Final answer:
The primary sex cell is haploid, which means sex cells such as sperm and eggs have just one set of chromosomes. In humans, these haploid cells combine during fertilization to form a diploid zygote. Meiosis is the cellular process that produces four unique haploid cells from one diploid cell.
Step-by-step explanation:
The primary sex cell is haploid. This means that sex cells, or gametes, such as sperm and eggs, contain a single set of chromosomes. They are designated by the symbol n. On the other hand, most of the cells in the human body are diploid, meaning they have two sets of chromosomes, symbolized as 2n. During sexual reproduction, a haploid sperm (n) and a haploid egg (n) combine to form a diploid zygote (2n), which will develop into a new individual. This union restores the diploid state with half the DNA coming from each parent.
Regarding the process of meiosis, it usually produces four haploid cells from one diploid cell, ensuring genetic diversity. To clarify, a diploid cell undergoes DNA replication and then two rounds of cellular division to produce four genetically unique haploid cells, which are the gametes. In diploid-dominant organisms like humans, meiosis occurs in specialized cells called germ cells, which are found within the gonads (testes and ovaries). These germ cells are capable of both mitosis and meiosis; they perform mitosis to maintain the germ cell line and meiosis to produce haploid gametes.