AP BIOLOGY

Detailed explanation-1: -The correct option is D Suberin. Suberin is a impermeable waxy substance present in the cell walls of corky tissues. The cork cells are compactly arranged without any intercellular spaces and the chemical called suberin in the cell walls of cork cells makes them impervious to gases and water.

Detailed explanation-2: -Cork tissue, consisting of dead cells surrounded by alternating layers of suberin and wax, has a particularly high suberin content. Cork cells are found in a secondary protective layer (periderm) in the bark of trees.

Detailed explanation-3: -Suberin is a water-impermeable waxy material which deposits in the cell walls of the endodermal cells.

Detailed explanation-4: -Suberin is found in the phellem layer of the periderm (or cork). This is outermost layer of the bark. The cells in this layer are dead and abundant in suberin, preventing water loss from the tissues below. Suberin can also be found in various other plant structures.