EVERYDAY SCIENCE

Detailed explanation-1: -Prothallium or prothallus is usually the gametophyte stage in the life cycle. The prothallium develops from a germinating spore. It is a short-lived structure, typically 2-5 millimeters wide, with a number of rhizoids (root-like hairs) growing underneath, and the sex organs: archegonium (female) and antheridium (male).

Detailed explanation-2: -The life cycle of the fern has two different stages; sporophyte, which releases spores, and gametophyte, which releases gametes. Gametophyte plants are haploid, sporophyte plants diploid. This type of life cycle is called alternation of generations.

Detailed explanation-3: -A prothallus, or prothallium, (from Latin pro = forwards and Greek (thallos) = twig) is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young gametophyte of a liverwort or peat moss as well.

Detailed explanation-4: -Prothallus is the heart shaped fern gametophyte in pteridophytes such as ferns that produce both male and female gametes. Female gametes are produced in the archegonia located at the top of the prothallus. Male gametes are formed in the antheridia located among rhizoids. Thus the correct answer is option A.

Detailed explanation-5: -Gametophytes contain both female (archegonium) and male (antheridium) sex organs. They mature at different times in order to increase the chances of cross-fertilisation and genetic variation. The prothallus is the fern gametophyte.