AP BIOLOGY

Detailed explanation-1: -Hence, the correct answer is option B, protonema of moss and prothallus of Dryopteris are gametophytic.

Detailed explanation-2: -The diploid sporophyte and haploid gametophyte of Dryopteris regularly alternate with each other. The haploid spore which gives rise to the gametophyte which is the monoecious prothallus and bears sex organs on its ventral side.

Detailed explanation-3: -The prothallus is haploid, since it grew from a spore which had been formed by meiosis. It does not have any vascular tissue and uses small rhizoids to anchor it to the ground. On the underside of the prothallus the sex organs form. The female structure, called an archegonium, contains a single egg.

Detailed explanation-4: -In pteridophytes, the spores germinate and give rise to prothallus. Prothallus are multicellular, free-living, mostly photosynthetic thalloid gametophytes.

Detailed explanation-5: -The prothallus of such plants is small, inconspicuous as the main plant body is sporophytic. But, this prothallus is free-living and photosynthetic thus not dependent on sporophyte. Prothallus requires cool shady places to grow and water for the fertilization of gametes to produce sporophyte.