Question

Crossing over occurs between:

Options

• sister chromatids

• non-sister chromatids

• centromeres

• none of these

Answer 1

non-sister chromatids

Explanation:

Crossing over occurs during meiosis between two non-sister chromatids of homologous chromosomes. These chromatids come into contact at specific points called chiasmata where they break and exchange segments of genetic material. This exchange results in new combinations of genes in the gametes, contributing to genetic variation. Sister chromatids, originating from the same chromosome, do not exchange segments with each other during crossing over.