Advanced Placement (AP) Biology Practice Exam

What is the primary purpose of meiosis in sexually reproducing organisms?

1. To produce identical cells

2. To create genetic variation

3. To repair damaged DNA

4. To facilitate asexual reproduction

The correct answer is: To create genetic variation

The primary purpose of meiosis in sexually reproducing organisms is to create genetic variation. This process occurs in two main stages, meiosis I and meiosis II, leading to the formation of gametes—sperm and eggs in animals. One of the key mechanisms of genetic variation introduced during meiosis is crossing over, where homologous chromosomes exchange genetic material. This recombination results in new combinations of alleles, contributing to the diversity of traits in offspring. Additionally, the independent assortment of chromosomes during meiosis further enhances genetic variation. This random distribution of maternal and paternal chromosomes into gametes results in numerous possible combinations, ensuring that no two gametes (and thus no two offspring from the same parents) are genetically identical, barring identical twins. In contrast, the other options do not accurately capture the primary role of meiosis. Producing identical cells is a function of mitosis, while repairing damaged DNA is primarily achieved through various cellular repair mechanisms, not meiosis. Asexual reproduction relies on processes like mitosis rather than meiosis, which is specifically geared towards generating genetic diversity that is crucial for evolution and adaptation in sexually reproducing populations.