Question

genes can sometimes be exchanged between homologous chromosome pairs. this process is known as crossing - over
which of the following statements is true of crossing - over?
a. only one gene may be exchanged at a time during crossing - over
b. crossing - over contributes to genetic diversity or variation.
c. the gene for eye color can be exchanged with the gene for hair color during crossing - over
d. crossing - over always results in a non - beneficial mutation

Explanation:

• Option A: Crossing - over can involve multiple genes, not just one at a time.
• Option B: Crossing - over leads to new combinations of genes on chromosomes. This creates genetic diversity as offspring receive a unique set of genetic material compared to their parents.
• Option C: Genes are located at specific loci on chromosomes. Eye - color and hair - color genes are likely on different chromosomes (or at least not on homologous regions in a way that would allow such an exchange). Crossing - over occurs between homologous chromosomes, and genes are exchanged in a more locus - specific (not arbitrary between non - homologous genes) manner.
• Option D: Crossing - over is a normal process of genetic recombination and does not always result in a non - beneficial mutation. It can lead to beneficial, neutral, or non - beneficial changes, but “always” is an incorrect absolute statement.

Answer:

B. Crossing - over contributes to genetic diversity or variation.