(b) Describe the process that results in the activation of multiple copies of PKB in response to the binding of a single molecule of insulin to its receptor. Explain why insulin can stimulate the activation PKB of but not the activation of PK. (c) Explain why an increase in glycogen phosphorylase activity might result in an increase in O2 consumption in the cell.

(d) A certain type of tumor results in the overproduction of glucagon. Researchers claim that treatment with insulin can counteract the effects of the excess glucagon on the pathway shown in Figure 2. Provide reasoning to justify the researchers' claim.