Explain briefly the following terms with suitable examples:-(i) protonema(ii) Antheridium(iii) Archegonium(iv) Diplontic(v) Sporophyll(vi) Isogamy

Question

Philoid · Accepted Answer

(i) protonemaThe predominant stage of the life cycle of a moss is the gametophyte, which consists of two stages. The first stage is the protonema stage, which develops directly from a spore. It is a creeping, green, branched and frequently filamentous stage. Example: Sphagnum.(ii) Antheridium:The male sex organ is called antheridium. They produce biflagellate antherozoids. Example: Selaginella.(iii) Archegonium:The female sex organ is called archegonium. They produce biflagellate antherozoids. Example: Cycas.(iv) Diplontic:The gametophytic phase is represented by the single to few-celled haploid gametophyte. This kind of lifecycle is termed as diplontic. All seed-bearing plants gymnosperms and angiosperms are following this pattern. Example: Pinus.(v) Sporophyll:The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls. Example: Nephrolepis.(vi) Isogamy:Reproduction by the union or fusion of gametes of the same size and structure is called isogamy. Example: Spirogyra.