Final answer:
The transport of glucose into a cell inhibits adenylate cyclase, leading to a decrease in the concentration of cyclic-AMP within the cell.
Step-by-step explanation:
The transport of glucose into a cell causes a decrease in the concentration of cyclic-AMP by inhibiting adenylate cyclase. When glucose levels are high, there is an increase in the phosphorylation of glycolytic intermediates which keeps cytoplasmic phosphate levels low. This leads to the unphosphorylated form of Enzyme IIA Glucose (EIIAGlc) which binds to the lactose permease enzyme, preventing it from bringing lactose into the cell. As a result, this inhibits adenylyl cyclase from converting ATP to cyclic AMP (cAMP), leading to a decrease in cAMP levels within the cell. Therefore, the correct answer to the student's question is 'a) Glucose; Decrease'.