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ISC Class 12 Biology — practice by topic

Browse 399 questions across 5 Biology topics. Choose what you want to revise, then open a question to check its answer and worked solution.

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Biology topics

Genetics and Evolution (109)Reproduction in Organisms & Plants (98)Biotechnology and Applications (84)Biology in Human Welfare & Health (58)Ecology and Environment (50)

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After microsporogenesis, the cells of the resulting microspore tetrad have a ploidy of:Read the answer and worked solution →The germ pores in a pollen grain are regions where:Read the answer and worked solution →In a mature 2-celled pollen grain at the time of shedding, the two cells present are:Read the answer and worked solution →Approximately what percentage of angiosperms shed pollen at the 2-celled stage?Read the answer and worked solution →

Worked practice questions

After microsporogenesis, the cells of the resulting microspore tetrad have a ploidy of:

  1. Diploid (2n)
  2. Haploid (n)
  3. Tetraploid (4n)
  4. Triploid (3n)
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Correct answer: B. Haploid (n)

Meiosis halves the chromosome number: PMC (2n) → tetrad of four **haploid (n)** microspores.

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The germ pores in a pollen grain are regions where:

  1. Cytoplasm is absent
  2. The intine is absent
  3. The exine is absent (no sporopollenin)
  4. The whole wall is absent
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Correct answer: C. The exine is absent (no sporopollenin)

**Germ pores** are apertures in the exine where **sporopollenin is absent** — the pollen tube emerges through one of these during germination.

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In a mature 2-celled pollen grain at the time of shedding, the two cells present are:

  1. Vegetative cell and generative cell
  2. Two male gametes
  3. Two synergids
  4. Egg cell and synergid
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Correct answer: A. Vegetative cell and generative cell

**Mature 2-celled pollen:** a **large vegetative cell** (with reserve food and irregular nucleus) and a **small spindle-shaped generative cell** floating in vegetative cell cytoplasm. The generative cell divides later to give two male gametes.

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