Final answer:
Twenty-three tetrads form during synapsis in prophase I of meiosis in humans, corresponding to the 23 pairs of chromosomes. This contributes to genetic diversity through the random orientation of tetrads at the metaphase plate.
Step-by-step explanation:
During synapsis, which occurs in prophase I of meiosis, tetrads form as pairs of homologous chromosomes come together. Each homologous pair of chromosomes consists of four chromatids, hence the term tetrad. The number of tetrads that form during synapsis is equal to the number of chromosome pairs present in the organism. For humans, this means that 23 tetrads form during synapsis, as humans have 23 pairs of chromosomes.
It's also important to note that the arrangement of tetrads during meiosis contributes to genetic diversity. The orientation of each tetrad is independent of the others, and there are two possibilities for orientation at the metaphase plate. This results in a great number of possible combinations of maternal and paternal chromosomes, specifically 2n alignments, where n is the number of chromosomes per haploid set.