Directions: In the following questions, a statement of assertion is followed by a statement of reason.
Mark the correct choice as:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
Q.1. Assertion : Algae and fungi are grouped in thallophyta.
Reason : Algae and fungi show no differentiation in thallus.
Answer
Answer: (a) On the basis of (i) Thallus like non-vascular plant body.(ii) Simple, unicellular non-jacketed sex organs and
(iii) No embryo development after gametic union, the algae and fungi have long been grouped together in thallophyta. The algae and fungi are the result of parallel development and do not indicate any phylogenetic relationship.
Q.2. Assertion : Chlorella could be utilised to keep the air pure in space vehicles.
Reason : The space travelers feed on Chlorella soup.
Answer
Answer: (b) Chlorella could be utilised to keep the air in space vehicles pure and supply food in space stations and prolonged space flight trips. The space travellers could feed on Chlorella soup. It is nourishing but not appetizing food.Q.3. Assertion : Members of phaeophyceae vary in colour from olive green to various shades of brown
Reason : Phaeophyceae possess chlorophyll a, c, carotenoids and xanthophylls. [AIIMS 2006]
Answer
Answer: (a) Phaeophyceae possesses chlorophyll a, c, carotenoids and xanthophylls. Members of phaeophyceae show variations in colour from olive green to different shades of brown depending upon the amount of xanthophyll pigments.Q.4. Assertion: Rhodophyta is red in colour of due to abundant formation of r-phycoerythrin.
Reason: r-phycoerythrin is able to absorb blue green wavelength of light and reflect red colour.
Answer
Answer: (a) The red colour of Rhodophyta is due to abundan of the pigment r-phycoerythrin. Phycoerythrin absorbs blue green wavelengths of light and reflects red light where a imparts red colour to algae.Q.5. Assertion: The colour of brown algae varies from olive green to brown.
Reason: In brown algae, fucoxanthin is responsible for colour variation.
Answer
Answer: (b) Brown algae show a range of colour from olive green to various shades of brown depending upon the amount of fucoxanthin the xanthophyll pigment, present in them.Q.6. Assertion: Plant body is usually grass green in colour in Chlorophyceae.
Reason: Members of Chlorophyceae possess chlorophyll a, c, carotenoids and xanthophyll.
Answer
Answer: (c) Chlorophyceae are commonly called green algae. The plant body may be unicellular, colonial or filamentous. They are usually grass green in colour due to the dominance of pigments, chlorophyll a and b.Q.7. Assertion: Chlorella and Spirulina are used as a food supplement by space travellers.
Reason: These are unicellular algae.
Answer
Answer: (b) Unicellular algae Chlorella and Spirullina are rich source of proteins and hence are used as food supplement by space travellers.Q.8. Assertion: Each group of algae show predominance of one pigment.
Reason: The algae are classified on this basis.
Answer
Answer: (a) The colour of the algal thallus is due to the presence of definite chemical compounds in their cells and varies in different classes of algae. These are called pigments. Each pigment has its own characteristic colour. The particular colour of an alga is due to the predominance of one pigment in a combination of several others. Each group of algae has its own particular combination of pigments and a characteristic colour which is not found in other algal groups.Q.9. Assertion: Only red algae are able to flourish at the great depths of sea.
Reason: Red algae has the pigments rphycoerythrin and r-phycocyanin.
Answer
Answer: (a) The red algae flourish and occur in abundance at great depths of sea where other plants do not. The sunlight, as it penetrates water, portions of spectrum such as red, orange, yellow and green light rays which are of short wavelengths are filtered out. Only the blue and violet rays of greater wavelengths remain and penetrate to great depths. The green pigment chlorophyll cannot trap these light rays of great wavelength and the green plants are thus, unable to carry on photosynthesis at these depths. The red pigment r-phycoerythrin and a blue pigment g-phycocyanin which are characteristic pigments of all the red algae, can utilize wavelengths of light (blue and violet rays) not absorbed by chlorophyll.Q.10. Assertion: Carpogonium of red algae bears trichogyne.
Reason: Trichogyne helps in reproduction.
Answer
Answer: (a) The carpogonium (female sex organ) in one of the simplest red alga Nemalion, consists of a swollen base containing the female nucleus and an elongated terminal hairlike structure called the trichogyne. During fertilization, the spermatium (male gamete) discharges its contents into the latter. The spermatium nucleus migrates downwards to fuse with the egg nucleus in the basal swollen part of the carpogonium. Soon after fertilization, the trichogyne disintegratesQ.11. Assertion: Spirogyra is slippery to touch.
Reason: Spirogyra consists of a gelatinous sheath.
Answer
Answer: (a) The outermost portion of pectose changes into pectin in Spirogyra. The latter dissolves in water to form a gelatinous sheath which is slimy. It envelopes the entire filament. This makes filament slippery to touch.Q.12. Assertion: Isogamy is a primitive type of sexual reproduction.
Reason: The gametes are of different sizes.
Answer
Answer: (c) The fusing gametes in the lower forms of algae are similar in size, structure and behaviour. They are indistinguishable with respect to sex. Such gametes are called isogametes. Sexual reproduction involving the fusion of isogametes is termed isogamous. It is a primitive type of sexual reproduction.Q.13. Assertion: Chlorella could serve as a potential source of food and energy.
Reason: Chlorella, when dried, has 15% protein, 45% fat, 10% carbohydrate, 20% fibre, and 10% minerals and vitamins.
Answer
Answer: (c) Chlorella could serve as a potential source of food and energy because of its photosynthetic efficiency. When dried, it has about 45% protein, 20%, fat, 20% carbohydrate, 5% fibre and 10% minerals and vitamins.Q.14. Assertion: Spirogyra shows haplontic life cycle.
Reason: Zygotic meiosis occurs in Spirogyra.
Answer
Answer: (a) Haplontic life cycle is characterized by a haploid thallus and zygotic meiosis. It is also called as haplobiontic because only a single type of free living individual is involved in the life cycle. Spirogyra shows haplontic life cycle and therefore, it shows zygotic nucleus as well.Q.15. Assertion: Red algae contributes in producing coral reef.
Reason: Some red algae secrete and deposit calcium carbonate on their walls.
Answer
Answer: (a) In some species of red algae, the cell walls become hardened with calcium carbonate. These algae are hence, important for the formation of coral reefs. Coral reefs are formed through the accumulation of calcareous exoskeletons of coral animals, calcareous red algae and molluscs. They form the foundation of reefs by secreting a calcium carbonate skeleton and provide protection for the coral polyps. Calcium carbonate is continuously secreted by the coral colony.Q.16. Assertion: In rhodophyceae, the cell wall is made of cellulose.
Reason: The flagella number is two in class Rhodophyceae.
Answer
Answer: (c) Flagella is absent in class Rhodophyceae.Q.17. Assertion : Red algae contributes in producing coral reefs.
Reason : Some red algae secrete and deposit calcium carbonate over their walls.
Answer
Answer: (a) Red algae generally grow attached to rocky stones. Some deep water red algae are calcareous and build up hard stony thalii responsible for the production of lime stones and coral reefs.Q.18. Assertion: Only anisogamous type of reproduction is seen in algae.
Reason: Gametes can never be non-flagellated in algae.
Answer
Answer: (a) In algae, sexual reproduction takes place by fusion of two gametes. These gametes can be flagellated and similar in size (Chlamydomonas) or non-flagellated (nonmotile) but similar in size (Spirogyra). Such reproduction is called isogamous. Fusion of two gametes that are dissimilar in size, as in some species of chlamydomonas is termed as anisogamous. Fusion between one large, non-motile female gamete and a smaller, motile male gamete is termed oogamous.Q.19. Assertion: The peristome is a fringe of teeth like projections found at the mouth of the capsule.
Reason: It may be of two types nematodontous and orthodontus.
Answer
Answer: (b) The peristome teeth are present at the mouth of capsule. The teeth may be solid cellular tissue or composed only of the thickened portions of the cell walls of adjacent cells. When the teeth of peristome are solid structures composed of bundles of dead cells, it is termed nematodontous peristome. It is found in Polytrichum, Pogonatum and Tetraphis. If peristome composed of thin, membranous, transversely barred teeth, each tooth is made up of the thickened portions of the cell walls of adjacent cells. Such a peristome is called orthodontous.Q.20. Assertion: Mosses are of great ecological importance.
Reason: They prevent soil erosion by forming dense mat on the soil.
Answer
Answer: (b) Mosses and lichens are the first organisms to colonise rocks and hence, are of great ecological importance. They cause decomposition of rocks making the substrate suitable for the growth of higher plants. Mosses form dense mats on the soil, and reduce the impact of falling rain and prevent soil erosion.Q.21. Assertion : Mosses are evolved from algae.
Reason : Protonema of mosses is similar to some green algae.
Answer
Answer: (a) According to some botanists, mosses originated from algae. Protonema of mosses is similar to certain algae.Q.22. Assertion: In mosses, spores are contained within the capsule.
Reason: The spores are formed by mitotic division in mosses.
Answer
Answer: (c) In mosses, vegetative reproduction takes place by fragmentation and budding in the secondary protonema. The zygote develops into a sporophyte after fertilisation and consists of a foot, seta and capsule. The sporophyte in mosses is more elaborate as compared to that in liverworts. The capsule contains spores. Spores are formed after meiosis and develop into new gametophyte.Q.23. Assertion: Bryophytes are claimed to be terrestrial amphibians.
Reason: They require an external layer of water on the soil surface for their existence.
Answer
Answer: (a) Bryophytes require an external layer of water on the soil surface for their existence and thus are called terrestrial amphibians. The external supply of water is required for>br> (a) dehiscence of antheridia and archegonia(b) swimming of male gametes to reach archegonia
(c) protection from transpiration and desiccation as the plant body is not covered by cuticle
(d) supply of water to all plants through capillarity in the absence of vascular tissues.
Q.24. Assertion: Bryophytes and tracheophytes have an embryo stage in their life cycle.
Reason: Embryophyta are terrestrial plants.
Answer
Answer: (b) Bryophytes and tracheophytes possess an embryo stage and are collectively called embryophyta. They are terrestrial plants. Bryophytes are nonvascular while tracheophytes possess vascular tissue.Q.25. Assertion: The sex organs in bryophytes are jacketed.
Reason: Bryophytes are land plants.
Answer
Answer: (a) Bryophytes are a group of non-vascular land plants. The sex organs in the bryophytes are multicellular and jacketed. The jacket of sterile cells around the sperms and eggs is an adaptation to a land habitat. It protects the sex cells against the drying effects of air.Q.26. Assertion: Bryophytes are mostly land dwellers.
Reason: Water is necessary to complete their life-cycle.
Answer
Answer: (b) Majority of the bryophytes are land dwellers and inhabit damp, shaded and humid localities. A few of them live in or float on water. The bryophytes cannot carry on their reproductive activities without sufficient moisture. Presence of water is necessary.Q.27. Assertion: The bryophytes exist in two phases gametophyte and sporophyte.
Reason: The sporophyte is nutritionally independent.
Answer
Answer: (c) The bryophytes have evolved a life which comprises of two phases-gametophyte and sporophytes. The gametophyte (haploid) is concerned with sexual reproduction and constitutes the most conspicuous, nutritionally independent phase in the life cycle. The sporophyte is partly or wholly dependent on the gametophyte for nutritional purpose.Q.28. Assertion: Bryophytes, unlike thallophytes, show formation of embryo.
Reason: The embryo gives rise to gametophyte of bryophytes.
Answer
Answer: (c) In thallophytes (algae and fungi), the formation of embryo is absent. In bryophytes, the zygote, on germination, does not produce the gametophyte plant. It undergoes segmentation to form an embryo. The embryo (diploid) by further segmentation and differentiation gives rise to sporophyte. The sporophyll obtains its nourishment directly from the parent gaemtophyte to which it is organically attached.Q.29. Assertion: Archegonium is the female sex organ in bryophytes.
Reason: Algae also possess the archegonium.
Answer
Answer: (c) Archegonium is the female sex organ of the bryophytes. It appears for the first time in the liverworts and mosses and continues in the pteridophytes. Archegonium is absent in thallophtes (algae and fungi). Sex organs in them are male gametes and female gametes.Q.30. Assertion: Bryophyte has an independent embryo.
Reason: The zygote of thallophyte is dependent.
Answer
Answer: (d) In bryophytes, the zygote, on germination, does not produce the gametophytic plant. It undergoes segmentation to form an embryo. But the embryo formation and its development to sporogonium and sporophyte are dependent on gametophyte plant as the sporophyte is dependent on the gametophyte for nutrition. They organically remain attached to the gametophytic plant. In algae, the zygote is independent and it does not form the sporophyte.Q.31. Assertion: Liverworts fail to spread to a new locality through fragmentation.
Reason: Gemmae are helpful in propagating liverworts in different locality.
Answer
Answer: (b) Fragmentation leads to an increase in the number of plants in a locality but it does not permit the spread of the plant to an entirely new locality. Gemmae are easily carried as they are small and sufficiently buoyant. They spread by water and wind currents to new habitats when detached, where each grows into a new individual immediately.Q.32. Assertion: Sperms of Riccia are biflagellate.
Reason: The sperms can swim.
Answer
Answer: (a) Each sperm of Riccia is a minute, slender and curved structure. It bears a pair of whiplash flagella at its anterior end. The sperms do not leave the antheridium until enough moisture is present that allow them to swim about.Q.33. Assertion: Among the liverworts, the sporogonium of Riccia is the simplest.
Reason: Sporophyte consists of capsule only.
Answer
Answer: (a) The sporogonium (capsule) of Riccia is the simplest among the liverworts. It lacks the foot and the seta. Elaters are absent. Unlike other liverworts, in Riccia, the embryo, sporogonium and spore mother cells develop no chloroplasts. Thus, no photosynthesis occurs there. The sporophyte is totally dependent upon the gametophytic thallus.Q.34. Assertion: In Funaria, the young stem is photosynthetic.
Reason: It contain hydroids.
Answer
Answer: (b) The cortical cells in young stems of Funaria, contain chloroplasts, and thus, they are photosynthetic. The central cylinder forms the core of the stem. It consists of vertically elongated, thinwalled, narrow, compactly arranged cells lacking protoplasm. These thin walled, elongate, dead cells with non-lignified walls are commonly called as hydroids.Q.35. Assertion: Funaria multiplies vegetatively by means of bulbils.
Reason: Bulbils and tubers are two distinct structures.
Answer
Answer: (c) In some mosses, the formation of small, underground resting, bud-like structures called the tubers has also been reported. Formerly, these underground bud-like structures were called the bulbils. The tubers develop singly on stem, leaves and rhizoids as small, spherical storage organs containing starch. These serve as means of perennation and enable the plant to survive over periods unfavourable for vegetative growth.Q.36. Assertion: In Funaria, gemmae formation occurs in unfavourable condition.
Reason: The gemmae form on the stem and leaves.
Answer
Answer: (b) In Funaria, the gemmae develop on the stem and leaves of the gametophore at the onset of conditions unfavourable for growth or during injury. These detached gemmae directly develop into new leafy gametophores under conditions favourable for vegetative growth.Q.37. Assertion: In Funaria is monoecious.
Reason: Cross fertilization occurs in Funaria.
Answer
Answer: (b) Funaria is monoecious. The antheridia (male sex organ) are formed at the summit of a relatively small, main leafy shoot which develops first from the parent plant. The female branch arises later as a lateral outgrowth from the base of the parent male shoot. When the two kinds of the sex organs are borne in separate clusters on two distinct branches of the same plant, the arrangement is called monoeciousQ.38. Assertion: In Funaria, the antheridia are projected from surface.
Reason: Its antheridial cluster is surrounded by perigonial leaves.
Answer
Answer: (b) In Funaria, the antheridia project from the surface of the receptacle and are aggregated to form a cluster. The leaves surrounding the antheridial cluster are known as the perigonial leaves. The antheridial cluster with the surrounding perigonial leaves is called the perigonium.Q.39. Assertion: Mosses are used as indicators of pollution.
Reason: They absorb metals.
Answer
Answer: (a) Rubling and Tyler (1979) showed that air dried mosses can absorb metals. The accumulation of heavy metal cations in mosses enables them to be used as pollution indicators.Q.40. Assertion: Bryophytes and pteridophytes contain well-developed antheridia.
Reason: Biflagellate sperms are formed by their antheridia.
Answer
Answer: (d) In bryophytes, antheridia are well developed and often possess a stalk. In pteridophytes, antheridia are less developed and are generally devoid of a stalk. Pteridophytes have multiflagellate sperm formed from androcyte cell of antheridium. Bryophytes have biflagellate sperm.Q.41. Assertion: In Liverworts, both male and female sex organs may be present on same thalli or different thalli.
Reason: A sporophyte is formed from the zygote which is differentiated into foot, seta and capsule.
Answer
Answer: (b) In Liverworts, antheridia(male) are produced on antheridiophore and archegonia(female) are borne on special stalked structure called archegoniophore. Both male and female sex organs may be present on same thalli or different thalli. Sporophyte is formed from the zygote which is differentiated into foot, seta and capsule.Q.42. Assertion: Bryophytes are known as the amphibians of plant kingdom.
Reason: They are found in swamps and the areas where land and water meet.
Answer
Answer: (b) Bryophytes are the dwellers of transitional habitat between the aquatic and terrestrial habitats. It is represented by the swamps and the areas where water and land meet. Bryophytes usually grow in amphibious situation and cannot complete their life cycle without external water.Q.43. Assertion: Zygote produces a multicellular sporophyte in pteridophytes.
Reason: The dominant phase in life cycle of pteridophytes is sporophyte.
Answer
Answer: (b) Gametophytes bear male and female sex organs called antheridia and archegonia, respectively in pteridophytes. Water is required for transfer of the male gametes released from the antheridia, to the mouth of archegonium. Fusion of male gamete with the egg present in the archegonium results in the formation of zygote. Zygote thereafter produces a multicellular welldifferentiated sporophyte, the dominant phase of the pteridophtyes.Q.44. Assertion: Selaginella and Salvinia are homosporous.
Reason: In Selaginella and Salvinia, similar kind of spores are produced .
Answer
Answer: (d) All the spores are of similar kinds in majority of the pteridophytes; such plants are called homosporous. Genera like Selaginella and Salvinia produce two kinds of spores i.e. macro (large) spores and micro (small) spores, hence, are known as heterosporous.Q.45. Assertion: The sorus of Pteridium is of coenosorus type.
Reason: Pteridium lacks sori.
Answer
Answer: (c) The sporangia of Pteridium are not grouped together in small seprate sori, but the sorus is continuous along the under margin of the pinnules, often for considerable distances. This type of sorus is known as continuous linear sorus (coenosorus).Q.46. Assertion: Coenosorus lacks true indusium.
Reason: Indusium covers sori.
Answer
Answer: (b) Indusium is an membranous epidermal outgrowth covering the sori in some ferns. The coenosorus is surrounded by two well formed indusial lips, between which the receptacle lies. The outer indusial lip is welldeveloped and is formed by the reflexed margin of the pinnule, which overlaps the coenosorus and its sporangia. This is commonly called the false indusium.Q.47. Assertion: The scales which cover young rhizome and leaves of Dryopteris are called ramenta.
Reason: Pteridium lacks ramenta.
Answer
Answer: (b) In Dryopteris, young rhizome and leaves are covered with dry, brown, chaffy scales known as ramenta. In Pteridium, the rhizome and the leaves especially while young, are covered by a felt of simple hairs, and the scales are conspicuously absent.Q.48. Assertion: The scale leaves present on the long shoots are called cataphylls.
Reason: Cataphylls lack mid rib.
Answer
Answer: (d) The scale leaves are present both on the long and dwarf branches. They fall off as the branches mature. The scale leaves on the dwarf shoots are called the cataphylls and possess a distinct midribQ.49. Assertion: Water is required for fertilization process in ferns.
Reason: Malic acid of archegonial neck attracts antherozoids.
Answer
Answer: (c) In ferns, fertilization usually takes place if the prothalli are watered from above as they would be by rain in the ordinary course of nature. They possess flagella for swimming towards archegonia through water. The discharged matter at the mouth of the opened archegonial neck probably contains some chemical substance, e.g. malic acid, which by positive chemotaxis attracts the free swimming antherozoids, that penetrate the neck and reach the ovum which is deeply seated.Q.50. Assertion: Sporophytes of pteridophyta are dominant individuals.
Reason: They do not show the formation of true root.
Answer
Answer: (c) In the pteridophytes, the sporophyte gains physiological independence and develops into the dominant, typically photosynthetic phase of the life cycle. It is organized into stem, leaves and roots. Psilophyta (a pteridophyte division) lack true roots.Q.51. Assertion: Adiantum caudatum is called walking fern.
Reason: It can reproduce by its leaf tips.
Answer
Answer: (c) Leaf tips of Adiantum caudatum, develop adventitious buds for vegetative propagation. Leaf tip when reaches the ground, develops into new plant, therefore, it appears that the plant is walking.Q.52. Assertion : Pinus displays the alternation of generations.
Reason : The gametophyte is dependent upon the sporophyte phase.
Answer
Answer: (b) Pinus show alternation of generations. The sporophyte phase is of long duration and is represented by the huge pine tree, which bears the staminate and ovulate cones since meiotic divisions occur at the same time of the differentiation of the pollen grains and megaspores.Q.53. Assertion : Conifer trees produce a large quantity of wind borne pollen grains.
Reason : The pollen grains have wings.
Answer
Answer: (a) In pinus, a conifer tree, the microspores are produced by microsporogenesis in microsporangium. Each microsporangium has an inner nourishing layer known as tapetum. A large number of dusty and two winged microspores are present. On maturity, the microsporangium wall bursts and microspores are released in the air which is called “shower of sulphur.”They are dispersed by wind due to presence of wings.Q.54. Assertion: Gymnosperms do not produce fruit.
Reason: Ovules of gymosperms are enclosed within the ovaries.
Answer
Answer: (c) The gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed, before and after fertilisation as well. The seeds that develop post-fertilisation, are not covered or are naked. After fertilization, zygote develops into an embryo and ovules into naked seeds.Q.55. Assertion: Gametophyte is dominant in diplontic life cycle.
Reason: In diplontic life cycle, free living sporophyte is absent.
Answer
Answer: (d) The diploid sporophyte is the dominant, photosynthetic and independent phase of the plant gametophyte in diplontic lifecycle. It is highly reduced and is retained within sporangia.Q.56. Assertion: In gymnosperms, stomata are found on the surface of leaves.
Reason: Cuticle of leaves is thin in gymnosperms.
Answer
Answer: (d) In gymnosperms, the leaves are welladapted to withstand extreme conditions of temperature, humidity and wind. The needle -like leaves reduce the surface area. Their thick cuticle and sunken stomata help in reducing water loss.Q.57. Assertion: Pinus shows the alternation of generations.
Reason: The gametophyte is dependent upon the sporophyte phase.
Answer
Answer: (b) Pinus shows alternation of generations. The sporophyte phase is long and represented by the huge pine tree bearing the staminate and ovulate cones. Meiotic divisions occur at the same time as the differentiation of the pollen grains and megaspores.Q.58. Assertion: Pinus embryo has many cotyledons.
Reason: It shows polyembryony.
Answer
Answer: (b) The embryo in Pinus is straight and consists of a short axis bearing a ring of about ten slender, yellow cotyledons at the end that is away from the micropylar end. In Pinus, more than one embryo is developed from a single egg by the splitting of the product of a single fertilization termed as cleavage polyembrony.Q.59. Assertion: The female cones take a long time to mature.
Reason: The seeds are shed when the cone is 22 months old.
Answer
Answer: (b) The ovulate or female cones take about three years to mature. The mature cones are hard, woody and very large in size. Many important changes take place in the female cone during the interval of about thirteen months between pollination and the actual act of fertilization.Q.60. Assertion: The female cones are same in number as the male cones.
Reason: Male and female cones appear alternately on the same branch of the Pinus.
Answer
Answer: (d) Female cones or ovulate cones are less in number and arise as single or in a small clusters of two to four, each as a bud in the axial of a scale leaf towards the end of the new shoots of unlimited growth (long shoots) which do not bear the male conesQ.61. Assertion: Pinus is monoecious.
Reason: Each sporophyll bears only one microsporangia.
Answer
Answer: (c) Pinus is monoecious for it bears both types of cones on the same tree on separate branches. The male cone comprises of a number of small spirally arranged microsporophylls. Each microsporophyll bears two microsporangia or pollen sacs on the lower surface of its horizontal position.Q.62. Assertion: The mesophyll of Pinus shows no distinction as mesophyll and palisade.
Reason: Parenchymatous cells are present in mesophyll of Pinus.
Answer
Answer: (c) The parenchymatous mesophyll is present within the hypodermis of Pinus leaf. It is compact and shows no differentiation into palisade and spongy tissues. It consists of thin walled cells which contain numerous chloroplasts and abundant starch. The mesophyll thus function as the chlorophyll bearing tissue which manufactures food for plants.Q.63. Assertion: Pinus shows formation of annual rings.
Reason: It grows in areas of environmental fluctuation.
Answer
Answer: (a) The secondary wood shows well marked growth rings which are formed annually due to environmental fluctuations. Each annual ring possesses a zone of spring and an autumn wood. Spring wood is formed during spring season under availability of enough water and minerals. It possess large polygonal, thin walled and wide tracheids with large bordered pits. Autumn wood is formed during autumn season. It possesses smaller, thick walled and narrow tracheids with small bordered pits. It is evident that the size of tracheids shows a marked variation with regards to amount of moisture available in the respective season.Q.64. Assertion: In gymnosperms, plants lack welldeveloped vessels and fibres.
Reason: Companion cells are absent in gymnosperm.
Answer
Answer: (c) In gymnosperms, xylem lacks true vessels and wood fibres. It consists of tracheids that are arranged in uniform radial rows and xylem parenchyma only. The phloem contains sieve tubes and parenchyma cells. There are no companion cells.Q.65. Assertion: Gymnosperms seeds are naked.
Reason: They lack ovary wall.
Answer
Answer: (a) The gymnosperms have their ovules freely exposed before and after fertilization. They are not enclosed by any ovary wall. The seeds formed by them lack seed coat. Hence, due to absence of ovary wall and seed coat, their seeds are naked.Q.66. Assertion: Pinus has a pyramidal appearance.
Reason: The older parts of long shoot have scars of fallen dwarf shoots.
Answer
Answer: (b) Long branches of Pinus gradually become shorter towards the apex. Hence, the pine tree has a conical or pyramidal appearance. Long branches bear short branches and older portion of long branches display the scars of fallen short branches.Q.67. Assertion: The female cone of Cycas is not a true cone.
Reason: Its formation checks the growth of the stem.
Answer
Answer: (c) There is no true and compact or properly organised female cone in Cycas. Megasporophylls are loosely arranged and thus, form a loose female strobilus. The growing point of the stem is unaffected by their development and continues its growth through the loose strobilus.Q.68. Assertion: All living species of Cycas are dioecious.
Reason: Cycas contains male and female cones on the separate plant.
Answer
Answer: (a) All living species of Cycas are dioecious as the male and female structures occur on separate plants. The microsporophylls are aggregated into large compact male strobili or cones. The megasporophylls are loosely arranged. They do not form a true cone.Q.69. Assertion: The male of Cycas changes in size when the microspores became mature.
Reason: The microspores are dispersed by wind.
Answer
Answer: (a) When the microspores mature, the male cone elongates considerably and rapidly. The scales separate from one another so that sporangia are exposed. The sporangia lose water and with the loss of water from its cells, the exothecium shrinks. The sporangia thus, opens by a slit on its outer face. The spores fall out and the liberated spores are dispersed by wind.Q.70. Assertion: The leaves in gymnosperm are well adapted to withstand extremes of temperature, humidity and wind.
Reason: Unlike bryophytes and pteridophytes, in gymnosperms, the male and female gametophytes do not have an independent free living existence.
Answer
Answer: (b) The leaves in gymnosperm are well adapted to withstand extremes of temperature, humidity and wind. In conifers, the needle like leaf reduce the surface area. Their thick cuticle and sunken stomata also help to reduce the water loss. Unlike bryophytes and pteridophytes, in gymnosperms, the male and female gametophytes do not have an independent free living existence. They remain within the sporangia retained on the sporophytesQ.71. Assertion: The male and female gametophytes do not have independent existence in gymnosperms.
Reason: They remain within the sporangia retained on the sporophyte.
Answer
Answer: (a) Gametophytes are retained within sporangia in gymnosperms.Q.72. Assertion : Angiosperm and Gymnosperms both form spermatophyta.
Reason : Angiosperm and Gymnosperms both form triploid endosperm.
Answer
Answer: (c) In angiosperms, endosperm is formed through triple fusion (fusion of sperms with two polar nuclei of the central cell) and is triploid. In gymnosperms, endosperm is formed before fertilization and therefore, it is haploid.Q.73. Assertion: Stamens are comparable to microsporophylls.
Reason: Ovules are comparable to megasporophylls.
Answer
Answer: (b) Stamens are specialized microsporophylls. Each stamen has a narrow stalk or filament and a broader tip called anther. Anther develops four microsporangia or pollen grains. Carpels are specialized megasporophylls. Each carpel has a swollen base named ovary. The interior of ovary contains one or more placentae for bearing ovules.Q.74. Assertion: Biennial plants flower in two years.
Reason: Biennial plants live for two years.
Answer
Answer: (b) Biennial plants survive for two favourable seasons. During the first season, the plants grow in size and store food. In the second season, they bear flowers that form fruits.Q.75. Assertion: Flagellate male gametes are absent in angiosperms.
Reason: For fertilization, sperms are not dependent on water.
Answer
Answer: (a) Angiosperms is the most highly evolved group of plant kingdom. It is adapted for terrestrial habitats. Swimming habit of sperms is completely absent in angiosperm. The pollen grains reach the stigma by an external agency and deliver the male gamete in the ovule through pollen tube.Q.76. Assertion: Ovules form seeds upon fertilization.
Reason: Ripened ovary forms fruit.
Answer
Answer: (b) Fertilized ovules ripen to form seeds. The seeds are covered by fruits. Technically, a fruit is a ripened ovary. Gymnosperms contain ovules but they lack ovary, therefore, seeds are formed but are not fruits. Angiosperms contain both ovule and ovary and therefore, are seed bearing and fruit forming plants.Q.77. Assertion: Pyrenoids are utilised during starvation.
Reason: Pyrenoids are proteinaceous bodies.
Answer
Answer: (b) The chloroplasts of green algae contain one or more distinct, rounded, proteinaceous bodies called the pyrenoids. These diminish in size and ultimately disappear if the plant is under conditions of starvation. They reappear when the conditions become favourable.Q.78. Assertion: The eye-spot is present in the cell in green algae.
Reason: Eye-spot is meant for respiration.
Answer
Answer: (c) The eye spot is usually associated with the chloroplast in green algae. It is considered as a photoreceptive organ.Q.79. Assertion: Flower is an aggregation of sporophylls.
Reason: In angiosperms, sporophylls are modified.
Answer
Answer: (b) Sporophylls are organised into flowers in angiosperm. Both microsporophylls and megasporophylls are specialised. A microsporophyll or stamen consists of a filament and an anther. A megasporophyll or carpel is rolled and partly sterilised to produce a stigma, style and ovary containing ovules.Q.80. Assertion: Plants show alternation of generation [between haploid gametophytic (n) phase and diploid sporophytic (2n) phase].
Reason: Plantae includes eukaryotic, heterotrophic, chlorophyll containing organism.
Answer
Answer: (c) The plant cell wall have eukaryotic structure with prominent chloroplast. Life cycle consists of alternating haploid gametophyte and diploid sporophyte generations. Plantae includes eukaryotic, autotrophic, chlorophyll containing organisms.Q.81. Assertion: Each cell of the embryo sac is haploid in angiosperms.
Reason: In angiosperms, meiosis preceeds embryo sac formation
Answer
Answer: (a) Pistil consists of an ovary enclosing one to many ovules in angiosperms. Highly reduced female gametophytes termed embryo sacs are present within ovules. The embryo-sac formation is preceded by meiosis and thus, each of the cells of an embryo-sac is haploid.In order to equip the students with the latest methodology of testing and evaluation in competitive exam segment in India Physics Gurukul has introduced successrouter.com for Online Testing and Assessment. Try our free tests for JEE and NEET Today!
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