AP BIOLOGY

Detailed explanation-1: -Prothallus of pteridophytes is inconspicuous small, multicellular, free living photosynthetic thalloid gametophyte. Haploid spore germinats to form a flat green heart shaped prothallus. It is monoecious, i.e., both sex organ male (antheridia) and female (archegonia) are present. Ferns exhibit alternation of generation.

Detailed explanation-2: -Some plant-like selaginella and Salvinia, possess micro and macro-sized spores and are termed heterosporous. The spore germinates and gives rise to small but multicellular free-living, inconspicuous, mostly photosynthetic thalloid gametophytes called prothallus.

Detailed explanation-3: -Prothallus of fern is flat, green, autotrophic, cordate (heart shaped), dorsiventral, about 1/8 to 113 inch in size (5-l0mm), free living independent, nonvascular gametophyte. Prothallium or prothallus is usually the gametophyte stage in the life cycle. The prothallium develops from a germinating spore.

Detailed explanation-4: -The prothallus is the fern gametophyte. It is a green, photosynthetic structure that is one cell thick, usually heart or kidney shaped, 3–10 mm long and 2–8 mm broad.

Detailed explanation-5: -In pteridophytes, the spores germinate and give rise to prothallus. Prothallus are multicellular, free-living, mostly photosynthetic thalloid gametophytes.