Multiple choice

Crossing over during meiosis occurs at 4 – strand stage called Pachytene stage. This was proved by which of the following observations?

  1. Chiasmata occurs at 4 strand stage.

  2. All 4 gametes show recombinations.

  3. Mostly 2 gametes out of 4 formed meiosis are recombinants.

  4. All are correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chromosomal crossover (or crossing over) is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs during prophase I of meiosis(pachytene) in a process called synapsis. Synapsis begins before the synaptonemal complex develops, and is not completed until near the end of prophase I. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome.

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