alternation of generations

noun Biology.

1. the alternation in an organism’s life cycle of dissimilar reproductive forms, especially the alternation of sexual with asexual reproduction.

noun

1. the production within the life cycle of an organism of alternating asexual and sexual reproductive forms. It occurs in many plants and lower animalsAlso called: metagenesis, heterogenesis, digenesis, xenogenesis

n.

1. The regular alternation of forms or of mode of reproduction in the life cycle of an organism, such as between diploid and haploid phases, or between sexual and asexual reproductive cycles.metagenesis xenogenesis

1. The regular alternation of forms or of mode of reproduction in the life cycle of an organism, especially the alternation between sexual and asexual reproductive phases in plants and some invertebrates. In plants, the alternation involves alternating generations of haploid and diploid organisms. Often one of these generations is the dominant form of the organism, and the other generation is nutritionally dependent upon it or just grows as a smaller plant. For example, in mosses and liverworts, the haploid phase is the large, familiar form of the plant. The diploid phase is smaller and grows upon the haploid phase. In angiosperms, however, the diploid phase of the organism is large and independent, while the haploid phase is reduced to the pollen grain and the eight-celled female gametophyte located in the ovule.