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Bioenergetics MCQs for MDCAT Practice

Biology section, Bioenergetics chapter. Up to eight free sample questions, each with the correct answer and a worked explanation. The full chapter opens in the app.

The bank has 2,020 active questions on this chapter. Your first 500 practice attempts are free, and every attempt includes a worked explanation.

  1. Question 1
    The final acceptor of electrons during the noncyclic electron pathway is:
    • Photosystem I
    • Photosystem II
    • ATP
    • NADP+ (correct answer)
    Correct answer: D
    The noncyclic electron pathway in photosynthesis culminates with electrons reducing NADP+ to NADPH, a crucial energy carrier.
  2. Question 2
    The reaction of carbon dioxide and RUBP is catalyzed by
    • ATP synthase
    • Globulin
    • RuBisCO (correct answer)
    • NADH dehydrogenase
    Correct answer: C
    This question tests your knowledge of the key enzyme responsible for carbon fixation in the Calvin cycle, a fundamental process in photosynthesis.
  3. Question 3
    Which of the following facilitates opening of stomatal aperture?
    • Decrease in turgidity of guard cells
    • Radial orientation of cellulose microfibrils in the cell wall of guard cells (correct answer)
    • Longitudinal orientation of cellulose microfibrils in the cell wall of guard cells
    • Contraction of outer wall of guard cells
    Correct answer: B
    Guard cell structure, specifically cellulose microfibril orientation, dictates stomatal opening mechanism, crucial for plant gas exchange.
  4. Question 4
    The primary function of ETC is to:
    • Synthesize ATP directly
    • Reduce NAD⁺
    • Control glycolysis
    • Release energy in controlled steps (correct answer)
    Correct answer: D
    The Electron Transport Chain (ETC) is crucial for cellular respiration, not for direct ATP synthesis, but for releasing energy gradually to power ATP production.
  5. Question 5
    In glycolysis, ultimately:
    • protein is converted to glucose
    • glucose is converted to fructose
    • starch is converted to glucose
    • glucose is converted to pyruvic acid (correct answer)
    Correct answer: D
    Glycolysis is the initial breakdown of glucose into pyruvic acid, a fundamental step in cellular respiration and energy production.
  6. Question 6
    Product of anaerobic respiration in animals is ___________.
    • Pyruvic acid
    • Lactic acid (correct answer)
    • Alcohol
    • NADPH-2
    Correct answer: B
    Anaerobic respiration in animals converts pyruvate to lactic acid to regenerate NAD+ for glycolysis, unlike plants or yeast which produce alcohol.
  7. Question 7
    Energy released during electron flow is used primarily for:
    • Pumping protons into intermembrane space (correct answer)
    • Reducing NAD⁺
    • Splitting water
    • Forming acetyl-CoA
    Correct answer: A
    Electron transport chain energy powers proton pumping, creating a gradient for ATP synthesis, not direct NAD+ reduction, water splitting, or acetyl-CoA formation.
  8. Question 8
    End product of light reaction of photosynthesis is:
    • ADP and NADPH
    • ATP and NADPH (correct answer)
    • Carbon dioxide and water
    • NADPH and AMP
    Correct answer: B
    The light-dependent reactions of photosynthesis produce ATP and NADPH, which are then used in the Calvin cycle to synthesize glucose.

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Read the full Bioenergetics chapter notes: Bioenergetics notes. Or browse every chapter.