What type of cell participates in sexual reproduction and combines to form a zygote?

Gametes are the specialized cells involved in sexual reproduction, specifically sperm and egg cells in animals. During fertilization, a sperm cell (which is haploid, containing one set of chromosomes) combines with an egg cell (also haploid) to form a zygote, which is the first cell of a new organism. The zygote is diploid, containing two sets of chromosomes—one set from each parent.

This process is fundamental to sexual reproduction, as gametes are produced through meiosis, a type of cell division that reduces the chromosome number by half, ensuring that when two gametes unite, the resulting zygote restores the diploid number characteristic of the species. In contrast, somatic cells are all the other non-reproductive cells in an organism and do not participate in reproduction. Stem cells are undifferentiated cells capable of developing into various cell types but are not specifically involved in forming a zygote. Diploid cells refer to cells that contain two complete sets of chromosomes but do not specifically indicate that they participate in reproduction.