Which of the following is true of crossing over during meiosis?

• A. It occurs during prophase I and increases genetic variation.
• B. It occurs during anaphase I and results in identical daughter cells.
• C. It occurs during metaphase II and reduces genetic variation.
• D. It occurs during telophase II and has no effect on genetic variation.

Answer: (A)

Verified step by step guidance

1. Understand the process of meiosis: Meiosis is a type of cell division that reduces the chromosome number by half, creating four haploid cells. It consists of two stages: meiosis I and meiosis II.
2. Identify the phases of meiosis I: Meiosis I includes prophase I, metaphase I, anaphase I, and telophase I. Crossing over occurs during prophase I.
3. Explain crossing over: Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis. This process increases genetic variation by producing new combinations of alleles.
4. Consider the effects of crossing over: By increasing genetic variation, crossing over contributes to the diversity of traits in a population, which is important for evolution and adaptation.
5. Review the options given: The correct statement is that crossing over occurs during prophase I and increases genetic variation. The other options incorrectly describe the timing and effects of crossing over.