AP BIOLOGY

LABORATORY REVIEW

MITOSIS AND MEIOSIS

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

During what phase(s) does crossing over occur?

A	prophase I
B	prophase I and II
C	prophase I and metaphase I
D	metaphase I and anaphase I

Explanation:

Detailed explanation-1: -Crossing over is an enzyme-mediated process, where the exchange of genetic material between non-sister chromatids of homologous chromosomes takes place. It occurs at the pachytene stage of prophase I of meiosis.

Detailed explanation-2: -Crossing over is the exchange of genetic materials between non-sister chromatids of homologous chromosome. It takes place at pachytene stage of prophase-I.

Detailed explanation-3: -Crossing over occurs only during prophase I. The complex that temporarily forms between homologous chromosomes is only present in prophase I, making this the only opportunity the cell has to move DNA segments between the homologous pair.

Detailed explanation-4: -During meiosis, crossing-over occurs at the pachytene stage, when homologous chromosomes are completely paired.

There is 1 question to complete.