Sexual Reproduction in Flowering Plants – important questions for Boards 2027

CBSE Class 12 Biology

1. VSA · 0.5 marks

   What role do flowers play in sexual reproduction in angiosperms?

   Answer

   Flowers are the sites of sexual reproduction in angiosperms, where male and female reproductive units develop.

2. VSA · 1 mark

   Name the innermost wall layer of a microsporangium and state its function.

   Answer

   The tapetum is the innermost wall layer of a microsporangium; it nourishes the developing pollen grains.

3. SA · 1.5 marks

   State what the primary endosperm cell and the zygote develop into.

   Answer

   The primary endosperm cell (PEC) develops into the endosperm, which contains reserve food materials used for the nutrition of the developing embryo. The zygote develops into an embryo.

4. SA · 2 marks

   What is a pollen grain, and what is its reproductive significance in flowering plants?

   Answer

   A pollen grain is the male gametophyte of a flowering plant. It develops from a microspore and carries the male reproductive cells, which reach the ovule through pollen-tube growth for fertilisation.

5. MA · 3 marks

   Explain the conditions required for autogamy. How do cleistogamous flowers ensure seed set even when pollinators are absent?

   Answer

   1. Autogamy is the transfer of pollen grains from the anther to the stigma of the same flower. Pollen release and stigma receptivity must coincide, and the anther and stigma must be positioned so pollen can reach that stigma. 2. Cleistogamous flowers remain closed and are invariably autogamous, with no chance of cross-pollen landing on the stigma. Their self-pollination ensures seed-set even when pollinators are absent.

6. LA · 4 marks

   Explain how an ovule and ovary develop after fertilisation, naming the resulting structures and the fruit wall. Distinguish true fruits from false fruits, and explain parthenocarpy with one example.

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7. LA · 5 marks

   Distinguish between geitonogamy and xenogamy with reference to the source of pollen and their genetic significance.

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8. VLA · 8 marks

   Describe how the integuments contribute to the mature seed and state the role of the micropyle during germination. Explain how seed maturation changes water content and embryo metabolism, and distinguish dormancy from germination by stating the conditions needed for germination.

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9. VSA · 0.5 marks

   What is floriculture?

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10. MCQ · 1 mark

    Megasporogenesis is the process by which: (A) a megaspore mother cell undergoes meiosis to form megaspores (B) a functional megaspore undergoes mitosis to form an embryo sac (C) an ovule develops into a seed (D) a pollen grain forms two male gametes

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