Free Bioenergetics MCQs with Answers

• A. External respiration
• B. Pulmonary respiration
• C. Cellular respiration
• D. Cutaneous respiration

Explanation: The correct answer is cellular respiration. This process involves the breakdown of carbon chain molecules, such as glucose, within cells…

• A. Ethyl alcohol, lactic acid, and carbon dioxide
• B. Ethyl alcohol, lactic acid, carbon dioxide, and water
• C. Glucose, oxygen, and water
• D. Pyruvic acid, carbon dioxide, and oxygen

Explanation: The correct end products of yeast fermentation, bacterial fermentation, and anaerobic respiration are ethyl alcohol, lactic acid, and…

• A. Chlorophyll absorbs light mainly in the blue and red regions of the spectrum
• B. Chlorophyll absorbs light mainly in the green region of the spectrum
• C. Carotenoids absorb light only in the red region of the spectrum
• D. The absorption spectrum of chlorophyll and the action spectrum of photosynthesis are completely different

Explanation: The correct statement is Option A: Chlorophyll absorbs light mainly in the blue and red regions of the spectrum.

• A. Ferredoxin
• B. Plastocyanin
• C. Plastoquinone
• D. Carotenoids

Explanation: The correct answer is plastoquinone. It directly accepts electrons from photosystem II and transfers them to the cytochrome b6f complex…

• A. A single enzyme
• B. Two enzymes
• C. Multi-enzyme complex
• D. No enzyme

Explanation: The conversion of pyruvic acid to acetyl CoA is a crucial step in cellular respiration and is catalyzed by the pyruvate dehydrogenase…

• A. NADH dehydrogenase
• B. Cytochrome oxidase
• C. Ubiquinase
• D. ATP synthase

Explanation: ATP synthase, or Complex V, is the enzyme that synthesizes ATP by utilizing the proton gradient created by the other complexes in the…

• A. Membrane system
• B. Set of enzymes
• C. Both A and B
• D. Chlorophyll

Explanation: The stroma is the fluid-filled matrix of the chloroplast that surrounds the thylakoid membranes.

• A. Thylakoid membranes
• B. Outer chloroplast membrane
• C. Lamellar membranes
• D. Inner chloroplast membrane

Explanation: Chlorophyll molecules are crucial for the light-dependent reactions of photosynthesis and are located in the thylakoid membranes within…

• A. Thylakoid membranes
• B. Outer chloroplast membrane
• C. Lamellar membranes
• D. Inner chloroplast membrane

Explanation: The correct answer is that thylakoid membranes are crucial structures within chloroplasts where the light-dependent reactions of…

• A. NADH and NADPH
• B. ATP and NADPH
• C. ATP and NADH
• D. FADH and NADPH

Explanation: During the light-dependent reactions of photosynthesis, chlorophyll and other pigments absorb light energy, which is then converted into…

• A. Radioactive substances
• B. Bioluminescent substances
• C. Pigments
• D. Fluorescent substances

Explanation: Pigments are substances that absorb visible light, which is crucial in processes such as photosynthesis, where they capture light energy.

• A. Same wavelength
• B. Single wavelength
• C. Different wavelengths
• D. Broad range of wavelengths

Explanation: Different pigments absorb light of different wavelengths due to variations in their molecular structure, which allows them to capture…

• A. Spectrometer
• B. Photometer
• C. Barometer
• D. Spectrophotometer

Explanation: A spectrometer separates and measures the spectral components of a physical phenomenon.

• A. Orange pigments
• B. Yellow pigments
• C. Red pigments
• D. Green pigments

Explanation: Carotenes are mostly orange pigments that play an important role in capturing light energy for photosynthesis.

• A. Yellow pigments
• B. Orange pigments
• C. Red pigments
• D. Yellow and red to orange pigments

Explanation: Carotenoids, which include carotenes and xanthophylls, are accessory pigments found in plants.

• A. Chlorophyll a and b
• B. Chlorophy c and d
• C. Chlorophyll b and c
• D. Bacteriochlorophylls

Explanation: The correct answer is bacteriochlorophylls. These pigments are found in photosynthetic bacteria that perform anoxygenic photosynthesis, a…

• A. Carotenes
• B. Xanthophylls
• C. Chlorophylls
• D. Carotenoids

Explanation: Chlorophylls are the primary pigments in plants responsible for photosynthesis.

• A. They absorb green light
• B. They reflect green light
• C. They transmit all colours equally
• D. They absorb only yellow and green wavelengths

Explanation: Plants appear green because chlorophyll, the main pigment involved in photosynthesis, reflects green light while absorbing red and blue…

• A. Porphyrin head
• B. Phytol tail
• C. Magnesium ion
• D. Carbon chain

Explanation: The light-absorbing hydrophilic part of chlorophyll is the porphyrin head, which is composed of four connected pyrrole rings, forming a…

• A. Light-absorbing part of chlorophyll
• B. Hydrophilic tail of chlorophyll
• C. Metal ion center
• D. Electron transport chain component

Explanation: The porphyrin ring represents the light-absorbing part of chlorophyll. It contains a magnesium ion at its center and a cyclic structure of…