When 10 000 Molecules of ATP Are Hydrolyzed to ADP

Multiple Choice

When 10 000 molecules of ATP are hydrolyzed to ADP and ᵢ in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?

A) Living systems harness the energy released to perform work.
B) Cells are less efficient at heat production than nonliving systems.
C) The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube.
D) The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes.
E) Reactant and product concentrations in the test tube are different from those in the cell.