Final answer:
Gametes are the sex cells in sexually reproducing species, with males producing sperm and females producing eggs. These cells are haploid and unite during fertilization to form a diploid zygote.
Step-by-step explanation:
The term for the sex cells in a sexually reproducing species is gametes. In sexual reproduction, two gametes combine to produce offspring with genetic material from both parents. The male gamete is typically called sperm, which can be motile and smaller, while the female gamete is called an egg, which is usually larger and sessile. Gametes are haploid cells, meaning they have half the number of chromosomes of normal body cells, which are diploid. In humans, this means that gametes contain 23 chromosomes.