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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Sexual Reproduction in Flowering Plants
Chapter – 2
REPRODUCTIONS
Very Short Answer Type Questions
Q.1. Define reproduction?
Ans : Reproduction is a process by which an organism gives birth to individuals of its own kind and thereby continues to maintains its race. Through reproduction an organism handed down its genetic identity to their offsprings.
Q.2. What is incompatibility?
Ans : Inability to reproduce.
Q.3. What is malacophily?
Ans : Pollination caused by snail is called malacophily.
Q.4. What types of flowers favours cross pollination?
Ans : Bisexual flowers.
Q.5. What types of pollination is found in a self incompatible plants?
Ans : Cross-pollination.
Q.6. Why sunflower is best suited for insect pollination?
Ans : Sunflower is advise shaped inflorescence containing a large number of flowers together. A single insect may pollinate the entire flowers by roaming all around in search of honey and nectar.
Q.7. What do you understand by double fertilization? Who discovered it?
Ans : Out of the two male gametes developed design microgametogenesis,one fertilizes the egg and the other fertilizes the secondary nucleus. The fertilized egg gives rise to embryo and the fertilized secondary nucleus gives rise to endosperm. As fertilization occurs twice it is called double fertilization.
Q.8. What is sporopollenin?
Ans : It is a special substance present in the test of pollen grain which protects the pollen grain from external influence such as heat acid enzyme action etc.
Q.9. What is the first cell to develop is female and malegametophyte of flowering plants?
Ans : Functional megaspore and pollen grain.
Q.10. Name two plants in which pollination occurs with the help of
(i) Birds
(ii) Bats.
Ans : (i) Coral tree (ii) Silk cotton.
Q.11. What is triple fusion?
Ans : Secondary nucleus contains two nuclei one from syner gids and the other from antipodal cells. Thus it is already diploid (2n). So when the second male gamete fuses with it during fertilization it become triploid nucleus (3n). This is called triple fusion.
Q.12. What do you meant by Parthenogenesis and Parthenocarpy?
Ans : When fruits develop without fertilization it is called parthenogenesis. It leads to production of seedless fruit. Production of seedless fruits is called parthenocarpy.
Q.13. Arránge the following terms in correct developmental sequence – Pollen grain, Sporogenous tissue, Microspore tetrad, Pollen mother cell, Male gametes.
Ans : Sporogenous tissue-pollen mother cell-Micro spore tetrad-pollen grain- Male gamete.
Q.14. How does endosperm in angiosperms become triploid?
Ans : Secondary nucleus in the ovule is a diploid one (2n). When during fertilization the second male gametes fuses with the diploid secondary nucleus the secondary nucleus transforms into triploid (3n) nucleus. This triploid nucleus is called endosperm nucleus. The endosperm nucleus gives rise to embryo.
Q.15. Mention the scientific term used for modified form of reproduction in which seed are formed without fusion of gametes.
Ans : Apomixis.
Q.16. A bilobed dithecous anther has 100 microspore mother cells per microsporangium. How many male gametophytes this anther can produce?
Ans : 400 male gametophytes and from each male gametophyte two male gametes are produced. So a total of 800 male gametes will be produced.
Q.17. Why should a beekeeper keep beehives in crop fields during flowing periods?
Ans : Two reasons one the bees get pollen and nectar to make honey; second, crop field gets enough insects to pollinate the flowers.
Q.18. If the chromosome number of somatic cell of a plant is 24. What would be the chromosome number of male gamete and endosperm cells of the plant.
Ans : 12 and 36 chromosomes respectively.
Q.19. What are the constituents cells of the egg apparatus in an embryo sac?
Ans : Two synergids and one egg cells.
Q.20. What are the three cells found in a pollen grain when it is ready to shed?
Ans : One vegetative cell or to be cell and one generative cell which gives rise to two male gametes.
Q.21. Name the parts of the pistil which develop into fruits and seeds?
Ans : Ovary and ovule .
Q.22. Name the cultivated plant in which neither fruits nor seeds are formed?
Ans : Potato, ginger, turmeric, sugarcane.
Q.23. Named the activities :
(i) Removal of anthers from the bisexual flower bud to make it a female flower.
Ans : Emasculation.
(ii) Sprinkling of desired pollen grains over the stigma of a flower.
Ans : Dusting of pollen grain over stigma.
Q.24. What are archesporial and tapetum layers?
Ans : Archesporial layer gives rise to sporogenous cells and tapetum provides nourishment to sporogenous cells.
Q.25. Differentiate true fruits from false fruits.
Ans : The fruits which develop from ovary are called true fruits and the fruits which develop from any part of flower other than ovary are called false fruits.
Q.26. How many haploid cells are present in a mature female gametophyte of a flowering plant?
Ans : Female gametophyte has eight cells which are haploid. Two synergids, an egg, two polar nuclei and three antipodal cells.
Q.27. Mention the ways by which seeds are develop without fertilization?
Ans : The way by which seeds are developed without fertilization is called parthenocarpy.
Q.28. How do flowers reward their insect pollinators?
Ans : The insect pollinating flowers reward their pollinators by providing water or honey which are formed at the base of flower.
(B). Fill up the blanks:
Q.1. Morphologically flower is a modified_____
Ans : Stem.
Q.2. Transfer of pollen grains from anther to the stigma of another flower of the same plant is called_____
Ans : Geitonogamy.
Q.3. The wind pollinated flowers are generally _____ Sexual in nature.
Ans : Unisexual.
Q.4. Entry of pollen tube into ovule through micropyle is known as ____
Ans : Porogami fertilization.
Q.5. Pollen grains are able to tolerate extremes of temperature and desiccation as its exine is made up of_____
Ans : Sporopollenin.
Q.6. Anthesis is a condition in which _____ takes place.
Ans : Flower.
Q.7. The ovule is attached to the placenta by _____
Ans Funicle.
Q.8. _____ is the first cell of Embryo sac.
Ans : Functional megaspore.
Q.9. Hilum is the point at which ____ of ____ remain attached.
Ans : Stem, seed.
Q.10. ____ is the formation of embryo from vegetative cells derived from Zygote.
Ans : Polyembryony.
Q.11. Parthenocarpy is the development ____ of is an unfertilized flower, resulting in a _____ fruit.
Ans : Fruit, seedless fruit.
Q.12. Apomixis is unusual sexual reproduction where there is no ____ and _____
Ans : Gametes, fertilization.
Q.13. Egg apparatus of empryosac consists of ____ cells.
Ans : Three cells.
Q.14. Definite or secondary nucleus of embryo sac is the product of ____ and _____ cells.
Ans : A antipodal cell, a synergid cell.
Q.15. In many dicots, food reserve in the ____ and consumed by the developing ____
Ans : Endosperm, embryo.
Q.16. ____ of pistil forms fruits and ____ in ovary form seeds.
Ans : Ovary/ base, Ovules/eggs.
Q.17. Milky water of tender coconut fruit is ____
Ans : endocarp.
(C). Select the true and false statement :
Q.1. In angiosperms, a mature male gametophyte is formed from a pollen mother cell through one meiotic and two mitotic divisions.
Ans : True.
Q.2. Tapetum is the innermost layer of pollen sac which help in protection of sporogenous cells.
Ans : False.
Q.3. Endosperms developed from secondary nucleus which is present in the middle of embryosac is diploid in chromosome set.
Ans : False.
Q.4. Apomixis is an event where a new plant is develop without the fusion of gametes.
Ans : True.
Q.5. Xenogamy, the type of pollination brings genetically different types of pollen grains to the stigma.
Ans : True.
Q.6. Fruits are formed in all phanerogams.
Ans : False.
Q.7. Commonly in a mature fertilized ovule n, 2n and 3n, condition is respectively found in synergids, zygote and endosperm cells.
Ans : True.
Q.8. A bisexual flower which never opens up in its life span is known as hemogamy.
Ans : False.
Q.9. Wind pollinated flowers are small producing large numbers of pollen grains.
Ans : True.
Q.10. The egg apparatus of an angiosperm embryosac comprises of an egg cell and two antipodal cells.
Ans : False.
Q.11. A monocarpic plant is one which has only one carpel.
Ans : True.
Q.12. The role of double fertilization in angiosperms is to produce only endosperms.
Ans : False.
Q.13. If any somatic cell of sporophyte produces gametophyte without reduction division is called parthenogenesis.
Ans : True.
Q.14. The egg apparatus of angiosperms embryo sae comprises of an egg and two synergids.
Ans : False.
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