Explain briefly the following terms with suitable examples:
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy

(i) Protonema – It is the first stage in the life cycle of a moss, developing directly from the spore. It consists of creeping, green, branched, and often filamentous structures.
(ii) Antheridium – It is the male sex organ present in bryophytes and pteridophytes. It enclose the sperm mother cells that give  rise to the male gametes. 
(iii) Archegonium – It is the female sex organ present in bryophytes, pteridophytes, and gymnosperms. In bryophytes and pteridophytes, it generally contains the female gamete called the egg. 
(iv) Diplontic –It is the kind of life cycle in which the diploid sporophyte is the dominant, photosynthetic, independent phase of the plant. The gametophytic phase is represented by the single to few-celled haploid gametophyte. 
(v) Sporophyll – The leaf like appendages which bear the sporangia is called sporophyll. These can bear both the microspores and megaspores.
(vi) Isogamy – It is a type of sexual reproduction involving the fusion of morphologically-similar gametes. This means that the gametes are of the same size, but perform different functions. This type of reproduction is commonly observed in Spirogyra.