Plant Kingdom NCERT Solutions for Class 11 Biology Chapter 3-Anand Classes

The chapter Plant Kingdom discusses the kingdom in detail. It includes algae, bryophytes, pteridophytes, angiosperms and gymnosperms. The different species are discussed in detail, providing students with information extensively on habitat, lifecycle, etc. It enlightens students with a detailed classification of the Plantae kingdom further, which is popularly known as the plant kingdom.

What is the basis for classification of algae?

Based on these criteria, algae are of three types i.e. red algae, brown algae and green algae.

When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?

Solution:

The reduction division takes place in the following stages:

(i) Liverworts

In the life cycle of a liverwort reduction division (meiosis) take place in the spore mother cells of the capsule in sporangium for the formation of haploid spores that will grow into gametophytic thallus after germination.

(ii) Mosses

In mosses, the gametes fertilise and a zygote is formed. The zygote develops into the sporophyte. In the capsule of the sporophyte, reduction division (meiosis) takes place and haploid spores are formed which on germination give rise to gametophytic thallus.

(iii) Ferns

In ferns, reduction division (meiosis) takes place in the sporangia present on fertile leaves for the production of spores

(iv) Gymnosperms

In Gymnosperms, 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.

(v) Angiosperms

In the case of angiosperms, 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.

Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.

Solution:

Bryophytes, Pteridophytes, and Gymnosperms are the plants that bear archegonia.

The life cycle of Bryophytes

(i) Bryophytes are haploid, and 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 in 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) Sporophytes undergo reduction division to produce haploid spores.

(vii) These spores germinate to produce gametophyte.

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 fern; gemma cell in Marchantia; meristem cell of monocot, ovum of a liverwort, and zygote of a fern.

Solution:

Write a note on the economic importance of algae and gymnosperms.

Solution:

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. For example, 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 travellers.

(viii) Chlorella and Caulerpa are used to obtain antibiotics also.

(ix) Green algae such as Ulva, Caulerpa, Enteromorpha, Chlorella etc are used as food rich in lipid, protein, vitamins, minerals etc.

(x) A number of green algae such as Chlamydomonas, Chlorella, Scenedesmus etc are used in sewage oxidation tanks.

Importance of Gymnosperms

(i) Gymnosperms are used as ornamental plants. Some are features in formal gardens – used for bonsai

(ii) Their fibers are used in the preparation of paper pulp. The wood from Picea, Pinus, Larix and Abies is used in the manufacture of paper

(iii) Resins containing terpenes, resin acids and esters can be obtained from gymnosperms. Resins are used in waterproofing, sealing joints etc.

(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. The seeds of Pinus gerardiana are roasted and eaten.

(vi) Occasionaly used to create silk and other textiles

(vii) The softwood of gymnosperms is used in the construction of furniture, plywood, packing cases, match sticks, railway sleepers etc

(viii) A drug called ephedrine is extracted from Ephedra which is a gymnosperm. This drug is useful in respiratory ailments such as asthma.

Both gymnosperms and angiosperms bear seeds, then why are they classified separately?

Solution:

The reasons for distinguishing angiosperms and gymnosperms are as follows.

Both gymnosperms and angiosperms come under the group spermatophyta or seed-bearing plants. However, angiosperms and gymnosperms are classified separately in spermatophyta because of the following reasons :

(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.

What is heterospory? Briefly comment on its significance. Give two examples.

Solution:

Heterospory refers to the existence of two types of meiospores i.e. microspores and megaspores in a single plant.

The importance of heterospory is as follows:

(i) Heterosporis causes the growth of seeds in gymnosperms and angiosperms.

(ii) It is required in the differentiation of male and female gametophytes.

Examples: Salvinia, Selaginella

Explain briefly the following terms with suitable examples:

(i) protonema

(ii) antheridium

(iii) archegonium

(iv) diplontic

(v) sporophyll

(vi) isogamy

Solution:

(i) Protonema

Protonema is the haploid stage in the bryophyte lifecycle where thread-like chain of cells are formed. For example, in mosses, protonema develops directly from a spore.

(ii) Antheridium

The male sex organ, producing male gametes in bryophyte and pteridophytes is called antheridium. For example, many fungi and algae have antheridia during their reproductive phases.

(iii) Archegonium

Archegonium is a female reproductive organ of bryophytes which is flask-shaped and produces a single egg. Observed in pteridiophytes, gymnosperms and bryophytes, they are jacketed and multicellular, possessing a neck and a swollen venter.

(iv) Diplontic

A life cycle in which dominant free living phase is diploid, generating haploid gametes. For example, Sargassum.

(v) Sporophyll

A leaf which bears sporangia is called a sporophyll, which may be microsporophyll or megasporophyll. These structures combine to form strobini(cones). For example, Pinus.

(vi) Isogamy

Sexual reproduction that takes place through fusion of two gametes which can be flagellated and are similar in size, or non-flagellated (non-motile) but similar in size. Such reproduction is called isogamy. For example, Ectocarpus

Differentiate between the following:

(i) red algae and brown algae

(ii) liverworts and moss

(iii) homosporous and heterosporous pteridophyte

(iv) syngamy and triple fusion

Solution:

Following are the differences:

(i) Differences between red algae and brown algae are as follows:

(ii) Differences between liverworts and mosses are as follows :

(iii) Differences between homosporous and heterosporous pteridophyte are as follows

(iv) The differences between syngamy and triple fusion are as follows:

How would you distinguish monocots from dicots?

Solution: Differences between monocots and dicots are as follows:

Match the following (column I with column II)

Solution:

Correct matching is (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)

Describe the important characteristics of gymnosperms.

Solution:

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 are 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