OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

When does meiosis occur in an organism?

1. During growth and repair

2. In the production of gametes

3. In the formation of tissues

4. During cell respiration

The correct answer is: In the production of gametes

Meiosis occurs specifically in the production of gametes, which are the reproductive cells needed for sexual reproduction. In animals, these gametes are sperm and eggs, while in plants, they can be pollen and ovules. This process involves two rounds of division, ultimately reducing the chromosome number by half, which is crucial for maintaining the species' chromosome number across generations. When a sperm and egg unite during fertilization, the original chromosome number is restored. The other options relate to different biological processes. Growth and repair typically occur through mitosis, where cells divide to produce identical copies for tissue replenishment. Formation of tissues is achieved through both mitosis and differentiation rather than meiosis. Cell respiration is a metabolic process that converts nutrients into energy but does not involve cell division or gamete formation. Thus, the role of meiosis is uniquely linked to gamete production, making this choice the most accurate.