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. NADH
- B. Cytochrome a3
- C. Water
- D. Oxygen
Explanation: Oxygen is the final electron acceptor in the respiratory chain; it combines with electrons and hydrogen ions to form water at the end of…
Correct answer: Oxygen- A. Brain
- B. Heart
- C. Liver
- D. Muscles
Explanation: Lactic acid fermentation occurs in muscle cells when oxygen supply is insufficient, allowing glycolysis to continue by regenerating NAD+.
Correct answer: Muscles- A. Chlorophyll a
- B. Chlorophyll b
- C. Xanthophyll
- D. Carotenes
Explanation: Chlorophyll a is the primary photosynthetic pigment because it is present in the reaction centres and directly converts light energy into…
Correct answer: Chlorophyll a84. The chlorophyll molecule is embedded in the core of thylakoid membrane which acts as___________?
- A. Hydrophilic
- B. Hydrophobic
- C. Both of these
- D. None of these
Explanation: The core of the thylakoid membrane is made largely of nonpolar lipid tails, so it is hydrophobic and can accommodate the nonpolar regions…
Correct answer: Hydrophobic- A. Acetaldehyde
- B. Methyl alcohol
- C. Ethyl alcohol
- D. Lactic acid
Explanation: In alcoholic fermentation, pyruvic acid first loses carbon dioxide to form acetaldehyde, which is then reduced to ethyl alcohol.
Correct answer: Ethyl alcohol- A. Magnesium
- B. Iron
- C. Chlorine
- D. Oxygen
Explanation: Magnesium is part of the chlorophyll molecule, so its deficiency reduces chlorophyll formation and produces yellowing, called chlorosis…
Correct answer: Magnesium- A. Alcoholic fermentation
- B. Lactic acid fermentation
- C. Aerobic respiration
- D. All of these
Explanation: Aerobic respiration completely oxidizes glucose to carbon dioxide and water through glycolysis, the Krebs cycle and the electron transport…
Correct answer: Aerobic respiration- A. Yellow
- B. Red
- C. Orange
- D. Green
Explanation: Xanthophylls are accessory carotenoid pigments that appear yellow and help absorb wavelengths that chlorophyll does not absorb…
Correct answer: Yellow- A. Stroma
- B. Grana
- C. Thylakoid
- D. Intergrana
Explanation: Chlorophyll molecules are embedded in thylakoid membranes, where they form photosystems and absorb light for the light-dependent…
Correct answer: Thylakoid- A. Grana
- B. Stroma
- C. Thylakoid
- D. None of these
Explanation: The stroma is the dense, enzyme-containing fluid region surrounding the thylakoids inside a chloroplast, and it is the site of the Calvin…
Correct answer: Stroma- A. 680 nm
- B. 100 m
- C. 700 nm
- D. 670 nm
Explanation: Photosystem II has a reaction-centre chlorophyll called P680 because it absorbs maximally at about 680 nm.
Correct answer: 680 nm- A. Antenna complex
- B. Reaction centre
- C. Photosystem
- D. None of these
Explanation: The antenna complex contains pigment molecules that capture light over a broad range of wavelengths and transfer the excitation energy to…
Correct answer: Antenna complex- A. Grana
- B. Stroma
- C. Nucleus
- D. None of these
Explanation: Thylakoids are flattened membrane sacs, and stacks of these sacs are called grana.
Correct answer: Grana- A. O2
- B. CO2
- C. H2O
- D. light energy
Explanation: In photosynthesis, carbon dioxide is reduced to carbohydrates because it gains hydrogen or electrons supplied through the light reactions.
Correct answer: CO2- A. Chlorophyll a
- B. Chlorophyll b.
- C. Chlorophyll c
- D. Chlorophyll d.
Explanation: Chlorophyll a is blue-green because its absorption spectrum and molecular structure give it that characteristic colour.
Correct answer: Chlorophyll a- A. 0.03 - 0.04%
- B. 10%
- C. 1-2 %
- D. 50%
Explanation: Stomata occupy only a small fraction of the leaf surface, commonly estimated at about 1 to 2%, while still providing extensive openings…
Correct answer: 1-2 %- A. C55H72O5N4Mg
- B. C55H70O6N4Mg
- C. C50H72O6N4Mg
- D. C55H70O5N4Mg
Explanation: Chlorophyll a has the molecular formula C55H72O5N4Mg, containing a magnesium atom at the centre of its porphyrin-like ring.
Correct answer: C55H72O5N4Mg- A. 1-2%
- B. 5%
- C. 10%
- D. 20%
Explanation: Terrestrial plants contribute about 10% of the total global photosynthesis, while aquatic organisms in oceans, lakes, and ponds perform…
Correct answer: 10%- A. It is a porphyrin ring or tetrapyrrole ring structure
- B. It is flat, square and light absorbing
- C. Composed of carbon and nitrogen atoms with Magnesium as central metal ion, which is coordinated with nitrogen.
- D. It is hydrophobic
Explanation: The chlorophyll head is a hydrophilic porphyrin ring containing carbon, nitrogen, and a central magnesium ion, whereas its phytol tail is…
Correct answer: It is hydrophobic- A. Blue
- B. Orange
- C. Red
- D. Violet
Explanation: Red light is absorbed efficiently by chlorophyll and drives photosynthesis at a high rate, especially near the red absorption peak of…
Correct answer: Red