NCERT Solutions for Class 11th: Ch 3 Plant Kingdom Biology
Page No: 44Exercises
1. What is the basis of classification of algae?
Answer
The presence or absence of pigments is the main basis of classification of algae.
• Chlorophyceae: Chlorophyll a and b are present in them and impart green colour. Chlorophyceae are also called ‘blue-green algae’.
• Phaeophyceae: Chlorophyll a and c and fuxoxanthin are present. Fucoxanthin imparts brown colour. Phaeophyceae are also called ‘brown algae’.
• Rhodophyceae: Chlorophyll a and d and phycoerythrin are present. Phycoerythrin imparts red colour. Rhodophyceae are also 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?
Answer
In liverwort, moss and fern, the saprophytic plant produces haploid spores after meiosis while in gymnosperm and angiosperm, meiosis takes place in antheridium and ovary for the formation of pollen grains and ovules.
3. Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
Answer
Life cycle of gymnosperms
• Reproduction: The gymnosperms are heterosporous; they produce haploid microspores and megaspores. The two kinds of spores are produced within sporangia that are borne on sporophylls which are arranged spirally along an axis to form lax or compact strobili or cones.
• Male gamete: The strobili bearing microsporophylls and microsporangia are called microsporangiate or male strobili. The microspores develop into a male gametophytic generation which is highly reduced and is confined to only a limited number of cells. This reduced gametophyte is called a pollen grain. The development of pollen grains takes place within the microsporangia.
• Male gamete: The strobili bearing microsporophylls and microsporangia are called microsporangiate or male strobili. The microspores develop into a male gametophytic generation which is highly reduced and is confined to only a limited number of cells. This reduced gametophyte is called a pollen grain. The development of pollen grains takes place within the microsporangia.
• Female gamete: The cones bearing megasporophylls with ovules or megasporangia are called macrosporangiate or female strobili. The male or female cones or strobili may be borne on the same tree (Pinus) or on different trees (Cycas). The megaspore mother cell is differentiated from one of the cells of the nucellus. The nucellus is protected by envelopes and the composite structure is called an ovule. The ovules are borne on megasporophylls which may be clustered to form the female cones. The megaspore mother cell divides meiotically to form four megaspores. One of the megaspores enclosed within the megasporangium (nucellus) develops into a multicellular female gametophyte that bears two or more archegonia or female sex organs. The multicellular female gametophyte is also retained within megasporangium.
• Fertilization: The pollen grain is released from the microsporangium. They are carried in air currents and come in contact with the opening of the ovules borne on megasporophylls. The pollen tube carrying the male gametes grows towards archegonia in the ovules and discharge their contents near the mouth of the archegonia. Following fertilisation, zygote develops into an embryo and the ovules into seeds.
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.
Answer
• Protonemal cell of a moss - Haploid
• Primary endosperm nucleus in a dicot - Triploid
• Leaf cell of a moss - Haploid
• Prothallus of a fern - Haploid
• Gemma cell in Marchantia- Haploid
• Meristem cell of a monocot - Diploid
• Ovum of a liverwort - Haploid
• Zygote of a fern - Diploid
5. Write a note on economic importance of algae and gymnosperms.
Answer
Economic importance of algae: Algae are useful to man in a variety of ways. They perform half of the total carbon dioxide-fixation on earth by photosynthesis, acting as the primary producers in aquatic habitats. Many species of marine algae such as Porphyra, Sargassum, and Laminaria are edible. Chlorella and Spirulina are rich in proteins. Thus, they are used as food supplements. Agar is used in the preparation of jellies and ice-cream. It is obtained from Gelidium and Gracilaria. Carrageenin is used as an emulsifier in chocolates, paints, and toothpastes. It is obtained from the red algae. Many red algae such as Corallina are used in treating worm infections.
Economic importance of gymnosperms: Gymnospermous plants are widely used as ornamentals. Many conifers such as pine, cedar, etc., are sources of the soft wood used in construction and packing. Medicinal uses: An anticancer drug Taxol is obtained from Taxus. Many species of Ephedraproduce ephedrine, which can be used in the treatment of asthma and bronchitis. The seeds of Pinus gerardiana are edible. Resins are used commercially for manufacturing sealing waxes and water-proof paints. A type of resin known as turpentine is obtained from various species of Pinus.
6. Both gymnosperms and angiosperms bear seeds, then why are they classified separately?
Answer
The seeds of gymnosperms are naked, while that of angiosperms are covered by a membrane. Therefore, they are classified separately.
7. What is heterospory? Briefly comment on its significance. Give two examples.
Answer
Heterospory is a phenomenon in which two kinds of spores are borne by the same plant. These spores differ in size. The smaller one are called microspore and the bigger ones are called megaspore. Microspore produce male gametophytes and megaspores produces female gametophyte. Thus it is considered as a crucial step in evolution as it is a precursor to the seed habit.
This ultimately led to seed development in gymnosperms and angiosperms.
Page No: 45
8. Explain briefly the following terms with suitable examples:-
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
Answer
(i) Protonema: It is the first stage in the life cycle of a moss, developing directly from the spore. It consists of creeping, green, branched, and often filamentous structures.
(ii) Antheridium: It is the male sex organ present in bryophytes and pteridophytes and is surrounded by a jacket of sterile cells. It encloses the sperm mother cells, which give rise to the male gametes.
(iii) Archegonium: It is the female sex organ present in bryophytes, pteridophytes, and gymnosperms. In bryophytes and pteridophytes, it generally has a swollen venter and a tubular neck, and contains the female gamete called the egg.
(iv) Diplontic: It is the term used for the life cycles of seed-bearing plants (gymnosperms and angiosperms). In these plants, the diploid sporophyte is dominant, photosynthetic, and independent. The gametophyte is represented by a single-celled (or a few-celled) structure.
(v) Sporophyll: In pteridophytes, the sporophytic plant body bears sporangia. These sporangia are subtended by leaf-like appendages known as sporophylls. In gymnosperms, microsporophylls and megasporophylls are found. These bear microspores and megaspores respectively.
(vi) Isogamy: It is a type of sexual reproduction involving the fusion of morphologically-similar gametes. This means that the gametes are of the same size, but perform different functions. This type of reproduction is commonly observed in Spirogyra.
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
Answer . Done it by yourself.
12. Describe the important characteristics of gymnosperms.
→ The seeds of these plants are not enclosed in fruits.
→The plant-body ranges from medium to tall trees and shrubs. The giant redwood tree Sequoia is one of the tallest trees in the world.
→ The root system consists of tap roots. The coralloid roots present in Cycas are associated with nitrogen-fixing cyanobacteria.
→ The stem can be branched (as in Pinus and Cedrus) or un-branched (as in Cycas).
→ The leaves can be simple (as in Pinus)or compound (pinnate in Cycas). The leaves are needle-like, with a thick cuticle and sunken stomata. These help in preventing water loss.
→ Gymnosperms are heterosporous. They bear two kinds of spores - microspores and megaspores.
→ Flowers are absent. The microsporophylls and megasporophylls are arranged to form compact male and female cones.
→ Pollination occurs mostly through wind and pollen grains reach the pollen chamber of the ovule through the micropyle.
→ The male and female gametophytes are dependent on the sporophyte.
→ The seeds contain haploid endosperms and remain uncovered.
Answer
Important characteristics of gymnosperms are:
→The plant-body ranges from medium to tall trees and shrubs. The giant redwood tree Sequoia is one of the tallest trees in the world.
→ The root system consists of tap roots. The coralloid roots present in Cycas are associated with nitrogen-fixing cyanobacteria.
→ The stem can be branched (as in Pinus and Cedrus) or un-branched (as in Cycas).
→ The leaves can be simple (as in Pinus)or compound (pinnate in Cycas). The leaves are needle-like, with a thick cuticle and sunken stomata. These help in preventing water loss.
→ Gymnosperms are heterosporous. They bear two kinds of spores - microspores and megaspores.
→ Flowers are absent. The microsporophylls and megasporophylls are arranged to form compact male and female cones.
→ Pollination occurs mostly through wind and pollen grains reach the pollen chamber of the ovule through the micropyle.
→ The male and female gametophytes are dependent on the sporophyte.
→ The seeds contain haploid endosperms and remain uncovered.
1. Mycorrhiza is an association between roots of higher plant and fungus. It is an example of
(a) Symbiosis
(b) Myremecophilly
(c) Helotism
(d) Parasitism
► (a) Symbiosis
2. Red algae is red due to the presence of:
(a) R-Phycocyanin
(b) R-Phycoerythrin
(c) C-Phycocyanin
(d) C-Phycoerythrin
► (b) R-Phycoerythrin
3. Zygotic meiosis is characteristic of :-
(a) Procaryotes
(b) Thallophyta
(c) Bryophyta
(d) Spermatophyta
► (b) Thallophyta
4. The outer cell-wall of Spirogyra is made up of:
(a) Cellulose
(b) Pectin/Pectose
(c) Hemicellulose
(d) Protein
► (b) Pectin/Pectose
5. Female sex organ of algae is called:
(a) Carpel
(b) Oogonium
(c) Archegonia
(d) Oosphere
► (b) Oogonium
6. Sexual reproduction in Thallophyta takes place by:
(a) Isogamy
(b) Anisogamy
(c) Oogamy
(d) Any of the above
► (d) Any of the above
7. Algae which have food conducting tubes similar to phloem in vascular plants are :-
(a) Red algae
(b) Brown algae
(c) Blue green algae
(d) Green algae
► (b) Brown algae
8. Main plant body of the selaginella is :
(a) A gametophyte
(b) A sporophyte
(c) Half gametophyte
(d) Haploid phase
► (b) A sporophyte
9. By which plant seed habit originated:
(a) Moss
(b) Little Club moss
(c) Pinus
(d) Angiosperm
► (b) Little Club moss
10. Who is popularly known as the "Father of Phycology''
(a) Fritsch
(b) Papenfus
(c) Smith
(d) Morris
► (a) Fritsch
11. Selaginella is a type of plant
(a) Oogamous and homosporous
(b) Oogamous and heterosporous
(c) Isogamous & heterosporous
(d) Isogamous & Homosporous
► (b) Oogamous and heterosporous
12. Change in colour of algae according to depth in sea is called:
(a) Bohr's effect
(b) Gaudikov's effect
(c) Fogg's effect
(d) Pasteur effect
► (b) Gaudikov's effect
13. Cephaleuros, which causes "Red rust of tea" is a:
(a) Red Algae
(b) Brown Algae
(c) Dinoflagellate
(d) Green Algae
► (d) Green Algae
14. Which of the following algae produces synzoospores:
(a) Chlamydomonas
(b) Polysiphonia
(c) Chlorella
(d) Vaucheria
► (d) Vaucheria
15. Yeast is different from penicillium and Rhizopus in being
(a) Acellular
(b) Unicellular
(c) Having unseptate hyphae
(d) multicellular
► (b) Unicellular
16. A prothallus is
(a) A structure in pteridophytes formed before the thallus develops
(b) A gametophyte free living structure formed in pteridophytes
(c) A sporophytic free living structure formed in pteridophytes
(d) A primitive structure formed after fertilization in pteridophytes
► (b) A gametophyte free living structure formed in pteridophytes
17. Irish moss, is a member of:
(a) True moss
(b) Lichen
(c) Algae
(d) Bryophyte
► (c) Algae
18. Sexual reproduction in spirogyra is:
(a) Anisogamous
(b) Physiological anisogamous
(c) Isogamous
(d) Oogamous
► (c) Isogamous
19. No Zoospore formation has been observed in the Algal members belonging to:-
(a) Chlorophyceae
(b) Xanthophyceae
(c) Phaeophyceae
(d) Cyanophyceae
► (d) Cyanophyceae
20. A prokaryotic autotrophic nitrogen fixing symbiont found in
(a) Pisum
(b) Alnus
(c) Cycas
(d) Cicer
► (c) Cycas
21. Bioluminescence is a phenomenon associated with
(a) chrysophyta
(b) phaeophyta
(c) pyrrophyta
(d) chlorophyta
► (c) pyrrophyta
22. Which of the following is essential for seed habit-
(a) Free gametophyte
(b) Dependent sporophyte
(c) Heterospory
(d) Haploid life cycle
► (c) Heterospory
23. By which type of leaf is found in selaginella
(a) Aligulate and microphyllous
(b) Ligulate and megaphyllous
(c) Ligulate and microphyllous
(d) Aligulate and megaphyllous
► (c) Ligulate and microphyllous
24. Most common phycobiont in a lichen is :
(a) Microcystis
(b) Trebouxia
(c) Ulothrix
(d) Spirogyra
► (b) Trebouxia
25. An evolutionary characteristic is found in selaginella:
(a) Presence of ligule
(b) Heterophilly habits
(c) Sporangia present in cone
(d) Heterospory
► (d) Heterospory
26. Common bread mould is:
(a) Yeast
(b) Mucor
(c) Bacteria
(d) Virus
► (b) Mucor
27. The zygospore of Spirogyra produces-
(a) 2-zoospores
(b) 4-zoospores
(c) 2-4 zoospores
(d) None of these
► (d) None of these
28. Spirogyra found in-
(a) Stagnant fresh water
(b) Running salt water
(c) Stagnant salt water
(d) Running fresh water
► (a) Stagnant fresh water
29. In chlorophyta the mode of sexual reproduction is :-
(a) Isogamy
(b) Anisogamy
(c) Oogamy
(d) Isogamy, Anisogamy and oogamy
► (d) Isogamy, Anisogamy and oogamy
30. Spirogyra belongs to-
(a) volvocales
(b) conjugales
(c) ulotrichales
(d) siphonales
► (b) conjugales
31. Lichens show
(a) Symbiosis
(b) Commensalism
(c) Parasitism
(d) Cooperation
► (a) Symbiosis
32. Cell wall of Spirogyra is-
(a) One layered
(b) Two layered
(c) Three layered
(d) Four layered
► (b) Two layered
No comments:
Post a Comment