Which observation suggested to sutherland the involvement of a second messenger in epinephrine’s effect on liver cells?
a. enzymatic activity was proportional to the amount of calcium added to a cell-free extract.
b. receptor studies indicated that epinephrine was a ligand.
c. glycogen breakdown was observed only when epinephrine was administered to intact cells.
d. glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined.

the answer to your question is b

what subject is this

answer:

the water molecules are transferred from the roots to the stem or top parts of the tall tree because of important properties of water which are adhesion, cohesion and capillary action. cohesion is the property of water molecules keeps water molecules in a combined state by sharing of bonds between them at the atomic level. adhesion allows the interaction of water molecules with other substances or substrate. adhesion will cause the attachment of water molecules to the wall of the vessel (xylem) of the plant. capillary action occurs when the adhesive force to the vessel wall is stronger than the cohesive force between water molecules. capillary action mimics the transfer of water from a tube or pipe. in this way water utilizes its property to transfer water from down to top level of the plant.