[Campbell Biology P.235] Referencing the provided graph for phosphofructokinase activity, un... | Practice Question

Referencing the provided graph for phosphofructokinase activity, under which condition does the enzyme exhibit the highest activity?

  • A: High ATP concentration and low fructose 6-phosphate concentration.
  • B: Low ATP concentration and high fructose 6-phosphate concentration.
  • C: High ATP concentration and high fructose 6-phosphate concentration.
  • D: Low ATP concentration and low fructose 6-phosphate concentration.

Explanation

The graph shows that phosphofructokinase activity is higher at low ATP concentration compared to high ATP concentration across all fructose 6-phosphate concentrations. Within the low ATP concentration curve, activity increases with increasing fructose 6-phosphate concentration. Therefore, the highest activity is observed at low ATP concentration and high fructose 6-phosphate concentration, as low ATP signals a need for more glycolysis to produce energy, and high substrate provides ample material for the enzyme to act upon.