. Thus the path of evolution is from algae to bryophytes to pteridophytes to gymnosperms and finally to angiosperm.

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(a) Angiosperms are highly evolved and well-adapted land plants. They have both vessels and tracheids in xylem for better conduction of water. Roots are modified into taproots, adventitious roots, pneumatophores, etc. to suit the desired climate. Sex organs are highly developed, sporophylls are organized into flowers and the flowers are highly coloured or modified to attract pollinators at different times and places. Insect pollination is more prevalent because it is more efficient and leads to less wastage of pollen grains as compared to wind pollination. So the flowers are made attractive to attract a variety of insects. Seed are more protected as they are enclosed inside a fruit.
All these adaptations have made angiosperms more adaptive in diverse habitats.

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(a) Seed-producing plants belong to spermatophyta. It includes gymnosperms and angiosperms. Seed habit or seed formation originated in gymnosperms. It requires the retention of megasporangium or the only on the parent plant and non-shedding of megaspore, development of integument and in site formation of female gametophyte. All these features developed in gymnosperms and angiosperms. Thallophytes, bryophytes, and pteridophytes lack these features and thus do not reproduce by producing seeds.
Fern and Funaria belong to pteridophytes and bryophytes respectively so they do not reproduce by producing seeds.

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(d) Spirogyra is a freshwater green alga which belongs to Class Chlorophyceae. The sexual reproduction in Spirogyra is called conjugation. It involves the fusion of two morphologically identical but physiologically dissimilar non-ciliated gametes. For development of gametes, some of the cells start to act like male and female gametangia in which the cell contents become separated from the cell wall, shrink and ultimately forms gametes. The fusion of these gametes takes place by scalariform conjugation or lateral conjugation.

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(a) Eichler divided plant kingdom into two subkingdoms – Cryptogamae and Phanerogamae. All plants without flowers and seeds are included in the Sub-kingdom Cryptogamae whereas Phanerogamae includes plants which bear flowers and seeds.
Cryptogams are further classified into three divisions. Thallophyta, Bryophyta and Pteridophyta.
Spore bearing plants such as mosses and ferns belong to cryptogams because instead of reproducing by flowers and seeds they reproduce by means of spores.

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(d) Spermatophyta includes seed bearing plants and this includes gymnosperms and angiosperms. Acacia and sugarcane both are angiosperms. Pinus and Cycas both are gymnosperms. Rhizopus belongs to Kingdom Fungi and Tritcum is an angiosperm. Ginkgo is gymnosperm and Pisum is an angiosperm. So Ginkgo and Pisum correctly represent the grouping spermatophyta.

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(b) In angiosperms presence of vessels is not an universal feature as there are certain angiosperms where vessels are absent e.g., Wintera, Trochodendron etc.
Secondary growth is increase in the girth or diameter of axis (root and stem) of the plant by formation of secondary tissue by the activity of lateral meristem. It occurs in dicotyledons of angiosperms and gymnosperms. But in monocotyledons of angiosperms the primary plant body is complete in itself and doesn’t produce any secondary tissue.
Autotrophic plants are those which synthesise their organic food themselves by the process of photosynthesis. But certain angiospermic plants have heterotrophic mode of nutrition. E.g. Rafflesia, Orobanche, Striga are root parasites.
But double fertilization is universal in all angiosperms. It involves fusion of one male gamete with the egg cell and another male gamete with the diploid secondary nuclei.

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(d) Maize, mint, and peepal are flowering plants or angiosperms but Pinus is a gymnosperm in which seeds are produced but flowers are not produced or seeds are not enclosed in flowers.

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(a) Cycas belongs to Order Cycadales of gymnosperms because it has naked seed. It is not enclosed inside a fruit. It does not have double fertilization and so the endosperm formed is haploid in nature and not triploid. So it is not included in angiosperms as they have ovules (or seeds) produced inside the fruit. This is the main difference between gymnosperms and angiosperms.

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(b) The algal Class Rhodophyceae contains a red pigment ( \(r\)-phycocrythrin) and a blue pigment \((r\)-phycocynin) in the chromatphores.
These pigments can utilize those wavelengths of light (blue-green region of the spectrum, i.e., \(480-520 \mathrm{~nm}\) ) that are not absorbed by chlorophyll. This enables red algae to grow at greater depths than other plants (upto \(300 \mathrm{ft}\). below water). In addition to these, chl. \(a\), chl.\(d\), carotenes and xanthophylls are present.
In phaeophyceae chromatophores are yellowish brown in colour possessing xanthophylls in abundance.
Bacillariophyceae are called ‘diatoms’ due to presence of an accessory brown pigment called ‘diatomin’, other pigments are chl. \(-a\), chl. \(-c\) (but not chl.-b), carotenes and xanthophylls.
In chlorophyceae colouring pigments are just like higher plants, i.e., Chl. \(-a\), Chl.-b, xanthophylls and carotenes.

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(a) A fern plant body is sporophytic ( \(2 n)\) and is differentiated into roots, stems, and leaves. On the ventral surface of leaves, sporangia are borne in a group called sori. Inside the sporangium are present the spores which are formed by reduction division. Thus the spores produced are haploid in nature and germinate to produce a prothallus that represents the gametophytic generation. Antheridium and archegonium are borne on this prothallus. Thus meiosis takes place at the stage of spore formation.

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(a) Gymnosperms are the most primitive seed plants. The plants are generally perennial, woody trees or shrubs. In general, the tallest trees are in gymnosperms e.g., Sequoia sempervirens is \(366 \mathrm{ft}\). in height. The male gametes of Cycas are the largest \((300 \mu)\) in size, they are visible to the naked eye and are oval in form and top-shaped. The ovule of Cycas is also the largest in the plant kingdom.

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(d) Androcytes or antherozoid mother cell of Funaria metamorphoses into a single biflagellate spermatozoid (antherozoids). It is a spirally coiled biflagellate (biciliated) structure.

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(b) In bryophytes the main plant body is gametophytic which is independent and may be thallose (no differentiation in root, stem, and leaves) e.g., Riccia, Marchantia, Anthoceros, etc. or foliose (having leafy axis) e.g. Sphagnum, Funaria, etc. The gametophyte bears the sex organs antheridium and archegonium. Sexual reproduction is of oogamous type. It forms zygote that gives rise to the sporophytic phase. It is differentiated into foot, seta and capsule. The capsule produces spores after meiosis that again gives rise to the gametophytic phase. The sporophyte is partially or full dependent upon the gametophyte and is of shorter duration.

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(a) Algae, bryophyte, and pteridophyte are cryptogams, but out of them algae, and bryophytes are lower cryptogams and do not possess vascular tissue (xylem and phloem), whereas in pteridophytes, vascular tissue system is well developed and so these are higher cryptogams or vascular cryptogams. The term cryptogams mean that these plants reproduce by means of spores and do not produce seeds.
The vascular tissue of pteridophytes is well developed. They contain both xylem and phloem. In xylem, vessels are absent and in phloem companion cells are absent.
So pteridophytes or vascular cryptogams are a group of seedless vascular plants, that have successfully invaded the land and reproduce by means of spores. Gymnosperms are naked seed bearing plants called phanerogams.

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(d) Bryophytes are green photosynthetic and thalloid structures where the plant body root, stems, and leaves. Instead of roots, rhizoids are present for attachment and absorption purposes. They have motile sperms and so they need water for fertilization. Archegonia evolved for the first time in bryophytes in the plant kingdom. It is a flask-shaped structure with swollen base called venter and an upper elongated neck. The venter contains a venter canal cell and an egg cell. It is surrounded by one-celled thick sterile jacket layer.

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(a) Dichotomous branching is characteristic feature of liverworts e.g. Riccia, Marchantia, Pellia, etc. It is a primitive form of branching. It is also called forked branching. In liverworts the thallus is flat and dorsiventral and dichotomously branched. The thallus has a notch at the anterior end. At the base of the notch, there is a growing point consisting of a single apical cell. It divides repeatedly to form two branches of the same size.

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(b) Cycas belongs to Order Cycadales of gymnosperms. Its leaves show circinate vernation i.e. the leaves are coiled in the young stage. The coralloid roots in Cycas arise from the lateral branches of the normal roots and contain blue-green algae like Nostoc and Anabaena. A well-developed flower like that of angiosperms is absent in Cycas. It has compact cones containing microsporophylls and megasporophylls. The megaspores are loosely arranged on the megasporophyll. The male cone is a compact structure. Vessels in xylem are absent and it contains only tracheids for the conduction of water.

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(b) Gymnosperms are the most primitive seed plants. The plants are generally perennial, woody trees or shrubs. In general, the tallest trees are in gymnosperms e.g., Sequoia sempervirens is \(366 \mathrm{ft}\). in height. The male gametes of Cycas are the largest \((300 \mu)\) in size, they are visible to the naked eye and are oval in form and top-shaped. The ovule of Cycas is also the largest in the plant kingdom.

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(c) Ulothrix is a green filamentous alga, belonging to Class Chlorophyceae. The plant body is an unbranched filament consisting of numerous cylindrical cells joined end and end. Under favourable conditions, each cell produces zoospores except holdfast. These zoospores are of two types macrozoospores and microzoospores. The macrozoospores are larger in size and are quadriflagellate and the microzoospores are smaller zoospores which may be biflagellate or quadrifagelleate. Under unfavourable conditions, nonmotile mitospores called aplanospores are produced. Sexual reproduction in Ulothrix is of isogamous type. The isogametes fuse to form a quadriflagellate zygospore which after meiosis forms 16 aplanospores or zoospores.

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(b) Bryophytes are called amphibians of the plant kingdom because they complete their vegetative phase on land but water is necessary for their reproductive phase. Water helps in the maturation and dehiscence of sex organs in bryophytes. It also helps in the transfer of sperms to the archegonium that makes water essential for the completion of the life cycle of bryophytes.

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(a) Walking fern is named so because when its leaf tips come in contact with soil, form new plants as adventitious buds develop at leaf tips. This helps in the spread of fern over a large soil surface and thus the name ‘walking fern’.

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(d) Transfusion tissue is a specialized tissue present on either side of midrib in between the palisade and spongy tissues of the leaf of Cycas and also in Pinus leaf at the sides of the sclerenchymtous region. It is made of horizontally arranged tracheids. These supply water and minerals to mesophyll tissue up to margins so that the mesophyll cells can carry out photosynthesis. It is of two types primary transfusion tissue present next to the midrib bundle and secondary transfusion tissue that runs up to margins of the leaf. In Pinus it consists of tracheids and albuminous cells.

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(b) Heterospory means the production of two different sizes of spores-megaspore and microspore. All bryophytes are homosporous. Heterospory originated in some pteridophytes like Selaginella. It is commonly called club moss or spike moss. Its leaves contain a flap-like outgrowth at the base on the adaxial side called ligule. The leaves are of two types – megasporophyll bearing megasporangia and microsporophylls bearing microsporangia. The megasporangia contain four large megaspores and the microsporangia contain a large number of small microspores. Thus Selaginella is heterosporous. In some species of Selaginella the embryo remains attached to the sporophyte for a long time and it is the habit towards seed habit.

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(a) Chlorella is a unicellular green alga that contains high percentage of proteins, lipids, and most of the known vitamins (carotene, riboflavin, vitamin \(\mathrm{B}_{12}\), choline, etc) and grows more quickly than Porphyra, so scientists are doing research to obtain food from it. The nutritional value is comparable to the mixture of soybeans and spinach.

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(c) Ulothrix belongs to Class Chlorophyceae of Division Thallophyta. The plant body consists of an unbranched filament, consisting of numerous cylindrical cells joined end to end. It is heterothallic and sexual reproduction is of isogamous type. Except holdfast, each cell of the filament can give rise to 64 to 128 gametes. The gametes are similar in size, shape, and other features. So these gametes are called isogametes. When two gametes of \((+)\) and ( \(-)\) strain come together they fuse and a quadriflagellate zygospore is formed.

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(a) Bryophytes and algae are both autotrophic, plant body thallus like, and devoid of vascular tissues. Instead of roots, rhizoids are present for attachment and absorption purposes. Both algae and bryophytes have motile sperms and need water for fertilization. But bryophytes can be separated from algae because archegonium originated for the first time in bryophytes in the plant kingdom. It is a flask-shaped structure with swollen base called venter and upper elongated neck. The venter contains a venter canal cell and an egg cell. It is surrounded by one-celled thick sterile jacket layer. In algae sex organs are non-jacketed and unicellular.

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(a) The Division Bryophyta includes three classes Hepaticopsida, Anthocerotopsida, and Bryopsida. The members of Hepaticopsida and Anthocerotopsida have a thallose plant body which is dorsiventrally differentiated and dichotomously branched. On the ventral surface unicellular or multicellular rhizoids are present. The member of Bryopsida have a main plant body that has a leafy gametophore made up of an axis having spirally arranged leaves. The rhizoids are multicellular and branched e.g. Sphagnum, Funaria, Riccia, Anthoceros. So only few member of bryophytes have leafy gametophytes.

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(a) Brown algae are the members of the Class Phaeophyceae. Their chromatopores are ellipsoidal or discoid. They contain chlorophyll \(a\), chl \(c, \beta\) – and \(c\)-carotenes and xanthophyll pigments (e.g., lutein, flavoxanthin, violaxanthin). They also contain large amount of a brown pigment – fucoxanthin which masks the green colour of chlorophyll pigment. This gives characteristic brown colour to these plants, hence the name brown algae.

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(d) Gymnosperms originated about 200 million years ago and were dominant species at that time. However, most of the members have become extinct now and only a few living forms are known today. There are around 900 living species of this group.

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(d) Bryophytes are called amphibians of the plant kingdom because they complete their vegetative phase on land but water is necessary for their reproductive phase. Water helps in maturation and dehiscence of sex organs in bryophytes. It also helps in the transfer of sperms to the archegonium that makes water essential for the completion of the life cycle of bryophytes.

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(b) Marchantia is a liverwort in which the sex organs are borne on disc-shaped 8-lobed receptacles borne at the tip of vertical gametophores. Sperms are attracted to opened archegonia by proteins and \(\mathrm{K}^{+}\) salts. Fertilization produces a parasitic sporophyte made of the foot, seta, and capsule. The capsule encloses sporocytes and elaters. These elaters show twisting movements due to spiral bands of thickenings and this leads to liberation and dispersal of spores. In Riccia elaters are absent and in Funaria peristome teeth help in spore dispersal.

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(b) Gymnosperms show distinct alternation of generations. The sporophytic phase is dominant. The sporphyte is differentiated into root, stem, and leaves. So the number of chromosomes in a leaf cell is diploid \((2 \mathrm{n}),(2 \mathrm{n}=16)\). Double fertilization is absent in gymnosperms. The endosperm develops before fertilization directly from the megaspore. So the number of chromosomes in endosperm will be \(8(n=8)\).

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(a) Pyrenoids are found in many bryophytes and algae. They are small, spherical bodies found in the cytoplasm of a plant cell. They are rich in proteins and are surrounded by a starch sheath.

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(b) Funaria is known as common moss or green moss. The plant body is foliose that consists of stem axis which bears many leaves and instead of roots, rhizoids are present. It is gametophytic (n) and independent.
It bears antheridia and archegonia on the same plant but on different branches.
After fertilization the zygote \((2 n)\) divides to form the sporophyte which consists of foot, seta, and capsule. The basal foot is embedded in the apex of female branch. It absorbs nutrients and provides support for the sporophyte. Inside the capsule haploid spores are produced as a result of meiosis. Thus again the gametophytic phase starts. So the gametophytic phase is the dominant phase of the life cycle of Funaria.

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(b) Nostoc belongs to Cyanophyceae. In this entire class sexual reproduction is completely absent. It reproduces by colony formation, hormogonia, akinetes, heterocysts, and endospres. However genetic recombination has been observed. It may be probably through transformation or conjugation.
The other three algae- Spirogyra, Ulothrix, and Volvox belong to Chlorophyceae. The members of this class show isogamous, anisogamous, and oogamous type of sexual reproduction.

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(d) Bryophytes and pteridophytes both have alternation of generation. The gametophytic phase is dominant in bryophytes whereas in pteridophytes it is short-lived. Sex organs are embedded is some members of bryophytes and pteridophytes. Sperms are flagellate and so water is required for fertilization. Sterile jacket is present around the sex organs for protection. Archegonium appeared for the first time in bryophytes in the plant kingdom. It is a flask-shaped structure. It has swollen basal portion called venter and an upper elongated neck. The venter has egg cells and venter canal cells. There are 4-6 vertical rows of neck cells enclosing neck canal cells in bryophytes. The archegonia have a short neck made of four rows of vertically elongated cells that encloses four neck canal cells in pteridophytes.

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(c) Some algae withstand or tolerate a very high temperature and these are often called thermal algae. Such forms are known to grow up to \(85^{\circ} \mathrm{C}\), nearly boiling water. Their cell wall is hard and protective. A typical cell wall of algae consists of two nonliving layers. The inner layer is firm consisting of microfibrils and the outer layer is gelatinous and amorphous. Various polysaccharides such as cellulose, pectin, and mucilage constitute the typical cell wall. The mucilage covering of the cell is thick and dense and is called the sheath. This sheath holds the cells in colonies together and is having water-absorbing and water-retaining capacity. It thus protects them under desiccating conditions. Thus they are able to survive under high temperature.

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(d) Nostoc belongs to Cyanophyceae. In this entire class sexual reproduction is completely absent. It reproduces by colony formation, hormogonia, akinetes, heterocysts, and endospores. However genetic recombination has been observed. It may be probably through transformation or conjugation.
The other three algae- Spirogyra, Ulothrix, and Volvox belong to Chlorophyceae. The members of this class show isogamous, anisogamous, and oogamous type of sexual reproduction.

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(a) Mature ovule with embryo constitutes seed. The seed is covered with hard seed coat. The outer layer of the seed coat is testa (from the middle stony layer). Testa encloses a brown, thin membranous tegmen (from the inner fleshy layer). The tegmen surrounds fleshy endosperm.
Inside the endosperm is present in the embryo. At maturity of seed, a thin layer of ovuliferous scale fuses with testa to form a wing (i.e., seeds are winged) which helps in the dispersal of seed.