Answered

Crossing over occurs when

A. sister chromatids are pulled apart at the centromere during anaphase II.

B. homologous chromosomes join together to form tetrads during prophase I.

C. chromosomes are grouped together into new nuclei during telophase II.

D. tetrads of homologous chromosomes randomly line up in metaphase I.

Answer :

B. Crossing over occurs when homologous chromosomes pair up and exchange genetic material at the chiasmata (site of exchange).

B. homologous chromosomes join together to form tetrads during prophase I.


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