Q.Name the two generations that alternate in the life cycle of a moss.

Every plant life cycle alternates a diploid sporophyte (2n) generation with a haploid gametophyte (n) generation: diploid cells in the sporophyte undergo meiosis to form haploid spores; spores divide by mitosis to build the gametophyte; the gametophyte produces gametes by mitosis; two gametes fuse at fertilisation to form a diploid zygote; and the zygote divides by mitosis to rebuild the sporophyte.

Three patterns are named by which phase is multicellular/dominant: haplontic (mitosis only on the haploid side; the zygote is the sole diploid cell and undergoes meiosis immediately -- e.g. some algae), diplontic (mitosis only on the diploid side; only the gametes are haploid -- e.g. animals), and haplo-diplontic (mitosis on both sides, so both a multicellular gametophyte and a multicellular sporophyte occur -- e.g. land plants and many algae). …