Extra Questions for Class 12 Biology Chapter 2 Sexual Reproduction in Flowering Plants
Here we are providing extra questions for class 12 biology. this post covers extra question for Chapter 2 Sexual Reproduction in Flowering Plants. Students can read and practice these questions to score better marks in the exam.
Q.1. State the function of filiform apparatus found in mature embryo sac of an angiosperm.
Ans. The filiform apparatus guides the pollen tube into the synergid.
Q.2. How many germ pores are there in the pollen grains of monocots and dicots?
Ans. There are three germ pores in dicots and one in monocots.
Q.3. The microscopic pollen grains of the past are obtained as fossils. Mention the characteristic of the pollen grains that makes it happen.
Ans. The exine of pollen grains have an outermost hard layer composed of a chemical, sporopollenin. It is highly resistant to high temperature, strong acids and alkali. So, pollen grains are obtained as fossils.
Q.4. Name the type of pollination in self-incompatible plants.
Ans. Xenogamy.
Q.5. Papaver and Michelia both have multicarpellary ovaries. How do they differ from each other?
Ans. Papaver has syncarpous gynoecium whereas Michelia has apocarpous gynoecium.
Q.6. Mention any two characteristics of pollen grains of plants such as maize and Cannabis.
Ans. (i) Pollen grains are small, dry and light in weight, non-sticky.
(ii) Pollen are produced in large numbers.
Q.7. Draw a diagram of a matured microspore of an angiosperm. Label its cellular components only.
Ans.
Q.8. Define parthenocarpy.
Ans. Parthenocarpy is an economically important process in which seedless fruit is formed without fertilisation, for example, banana.
Q.9. Give an example of a plant which came into India as a contaminant and is a cause of pollen allergy.
Ans. Parthenium or Carrot grass.
Q.10. Name the component cells of the ‘egg apparatus’ in an embryo sac.
Ans. Two synergids and an egg.
Q.11. In a case of polyembryony, if an embryo develops from the synergid and another from the nucellus, which is haploid and which is diploid?
Ans. Synergid embryo is haploid and nucellar embryo is diploid.
Q.12. Name the tissue present in the fertilised ovules of angiospermic plants that supplies food and nourishment to the developing embryo.
Ans. Endosperm
Q.13. What is funiculus?
Ans. Funiculus is the stalk of ovule that attaches it to the placenta.
Q.14. What is an anatropous ovule?
Ans. It is an ovule that is completely inverted through 180° such that the micropyle comes close to the base of the funiculus and nucellus remains straight.
Q.15. In maximum angiosperms pollen grains are shed at the two-celled stage. Name the 2 cells.
Ans. Vegetative cell and generative cell are the two-celled stage in which pollen grains are shed.
Q.16. How many cells are found in a typical embryo sac?
Ans. There are seven cells in a typical embryo sac. These are one egg cell, two synergids, three antipodal cells and a central cell.
Q.17. A bilobed, dithecous anther has 100 microspore mother cells per microsporangium. How many male gametophytes this anther can produce?
Ans. The bilobed anther can produce 1600 male gametophytes.
Q.18. An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give any one reason.
Ans. A malfunctioning tapetum does not provide enough nourishment to the developing male gametophytes and thus fail to produce viable male gametophytes.
Q.19. Why do pollen grains of some flowers trigger ‘sneezing’ in some people?
Ans. They result in an allergic reaction.
Q.20. What is pollen–pistil interaction and how is it mediated?
Ans. The ability of the pistil to recognize the pollen followed by its acceptance or rejection is called pollen–pistil interaction. It is mediated by chemical components of pollen interacting with those of pistil.
Q.21. How is it possible in Oxalis and Viola plants to produce assured seed-sets even in the absence of pollinators?
Ans. By presence of cleistogamous flowers.
Q.22. The diploid number of chromosomes in an angiospermic plant is 16. What will be the number of chromosomes in its endosperm and antipodal cells?
Ans. Endosperm—24 chromosomes, Antipodals—8 chromosomes.
Q.23. How do flowers of Vallisneria get pollinated?
Ans. In Vallisneria, the female flower stalk is long to reach the water surface to receive the pollen grains carried by water currents and then it gets coiled after pollination.
Q.24. How many microspore mother cells would be required to produce one hundred pollen grains in a pollen sac? And why?
Ans. 1 microspore mother cell undergoes meiosis to form 4 pollen grains. In order to produce 100 pollen grains, 25 microspore mother cells must undergo meiosis.
Q.25. How many microsporangia are present in a typical anther of an angiosperm?
Ans. Four
Q.26. Name the common function that cotyledons and nucellus perform.
Ans. Cotyledons and nucellus provide nourishment.
Q.27. Pea flowers produce assured seed sets. Give a reason.
Ans. Pea flowers are cleistogamous, i.e., anther and stigma lie close to each other in closed flowers. So when anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, assured seeds are produced in pea.
Q.28. What features of flowers facilitate pollination by birds?
Ans. Presence of a large quantity of nectar, bright colours of petal, fragrance and large flowers attract birds from long distances.
Q.29. Name the part of the flower which the tassels of the corn-cob represent.
Ans. Style and stigma
Q.30. Name a plant in which dichogamy is found.
Ans. Magnolia
Q.31. Write the function of coleoptile.
Ans. It protects the plumule of the monocot embryo.
Q.32. Write the function of scutellum.
Ans. It provides nourishment and protection to the developing embryo.
Q.33. Name the part of gynoecium that determines the compatible nature of pollen grain.
Ans. Stigma
Q.34. Which are the three cells found in a pollen grain when it is shed at the three-celled stage?
Ans. One vegetative cell and two male gametes.
Q.35. What is nucellus?
Ans. The body of the ovule consists of a mass of parenchymatous cells rich in reserve food material which is called nucellus.
Q. 36. Who discovered double fertilisation in angiosperms?
Ans. S. G. Nawaschin (1897) discovered double fertilisation in angiosperms.