Life cycle refers to the series of changes that the members of a species undergo as they pass from the beginning of a given developmental stage to the beginning of that same developmental stage in a subsequent generation.

In many simple organisms, including bacteria and various protists, the life cycle is completed within a single generation: an organism begins with the fission of an existing individual; the new organism grows to maturity; and it then splits into two new individuals, thus completing the cycle. In higher animals, the life cycle is also complete in a single generation. The individual animal begins with the union of male and female sex cells (gametes); it grows to reproductive maturity; and it then produces gametes, at which point the cycle begins anew.

By contrast, in most plants, the life cycle is multigenerational. An individual plant begins with the germination of...