Free Bioenergetics MCQs with Answers
1,378 Bioenergetics MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Cellular respiration explains how cells release energy from glucose through glycolysis, the link reaction, Krebs cycle and electron transport chain. It includes ATP production, substrate-level and oxidative phosphorylation, aerobic versus anaerobic respiration, and the roles of mitochondria, oxygen and fermentation in energy transfer.
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- A. NADH
- B. Cytochrome c
- C. FADH2
- D. Cytochrome a
Explanation: The correct answer is NADH. In the respiratory electron transport chain, coenzyme Q is reduced by electrons that originate from NADH…
Correct answer: NADH- A. NADH
- B. FADH
- C. Cytochrome c
- D. Coenzyme Q
Explanation: The correct answer is coenzyme Q because it directly donates electrons to cytochrome b within Complex III of the respiratory electron…
Correct answer: Coenzyme Q- A. NADH
- B. FADH
- C. Cytochrome c
- D. Coenzyme Q
Explanation: The correct answer is cytochrome c because it directly transfers electrons to cytochrome a in Complex IV of the respiratory electron…
Correct answer: Cytochrome c- A. NADH
- B. Cytochrome b
- C. Cytochrome c
- D. Cytochrome a3
Explanation: Cytochrome a3 is the correct option because it is the terminal component of the respiratory electron transport chain where the final…
Correct answer: Cytochrome a3- A. Photosynthetic electron transport chain
- B. Non-cyclic electron transport chain
- C. Respiratory electron transport chain
- D. Cyclic electron transport chain
Explanation: Oxidative phosphorylation is the final stage of cellular respiration and takes place in the mitochondria.
Correct answer: Respiratory electron transport chain- A. Glycolysis
- B. Respiratory chain
- C. Krebs cycle
- D. Photosynthetic electron transport chain
Explanation: The correct answer is the respiratory chain. This process, also known as the electron transport chain, is the final stage of cellular…
Correct answer: Respiratory chain- A. Oxidative phosphorylation
- B. Cyclic photophosphorylation
- C. Photophosphorylation
- D. Non-cyclic photophosphorylation
Explanation: The correct answer is oxidative phosphorylation. This process takes place in the mitochondria, specifically across its inner membrane…
Correct answer: Oxidative phosphorylation- A. Citrate synthase
- B. Isocitrate dehydrogenase
- C. α-Ketoglutarate dehydrogenase
- D. Pyruvate dehydrogenase
Explanation: Accumulation of NADH inhibits the Krebs cycle primarily by suppressing enzymes involved in oxidative reactions.
Correct answer: Pyruvate dehydrogenase- A. Electron transport chain
- B. Glycolysis
- C. Kreb cycle
- D. Fermentation
Explanation: The electron transport chain is the correct answer because it is the final phase of cellular respiration where NADH and FADH₂ are…
Correct answer: Electron transport chain- A. Light independent reaction
- B. Light reaction
- C. Calvin cycle
- D. Dark reaction
Explanation: The correct answer is the light reaction, also known as the light-dependent reaction.
Correct answer: Light reaction- A. Light reaction
- B. Light dependent reaction
- C. Light independent reaction
- D. Synthesis of ATP and NADPH2
Explanation: The correct answer is the light-independent reaction, also known as the Calvin cycle.
Correct answer: Light independent reaction- A. Reduction
- B. Oxidative phosphorylation
- C. Oxidation
- D. Oxidation-reduction reaction
Explanation: The correct answer is oxidation. Oxidation involves the removal of electrons from an atom or compound, which results in an increase in its…
Correct answer: Oxidation- A. Electron debt
- B. Oxygen debt
- C. Hydrogen debt
- D. Carbon debt
Explanation: The correct answer is oxygen debt. During intense exercise, the body often performs anaerobic metabolism, leading to the buildup of…
Correct answer: Oxygen debt- A. Photosystem I and II
- B. Light systems
- C. Pigment systems
- D. PS 660 and PS 730
Explanation: The correct answer is Photosystem I and II. These are the primary molecular systems in plants, algae, and cyanobacteria that convert light…
Correct answer: Photosystem I and II- A. Ferredoxin
- B. ATP synthase
- C. Cytochrome complex
- D. Plastoquinone
Explanation: The correct answer is ATP synthase. During the light-dependent reactions of photosynthesis, ATP synthase uses the proton gradient created…
Correct answer: ATP synthase- A. PS I
- B. PS I and PS II
- C. PS II
- D. P680
Explanation: Cyclic photophosphorylation involves only Photosystem I (PS I). In this process, electrons are transferred cyclically back to the PS I…
Correct answer: PS I- A. Stroma of chloroplast
- B. Grana of chloroplast
- C. Matrix of mitochondria
- D. Inner membrane of mitochondria
Explanation: Photosystem I and photosystem II are integral components of the light-dependent reactions in photosynthesis.
Correct answer: Grana of chloroplast- A. Formation of ATP from ADP in presence of light
- B. Formation of NADP
- C. Formation of ADP from ATP
- D. Formation of PGA
Explanation: Photophosphorylation is the process by which ATP is synthesized from ADP and inorganic phosphate using the energy of sunlight, which is…
Correct answer: Formation of ATP from ADP in presence of light- A. Carbon dioxide is oxidized and water is reduced
- B. Water is oxidized and carbon dioxide is reduced
- C. Both CO₂ and water are oxidized
- D. Both CO₂ and water are reduced
Explanation: Photosynthesis is a redox process where light energy is used to convert water and carbon dioxide into glucose and oxygen.
Correct answer: Water is oxidized and carbon dioxide is reduced- A. Reduction
- B. Oxidation
- C. Hydrolysis
- D. Oxidative decarboxylation
Explanation: The conversion of pyruvic acid into acetyl-CoA takes place through the process of oxidative decarboxylation.
Correct answer: Oxidative decarboxylation