Plant Kingdom Class 11 Science Biology NCERT Solutions
Plant Kingdom Class 11 Science Biology NCERT Solutions: Plant Kingdom is the chapter 3 from class 11 Science Biology. Here you'll get Plant Kingdom class 11 Science/Plant Kingdom class 11 Science Biology NCERT Solutions.
Plant Kingdom Class 11 Biology chapter 3 Main Points / Summary
Plant kingdom includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms. Algae are chlorophyll-bearing simple, thalloid, autotrophic and largely aquatic organisms. Depending on the type of pigment possesed and the type of stored food, algae are classfied into three classes, namely Chlorophyceae, Phaeophyceae and Rhodophyceae.
Algae usually reproduce vegetatively by fragmentation, asexually by formation of different types of spores and sexually by formation of gametes which may show isogamy, anisogamy or oogamy.
Bryophytes are plants which can live in soil but are dependent on water for sexual reproduction. Their plant body is more differentiated than that of algae. It is thallus-like and prostrate or erect and attached to the substratum by rhizoids.
They possess root-like, leaf-like and stem-like structures. The bryophytes are divided into liverworts and mosses. The plant body of liverworts is thalloid and dorsiventral whereas mosses have upright, slender axes bearing spirally arranged leaves.
The main plant body of a bryophyte is gamete-producing and is called a gametophyte. It bears the male sex organs called antheridia and female sex organs called archegonia. The male and female gametes produced fuse to form zygote which produces a multicellular body called a sporophyte. It produces haploid spores.
The spores germinate to form gametophytes. In pteridophytes the main plant is a sporophyte which is differentiated into true root, stem and leaves. These organs possess well-differentiated vascular tissues. The sporophytes bear sporangia which produce spores. The spores germinate to form gametophytes which require cool, damp places to grow.
The gametophytes bear male and female sex organs called antheridia and archegonia, respectively. Water is required for transfer of male gametes to archegonium where zygote is formed after fertilisation. The zygote produces a sporophyte.
Plant Kingdom Class 11 Biology chapter 3 Notes
The gymnosperms are the plants in which ovules are not enclosed by any ovary wall. After fertilisation the seeds remain exposed and therefore these plants are called naked-seeded plants. The gymnosperms produce microspores and megaspores which are produced in microsporangia and megasporangia borne on the sporophylls.
The sporophylls – microsporophylls and megasporophylls – are arranged spirally on axis to form male and female cones, respectively. The pollen grain germinates and pollen tube releases the male gamete into the ovule, where it fuses with the egg cell in archegonia. Following fertilisation, the zygote develops into embryo and the ovules into seeds.
In angiosperms, the male sex organs (stamen) and female sex organs (pistil) are borne in a flower. Each stamen consists of a filament and an anther. The anther produces pollen grains (male gametophyte) after meiosis. The pistil consists of an ovary enclosing one to many ovules. Within the ovule is the female gametophyte or embryo sac which contains the egg cell.
The pollen tube enters the embryo-sac where two male gametes are discharged. One male gamete fuses with egg cell (syngamy) and other fuses with diploid secondary nucleus (triple fusion). This phenomenon of two fusions is called double fertilisation and is unique to angiosperms. The angiosperms are divided into two classes – the dicotyledons and the monocotyledons.
During the life cycle of any sexually reproducing plant, there is alternation of generations between gamete producing haploid gametophyte and spore producing diploid sporophyte. However, different plant groups as well as individuals may show different patterns of life cycles – haplontic, diplontic or intermediate.
NCERT Solutions for Class 11 Biology Chapter 3 Plant Kingdom
1. What is the basis of classification of algae ?
Ans: The presence of pigments that give the traditional colour on algae is the main basis for the classification of algae. Algae is divided into 11 classes but among them 3 main classes are Chlorophyceae, Phaeophyceae and Rhodophyceae.
Chlorophyceae: The members of Chlorophyceae are commonly called green algae.
Phaeophyceae: The members of Phaeophyceae or brown algae, are found primarily in marine habitats.
Rhodophyceae: Rhodophyta is commonly called red algae.
2. When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm ?
Ans: The reduction division takes place in the following stages:
(i) Liverworts: meiosis takes place in the spore mother cells of the capsule in sporangium resulting in haploid spore formation
(ii) Moss: meiosis occurs in spore mother cells of spore sacs in the capsule of sporangium.
(iii) Fern: sporangia are endured on sporophylls (fertile leaves). The process of meiosis occurs in spore mother cells of sporangium for the formation of haploid spores.
(iv) Gymnosperm: meiosis occurs in microsporangia located in the microsporophylls, in the microspore mother cells for the formation of haploid pollen grains giving rise to male gametophyte
(iv) Angiosperm: pollen grains that are formed in microspore mother cells leads to the formation of male gametophyte in the anther of the stamen. The megaspore mother cell located in the nucleus of the ovule undergoes meiosis for the formation of haploid megaspore, which eventually forms the female gametophyte.
3. Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
Ans: Bryophytes, Pteridophytes, and Gymnosperms are the plants that bear archegonia.
The life cycle of Bryophytes;
(i) Bryophytes are haploid, and they produce gametes. The sexual organs in bryophytes are multicellular.
(ii) The male sex organ is the antheridium, which produces biflagellate anterozoids. Female sexual organs are called archegonium, which produces a single egg.
(iii) Antheridium releases anthrozoids into the water that come into contact with the archegonium.
(iv) An antherozoid fuses with the egg to produce the zygote.
(v) The zygote undergoes reduction division to produce a multicellular body called a sporophyte.
(vi) Saprophytes undergo reduction division to produce haploid spores.
(vii) These spores germinate to produce gametophyte.
NCERT Solutions of Class 11 Biology Chapter 3 Plant Kingdom
4. Mention the ploidy of the following: protonemal cell of a moss; primary endosperm nucleus in dicot, leaf cell of a moss; prothallus cell of a ferm; gemma cell in Marchantia; meristem cell of monocot, ovum of a liverwort, and zygote of a fern.
Ans: Protonemal cell of a moss – haploid.
Primary endosperm nucleus in dicot – triploid
Leaf cell of a moss – haploid.
Prothallus cell of a fern – haploid.
Gemma cell in Marchantia – haploid.
Meristem cell of monocot – diploid.
Ovum of a liverwort – haploid.
Zygote of a fern – diploid.
5. Write a note on economic importance of algae and gymnosperms.
Ans:
Economic Importance of Algae
(i) Algae fixes Carbon dioxide with the help of photosynthesis
(ii) It increases the level of dissolved oxygen in their immediate environment
(iii) They produce rich compounds that serve as food for aquatic animals.
(iv) Marine algae are used as food. Eg: Laminaria and Sargassum
(v) Certain algae are used as hydrocolloids
(vi) Agar is used in growing microorganisms and in the preparation of jellies.
(vii) Chlorella is used as food by space travelers.
Economic importance of Gymnosperms
(i) Gymnosperms plants are used as ornamentals. Some are features in formal gardens – used for bonsai
(ii) Their fibers are used in the preparation of paper pulp.
(iii) Turpentine and resins are obtained from confers resin
(iv) Useful oils are extracted from gymnosperms like junipers, pines, hemlock, fir, spruces, and arborvitae.
(v) Gymnosperm seeds are used as food products such as bakery items.
(vi) Occassionally used to create silk and other textiles
6. Both gymnosperms and angiosperms bear seeds, then why are they classified separately ?
Ans: Both gymnosperms and angiosperms bear seeds, but the are classified separately. The reasons for distinguishing gymnosperms and angiosperms are as follows.
(i) In gymnosperms, the ovules are naked but in angiosperms they are enclosed within the ovary.
(ii) In Gymnosperms endospore is haploid and produced before fertilization whereas in Angiosperms endosperm is triploid and formed after double fertilization.
(iii) Double fertilization does not occur in gymnosperms, but in angiosperms, double fertilization occurs.
(iv) In gymnosperms, wood is nonporous and in angiosperms wood is porous.
7. What is heterospory ? Briefly comment on its significance. Give two examples.
Ans: The phenomenon of producing two different types of spores in the same plant is called heterosporis. The Significance of heterospory:
(i) Heterospory has led to the development of seeds in gymnosperms and angiosperms.
(ii) It has helped in the differentiation of male and female gametophytes.
Examples: Salvinia, Selaginella
Plant Kingdom class 11 NCERT Solutions
8. Explain briefly the following terms with suitable examples:-
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
Ans:
(i) Protonema: It is the first, usually branched, green and filamentous structure produced by a germinating moss or fern spore. The protonema of mosses bears buds that develop into the gametophyte plant. In fern the protonema becomes the prothallus.
(ii) Antheridium: The male sex organ of cryptogams (algae, fungi, bryophytes andpteridophytes) is known as antheridium. It produces the male gametes or anthero-zoids. It may consist of a single cell or it may have a wall that is made up of one or several layers forming a sterile jacket around the developing gametes.
(iii) Archegonium: The multicellular flask shaped female sex organ of bryophytes, pteridophytes and many gymnosperms is known as archegonium. Its dialated base called the venter contains the female gamete or egg or oosphere. The cells of the narrow neck of archegonium liquify to allow the male gametes to swim towards the oosphere.
(iv) Diplontic: It is the kind of life cycle in which the diploid sporophyte is dominant and this diploid phase is photosynthetic. The gametophytic phase is represented either by gametes only, that are formed through meiosis or by a highly reduced few celled gametophyte. E.g. all seed-bearing plants (gymnosperms and angiosperms).
(v) Sporophyll: It is a type of leaf bearing sporangia. In ferns, the sporophylls are the normal foliage leaves, but in other plants the sporophylls are modified and arise in specialised structure such as the strobili of club-moss, gymnosperms and the flower of angiosperms. In most plants sporophylls are of two types – microsporophylls and megasporophylls.
(vi) Isogamy: It is a type of sexual reproduction where fusion takes place between two identical gametes. The gametes are similar in size and structure and they show equal motility during sexual reproduction, e.g. Spirogyra (algae).
9. Differentiate between the following:-
(i) red algae and brown algae
(ii) liverworts and moss
(iii) homosporous and heterosporous pteridophyte
(iv) syngamy and triple fusion
Ans:
(i). Red algae:
a) Red algae contain chlorophyll a and chlorophyll d.
b) Phycobilins are present.
c) Red algae are not flagellated.
Brown algae:
a) Brown algae contain chlorophyll a and c.
b) Brown algae do not have phycobilins.
c) Brown algae are flagellated.
(ii) liverworts:
a) There is no protonema phase in the liverworts.
Moss:
a) Life cycle in the moss begins with the protonema.
(iii) Homosporous:
a) Homosporous possesses only one type of spores.
Heterosporous:
a) heterosporous will have morphologically different spores in different sporangia.
(iv) Syngamy:
a) Syngamy is the fusion of the male gamete with the ovum.
Triple fusion:
b) Triple fusion is the fusion of another male gamete with two polar nuclei.
Plant Kingdom Class 11 Biology Chapter 3 Questions Answers
10. How would you distinguish monocots from dicots ?
Ans:
Monocots:
(i) Have single cotyledon seed.
(ii) Flowers are trimerous.
(iii) Venation in leaves is parallel.
(iv) Vascular bundle is scattered.
(v) Absence of vascular cambium.
(vi) Primary root replaced by adventitious roots and are short-lived.
Dicots:
(i) Seeds having two cotyledons.
(ii) Flowers are tetramerous or pentamerous.
(iii) Have reticulate venations in leaves.
(iv) Vascular bundle are organized in a ring.
(v) Presence of vascular cambium.
(vi) Primary roots occur in a few cases. Primary root is long-lived.
11. Match the following (column I with column II)
Column I Column II
(a) Chlamydomonas (i) Moss
(b) Cycas (ii) Pteridophyte
(c) Selaginella (iii) Algae
(d) Sphagnum (iv) Gymnosperm
Ans: Column I Column II
(a) Chlamydomonas (iii) Algae
(b) Cycas (iv) Gymnosperm
(c) Selaginella (ii) Pteridophyte
(d) Sphagnum (i) Moss
Plant Kingdom class 11/ HS 1st Year Science Biology chapter 3
12. Describe the important characteristics of gymnosperms.
Ans: The main characteristics of gymnosperms are as follows
(i) In Gymnosperm the ovules are not enclosed by ovary. They are exposed before and after fertilization.
(ii) The seeds are naked
(iii) Gymnosperms include medium sized trees or tall trees and shrubs.
(iv) The roots are taproots
(v) The stems are branched or unbranched.
(vi) Leaves simple and compound
(vii) The plant body is separated into roots, stems and leaves and is sporophyte
(viii) They produce two kinds of spores, so they are called heterosporous
(ix) Fertilization takes place in the absence of external water from syphonogamy.
Class 11 / HS 1st Year Science Biology English Medium
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