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. Glycolysis
- B. Electron transport chain
- C. Krebs cycle
- D. Fermentation
Explanation: The Krebs cycle is the stage of cellular respiration where NADH and FADH₂ are produced through the oxidation of acetyl-CoA.
Correct answer: Krebs cycle- A. NADH
- B. FADH2
- C. ATP
- D. ADP
Explanation: Before entering the citric acid cycle, pyruvate undergoes a preparatory step where it is decarboxylated and oxidized, resulting in the…
Correct answer: NADH- A. 1
- B. 2
- C. 3
- D. 4
Explanation: Starting from pyruvate, the end product of glycolysis, 1 molecule of CO₂ is released up to the formation of succinate in a single turn of…
Correct answer: 1- A. Decarboxylation
- B. Dehydration
- C. Dehydrogenation
- D. Both A and C
Explanation: The conversion of pyruvate to acetyl-CoA is a crucial step in cellular respiration.
Correct answer: Both A and C- A. Carboxylase
- B. Hydrogenase
- C. Dehydrogenase
- D. Catalase
Explanation: Biological oxidation involves the removal of hydrogen atoms from organic molecules, a process that is closely linked with specific…
Correct answer: Dehydrogenase- A. Photophosphorylation
- B. Oxidative phosphorylation
- C. Chemiosmosis
- D. Substrate level phosphorylation
Explanation: During glycolysis, ATP is produced through substrate-level phosphorylation.
Correct answer: Substrate level phosphorylation- A. α-ketoglutaric acid
- B. Glyceric acid
- C. Citric acid
- D. Acetyl-CoA
Explanation: Glycolysis results in the formation of pyruvate, which is transported into the mitochondria.
Correct answer: Acetyl-CoA- A. Glucose
- B. Dihydroxyacetone
- C. Glyceraldehyde 3-phosphate
- D. Fructose
Explanation: The correct answer is glyceraldehyde-3-phosphate (G3P), which is an aldose sugar that functions as an intermediate in both glycolysis and…
Correct answer: Glyceraldehyde 3-phosphate- A. Mitochondria
- B. Chloroplast
- C. Golgi apparatus
- D. Endoplasmic reticulum
Explanation: The correct answer is chloroplast. In the chloroplast, G3P (glyceraldehyde-3-phosphate) is a product of the Calvin cycle, which is part of…
Correct answer: Chloroplast- A. 8
- B. 18
- C. 9
- D. 36
Explanation: An 18-carbon fatty acid, when broken down through beta-oxidation, produces 9 acetyl-CoA molecules.
Correct answer: 9- A. High ATP and NADPH levels, but low Calvin cycle activity
- B. Low ATP and NADPH levels due to fast Calvin cycle activity
- C. Low ATP and NADPH levels due to weak light reactions
- D. High ATP and NADPH use because CO₂ fixation increases
Explanation: Under high light intensity and low CO₂ concentration, photosynthetic cells accumulate ATP and NADPH since the light reactions are active…
Correct answer: High ATP and NADPH levels, but low Calvin cycle activity- A. Acetyle coenzyme A
- B. Ribulose-1,5-bisphosphate
- C. Fructose 1, 6-bisphosphate
- D. Triose phosphate
Explanation: Yes, the correct answer is triose phosphate. In the process of glycolysis, a six-carbon sugar called glucose is first converted into a…
Correct answer: Triose phosphate- A. Oxygen is the final electron acceptor in the electron transport chain
- B. Oxygen breaks down glucose during glycolysis
- C. Oxygen is used to directly produce ATP in the Krebs cycle
- D. Oxygen acts as an enzyme to speed up cellular reactions
Explanation: The correct answer is A-Oxygen is the final electron acceptor in the electron transport chain.
Correct answer: Oxygen is the final electron acceptor in the electron transport chain- A. Photolysis
- B. ATP synthesis
- C. Transport of electrons
- D. Dark reaction
Explanation: The correct answer is photolysis, which occurs in the thylakoid interior space during the light-dependent reactions of photosynthesis.
Correct answer: Photolysis- A. Blue to green
- B. Red to orange
- C. Yellow to orange
- D. Yellow to red
Explanation: Carotenes are pigments that appear red to orange because they reflect these colors of light and do not absorb them efficiently.
Correct answer: Red to orange- A. Malate
- B. Fumarate
- C. FAD
- D. Succinate
Explanation: The correct answer is succinate. In the citric acid cycle, succinate is oxidized to fumarate by the enzyme succinate dehydrogenase.
Correct answer: Succinate- A. NADPH
- B. ATP an NADPH2
- C. ADP
- D. RuBP
Explanation: During the light-dependent reactions of photosynthesis, light energy is captured and converted into chemical energy in the form of ATP and…
Correct answer: ATP an NADPH2- A. Lysosomes
- B. Ribosomes
- C. Oxysomes
- D. Chloroplast
Explanation: The correct answer is chloroplast. The stroma is the ground matrix of a chloroplast, which is crucial for the photosynthesis process.
Correct answer: Chloroplast- A. Red light
- B. Blue light
- C. Green light
- D. Far-red light
Explanation: Blue light around 450 nanometers helps plants grow strong leaves and stems, playing a good role in photosynthesis but not reaching its…
Correct answer: Red light- A. Water
- B. Carbon dioxide
- C. Excited chlorophyll molecules
- D. Rubisco
Explanation: In the light-dependent reactions of photosynthesis, which occur in the thylakoid membranes of chloroplasts, water is split in a process…
Correct answer: Water