Sexual Reproduction in Flowering Plants: Class 12 Important Questions with Answers

Practice set: test yourself

Try every question before looking at the answers below. 64 or more out of 80 means you are ready for the board.

C. Very short answer (1 mark each)

1. Name the stalk of the ovule.
2. Where is the egg apparatus located?
3. Name a plant with cleistogamous flowers.
4. Name a water-pollinated plant whose pollen floats.
5. Ploidy of the nucellus.
6. Name the oldest viable seed recorded.
7. What is a false fruit? Give an example.
8. Which part of the ovule forms the seed coat?
9. Name a monoecious plant.
10. Give one example of parthenocarpic fruit.

D. Short answer I (2 marks each)

1. Distinguish between autogamy and geitonogamy.
2. Why is the exine resistant? Where is it absent?
3. Give two adaptations of wind-pollinated flowers.
4. What are floral rewards? Give two examples.
5. How many pollen grains form from 100 PMCs, and why?
6. Give two differences between albuminous and non-albuminous seeds.
7. What is polyembryony? Give an example.
8. Why are pollen banks useful?

E. Short answer II (3 marks each)

1. Draw a labelled diagram of the L.S. of a pistil showing pollen tube growth.
2. Describe the structure of a dicot embryo.
3. Explain the steps of an artificial hybridisation programme.
4. How is pollination carried out in Vallisneria and Zostera?
5. Describe the development of the endosperm and its types with examples.
6. Explain the relationship between Yucca and its moth.

F. Long answer (5 marks each)

1. Describe the post-pollination events from pollen–pistil interaction to the formation of the zygote and the PEN.
2. Describe megasporogenesis and the development of the embryo sac with a diagram.

G. HOTS (higher-order thinking)

1. Why do most flowers favour cross-pollination although self-pollination is easier?
2. A plant has flowers whose pollen and stigma mature together but sit far apart. Which pollination is prevented and why?
3. Why does the endosperm develop before the embryo?
4. Why would a seed with 3n cells and 2n cells come from one ovule?

20 MCQs

1. The innermost wall layer of the microsporangium
   (a) endothecium (b) epidermis (c) tapetum (d) middle layer
2. Number of microsporangia in a typical anther
   (a) 4 (b) 2 (c) 1 (d) 8
3. Exine is made of
   (a) cellulose (b) lignin (c) pectin (d) sporopollenin
4. In over 60% of angiosperms pollen is shed at the
   (a) 3-celled stage (b) 2-celled stage (c) tetrad stage (d) microspore stage
5. The embryo sac develops from
   (a) all four megaspores (b) one functional megaspore (c) the nucellus (d) the MMC directly
6. Number of free-nuclear divisions in embryo sac formation
   (a) 2 (b) 1 (c) 4 (d) 3
7. The filiform apparatus is present in
   (a) synergids (b) antipodals (c) egg (d) central cell
8. Geitonogamy is transfer of pollen to
   (a) the same flower (b) another plant (c) another flower of the same plant (d) none
9. Which is water-pollinated?
   (a) water hyacinth (b) lotus (c) water lily (d) Vallisneria
10. Dioecious plant
    (a) maize (b) papaya (c) castor (d) pea
11. Ploidy of the endosperm
    (a) n (b) 2n (c) 3n (d) 4n
12. Coconut water is
    (a) free-nuclear endosperm (b) cellular endosperm (c) perisperm (d) nucellus
13. Scutellum is
    (a) radicle sheath (b) the cotyledon of grasses (c) plumule sheath (d) seed coat
14. Perisperm is found in
    (a) wheat (b) pea (c) black pepper (d) castor
15. Apple is a false fruit because the fruit forms partly from
    (a) ovule (b) style (c) pericarp (d) thalamus
16. Seedless fruits formed without fertilisation are
    (a) parthenocarpic (b) apomictic (c) polyembryonic (d) cleistogamous
17. Polyembryony from nucellar cells occurs in
    (a) Citrus (b) wheat (c) pea (d) maize
18. The oldest viable seed recorded
    (a) date palm (b) wheat (c) lotus (d) Lupinus arcticus
19. Emasculation is not needed in
    (a) pea (b) unisexual female flowers (c) wheat (d) rice
20. The zygote is formed by
    (a) triple fusion (b) apomixis (c) syngamy (d) parthenocarpy

1 (c) · 2 (a) · 3 (d) · 4 (b) · 5 (b) · 6 (d) · 7 (a) · 8 (c) · 9 (d) · 10 (b) · 11 (c) · 12 (a) · 13 (b) · 14 (c) · 15 (d) · 16 (a) · 17 (a) · 18 (d) · 19 (b) · 20 (c)

Assertion–Reason (6)

(a) Both true, R explains A. (b) Both true, R does not explain A. (c) A true, R false. (d) A false, R true.

1. A: Pollen grains are well preserved as fossils. R: Their exine is made of sporopollenin, which no enzyme can degrade.
2. A: Cleistogamous flowers produce assured seed sets. R: They are invariably autogamous and need no pollinator.
3. A: The embryo sac is 7-celled. R: It has 8 nuclei.
4. A: Papaya shows geitonogamy. R: Papaya is dioecious.
5. A: The zygote divides only after some endosperm forms. R: The endosperm nourishes the developing embryo.
6. A: Apomictic seeds are genetically identical to the parent. R: Apomixis involves fertilisation between genetically similar plants.

Key: 1 (a) · 2 (a) · 3 (b) · 4 (d) · 5 (a) · 6 (c)

Answers to the practice set