Class 11 Biology Chapter 3 Plant Kingdom

Class 11 Biology Chapter 3 Plant Kingdom, AHSEC Class 11 Biology Question Answer, HS 1st year Biology notes to each chapter are provided in the list so that you can easily browse throughout different chapter Assam Board Class 11 Biology Chapter 3 Plant Kingdom Question Answer and select needs one.

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Class 11 Biology Chapter 3 Plant Kingdom

Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board Class 11 Biology Chapter 3 Plant Kingdom Solutions for All Subject, You can practice these here.

Plant Kingdom

Chapter – 3


Q.1. Which system of classification is known as first scientific system of classification?

Ans :- Artificial system of classification is known as first scientific system of classification.

Q.2. Who proposed the artificial system of classification?

Ans :- Carolus Linnoeus proposed the artificial system of classification.

Q.3. Who proposed the natural system of classification?

Ans :- Benthom and Hooker proposed the natural system of classification. 

Q.4. On what factors is cytotaxonomy based upon?

Ans :- Cytotaxonomy is based on cytological information like chromosome number, structure and behaviour.

Q.5. What are algae?

Ans :- Algae are chlorophyll-bearing simple, thalloid, autotrophic aquatic organism e.g. Volvox, Ulothrix.

Q.6. What are the different mode of reproduction seen in algae?

Ans :- Algae reproduces by vegetative, asexual and sexual method.

Q.7. What is isogamy, anisogamy and oogamy?

Ans :- Union of two morphologically identical gametes is known as isogamy e.g. spirogyra.

Union of two flagellated gametes of unequal size in which small one is male and bigger one is female is known as anisogamy e.g. chlamydomonas.

Fusion between one large non-motile female gamete and a smaller, motile male gamete is termed as oogamy, e.g. Volvox.

Q.8. Write the name of different classes of algae?

Ans :- The different classes of algae are-

(i) Chlorophyceae

(ii) Phaeophyceae

(iii) Rhodophyceae

Q.9. Why are ‘chlorophyceae’ so called?

Ans :- Chlorophyceae are so called due to the pigments chlorophyll a and b.

Q.10. Write the pigments present in the brown algae?

Ans :- The pigments present in brown algae are chlorophyll a, c, carotenoid and xanthophylls. Fucoxanthin is the main pigment responsible for brown colour.

Q.11. Write the name of the red pigment found in red algae?

Ans :- The red pigment found in red algae is r-phycoerythrin.

Q.12. Why are bryophytes called amphibians of the plant kingdom?

Ans :- Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction. 

Q.13. Mention the name of sex organs of bryophytes?

Ans :- The male sex organ is antheridium and female sex organ is archegonium.

Q.14. Write the name of one moss species which serves as fuel?

Ans :- Sphagnum serves as fuel.

Q.15. Mention the main divisions of bryophytes?

Ans :- Bryophytes are divided into liverwort and moss.

Q.16. What is gemmae?

Ans :- Gemmae are green, multicellular, asexual buds which become detached from the parent body and germinate to form new individuals.

Q.17. Which is the first and second stage in the life cycle of moss?

Ans :- Protonema is the first stage and leafy stage is the second stage in the life cycle of moss.

Q.18. What are sporophyll?

Ans :- The sporophyll bears sporangia that are subtended by leaf like appendage called sporophylls.

Q.19. What kind of spores are observed in case of pteridophytes?

Ans :- The spores of pteridophytes are of homosporous kind in majority of them and genera like Selaginella and Salvinia are heterosporous.

Q.20. What is mycorrhiza?

Ans :- Mycorrhiza is a symbiotic association between fungus and roots of higher plants.

Q.21. What is the basic difference between angiosperms and gymnosperms?

Ans :- In angiosperms, the ovules are enclosed in specialised structure called flowers but in gymnospera the ovules are naked.

Q.22. Mention the main classes of angiosperm?

Ans :- The main classes of angiosperm are dicotyledon and monocotyledon.

Q.23. What is pollination?

Ans :- The transfer of pollen grain from anther to the stigma of flowers of the same or different plant is known as pollination.

Q.24. What do you mean by double fertilisation?

Ans :- The process of fertilisation in angiosperm involving both male gametes to give rise to embryo and endosperm is called double fertilisation.

Q.25. What is haplontic life cycle?

Ans :- In majority of algae, the gametophyte phase is the dominant phase. This type of life cycle is termed as haplontic life cycle.

Q.26. What is haplo – diplontic cycle?

Ans :- In bryophytes in pteridophytes, the diploid sporophyte alternate with short – lived haploid gametophyte. Such a pattern is known as haplo – diplontic life cycle.

Choose the correct one :-

Q.1. Unicellular green algae are included in –

(a) Protista

(b) Monera

(c) Plantae

(d) Fungi

Ans :- Protista.

Q.2. The characteristic pigment of brown algae is –

(a) Phycobilin

(b) Fucoxanthin

(c)  Chlorophyll

(d) Carotenoid

Ans :- Fucoxanthin.

Q.3. The sexual reproduction in red algae is –

(a) Isogamous

(b) Infamous     

(c) Anisogamous

(d) Conjugation

Ans :- Oogamous.

Q.4. Agar -agar is obtained from –

(a) Red algae

(b) Brown algae

(c) Green algae

(d) None

Ans :- Red algae.

Q.5. The earliest land plant belongs to –

(a) Bryophytes

(b) Pteridophytes

(c) Gymnosperm

(d) Angiosperm

Ans :- Bryophytes.

Q.6. Protonema is found in –

(a) Fern

(b) Moss

(c) Marchantia 

(d) Algae

Ans :- Moss.

Q.7. Gymnosperm differ from bryophytes in –

(a) Reproduction

(b) Development of seed

(c) Development of stem

(d) All the above

Ans :- All the above.

Q.8. Which of the following is an amphibian of plant kingdom –

(a) Red algae

(b) Fungi

(c) Moss

(d) Pinus

Ans :- (c) Moss

Q.9. Fucoxanthin is the dominating pigment in –

(a) Green algae

(b) Blue algae

(c) Blue-green algae

(d) Brown algae

Ans :- Brown algae.

Q.10. Vascular tissue is absent in –

Ans :-  Algae.

Fill in the blanks :-

Q.1. Angiosperm : Root :: Rhodophyta : _____.

Ans :- Holdfast.

Q.2. Moss : Capsule :: Fern : ____.

Ans :-  Sporangium.

Q.3. Sporangia bearing leaves are known as _____.

Ans :- Sporophyll.

Q.4. Bryophytes show _____ alternation of generation.

Ans :- Heteromorphic.

Q.5. Gymnosperm lack fruits because they lack _____.

Ans :- Ovary.


Q.1. Write 2 differences between artificial and natural system of classification?

Ans :- Artificial System :-

(i) Artificial system is based on one or two morphological characters.

(ii) It is based on superficial characters like habit, and habitat.

Natural System :-

(i) Natural system is based on number of characters.

(ii) It is based on biology, anatomy, cytotaxonomy.

Q.2. Write briefly about the mode of reproduction seen in algae ?

Ans :- Algae reproduces by vegetative, asexual and sexual method. Vegetative reproduction is by fragmentation. Asexual reproduction is by the production of zoospores. Sexual reproduction takes place by the fusion of two gametes. The gametes may be similar in size (isogametes) or dissimilar in size (anisogametes).

Q.3. State the economic importance of algae?

Ans :- Algae are economically important in many ways –

(i) As fertiliser :- Blue-green algae fix nitrogen. Several see-weeds are used as fertilisers.

(ii) In industry :- Agar is dried and gelatinous extract obtained from red algae is used in nutrient medium culture. It also used in making breads and jelly.

Q.4. Mention the distinguishing features of green algae ?

Ans :- Some of the distinguishing features of green algae are –

(i) They are grass green due to the presence of photosynthetic pigment- chlorophyll ‘a’ and ‘b’.

(ii) Cell wall is made of cellulose.

(iii) Reserve food materials is starch.

(iv) Pyrenoid is generally present in the chloroplast. e.g. Volvox, Ulothrix, Spirogyra.

Q.5. Mention the distinguishing characters of brown algae ?

Ans :- Some of the distinguishing characters of brown algae are –

(i) The vegetative body is always multicellular with definite size and shape.

(ii) They are named so because they look brown due to the presence of fucoxanthin.

(iii) Photosynthetic pigments are chlorophyll ‘a’ and ‘b’ carotene and large amount of fucoxanthin and diatoxanthin.

(iv) Brown algae are mainly found in sea -water.

Q.6. Write a note on the gametophytic phase of bryophytes?

Ans :- The plant body of bryophytes is thallus like and attached to the substratum by unicellular or multicellular rhizoid. The main plant body is haploid. It produces gametes, hence is called gametophyte. The male sex organ is called antheridium and female sex organ is called archegonium.

Q.7. How does liverworts reproduce?

Ans :- Liverworts reproduce asexually by fragmentation of thallus or by the formation of specialised structure called gammae . Gemma are green, multicellular, asexual buds which develop in small receptacle called gemmae cup located on the thallus. The gemmae become detached from the parent body and germinate to form new individuals.

Sexual reproduction occurs by the fusion of male and female gametes.

Q.8. Write briefly about the stages observed in mosses?

Ans :- The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages. The first stage is protonema stage which develops directly from a spore.The second stage is the leafy stage which develops from the secondary protonema as a lateral bud. It consists of spirally arranged leaves. They are attached to the soil through branched rhizoids.

Q.9. Write a note on sporophyte phase of pteridophyte?

Ans :- The main plant body of pteridophyte is a sporophyte which is differentiated into true root, stem and leaves. The sporophyte bears sporangia that are subtended by leaf like appendage called sporophyll. In some cases, sporophyll form distinct compact structures called strobilus or cones, e.g. selaginella. The sporangia produces spores by meiosis in the spore mother cells. The spores germinate to give rise to photosynthetic thalloid gametophyte called prothallus.

Q.10. Gymnosperms are heterosporous. Comment.

Ans :- Gymnosperms produces haploid microspores and megastores. The two kinds of spores  are present within sporangia that are borne on sporophyll which are arranged spirally along an axis to form compact strobilus or cones. 

The strobilus bearing microsporophyll and microsporangia are called male cones. The microspores are produces from microsporangia. The strobilus bearing megasporophyll and megasporangia are called female cones. Ovules are produced in the megasporangium.


Q.1. When and where does reduction division take place in the life cycle of liverwort, moss, fern, gymnosperms and an angiosperm?

Ans :- Liverworts : In liverworts, the dominant stage of the life cycle is the gametophyte. The archegonium produces egg and antheridium produces antherozoid. Both of them fuses to form zygote that marks the beginning of sporophytic phase. Sporophyte is differentiated into foot, seta and capsule. Within the capsule reduction division takes place and haploid spores are produced.

Moss :- Same as liverworts.

Fern :- In fern, the main plant body is sporophytic (2n). It produces sporangia that are subtended by leaf like appendages called sporophylls. In the sporangia reduction division takes place and spores are formed from spore mother cells. The spores (n) give rise to gametophytic phase in ferns.

Gymnosperms :- The sporophytic phase is dominant in gymnosperms. It bears male and female cone which produces microspore or pollen grains and megaspore or embryo-sac from their respective mother cell. In these mother cell, reduction division takes place forming microspore and megaspore which are both haploid.

Angiosperm :- In angiosperms too, the sporophytic phase is the dominant phase in its life cycle. The sporophytic plant bears megasporangium and microsporangium in which megaspore mother cell and microspore mother cell is present. In megaspore and microspore mother cell (2n) reduction division takes place and as a result haploid megaspore and microspores are formed.

Q.2. Name three groups of plants that bears archegonia. Briefly describe the life cycle of any one of them.

Ans :- The three groups of plants that bears archegonia are bryophytes, pteridophytes and gymnosperm.

The life cycle of gymnosperm is follows :-

The life cycle of pinus is completed in two generation – sporophytic and gametophytic. These occurs regularly one after another alternatively with each other. The sporophytic generation is dominant and it bears male and female cone which produces microspore or pollen grain and megaspore or embryo-sac respectively using the process of formation of microspore and megaspore from their respective mother cell. Meiotic cell division takes place to produce haploid microspore and megaspore. These are the initial cells of gametophytic generation. The microspore and megaspore produces male and female gametes. The male gametes fertilizes with the egg after pollination. The zygote (2n) is the first cell of the sporophytic generation. It develops into a seed. The seed on germination grows into a seedling which in twin develops into a pine tree.

Q.3. Explain briefly the following terms with the suitable diagram.

(i) Protonema

(ii) Antheridium

(iii) Archegonium

(iv) Diplontic

(v) Sporophyll

(vi) Isogamy

Ans :- (i) Protonema :- The sporophyte of moss capsule produces haploid spores. The spores on liberation from the moss capsule germinate to produce a tube like structure with filamentous branched structure called protonema. It develops rhizoids and some buds. The buds later develops into gametophyte.

(ii) Antheridium :- The male reproductive organ present in bryophyte, pteridophyte and gymnosperm is known as antheridium. The antheridium are borne at the apex of male gametophore. It is usually club shaped, long, stalked structure. It has a jacket within which large number of sperm mother cell or androcytes are present. Each of the androcytes give rise to one antherozoid. On maturity they are liberated from the antheridium.

(iii) Archegonium :- It is the female reproductive organ. The archegonium is flask shaped body which consists of swollen basal portion called venter and a slender tube called neck. The venter encloses an egg in it.

(iv) Diplontic :- The life cycle of an organism in which the diploid sporophyte is dominant phase in known as diplontic life cycle. The gametophyte phase is represented by the single to few – celled haploid gametophyte. All seed bearing plants i.e. gymnosperms and angiosperms follow diplontic life cycle.

(v) Sporophyll :- The foliage leaves bear many greenish brown structure on their under surface called sorus. They are developed directly on the veins so that the foliage leaves are called sporophyll. In some cases, sporophyll may form distinct compact structure called strobilus or cones.

(vi) Isogamy :- It is a type of reproduction which take place by the fusion of two identical gametes called isogametes. These gametes can be flagellated and similar in size as in chlamydomonas or non-flagellated but similar in size as in spirogyra.

Q.4. Write a note on economic importance of bryophytes and gymnosperms?

Ans :- The economic importance of bryophytes are –

(i) Mosses prevent soil erosion by binding the soil.

(ii) Some moss provide food for herbivorous mammals, birds and other animals.

(iii) The dried mosses form humus which increases the fertility of the soil.

(iv) Sphagnum was used in surgical dressing during the second world war.

The economic importance of gymnosperms are –

(i) Pinus produces good quality of timber which is used as building material, packing, plywood, fuel, furniture, paper etc.

(ii) Turpentine, methyl alcohol and resin are obtained from pine.

(iii) The seeds of Gnetum is edible as that are highly nutritious.

(iv) The wonder drug ‘taxol’ is extracted from Taxus which is highly effective in the treatment of cancer.

(v) The seeds of pines called ‘chilgoza’ are eaten as dry-fruits.

Q.5. With the help of life history of a moss plant, discuss the alternation generation in bryophytes.

Ans :- Mosses are the earliest group of green land plants. The life history moss passes through gametophytic and sporophytic phases.

Gametophytic phase :- It is small and consists of stem-like body, bears rhizoids for absorption of water and minerals. The gametophytic plant bears male and female reproductive structure called antheridium and archegonium. Antheridium is a club-shaped structure. It contains sperm mother cell or androcytes. Each of the androcyte give rise to one antherozoid or male gamete. Archegonium contains an egg which finally fuses with the antherozoid to form a zygote or oospore. The zygote, develops into a sporophytic plant.

Sporophytic Phase :- The sporophyte is a multicellular body, is not free-living and is dependent on the gametophyte for nourishment. Some cell of the sporophyte undergo reduction division (meiosis) to produce haploid spores.These spores germinate to produce gametophyte.

Alternation of generation :- The life cycle of moss has two prominent phases-gametophytic phase (n) and sporophytic phase (2n), which regularly alternate each other. The dominant phase i.e. gametophyte bears on the radium and archegonium which in turn bears antherozoid and egg. They fuse to form diploid oospore. It develops into an embryo which later on produces sporophytic plant. The sporophytic plant is diploid and it produces spores by meiotic cell division of the spore mother cell. Spores are liberated from the sporophytic plant and they germinate to produce gametophytic plant. This alternative cyclic manner of life cycle is called alternation of generation.

Q.6. What is heterospory? Briefly comment on its significance. Give examples.

Ans :- Most of the pteridophyte produces only one kind of spores. But some produce two kind of spores, differing in size. The smaller one is known as microspore and the longer one is known as megaspore. They are developer within microsporangia and megasporangia respectively. The phenomenon where two types of spores formed on the same plant is known as heterospory.

The first step towards a seed-habit is a heterosporous life cycle. The second step is the retention of megaspore within the megasporangium. The third feature is transport of sperm nuclei to the female gametophyte. The fourth step is to develope a means for the protection of embryo by a seed-coat. Thus heterospory is a great step towards evolution as seed-habit is a important step in evolution.

Example :- Psilotum, Dryopteris.

Q.7. Write the similarities and difference in between pteridophytes and gymnosperms.

Ans :- Similarities between pteridophytes and gymnosperms are –

(i) Sporophytic phase is dominant in both groups.

(ii) Plant body is differentiated into distinct stem, leaves and root.

(iii) Many pteridophytes (Selaginella, Azolla) and all gymnosperms are heterosporous.

(iv) As in gymnosperms, the megaspore is retained in the megasporangium after fertilisation in many pteridophytes.

The differences between pteridophytes and gymnosperms are –

Pteridophytes :-

(i) Usually grow in moist, shady conditions.

(ii) Spore germinate only after their liberation from the sporangium.

(iii) Pollen tube is not found.

(iv) Neck canal cells are present.

Gymnosperms :-

(i) They occur in xerophytic conditions.

(ii) Partial development of the male gametophyte occurs within the sporangium.

(iii) Pollen tube is sperm carrier.

(iv) Neck canal cells are absent.

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