AP BIOLOGY

Detailed explanation-1: -Cell-Surface Receptors These receptors are also known as transmembrane receptors. These are proteins that are found on the surface of cells and span the plasma membrane. They bind to ligands that cannot themselves pass through the plasma membrane.

Detailed explanation-2: -Receptors come in many types, but they can be divided into two categories: intracellular receptors, which are found inside of the cell (in the cytoplasm or nucleus), and cell surface receptors, which are found in the plasma membrane.

Detailed explanation-3: -Cell surface receptors are transmembrane proteins embedded into the plasma membrane which play an essential role in maintaining communication between the internal processes within the cell and various types of extracellular signals.

Detailed explanation-4: -All the statements about receptors are true except D; That receptors catalyse reactions on chemical messengers. Receptors do not catalyze reactions but only provide binding sites for ligands.