In A type of life cycle, the haploid organisms (n) gives rise to haploid gametes, which fuse to form diploid zygote (2n). Meiosis occurs in zygote at the time of germination and is producing haploid individuals. Such kind of life cycle is called haplontic and is primitive and exhibited in lower groups of plants such as certain algae.
In life cycle B, the diploid individual (2n) produces haploid gametes (n) by meiosis, which fuse to form diploid zygote (2n). This is diplontic life cycle in which haploid gametophytic somatic phase gets eliminated through progressive evolution. This kind of life cycle is exhibited by higher plants such as gymnosperms and angiosperms.
