Question

The insulin to glucagon ratio is decreased. Which enzyme is active at this time?

• A. Glucokinase
• B. Hexokinase
• C. Phosphofructokinase
• D. Glucose-6-phosphatase

Hint:

Low insulin to glucagon means fasting; pick the enzyme that frees glucose for export.

Answer 1

The Correct Option is D

Translate the hormone clue first: a falling insulin to glucagon ratio is the biochemical signature of fasting. In fasting, the liver's job is to put glucose into the blood, which means it runs gluconeogenesis and glycogenolysis and turns glycolysis off. Now sort the options by pathway. Glucokinase and hexokinase phosphorylate glucose to keep it inside the cell, and phosphofructokinase-1 drives the committed step of glycolysis, so all three are glycolytic, fed-state enzymes that go quiet when insulin is low. The odd one out is glucose-6-phosphatase, the final enzyme that strips phosphate off glucose-6-phosphate so glucose can exit the hepatocyte into circulation. That is precisely what fasting demands, so it is the active enzyme and the answer is (d). Memory hook: the phosphatase that lets glucose escape is the fasting enzyme; the kinases that imprison glucose are fed-state enzymes.