AP BIOLOGY

Detailed explanation-1: -The majority of the lichen thallus is comprised of fungal filaments called the medulla. It is made of fungal cells that are loosely packed in the middle of the lichen thallus, have thin cell walls, and are threadlike. The result is a cotton-like substance underneath the outer cortex.

Detailed explanation-2: -Flattened or foliaceous: The thalli develop as the primary filament cells divide in all directions and the essential filamentous structure is lost, eg, Porphyra, Ulva, and Enteromorpha (Fig. 3.1). Complex: Flat foliose or tubular thalli are formed by the division of cells in two or more planes.

Detailed explanation-3: -The thallus is dorsiventrally differentiated. Its upper (dorsal) surface is green and chlorophyll-bearing, with a mid-dorsal longitudinal sulcus (furrow or groove). Air pores occasionally break through the dorsal surface, giving the thallus a dimpled appearance.

Detailed explanation-4: -Thallose liverworts, which are branching and ribbonlike, grow commonly on moist soil or damp rocks, while leafy liverworts are found in similar habitats as well as on tree trunks in damp woods. The thallus (body) of thallose liverworts resembles a lobed liver-hence the common name…