Ace the AP Biology Challenge 2025 – Unleash Your Inner Scientist and Conquer the Course!

The correct answer, gametes, refers to the specialized reproductive cells involved in sexual reproduction. In humans and many other organisms, gametes are the sperm and egg cells. These cells are haploid, meaning they contain half the number of chromosomes compared to somatic cells, which are diploid and make up the bulk of an organism’s body. When gametes fuse during fertilization, they restore the diploid state in the resulting zygote.

Gametes undergo a process called meiosis, which reduces the chromosome number by half and introduces genetic variation through recombination and independent assortment. This is crucial for evolution and the genetic diversity of populations.

In contrast, sister chromatids are identical copies of a chromosome that are formed during DNA replication but are not involved in reproduction themselves. Somatic cells are all the body cells not involved in forming gametes, and while diploid cells contain two sets of chromosomes, they do not directly participate in reproduction. Only gametes are specifically designed for the purpose of passing genetic material to the next generation.