Based on Figure 1, which of the following statements best describes the epinephrine signaling pathway? Group of answer choices

It involves the opening and closing of ion channels.

In involves enzymes activating other enzymes.

It involves changes in the expression of target genes.

It involves protons moving down a concentration gradient.

It involves enzymes activating other enzymes.

Explanation:

Epinephrine activates glycolysis (i.e., glycogen breakdown) in skeletal muscle and at a lower level in the liver, which is more responsive to glucagon. When epinephrine binds to a G protein-coupled receptor, the receptor changes its conformation and then triggers a molecular cascade that involves the production of cyclic adenosine monophosphate (cAMP), a well known second messenger molecule in signal transduction pathways. Moreover, the beta-2 adrenergic receptor (ADRB2) is a G-protein-coupled receptor known to activate adenylate cyclase enzyme that leads to appropriate increases in cAMP and activation of protein kinase A (PKA).

they are known to reach a speed of 21 miles per hour

"do a testcross with a homozygous recessive plant."