Question

Match the stages of prophase I given in Column-I with their features in Column-II and choose the correct options from the choices given below:

 

• A. a-iv, b-i, c-ii, d-iii, e-v
• B. a-ii, b-iv, c-i, d-iii, e-v
• C. a-i, b-ii, c-iii, d-iv, e-v
• D. a-v, b-iv, c-i, d-iii, e-ii

Hint:

Zygotene involves synapsis, while Pachytene is the stage for crossing over in prophase I.

Answer 1

The Correct Option is B

• Prophase I Stages: Prophase I of meiosis I involves five sub-stages with distinct features.
• Stage Analysis:
  • (a) Leptotene: Chromosomes begin to condense and become visible under a light microscope. Matches (ii).
  • (b) Zygote: This is not a stage of prophase I; it is the fertilized egg. The intended stage might be a mislabel (possibly meant to be Zygotene). In Zygotene, chromosomes start pairing (synapsis), matching (iv).
  • (c) Pachytene: Crossing over occurs, involving the exchange of genetic material between non-sister chromatids of homologous chromosomes, matching (i).
  • (d) Diplotene: The synaptonemal complex dissolves, and homologous chromosomes begin to separate, matching (iii).
  • (e) Diakinesis: Terminalisation of chiasmata occurs as the final step before metaphase I, matching (v).
• Correction Note: The term "Zygote" appears to be a mistake. In meiosis context, "Zygotene" is the correct stage where chromosome pairing begins. Assuming this typo, the matching proceeds with Zygotene.
• Option Analysis:
  • (1) a-iv, b-i, c-ii, d-iii, e-v: Incorrect for a (should be ii) and b (should be iv if Zygotene).
  • (2) a-ii, b-iv, c-i, d-iii, e-v: Correct if b is interpreted as Zygotene (chromosome pairing). Matches the sequence.
  • (3) a-i, b-ii, c-iii, d-iv, e-v: Incorrect for a (should be ii) and b (should be iv).
  • (4) a-v, b-iv, c-i, d-iii, e-ii: Incorrect for a (should be ii) and e (should be v).
• Conclusion: The correct option is (2), assuming "Zygote" is a typo for "Zygotene," where a-ii (Leptotene: chromosomes visible), b-iv (Zygotene: chromosomes pair), c-i (Pachytene: genetic exchange), d-iii (Diplotene: synaptonemal complex dissolution), e-v (Diakinesis: chiasmata terminalisation) align with prophase I features.