Epinephrine is a hormone that regulates cellular energy metabolism to break down glycogen into glucose. The signal transduction pathway involves the production of cAMP. If caffeine blocks the activity of cAMP, what would happen to the signal transduction pathway? The signaling pathway will amplify and produce more glucose.
The signaling pathway will conform to bind to the receptor cells.
The downstream components will be altered and ultimately affect production of glucose.
The downstream components will function normally.

The downstream components will be altered and ultimately affect production of glucose.

Explanation: Epinephrine is a hormone that belongs to a class of biomolecules called catecholamines. When it reaches the target cell it binds to a receptor that is connected to an enzyme called adenylate cyclase that converts ATP into cAMP(cyclic adenosine monophosphate). cAMP plays an important role in the phosphorylation of proteins which alters their activity. In this case the activity of the enzyme that hydrolyses glycogen to glucose. When caffeine blocks the activity of cAMP it ultimately inhibits the action of the downstream components.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.