AP BIOLOGY

Detailed explanation-1: -A whisk fern has water-and food-conducting tissues but lacks true leaves and roots. Photosynthesis occurs in the aerial stems, and water and mineral absorption occurs in the horizontal underground rootlike stems (rhizomes), which receive water and nutrients from fungi through a mycorrhizal association.

Detailed explanation-2: -The dominate phase of the whisk fern life cycle, the sporophyte, has distinctive dichotomously branching stems which are solely responsible for photosynthesis and gas exchange.

Detailed explanation-3: -Photosynthesis occurs in the stems of whisk ferns, which lack roots and leaves. Most ferns have branching roots and form large compound leaves, or fronds, that perform photosynthesis and carry the reproductive organs of the plant.

Detailed explanation-4: -Whisk ferns in the genus Psilotum lack true roots but are anchored by creeping rhizomes. The stems have many branches with paired enations, which look like small leaves but have no vascular tissue.

Detailed explanation-5: -The underground stems are rhizoid-bearing rhizomes with endophytic mycorrhizae; aerial stems are photosynthetic, terete, ridged, or flattened, and are dichotomously branched or unbranched, the vasculature a protostele or solenostele.