AP BIOLOGY

Detailed explanation-1: -The majority of animal species reproduce sexually. Sexual reproduction is generally considered to be advantageous because it results in genetically variable progeny due to segregation and recombination events (Williams, 1975; Maynard Smith, 1978; Bell, 1982).

Detailed explanation-2: -Scientists believe that sexual reproduction offers two big advantages: It can sweep bad mutations out of the gene pool more quickly. Also, by shuffling parents’ genetic material each generation, it increases the likelihood that new genetic combinations will arise that help organisms adapt to their environment.

Detailed explanation-3: -Despite this, up to 99% of complex organisms reproduce sexually, at least some of the time. So it must convey some type of advantage.

Detailed explanation-4: -Sexual reproduction occurs in a variety of ways in animals. In some species, such as fish, the male releases sperm over the eggs after the female has laid them. In other species, such as birds and most mammals-including human beings-the male releases sperm into the female reproductive tract.

Detailed explanation-5: -The vast majority of animals need to breed to reproduce. But a small subset of animals can have offspring without mating. The process, called parthenogenesis, allows creatures from honey bees to rattlesnakes to have so-called “virgin births.”