AQA AS Biology 2025 – 400 Free Practice Questions to Pass the Exam

Meiosis plays a crucial role in sexually reproducing organisms by halving the chromosome number. This process is essential for the formation of gametes (sperm and eggs). During fertilization, when two gametes fuse, they restore the original diploid number of chromosomes in the resulting zygote. By reducing the chromosome number to haploid, meiosis ensures that offspring inherit a balanced combination of genetic material from both parents, maintaining stability in the chromosome number across generations. This reduction also allows for genetic variation through processes such as crossing over and independent assortment, contributing to the diversity observed in sexually reproductive species. This is fundamental for evolution and adaptation as it enhances genetic diversity in populations.