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.
Last updated
Read the Bioenergetics notesFree MDCAT chapter notes with key terms1,378 questions · page 44 of 69
- A. Fructose-6-phosphate → Fructose-1,6-bisphosphate
- B. Glucose → Glucose-6-phosphate
- C. Glyceraldehyde-3-phosphate → 1,3-Bisphosphoglycerate
- D. Phosphoenolpyruvate → Pyruvate
Explanation: In glycolysis, most reactions involve phosphorylation, but only one includes oxidation.
Correct answer: Glyceraldehyde-3-phosphate → 1,3-Bisphosphoglycerate- A. Outer membrane of mitochondrion
- B. Inner membrane of mitochondrion
- C. Matrix of mitochondrion
- D. Inner side of thylakoid membrane
Explanation: The inner mitochondrial membrane is the correct site of oxidative phosphorylation because it contains the electron transport chain…
Correct answer: Inner membrane of mitochondrion- A. Coenzymes
- B. Prosthetic group
- C. Activator
- D. Ribozyme
Explanation: Cytochromes are electron transport intermediates that contain heme as a prosthetic group.
Correct answer: Prosthetic group864. C₃H₆O₃ is:
- A. Pyruvic acid
- B. Lactic acid
- C. Ethyl alcohol
- D. Acetyl-CoA
Explanation: The chemical formula C₃H₆O₃ corresponds to lactic acid, which is produced during anaerobic respiration, particularly in muscle cells when…
Correct answer: Lactic acid- A. From cytochrome b to cytochrome c
- B. From cytochrome c to cytochrome a
- C. From NADH to coenzyme Q
- D. From cytochrome a to oxygen
Explanation: Energy is released to yield ATP mainly during the transfer of electrons from NADH to coenzyme Q in the electron transport chain.
Correct answer: From NADH to coenzyme Q- A. Cytochrome
- B. Coenzyme Q
- C. Ferredoxin
- D. Flavoproteins
Explanation: Most electron transport intermediates in mitochondria include cytochromes, coenzyme Q, and flavoproteins, all of which play essential…
Correct answer: Ferredoxin867. The Z-scheme is
- A. Non-cyclic photophosphorylation
- B. Cyclic photophosphorylation
- C. Cyclic oxidation
- D. Oxidative phosphorylation
Explanation: The Z-scheme is a model of the electron transport pathway during non-cyclic photophosphorylation in chloroplasts.
Correct answer: Non-cyclic photophosphorylation- A. ATP
- B. NADPH
- C. ATP and NADPH
- D. ATP and oxygen
Explanation: ATP is the correct option because cyclic phosphorylation involves electrons moving in a circular path from chlorophyll through the…
Correct answer: ATP- A. 2 ATP
- B. 3ATP
- C. 4 ATP
- D. 6 ATP
Explanation: The correct option is 3 ATP because each NADH molecule donates high-energy electrons to Complex I of the electron transport chain…
Correct answer: 3ATP- A. ATP
- B. NADPH
- C. Glucose
- D. Oxygen
Explanation: ATP is the correct option because it is the direct form of chemical energy produced during the light-dependent reactions of…
Correct answer: ATP- A. Cytochrome complex
- B. Photosystem II
- C. Ferredoxin
- D. NADP⁺ reductase
Explanation: Cytochrome complex is the correct option because it functions in both cyclic and non-cyclic photophosphorylation as a central part of the…
Correct answer: Cytochrome complex- A. Plastoquinone
- B. Ferredoxin
- C. Cytochrome complex
- D. Plastocyanin
Explanation: Ferredoxin is the correct answer because it is the final electron carrier in the photosynthetic electron transport chain that directly…
Correct answer: Ferredoxin873. Coenzyme NAD+ is:
- A. Two adenine nucleotides
- B. One adenine nucleotide and one nicotinamide nucleotide
- C. One guanine nucleotide and one cytosine nucleotide
- D. Two nicotinamide nucleotides
Explanation: The coenzyme NAD⁺ (nicotinamide adenine dinucleotide) is made up of two nucleotides joined by their phosphate groups.
Correct answer: One adenine nucleotide and one nicotinamide nucleotide- A. Photolysis
- B. Electron transport chain
- C. Phosphorylation
- D. Carboxylation
Explanation: Oxygen is released during photolysis, which occurs in the light-dependent reactions of photosynthesis.
Correct answer: Photolysis- A. Mitochondria
- B. Cytoplasm
- C. Stroma of the chloroplast
- D. Thylakoid membrane
Explanation: The Calvin cycle takes place in the chloroplast, specifically in the stroma, which is the fluid-filled space surrounding the thylakoid…
Correct answer: Stroma of the chloroplast- A. 6
- B. 2
- C. 3
- D. 12
Explanation: Six is the correct option because during the Calvin cycle, six molecules of G3P are formed after three turns of the cycle, using six…
Correct answer: 6- A. Glycolysis
- B. Pyruvic acid oxidation
- C. Krebs cycle
- D. Respiratory chain
Explanation: The correct answer is glycolysis. This is the common pathway for both aerobic and anaerobic respiration and takes place in the cytoplasm…
Correct answer: Glycolysis- A. Citrate → Isocitrate
- B. Isocitrate → α-Ketoglutarate
- C. Succinyl-CoA → Succinate
- D. Succinate → Fumarate
Explanation: The correct answer is option B, Step 3, where isocitrate is converted to α-ketoglutarate.
Correct answer: Isocitrate → α-Ketoglutarate- A. Acetyl-CoA
- B. Oxaloacetate
- C. Lactic acid
- D. Ethanol
Explanation: Before entering the tricarboxylic acid (TCA) cycle, pyruvate is converted into acetyl-CoA.
Correct answer: Acetyl-CoA- A. 1 mole
- B. 2 mole
- C. 3
- D. 4
Explanation: The complete oxidation of one mole of pyruvate produces three moles of carbon dioxide.
Correct answer: 3