Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants

Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 2nd Year Biology Chapter 2 Sexual Reproduction in Flowering Plants Question Answer.

Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants

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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 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants Solutions for All Subjects, You can practice these here.

III. QUESTIONS FOR 3 MARKS : 

Q.1. What is self incompatibility? Why does self pollination does not lead to seed formation is self incompatible flower. 

Ans : When the pollen grain of a flower cannot fertilization the ovule of the same flower it is called self-compatibility. It is due to sterility towards each other. But the same pollen grain can fertilize the ovule of another flower. This is an adaptation to prevent in breeding. 

Q.2. What do you mean by pollination. Discuss its importance in flowering plants. Describe the role of various agencies responsible for the phenomenon. 

Ans : Pollination means transfer of pollen grains from anther to stigma of same or another flower. Pollination leads to fertilization which is essential for the development of seeds a fruits. Each poller grain gives rise to tvo formation. Both the gametes take part in fertilization that leads to formation of embryo and endosperm of the seed and the ovary in which the embryo and the endosperm are located is transform into fruit. 

Role of Agents in Pollination : 

(a) Insects : Pollination done by insects are called entomophily and the flowers are called entomophilous. They are colorful and with good smell and nectar. 

(ii) Wind : Pollination is brought about by wind in flowers which are small and inconspicuous. They are not coloured or showy. They have not nectar, scent etc. 

(iii) Water : Pollen grains of aquatic plant may be carried by water current and may get in touch with the stigma at the surface of water. The plants are Hydrophilous and the pollination is called hydrophily. 

(iv) Animals : Pollination may be brought about by various animals. When pollination done by bat is called chiropterophily. When the pollination takes place through birds then it is called ornithophily and when by snail called malacophily. 

Even the pollination may take place by squirrel, monkey and man. Here a number of adaptation may be found in the process of pollination. Sometimes the pollen grains may be sticky or with scented etc. 

Q.3. What is vegetative propagation. State the importance of vegetative propagation in horticulture practices, giving examples. 

Ans : When a part of plant body is detached from the main body and regenerates to give rise to an independent plant it is called vegetative propagation.

Farmers use the method of vegetative propagation in many agricultural; practice such as in cultivation of potato, ginger, turmeric, sugarcane, sweet potato, strawberry, dahlia, lemon, litchi, pineapple, mango and many more. 

Q.4. Define triple fusion. What is the product of this process. What does the product develop into? 

Ans : The secondary nucleus contains diploid nucleus (2n). During fertilization one male gamete (n) fertilizes the egg and the other male gamete (n) fertilizes the secondary nucleus (2n). As a result the product of fertilization between secondary nucleus and a male gamete the endosperm nucleus. Becomes triploid (3n) this is called triple fusion. Endosperm nucleus develops into endosperm.

Q.5. Match the items of column ‘A’ with the items of column ‘B’ of the following- 

Ans :

Q.6. What is agamospermy? How is agamospermy different from parthenogenesis and parthenocarpy? 

Ans : Development of embryo without fertilization is called agamospermy. Parthenogenesis means development of ovary and fruit without fertilization. 

Q.7. What is meant by emasculation? When and why does a plant breeder employ this technique? 

Ans : In hybridization the pollen grains are r.not allowed to fertilize the stigma of the same flower and to achieve this the anther is removed before it is matured. The stigma is then covered by a bag to prevent pollination by unwanted pollen grains. When stigma becomes matured pollen taken from desired plants are brushed upon the stigma. The bag is again put over the sigma till fertilization is over. 

Plant breeders introduce desired character into plants by preventing self pollination and also cross pollination by pollen grains of undesirable plants by the technique emasculation. plant breeders artificially pollinate the pistil by pollen grains which are taken from a desired characters. 

Emasculation technique is used to produce desired quality seeds or fruits in short period or time spam. 

Q.8. What is poly empryony and how can it be commercially exploited? 

Ans : A seed carrying more than one embryo is called polyembryony. Polyembryony can be used prevent reversibility of hybrid character. 

Q.9. Write the characteristic features of anther, pollen and stigma of wind pollinated flowers. Discuss briefly how do flowers reward their insect pollinators. 

Ans : Pollen grains are flat, thin basifixed, having long filament. The stigma are feathery. The flower rewards the insect by allowing them to collect honey and nectar. 

Q.10. Draw a longitudinal section of a post pollinated pistil showing entry of pollen tube into a mature embryosac of an angiosperm ovary. Label all the constituent bodies found there. 

Ans :              

Q.11. Discuss the need and significance of pollination in plants. 

Ans : The pollination is essential for the transfer of male gametes to the female sex part i.e. gynoecium a stigma. 

Moreover pollination plays a significant role for the formation of Zygote by the process of fertilization in the ovary. The main significance of pollination is that it can produce the seeds with different genetical makeup.

Q.12. What do you meant by dormancy of seeds? Mention the advantages of seed dormancy in crop plants. 

Ans : Dormancy can be defined as the condition of seeds when it fails to germinate even though conditions necessary for germination are provided. The main advantages of dormancy of seed of crop plant is that we can store the plant seeds for a longer period and it can germinate when we need to grow it. 

Q.13. What is apomixis? How is it different from polyembryony? 

Ans : Apomixis is the formation of new individuals through asexual reproduction without involving the formation and usion of gametes. In polyembryony two or more embryos in one ovule may be formed by the cleavage where fusion of gametes is must or can say that it is a made of sexual reproduction where cleavage is followed. But apomixis is an asexual method of reproduction where it mimics the sexual method. 

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