Free Bioenergetics MCQs with Answers

• A. Interior space of the thylakoid
• B. Outside the thylakoid membrane
• C. Into the stroma
• D. At the ATP synthase complex

Explanation: Water splitting, or photolysis, is a critical step in the light-dependent reactions of photosynthesis.

• A. Ferredoxin
• B. Photosystem II
• C. Plastoquinone
• D. Cytochrome b6f

Explanation: NADP⁺ reductase specifically accepts electrons from ferredoxin, the last carrier in Photosystem I's linear electron transport chain.

• A. Water → Photosystem II (P680) → Plastoquinone (PQ) → Cytochrome b6f → Plastocyanin (PC) → Photosystem I (P700) → Ferredoxin (Fd) → NADP⁺
• B. Water → Photosystem I (P700) → Plastoquinone (PQ) → Cytochrome b6f → Plastocyanin (PC) → Photosystem II (P680) → Ferredoxin (Fd) → NADP⁺
• C. NADP⁺ → Ferredoxin (Fd) → Photosystem I (P700) → Plastocyanin (PC) → Cytochrome b6f → Plastoquinone (PQ) → Photosystem II (P680) → Water
• D. Water → Photosystem II (P680) → Photosystem I (P700) → Ferredoxin (Fd) → Cytochrome b6f → NADP⁺

Explanation: In non-cyclic photophosphorylation, electrons originate from water molecules, which are split by Photosystem II (P680), releasing oxygen…

• A. Electrons originate from water molecules
• B. Both ATP and NADPH are produced
• C. Electrons return to Photosystem I after reaching NADP⁺
• D. Oxygen is released as a by-product of water splitting

Explanation: Non-cyclic photophosphorylation, or the non-cyclic electron pathway, is the linear flow of electrons from water to NADP⁺ in the thylakoid…

• A. Dark reaction
• B. Pseudo-cyclic photophosphorylation
• C. Non-cyclic photophosphorylation
• D. Cyclic photophosphorylation

Explanation: The correct answer is noncyclic photophosphorylation. This process occurs in the light-dependent reactions of photosynthesis, wherein…

• A. Cyclic photophosphorylation
• B. Calvin cycle
• C. Non-cyclic photophosphorylation
• D. Oxidative photophosphorylation

Explanation: The 'Z-scheme' refers to the process of non-cyclic photophosphorylation in the light-dependent reactions of photosynthesis.

• A. Does not require light directly
• B. It uses ATP
• C. Also called Z-scheme
• D. G3P is produced

Explanation: The correct answer is that the dark reaction is not called the Z-scheme.

• A. Glycolysis
• B. Calvin cycle
• C. Krebs cycle
• D. Light dependent reactions

Explanation: The correct answer is the Calvin cycle, which is the light-independent process of photosynthesis where carbon dioxide is fixed into…

• A. ATP production
• B. Oxygen production
• C. Carbon dioxide fixation
• D. Carbon dioxide production

Explanation: The Calvin cycle, also known as the light-independent reactions, takes place in the stroma of chloroplasts and involves the fixation of…

• A. ATP
• B. NADPH
• C. G3P
• D. PEP

Explanation: The correct answer is glyceraldehyde 3-phosphate (G3P), which is the primary carbohydrate product of the Calvin cycle, also known as the…

• A. One
• B. Six
• C. Two
• D. Twelve

Explanation: In the Calvin cycle, the fixation of carbon dioxide into glucose requires both ATP and NADPH.

• A. Initial incorporation of 3 CO₂ molecules
• B. Production of 3-carbon G3P
• C. Production of 3-carbon 3PGA
• D. Cycle has 3 steps

Explanation: The Calvin cycle, also known as the C3 pathway, is named for the production of a 3-carbon compound, 3-phosphoglycerate (3PGA), as the…

• A. 9ATP + 6NADPH
• B. 18ATP + 12NADPH
• C. 6ATP + 9NADPH
• D. 3ATP + 3NADPH

Explanation: The Calvin cycle, also known as the light-independent reactions of photosynthesis, requires 3 ATP and 2 NADPH molecules for the fixation…

• A. Bacteria
• B. Yeast
• C. Skeletal muscles
• D. All of these

Explanation: All the options listed-bacteria, yeast, and skeletal muscles-are capable of performing anaerobic respiration under certain conditions.

• A. 4%
• B. 2%
• C. 6%
• D. 8%

Explanation: During anaerobic respiration, such as in fermentation processes, only about 2% of the energy stored in a glucose molecule is extracted.

• A. ATP
• B. Oxygen
• C. NADH
• D. Glucose

Explanation: In cellular respiration, the primary product formed as a result of the release of energy is adenosine triphosphate (ATP).

• A. 2
• B. 4
• C. 1
• D. 6

Explanation: In glycolysis, the preparatory phase involves the conversion of glucose into two 3-carbon molecules known as glyceraldehyde-3-phosphate.

• A. Photosynthesis
• B. Respiration
• C. Transpiration
• D. Water absorption

Explanation: The correct answer is respiration. In cellular respiration, plants break down glucose molecules to release energy stored in their chemical…

• A. Fructose 1-phosphate → Fructose 1,6-bisphosphate
• B. Fructose 1,3-bisphosphoglycerate → 3-phosphoglycerate
• C. Fructose 1-phosphate → Fructose 6-phosphate
• D. Glucose 6-phosphate → Fructose 1-phosphate

Explanation: Dephosphorylation is the process of removing a phosphate group from a molecule.

• A. 2 ATP
• B. 38 ATP
• C. 4 ATP
• D. 40 ATP

Explanation: During aerobic respiration in prokaryotes, one molecule of glucose is completely oxidized through glycolysis, the citric acid cycle, and…