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 7 of 69
- A. 25%
- B. 10%
- C. 5%
- D. 1%
Explanation: Only about 1% of the sunlight reaching Earth is captured by green plants and converted into chemical energy through photosynthesis.
Correct answer: 1%- A. Cytohrome c
- B. Cytochrome a
- C. Cytochrome a3
- D. Cytochrome b
Explanation: Cytochrome c is a mobile electron carrier in the electron transport chain and transfers electrons between respiratory complexes, making it…
Correct answer: Cytohrome c123. Interconversion of carbohydrates proteins and lipids in living cells are an example of____________?
- A. Coordinated catabolic activities
- B. Coordinated anabolic activities
- C. Both A and B
- D. Any one
Explanation: Cells interconvert carbohydrates, proteins and lipids through linked metabolic pathways, so both breakdown reactions and synthesis…
Correct answer: Both A and B- A. Glyceraldehydes
- B. Dihydroxy acetone
- C. Both of these
- D. None of these
Explanation: Glyceraldehyde-3-phosphate and dihydroxyacetone phosphate are three-carbon intermediates found in pathways of both photosynthesis and…
Correct answer: Both of these- A. As an energy currency of the cell
- B. As a coenzyme
- C. Both a and b
- D. None of these
Explanation: ATP stores usable chemical energy in its phosphate bonds and transfers that energy to cellular processes, so it is called the energy…
Correct answer: As an energy currency of the cell- A. Release of CO2
- B. Reduction of NAD
- C. Formation of ATP
- D. Production of ethanol from acetaldehyde
Explanation: In alcoholic fermentation, acetaldehyde accepts hydrogen from reduced NAD and is converted into ethanol, regenerating NAD for glycolysis.
Correct answer: Production of ethanol from acetaldehyde127. How many moles of carbon dioxide are produced by complete oxidation of one mole of puruvic acid?
- A. 1
- B. 2
- C. 3
- D. 6
Explanation: One pyruvic acid molecule has three carbon atoms, and complete oxidation releases all three as carbon dioxide: one during the link…
Correct answer: 3- A. Metabolic reactions
- B. Catabolic reactions
- C. Anabolic reactions
- D. None of these
Explanation: Anabolic reactions build complex molecules from simpler substances and usually require an input of energy, such as the formation of…
Correct answer: Anabolic reactions129. In which of the following location enzymes controlling cellular respiration are present____________?
- A. Nucleus
- B. Chlorophast
- C. Milochondria
- D. Ribosome
Explanation: In eukaryotic cells, the major enzymes controlling aerobic cellular respiration are located in mitochondria, especially the matrix and…
Correct answer: Milochondria- A. AMP
- B. ADP
- C. ATP
- D. All of these
Explanation: Mitochondria regenerate ATP from ADP by adding inorganic phosphate during oxidative phosphorylation: ADP + phosphate forms ATP.
Correct answer: ATP- A. C-H bond
- B. C-O bond
- C. C-N bond
- D. P-O-C bond
Explanation: C-H bonds in organic food molecules contain potential chemical energy, which is released stepwise during cellular respiration and…
Correct answer: C-H bond- A. Peroxisome
- B. Glyoxisome
- C. Lysosome
- D. Golgi bodies
Explanation: Glyoxisomes contain enzymes of the glyoxylate cycle, which allows plant cells to convert fatty-acid products into succinate and other…
Correct answer: Glyoxisome- A. Bacteriochlorophylls
- B. Redox process
- C. Photosystems
- D. Compensation point
Explanation: The compensation point is when the rate of photosynthesis matches the rate of respiration, resulting in no net gas exchange because carbon…
Correct answer: Compensation point- A. Glycolysis
- B. The oxidation of pyruvate
- C. Krebs cycle
- D. None of these.
Explanation: The Krebs cycle, occurring in the mitochondrial matrix, is where FADH is produced as a result of the oxidation of acetyl-CoA.
Correct answer: Krebs cycle135. NADH is oxidized by:
- A. Co-enzyme Q
- B. Cytochrome b
- C. Cytochrome c
- D. Cytochrome a
Explanation: NADH is oxidized by Coenzyme Q. This oxidation yields enough free energy to permit the synthesis of a molecule of ATP from ADP and…
Correct answer: Co-enzyme Q- A. Inner membrane of mitochondria
- B. Outer membrane of mitochondria
- C. Thylakoid membrane
- D. Both A and C
Explanation: The electron transport chain is located in the inner mitochondrial membrane.
Correct answer: Inner membrane of mitochondria- A. Chemiosmosis
- B. ATP Synthase
- C. Dark reactions
- D. Light reactions
Explanation: Chemiosmosis is the process in which the flow of electrons through the photosynthetic pathway pumps protons across the thylakoid membrane…
Correct answer: Chemiosmosis- A. Cytochrome b
- B. Cytochrome c
- C. Cytochrome a3
- D. Cytochrome a1
Explanation: Cytochrome a is a subunit of cytochrome c oxidase, which is the terminal complex (complex IV) in the electron transport chain.
Correct answer: Cytochrome a3- A. Cell Respiration
- B. Glycolysis
- C. External respiration
- D. Alcoholic fermentation
Explanation: External respiration involves the exchange of respiratory gases (oxygen and carbon dioxide) between the organism and the external…
Correct answer: External respiration- A. Fructose-1-phosphate
- B. Glucose-6-Phosphate
- C. Fructose-6-phosphate
- D. Fructose-1,6-bisphosphate
Explanation: This is the direct product formed when a phosphate group is transferred from ATP to Glucose 6 phosphate in the first step of glycolysis.
Correct answer: Glucose-6-Phosphate