Important Questions for CBSE Class 11 Biology Chapter 3 - Plant Kingdom

Very Short Answer Questions: (1 Marks)

1. Define Gemma.

Ans: Gemma is green, multicellular, asexual buds that develop in receptacles called gemma cups.

2. Which group of plants is regarded as the first terrestrial plant? Why?

Ans: Pteridophytes are the group of plants that are regarded as the first terrestrial plant as they possess both the vascular tissues – xylem and phloem.

3. The gametes and spores of Phaeophyceae have a distinct morphology. Give its name. 

Ans: The gametes and spores of Phaeophyceae are Pyriform (pear-shaped). They bear two laterally attached flagella.

4. Which substance has structural similarity to Floridian starch?

Ans: Amylopectin and glycogen both have structural similarities to Floridian starch.

5. Name the organisms which exhibit heterospory and seed habits.

Ans: Selaginella and Salvinia are organisms that exhibit heterospory and seed habits.

6. Name seedless vascular plants.

Ans: Pteridophytes have seedless vascular plants.

7. Which pigment is responsible for the red colour of red algae?

Ans: Phycobilin, phycoerythrin and phycocyanin are the pigments responsible for the red colour of red algae.

8. What is a cone?

Ans: The fruiting body of gymnosperms consisting of both micro and megasporophyll are called cones.

9. Name unicellular algae.

Ans: Chlamydomonas is a unicellular algae.

10. Why some bryophytes are called liverworts.

Ans: Some of the bryophytes are called liverworts because they are liver shaped eg. Marchantia.

11. What are rhizoids?

Ans: Rhizoids are slender, unicellular or multicellular hair-like structures that penetrate in moist soil and absorb water for plants.

12. Name the algae which are used for fodder for poultry birds.

Ans: Laminaria is used for fodder for poultry birds.

13. Which groups of plants are called vascular cryptogam?

Ans: The plants of group Pteridophytes are called vascular cryptogam.

14. What is a cone?

Ans: The fruiting body of the gymnosperm which consists of micro and megasporophyll are called cones.

15. What are cone-bearing plants called?

Ans: Conifers are cone-bearing plants.

16. Name any red algae which are used as vegetables?

Ans: Porphyra is the red algae that are used as vegetables.

17. What do you mean by thallus?

Ans: The thallus is a plant body that is not differentiated into root, stem and leaves.

18. Name the vascular plants which produce only spores but no flowers or seeds?

Ans: Pteridophytes produce spores but no flowers or seeds.

19. Where are the antheridia and archegonia located in ferns?

Ans: The antheridia and archegonia are located in the prothallus in ferns.

20. What are the two main classes of bryophytes?

Ans: Liverwort and mosses are the two main classes of bryophytes.

Short Answer Questions: (2 Marks)

1. Sphagnum has a lot of economic importance. Justify.

Ans: Sphagnum has a lot of economic importance as it provides peat which is used as a fuel. It is also used as packaging material for the transhipment of living material.

2. Gymnosperms can show polyembryony. Why do you think so?

Ans: Gymnosperms have the ability to show polyembryony as they have two or more archegonia.

3. How is the leafy stage formed in mosses? How is it different from protonema?

Ans: The leafy stage develops from the secondary protonema as a lateral bud in mosses. 

Protonema is green creeping, branched frequently in the filamentous stage whereas leafy stage is upright with the spiral arrangement of the leaves.

4. What features led to the dominance of vascular plants?

Ans: The features which led to the dominance of vascular plants are:

(i) Development of deep roots with the ability to penetrate the soil.

(ii) Development of water-proofing material eg. cutin on aerial surfaces, to reduce water loss through evaporation.

(iii) Development of strong woody material anchor and support above-ground structures.

5. Differentiate between Red algae and brown algae?

Ans: The difference between red and brown algae has been listed below:

6. Give some important features of dicots?

Ans: Dicotyledons are characterized by either woody or herbaceous habitats. They have two cotyledons in their seeds. Their leaves are net-veined, the vascular bundles are arranged in a circle or ring within the stem. 

7. List four classes of plants belonging to the fern group.

Ans: Pteridophytes or fern groups are divided into four classes:

(i) Class 1: Psilopsida . Example- Psilotum nudum

(ii) Class 2: Lycopsida. Example- Lycopodium phlegmasia

(iii) Class 3: Sphenopsida. Example- Equisetum

(iv) Class 4: Pteropsida. Example- Adiantum and Pteridium

8. How will you differentiate between red algae and green algae.

Ans: The difference between red and green algae has been listed below:

9. Write two important characteristics of gymnosperms?

Ans: The two important characteristics of gymnosperms are:

(i) It is a group of vascular plants which possess naked seeds attached to the surface of megasporophyll

(ii) Megasporophyll is not folded to form an ovary so no fruit formation occurs.

10. How do fungi differ from algae?

Ans: Fungi differ from algae as:

11. Both gymnosperms and angiosperms bear seeds but then why are they classified separately?

Ans: Gymnosperms are plants that bear ovules. These ovules are not covered by any ovary wall therefore, remain exposed. The seeds of gymnosperms are not covered that is they are naked but in Angiosperms, the seeds remain closed inside the fruit hence both of these are classified separately.

12. List any three characteristic features of Bryophytes.

Ans:

(i) They are small, erect plants growing in moist shady places

(ii) They have no structure that would resemble a leaf, a stem or any root.

(iii) Most of the plants are gametophytes that develop from haploid spores.

13. List any two differences between gymnosperms and angiosperms?

Ans: The two differences between gymnosperms and angiosperms are:

14. What is the role of the capsule in the life history of moss?

Ans: The capsule is an important structure of the sporophyte of the moss plant. In the capsule, spores are produced. When the capsule ripens its dehiscence takes place and spores are liberated by winds. The spores develop favourable conditions into protonema.

15. What is the difference between syngamy and triple fusion?

Ans: The difference between Syngamy and triple fusion is that syngamy is the fusion of male gametes (sperm) with the female gamete (egg) for the formation of a zygote whereas, in triple fusion, another male gamete fuses with the diploid secondary nucleus to form primary endosperm nucleus.

16. Mention some of the uses of ferns?

Ans: Some of the uses of ferns are:

(i) Ferns are used by florists for decoration purposes.

(ii) They are also grown as ornamental plants.

(iii) Wood from tropical tree fern is used in building material as they resist termite decay.

(iv) Ferns are also used as an astringent during childbirth in order to stop bleeding.

(v) Maidenhair fern is a source of the expectorant.

17. Tabulate differences between Gymnosperm and pteridophytes.

Ans: The differences between gymnosperms and pteridophytes are listed below:

18. What is heterospory? What is its significance?

Ans: Heterospory refers to the production of two kinds of spores in pteridophytes eg. Salvinia and selaginella produce two kinds of spores macrospores and microspores. These mega and microspores germinate and then give rise to male and female gametophytes. The female gametophyte is retained on the parent sporophyte for a variable period of time. So, this event is a precursor to seed habit.

19. What are gymnosperms? What are its four classes?

Ans: Gymnosperms are vascular plants with naked seeds. The seeds are exposed to the surface of the sporophyll. The reproductive organs are usually borne in cones on which spores are spirally arranged. 

Gymnosperms are classified into four groups: Conifers, Cycads, Ginkgo, Gnetophytes.

20. How would you distinguish between monocots and dicots? 

Ans: Monocots and dicots differ from each other as:

Short Answer Questions: (3 Marks)

1. The leaves in gymnosperms are adapted to withstand xerophytes conditions. Justify.

Ans: Gymnosperms like conifers have needle-shaped Ieaves to reduce surface area, thick cuticle and sunken stomata to reduce water loss therefore, the leaves in gymnosperms are adapted to withstand xerophytes conditions.

2. The gametophytes of bryophytes and pteridophytes are different from that of gymnosperms. How?

Ans: The gametophytes of bryophytes and pteridophytes differ from that of gymnosperms because the male and female gametophytes have free existence in bryophytes and pteridophytes but not in gymnosperms.

3. Roots of some gymnosperms have a fungal or algal association. Give examples, their names and their role in the plants.

Ans: Roots of some gymnosperms have a fungal or algal association for example- Pinus has a fungal association to form mycorrhiza which helps ii absorptions of water and minerals. Cycas in its roots forms coralloid roots and helps in nitrogen fixation.

4. Explain in brief the structure of the prothallus of the fern?

Ans: The structure of the Prothallus of fern has been defined below:

(i) Heart-shaped structure.

(ii) Sex organs antheridia and archegonia are present on the lower surface of the prothallus. 

(iv) Prothallus is produced from meiospore as a gametophyte of fern.

(v) Below the sex organs are rhizoids

(vi) The sex organs which are Archegonia and antheridia are flask and globose shaped respectively. 

(vii) Male and female gametes are produced in the antheridia and the archegonia.

5. Point out differences in sexual reproduction of moss and fern?

Ans: The differences in sexual reproduction of moss and fern are listed below:

6. Describe the main features of pteridophytes?

Ans: The main features of Pteridophytes are:

(i) They are small-sized and occur in humid and tropic climates mostly growing as epiphytes. Some of them even appear like small trees.

(ii) Their plant body is divided into- root, stem and leaves.

(iv) Lycopodium, Selaginella and Equisetum are some of the members of Pteridophytes.

(v) Leaves are of two types- compound and sporophylls leaves

(vi) Plant body is sporophytic.

(vii) They are vascular cryptogams.

(viii) Alternation of generation occurs.

(ix) Prothallus represent the gametophytic phase.

(x) Pteridophyta is divided into psilopsida, lycopsids, sphenopsida and pteropsida classes

7. “Algae and Bryophytes are different from each other.” Point out the main differences between them?

Ans: Algae and Bryophytes are different from each other as:

8. What are the identifying features of angiosperms flowering plants.

Ans:  The identifying features of angiosperms flowering plants are:

(i) Most of the plants around us are Angiosperms.

(ii) The flowering plants show diversities in their habitat, forms, duration of life, mode of nutrition etc.

(iii) Plants with stems vary from a a few mm to several metres in height. Accordingly, they are termed as herbs, shrubs and trees.

(iv) Plants which survive for a year are annual, those which survive two year are biennials and those which live more than two years are perennials.

(v) Plants surviving in dry conditions are Xerophytes; plants living in water are hydrophytes; those living in moderate conditions are mesophytes.

(vi) All flowering plants have roots, stems and leaves and produce flowers, seeds and fruits.

(vii) The economic uses of plants depend on the species.

9. Describe the similarities in the sexual reproduction of moss and fern.

Ans: The similarities in sexual reproduction of moss and fern are:

(i) Oogamous mode of sexual reproduction involves fertilization of non-motile female gametes or eggs through motile male gamete/sperm.

(ii) In both, the male sex organ consists of a jacket of sterile cells enclosing a spermatogenous tissue.

(iii) Sperms are flagellate.

(iv) Female sex organs (archegonia) are flask-shaped and have a tubular neck with a swollen basal venter. 

(v) External source of water is required for the swimming of sperms in order to reach the open archegonia.

10. Why are Bryophytes regarded as “the amphibians of the plant kingdom”?

Ans: Amphibians live both on land and water however, they must come in contact with water during the breeding season to lay their eggs. Hence, it is essential for amphibians to breed.

Bryophytes live on land but require water to complete their life cycle. Through the medium of water, antherozoids reach the archegonia and fertilise the egg. If water is not available, they do not survive. With this similarity, bryophytes are called ``Amphibians of the plant kingdom”.

11. Describe the important characteristics of gymnosperms?

Ans: The important characteristics of gymnosperms are:

(i) They grow in cool and warm climates.

(ii) They are evergreen woody, perennial plants

(iii) They have a well-developed vascular system but their xylem lacks a vessel and the phloem is without a companion cell.

(iv) Plants are heterosporous.

(v) Conifers are cone-bearing trees and have evergreen needle-like leaves that are adapted to withstand extremes of temperature, humidity etc.

(viii) Leaves have less surface area, thick cuticles and sunken stomata to conserve moisture and reduce loss of water by transpiration.

(ix) Ovules are exposed to receive pollen grains.

(x) Gymnosperms possess exposed or naked seeds.

(xi) Polyembryony is commonly observed.

12. List common modes of reproduction in Algae?
Ans: The modes of reproduction in algae are-

(i) Vegetative Reproduction: It occurs by fragmentation, zoospores, aplanospores, palmella stages etc.

(ii) Sexual Reproduction in Chlamydomonas: Flagellated, motile gametes unite to form a quadrille flagellate zygote. It is converted into a zygospore. When the flagella are lost and a cyst wall is formed around them, the zygospore germinates by meiosis to form four haploid meiospores.

(iii) Palmella Stage: If the conditions are unfavourable, daughter cells are divided into numerous cells. Their walls become gelatinous and cells remain together. This stage is the palmella stage. In return for favourable conditions, the cells inside the gelatinous mass develop cilia.

(iv) Asexual Reproduction in Chlamydomonas: It takes place by the formation of zoospores in which cilia from the Chlamydomonas are withdrawn. The cell content gets divided into 4 to 8 daughter cells. In this way, they become motile and called zoospores.

13. What are ferns? Describe its salient features.

Ans: Ferns are found in warm moist tropical regions as well as dry rocky places. 

• The plant body is distinguished into three parts- i) underground stem rhizome ii) it bears roots and iii) it sends aerial shoots with leaves. 

• Leaves of ferns are of two types- a) simple leaves with a single vein and b) compound leaves with several leaflets. 

• The sporophyte phase is dominant in ferns. 

• Spores are produced after meiosis, sporangium has an annulus made up of a band of thickened cells that dry out pulling it open. So spores are released which then germinate into a prothallus, the gametophyte. 

• Gametophyte bears antheridia and archegonia on the underside. Antheridia bear flagellated sperms and egg lies at the base of archegonia. The process of fertilization starts with the availability of water for flagellated sperms to swim to reach the egg.

14. Differentiate between Red, Brown and Green algae.

Ans: Red, brown and green algae differ  from each other as:

Long Answer Questions: (5 Marks)

1. Explain the life cycle in green algae?

Ans: There are three types of life cycle found in green algae:

(a) Haplontic Life Cycle: The dominant phase is haploid. A diploid state is found only in the form of a zygote or zygospores. Meiosis takes place at the time of its germination. Example: Ulothrix, Spirogyra.

(b) Diplontic Life Cycle: The dominant phase alga is diploid. It gives rise to haploid gametes through meiosis. Gametes unit and the zygote regenerates the diploid phase.

(c) Diplohaplontic Life Cycle: It has well developed multicellular haploid and diploid phases. These are respectively called gametophyte and sporophyte. Haploid gametophytes produce haploid gametes. 

Sporophytes produce haploid spores by meiosis. The meiospores germinate into new gametophytes.

2. Explain briefly the alternation of generation in bryophytes?

Ans: The life cycle of moss represents two distinct generations: gametophytic and sporophytic. The Moss plant is a gametophyte. Spore is the beginning of gametophytic generation. It develops into protonema which gives rise to male and female gametophytes.

Gametophyte consists of green thallus having archegoniophores and antheridiophores which bear sex organs and the gametes are produced in them either monoecious or diecious. Club shaped antheridium bears biflagellate sperms or antherozoids. Flask shaped archegonium encloses the female egg. A zygote is formed after the fertilization of male and female gametes. Repeated divisions of the zygote lead to the formation of the embryo (2N) which develops into a sporophyte. The sporophyte of moss gets differentiated into- foot, seta and capsule. Inside the capsule, single-celled spores are produced. After dehiscence, they begin to germinate and give rise to protonema to initiate the cycle again.

Gametophytic Generation alternates the sporophytic generation.

3. Describe the common mode of reproduction in Angiosperms.

Ans: Stamens and pistils are the two reproductive parts of a flower. The stamen consists of a slender filament with anthers at the tip. Each pistil is made of three parts- ovary, style and stigma. The ovary contains one to many ovules. Each ovule contains a megaspore mother cell it produces four haploid megaspores after meiosis of them three degenerate and the remaining one is a functional megaspore. It divides by meiosis forming a megagametophyte. It consists of 8 haploid nuclei embedded in the cytoplasm of which 3 cells lie at the micropylar end and 3 antipodal lies at the chalazal end. The two remaining nuclei move to the centre to make a diploid nucleus.

The anthers have a pollen sac and contain many microspore mother cells. Each of them produces four haploid microspores after meiosis and each becomes a microgametophyte. It contains two nuclei generative nucleus and the tube nucleus. The pollen is carried away by air and other agencies and reaches the stigma of the pistil of the same or different plants. This process is called pollination. Pollen grains germinate and produce a pollen tube it grows within the style and reaches the ovule of the ovary. The generative nucleus divides pollen tubes producing two male gametes.

On reaching the ovule, the pollen tube burst to release male gametes. One of the two gametes fertilise the egg and forms a diploid zygote. The other male gamete fertilizes with polar nuclei to form triploid endosperm. This is known as double fertilization.

4. Classify plant kingdom?

Ans:

(i) Thallophytic: The plant body is thallus i.e. not differentiated into root, stem and leaves. Example: Chlorella, Ulothrix, Spirogyra.

(ii) Bryophyta: Amphibious inhabit, water is necessary for fertilization, Vascular tissues are absent. Example: Riccia, Marchantia, Funaria.

(iii) Pteridophyta: The plant body is differentiated into distinct underground stem-like rhizome bearing roots and aerial shoots with leaves. Example: Equisetum, Adiantum, Pteris

(iv) Gymnosperm: Seeds are naked. Example: Cycas, Pinus, Cedars 

(v) Angiosperm: Seeds are protected inside the fruits. Example Monocotyledones- grass, maize, rice and; dicotyledons- gram, pea, sunflower

CBSE Class 11 Biology Chapter- 3 Important Questions - Benefits to the CBSE Class 11 Students

With the help of studying from this material resource, the students will be benefitted abundantly. How?

1. The important questions are taken up after a thorough scanning process. 

2. Only those questions which are very vital from the examination point of view are drafted in this PDF. 

3. The important questions and answers are to be studied conveniently and thus they are put in a free PDF which can be used free of cost and also saved for future study. 

4. Studying the important questions and answers will help you to understand the important topics from this chapter. 

5. Studying important questions and answers will give you insight into how to approach the topics.  

Important Questions Class 11 Biology Chapter 3 - Topics Covered 

Topics covered in the Class 11 Biology Chapter 3 plant kingdom are:

• Algae

• Bryophytes

• Pteridophytes

• Gymnosperms

• Plant life cycles

• Alternation of generations.

Chapter 3 Plant Kingdom Summary

The plant kingdom mainly includes algae, bryophytes, pteridophytes, gymnosperms, and angiosperms. Now let us know some of the basic details about them: algae are chlorophyll-bearing simple, thalloid, autotrophic, and largely aquatic organisms. Algae are mainly classified into three classes, namely Chlorophyceae, Phaeophyceae, and Rhodophyceae. depending on the type of pigment possessed and the type of stored food. They reproduce vegetatively by fragmentation, asexually by the formation of different types of spores, and sexually by the formation of gametes which may show isogamy, anisogamy, or oogamy.

Bryophytes: Bryophytes can live on soil but are dependent on water for sexual reproduction. The bryophytes plant body is more differentiated when compared with algae. Bryophytes are thallus-like and prostate attached to the substratum by rhizoids and they also possess root-like, leaf-like, and stem-like structures. The bryophytes are divided into two types:  liverworts and mosses. The plant body of liverworts is thalloid and dorsiventral in structure, but mosses have upright slender axes bearing spirally arranged leaves.

In Bryophytes, the plant's main part is a gamete-producing cell known as a gametophyte. It bears two types of sex antheridia and archegonia, antheridia is the male sex organ and archegonia is the female sex organ. Both the gametes produced fuses to form a zygote. It produces a multicellular body called a sporophyte. It produces haploid spores and that spore germinates to form gametophytes.

Pteridophytes: In pteridophytes, the main plant is a sporophyte and  It is differentiated into true roots, stem, and leaves. The organs of the sporophyte possess well-differentiated vascular tissues. And it bears sporangia which produce spores and these spores germinate to form gametophytes. The conditions required to grow gametophytes are cool and damp places. The gametophytes bear the male sex organs - antheridia and the female sex organs called archegonia. Water is an essential component required for the transfer of male gametes to archegonium, where the formation of the zygote takes place after fertilisation.

In the life cycle of sexually reproducing plants, different plant groups, as well as individuals, may show different patterns of life cycles are haplontic, diplontic, or intermediate. There is an alternation of generations between gamete-producing haploid gametophyte and spore-producing diploid sporophyte.

Important Questions for CBSE Class 11 Biology Chapter 3 - Plant Kingdom - Extra Questions and Answers (Solved)

1. Which group of algae have mannitol as reserve food material? 

Ans. The Phaeophyceae group, also known as the brown algae, stores food material in the form of mannitol. 

2. What is the botanical name for the sea palm?

Ans. Postelsia palmaeformis is the botanical name for the sea palm. 

3. How many cells make up an embryo sac?

Ans. An embryo sac is made up of - two synergids, one egg cell, three antipodal cells, and one secondary nucleus.

Preparation Tips for CBSE Class 11 Biology Exam

• Students are suggested to study the chapter conceptually.

• These theories are based on one’s understanding and thus they are required to understand the concepts first before proceeding to memorise them. 

• Students should draw labelled diagrams and study the concepts which demand such diagrams. 

• Give regular tests like mock tests and class tests which will help you to stay updated about your own performance. 

• Study the difficult biological terms by jotting them down on paper. 

Conclusion

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CBSE Class 11 Biology Chapter-wise Important Questions

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