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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Read the Bioenergetics notesFree MDCAT chapter notes with key terms1,378 questions · page 14 of 69
- A. Non-cyclic electron flow
- B. Cyclic electron flow
- C. Circular electron flow
- D. Both Options B and C are correct
Explanation: Circular electron flow is not a well-known or commonly occurring electron transport chain.
Correct answer: Both Options B and C are correct- A. Malate
- B. Succinate
- C. Oxaloacetate
- D. Fumarate
Explanation: The Krebs cycle, also known as the citric acid cycle, begins when acetyl-CoA combines with oxaloacetate to form citrate.
Correct answer: Oxaloacetate- A. Fe²⁺
- B. Zn²⁺
- C. Cu²⁺
- D. Mg²⁺
Explanation: Magnesium is the central atom in a chlorophyll molecule, essential for its function in photosynthesis.
Correct answer: Mg²⁺- A. ATP
- B. Carbon dioxide
- C. Water
- D. Both Options A and C are correct
Explanation: The end products of the electron transport chain are water and ATP. A number of intermediate compounds of the citric acid cycle can be…
Correct answer: Both Options A and C are correct- A. CO2
- B. O2
- C. NADH
- D. NAD+
Explanation: NAD+ is the oxidized form of the molecule; NADH is the reduced form of the molecule after it has accepted two electrons and a proton…
Correct answer: NADH- A. Stroma
- B. Chloroplast envelope
- C. Thylakoid membranes
- D. Intergrana
Explanation: Photosystems I and II are integral parts of the thylakoid membranes within chloroplasts, where they play a critical role in the…
Correct answer: Thylakoid membranes- A. Myoglobin
- B. Haem
- C. Globulin
- D. Fibrin
Explanation: Cytochromes are proteins that contain "haem" as a prosthetic group. They function as electron carriers in redox reactions, playing a vital…
Correct answer: Haem- A. Outer membrane of the chloroplast
- B. Inner membrane of the chloroplast
- C. Stroma of the chloroplast
- D. Thylakoid membranes of the chloroplast
Explanation: Enzymes for light-dependent reactions are associated with the thylakoid membranes of the chloroplasts since Light dependent reaction…
Correct answer: Thylakoid membranes of the chloroplast- A. Pq
- B. Pc
- C. Pt
- D. Po
- E. Both A and B
Explanation: Pq (plastoquinone) is the electron carrier in the electron transport chain of plants.Pc (plastocyanin) is another electron carrier…
Correct answer: Both A and B- A. S scheme
- B. X scheme
- C. Z scheme
- D. Y scheme
Explanation: The Z scheme describes the electron transport pathway through Photosystem II (PSII) and Photosystem I (PSI) in the light-dependent…
Correct answer: Z scheme- A. ETC
- B. Chemiosmosis
- C. Photolysis
- D. Photosynthesis
Explanation: Light excites electrons in chlorophyll P680 in PSII.These high-energy electrons are transferred to the primary electron acceptor of…
Correct answer: ETC- A. Alcoholic fermentation
- B. Lactic acid fermentation
- C. Aerobic respiration
- D. None of these options are correct
Explanation: Aerobic respiration is the process where cells use oxygen to convert glucose into energy (ATP), releasing carbon dioxide and water as…
Correct answer: Aerobic respiration- A. F¹ particles
- B. Lysosomes
- C. Cytoplasm
- D. Matrix
Explanation: The Krebs cycle enzymes are membrane proteins found within the matrix of the mitochondria, except for succinate dehydrogenase, which is an…
Correct answer: Matrix- A. Thylakoid membrane
- B. Thylakoid space
- C. Stroma
- D. Grana
Explanation: The light-dependent reactions take place on the thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside…
Correct answer: Stroma- A. Golgi Apparatus
- B. Cell cytoplasm
- C. Inner Mitochondrial Membrane
- D. Matrix of Mitochondria
Explanation: Glycolysis is the process where glucose breaks partially to form pyruvic acid.
Correct answer: Cell cytoplasm- A. Pyruvate is completely oxidized to form carbon dioxide and water
- B. Pyruvate is completely oxidized to form oxygen and water
- C. Pyruvate carboxylated to produce citrate
- D. Pyruvate is converted to ethanol and carbon dioxide
Explanation: In aerobic respiration, glucose is oxidised to form pyruvate during glycolysis.
Correct answer: Pyruvate is completely oxidized to form carbon dioxide and water- A. Pyruvic acid/ Pyruvate
- B. Lactic acid
- C. Ethyl Alcohol
- D. Fructose Phosphate
Explanation: The last step in glycolysis is catalyzed by the enzyme pyruvate kinase.
Correct answer: Pyruvic acid/ Pyruvate- A. OH group
- B. O2 group
- C. Hydrogen
- D. Phosphate
Explanation: NADP+ is a coenzyme that functions as a universal electron carrier, accepting electrons and hydrogen atoms to form NADPH, or nicotinamide…
Correct answer: Hydrogen- A. Violet in color
- B. Blue green in color
- C. Yellow green in color
- D. Yellow to orange red in color
Explanation: Carotenoids also called tetraterpenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as…
Correct answer: Yellow to orange red in color280. In which of the following does no net gaseous exchange take place between leaves and the atmosphere?
- A. Day
- B. Night
- C. Dawn and Dusk
- D. Midnight
Explanation: At dawn and dusk, the intensity of light is low. At this moment the amount of oxygen released from photosynthesis is equal to the amount…
Correct answer: Dawn and Dusk