Anatomy and Physiology II Practice Test

Primary spermatocytes undergo meiosis to form sperm cells. During this specialized type of cell division, a primary spermatocyte, which is diploid (having two sets of chromosomes), divides into two secondary spermatocytes through the first meiotic division. Each secondary spermatocyte is haploid, containing one set of chromosomes. Following this, each secondary spermatocyte undergoes a second meiotic division, resulting in a total of four haploid spermatids. These spermatids will then undergo further development to become mature sperm cells.

Meiosis is crucial in sexual reproduction because it reduces the chromosome number by half, ensuring that when sperm and egg unite during fertilization, the resulting zygote has the correct diploid number of chromosomes. This process also leads to genetic variation, as it involves recombination and independent assortment of chromosomes.

In contrast, mitosis serves to make identical copies of cells for growth and repair and does not reduce chromosome numbers. Binary fission is a method of reproduction seen in prokaryotic organisms, while clonal expansion refers to a process involving the proliferation of a single type of cell, particularly in the context of immune responses.