Which of these is a receptor molecule? a. cell membrane with an integral molecule marked b. there is a specific recess in this molecule on the extracellular side. c. a molecule in the intracellular fluid, whose shape is identical to this recess, is marked a. d. letter c marks a molecule connected to molecule b and is located in the cytoplasm. e. letter d marks a molecule in the cytoplasm, near molecule c. f. letter e marks a molecule in the cytoplasm located below molecule d.

B molecule.

Explanation:

Receptor may be defined as the molecule to which the ligands or the signalling molecule binds. The binding of the molecules with its receptor helps in initiating the signalling cascade of the body.

The molecule that are marked B can acts as receptor because the receptor may present on the cell membrane or in the cytosol or in the nucleus. The B molecule shows the recess marked with the other molecule.

Thus, the correct answer is B.

c. heat from the poles back down towards the equator.