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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281. The spent energy in the form of ADP is regenerated by mitochondria into which of the following form?
- A. AMP
- B. ATP
- C. ADP
- D. All of these options are correct
Explanation: Mitochondria are membrane-bound organelles, and those membranes function for the purpose of mitochondria, which is essential to produce…
Correct answer: ATP- A. Alcoholic fermentation
- B. Lactic acid fermentation
- C. Glycolysis
- D. None of these
Explanation: Pyruvate is produced through the process of glycolysis, which is the initial step in cellular respiration that occurs in the cytoplasm of…
Correct answer: Glycolysis- A. Hydrolysis
- B. Chemiosmosis
- C. Photolysis
- D. Photosynthesis
Explanation: The correct answer is Photolysis. Photolysis refers to the light-dependent splitting of water molecules into hydrogen ions, oxygen, and…
Correct answer: Photolysis- A. A 5-Carbon carbohydrate accepts carbon dioxide and is then reduced by NADPH derived from photophosphorylation
- B. A 3-Carbon carbohydrate is regenerated and reduced by hydrogen molecules derived from photophosphorylation
- C. Photolysis uses light to produce reduced NADP and oxygen which are used to reduce a 3-Carbon carbohydrate
- D. Photolysis produces NADPH and ATP which are used to reduce a 5-Carbon carbohydrate
Explanation: During the light-independent reactions, a 5-carbon carbohydrate called RuBP accepts carbon dioxide to form 3-carbon phosphoglycerate…
Correct answer: A 5-Carbon carbohydrate accepts carbon dioxide and is then reduced by NADPH derived from photophosphorylation- A. It takes place only in the dark
- B. It does not require light directly
- C. It occurs during the night only
- D. It involves only dark-colored pigments
Explanation: The dark reaction is called so because it does not need light directly and uses ATP and NADPH from the light reaction to make glucose from…
Correct answer: It does not require light directly- A. Absorption of light
- B. Carbon dioxide consumption
- C. Emission of light
- D. Both Options A and B are correct
Explanation: The action spectrum represents the efficiency with which different wavelengths of light are absorbed by a photosynthetic pigment to drive…
Correct answer: Absorption of light- A. Cytochrome a
- B. Coenzyme Q
- C. Coenzyme b
- D. Coenzyme a3
Explanation: In the ETC, electrons are passed down a chain of carriers from higher to lower energy states.
Correct answer: Cytochrome a- A. Granum
- B. Centrosome
- C. Stroma
- D. Multinucleate
Explanation: The correct answer is Granum. In plants, thylakoids are organized into stacks called grana, which are essential for the light-dependent…
Correct answer: Granum- A. 1
- B. 2
- C. 3
- D. 4
Explanation: From one molecule of pyruvate passing through the Krebs cycle, three molecules of NADH are formed.
Correct answer: 3- A. Light independent reactions
- B. Light dependent reactions
- C. Both A and B
- D. None of these
Explanation: The light-independent reactions, also known as the Calvin Cycle, are where sugar formation occurs in photosynthesis.
Correct answer: Light independent reactions- A. 750
- B. 650
- C. 680
- D. 670
Explanation: The chlorophyll, a special pair of the two photosystems, absorb different wavelengths of light.
Correct answer: 680292. How many molecules of carbon dioxide enter the Calvin cycle to produce one molecule of carbohydrate?
- A. 2
- B. 3
- C. 4
- D. 1
Explanation: During the Calvin cycle, three molecules of carbon dioxide (CO₂) combine with three molecules of ribulose-1,5-bisphosphate (RuBP) through…
Correct answer: 3293. ATP is used when _
- A. To synthesize the macromolecules
- B. To transport molecules and ions
- C. To perform mechanical work
- D. All of the above
Explanation: ATP (Adenosine Triphosphate) is a molecule that serves as the primary energy currency of the cell.
Correct answer: All of the above- A. Hydrophilic
- B. Hydrophobic
- C. Both of these
- D. None of these
Explanation: Phytol tail of chlorophyll is a long hydrocarbon chain that is hydrophobic in nature.
Correct answer: Hydrophobic- A. 45°C
- B. 35°C
- C. 15°C
- D. 25°C
Explanation: Despite the fact that the stomata open in response to light, they may close on a hot day in order to conserve water.
Correct answer: 45°C- A. Glycolysis
- B. Fermentation
- C. Oxidation of pyruvate
- D. The citric acid cycle
Explanation: Hans Krebs (1900-1981) was a distinguished biochemist who did discovery of the "Krebs cycle" also known as the citric acid cycle and the…
Correct answer: The citric acid cycle- A. The Calvin cycle
- B. Photosystem I
- C. Photosystem II
- D. The light reaction
Explanation: The Calvin cycle is a process that plants and algae use to turn carbon dioxide from the air into sugar, it is a light independent process.
Correct answer: The Calvin cycle- A. Kreb's cycle
- B. Calvin cycle
- C. Chemiosmosis
- D. Electron transport chain
Explanation: The Calvin cycle is the correct answer because it is the phase of photosynthesis where carbon fixation occurs, leading to the production…
Correct answer: Calvin cycle- A. ATP synthesis
- B. Reduction of NADP
- C. Cyclic photophosphorylation
- D. Oxidation of the reaction center of photosystem I
Explanation: For reduction of NADP to take place, non-cyclic electron flow should occur.
Correct answer: Reduction of NADP- A. P680, P700, water, NADP
- B. Water, P700, NADP, P680
- C. P700, P680, NADP, water
- D. Water, P680, P700, NADP
Explanation: In the presence of light, the "photolysis (breaking in the presence of light ) of water occurs in the water splitting center within…
Correct answer: Water, P680, P700, NADP