Substrate-level phosphorylation

Question

18.Substrate-level phosphorylation     

      (A) Energy released from ATP hydrolysis is used to phosphorylate the substrate

      (B) Energy released from the chemical reaction is used to directly phosphorylate ADP

      (C) Energy released from ATP hydrolysis is used to phosphorylate ADP

      (D) Energy released from the chemical reaction is used to directly reduce NAD⁺

Answer 1

Best answer is B: During glycolysis PEP via an enzyme adds a phosphate to ADP to produce ATP. Substrate level implies an enzyme-substrate complex rather than ATP formation via oxidative phosphorylation. A similar process forms ATP in the Krebs cycle.