Unit 3: Cellular Energetics

AP Biology — 35 practice questions with detailed explanations. Use the links below to open each full question page (ideal for search indexing and deep study).

Unit summary

This unit covers core ideas tested on the AP exam. Each listed item links to a standalone page with the full stem, answer choices where applicable, a step-by-step explanation, and the correct answer. Difficulty labels help you prioritize review.

Questions in this unit

Sample prompts

Short previews of topics covered (not full question text).

  • For every three molecules of CO2 that enter the Calvin cycle, the cycle produces…
  • During the light-dependent reactions of photosynthesis, water molecules are spli…
  • During strenuous exercise, muscle cells may shift from aerobic respiration to la…
  • Cyanide blocks the transfer of electrons from cytochrome c oxidase (Complex IV) …
  • During one turn of the Krebs cycle, how many molecules of NADH are produced per …
  • During glycolysis, the enzyme aldolase cleaves fructose-1,6-bisphosphate into tw…
  • Pepsin functions optimally in the human stomach at approximately pH 2. A student…
  • A researcher adds a molecule to an enzyme-catalyzed reaction and observes that t…
  • The electron transport chain is responsible for the production of ATP in which o…
  • A cell is deprived of oxygen and is forced to shift to anaerobic glycolysis. Whi…
  • The citric acid cycle is essential for the production of which of the following …
  • Based on the data from a photosynthetic experiment, which of the following is th…