PMDC Verified Question 24 of 94
In which phase of meiosis crossing over takes place?
A
Leptotene
B
Diplotene
C
Pachytene
D
Zygotene
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Pachytene
Concept:

Prophase I of meiosis is a complex, extended phase subdivided into five distinct stages based on chromosomal behavior.

Solution:

  • Zygotene: Homologous chromosomes begin to pair up (synapsis) to form bivalents.
  • Pachytene: The chromosomes fully thicken, and non-sister chromatids intertwine. It is in this specific stage that the physical exchange of genetic material (crossing over) actually takes place.
  • Diplotene: The chromosomes begin to separate, and the points of crossing over become visible as chiasmata.


Why other options are incorrect:

  • Crossing over is an active, enzymatic process that is exclusively localized to the Pachytene stage.

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