NEET Biology Sexual Reproduction in Flowering Plants Important Questions Set 02

These Class 12 NEET Biology important questions on Sexual Reproduction in Flowering Plants give 21 questions with step-by-step answers, arranged as very short, short and long answer types, taken from a model test paper. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. In the following figure of fruit, identify the part which is developed from ovary wall and that which is responsible for producing new plants. A B C
Answer: A - Pericarp; B - Seed (produce new plant)

Question 2. Name the plant in which each fruit contain thousands of tiny seeds.
Answer: Orchids

Question 3.

Which of the following plant showns insect pollination?

Answer:

Water hyacinth

Question 4. Why is strawberry called as false fruit?
Answer: Strawberry is a false fruit because the thalamus takes part in fruit formation along with ovary.

Question 5. The pollen grains can be well-preserved as fossils. Mention the characteristic of pollen grain that makes it happen.
Answer: The outer layer of pollen wall is made of sporopollenin which is one of the most resistant organic material known. Hence, pollen grains are preserved as fossils.

Question 6. What is the number of chromosomes in secondary nucleus if leaf cell of angiospermic plant contain 12 chromosomes?
Answer: Seconday nucleus (diploid) = 12.

Short Answer Type Questions

Question 7. Explain how geitonogamy is functionally similar to cross-pollination and genetically similar to autogamy.
Answer: Geitonogamy involves transfer of pollen grains from anther to stigma of another flower on the same plant. It needs a pollinating agent for this transfer hence is functionally similar to cross-pollination. As the transfer takes place between genetically similar flowers, it is genetically autogamous.

Question 8. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm.
Answer: Zygote is a product of syngamy which involves fusion of one male gamete (n) and the egg (n). Hence, the product (zygote) is diploid. Primary endosperm nucleus is a product of triple fusion which involves fusion of three haploid nuclei i.e. one male gamete and two haploid polar nuclei. Hence, it is triploid.

Question 9. Name the haploid cells present at chalazal site of mature female gametophyle of a flowering plant. How many haploid nuclei are present in a mature embryo sac?
Answer: The haploid cells present at chalazal end in a mature female gametophyte of a flowering plant are antipodal cells. There are eight nuclei present in a mature embryo sac.

Question 10. If you squeeze a seed of orange you might observe many embryos of different sizes. How is it possible? Explain.
Answer: Orange show polyembryony. The various types of embryo seen inside the orange seeds are :
(i) Single zygote embryo formed as a result of sexual reproduction.
(ii) Nucellar embryos formed as a result of proliferation of cells of nucellus.

Question 11. In Viola, assured seed set is there. Give reasons.
Answer: Because it possesses cleistogamous flowers. In such flowers, anthers and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination.

Short Answer Type Questions

Question 12. How do flowers reward their insect pollinators. Explain.
Answer: Flowers reward their insect pollinators by providing them with
(a) Nectar
(b) Pollen
(c) Safe place to lay eggs, for example, Amorphophallus.

Question 13. Describe in brief the different wall layers of anther with the help of well-labelled diagram.
Answer: Connective Epidermis Endothecium Sporogenous Middle layers tissue Tapetum The different wall layers are as follows :
(i) Epidermis : Protective in function.
(ii) Endothecium : Has fibrous thickening and help in dehiscence of anther.
(iii) Middle layers : Usually undergo degeneration and nourish sporogenous tissue.
(iv) Tapetum : Nutritive in function. Also responsible for production of enzymes, sporopollenin and compatibility proteins.

Question 14. Draw a well-labelled diagram of an anatropous ovule.
Answer: A well-labelled diagram should show these parts: Hilum; Funicle; Micropyle; Micropylar pole; Outer integument; Inner integument; Nucellus; Embryo sac; Chalazal pole.

Question 15. Differentiate between vegetative cells and generative cell of pollen.

Answer:

Question 16. Mention any four strategies adopted by flowering plants to promote self-pollination.
Answer: Four strategies adopted by flowering plants to promote self-pollination are :
(i) Same maturation time of anther and stigma. Hence, pollen release and stigma receptivity are synchronised.
(ii) Cleistogamy
(iii) Production of bisexual flowers.

Question 17. (i) Even though each pollen grain has two male gametes why are at least ten pollen grains and not five pollen grains are required to fertilise ten eggs present in a particular carpel.
(ii) What is seed dormancy?
Answer: (i) Because in each pollen only one of the male gametes contributes to zygote formation (syngamy). The other is involved in triple fusion.
(ii) The inability of the seed to germinate even in the presence of favourable condition is called seed dormancy.

Question 18. Make the labelled diagram of castor seed.
Answer: Castor seed

Question 19. Explain the following terms :
(i) Parthenocarpic fruits
(ii) Apomixis
(iii) Exalbuminous seeds
Answer: (i) Parthenocarpic fruits are seedless fruits produced without fertilisation.
(ii) Apomixis is production of seeds without fertilisation.
(iii) Seed in which the endosperm is consumed and is not a part of mature seed.

Long Answer Type Questions

Question 20. Explain the process of artificial hybridisation to get improved crop variety in
(i) Plants bearing bisexual flowers.
(ii) Female parent producing unisexual flowers.
Answer: (i) In plants, bearing bisexual flowers removal of anthers from the flower bud before anther dehisces is necessary. This step is called as emasculation. Emasculated flowers have to be covered with a bag to prevent contamination of the stigma with unwanted pollen. This process is called bagging. When the stigma of bagged flowers attains receptivity, mature pollen grains collected from anthers of the male parent are dusted on the stigma and the flowers are rebagged.
(ii) If the female parent produces unisexual flowers, there is no need of emasculation. The female flowers buds are bagged before the flowers open when the stigma becomes receptive, pollination is carried out using the desired pollen and the flower is rebagged.

Question 21. Draw labelled diagrams for :
(a) Angiospermic dicot embryo
(b) Longitudinal section of a flower showing growth of pollen tube
Answer: A well-labelled diagram should show these parts: (a); (b); Pollen tube; Antipodal; Polar nuclei; Egg cell; Synergid; .