All Free Biology MCQs with Answers

• A. Absorbing excessive light energy
• B. Dissipating excessive light energy
• C. Transferring excessive light energy to chlorophyll a
• D. Both A and B

Explanation: Option D is correct.Some carotenoids protect chlorophyll from intense light by both absorbing and dissipating excessive light energy.

• A. Antenna complex
• B. Reaction complex
• C. Antenna complex and a reaction centre
• D. Primary electron acceptor

Explanation: Each photosystem consists of a light gathering antenna complex and a reaction center.

• A. Cyclic phosphorylation
• B. Photophosphorylation
• C. Oxidative phosphorylation
• D. Z - scheme

Explanation: Same electrons are again and again cycled back and each time yield one ATP.

• A. ATPs generated by light reactions
• B. NADH2 generated by light reactions
• C. FADH2 generated by light reactions
• D. Oxygen generated by light reactions

Explanation: ATP (assimilatory power) is synthesized in light reaction which is used later on in dark reaction to synthesize sugar.

• A. Coupling of ETC by chemiosmosis
• B. Involvement of chemiosmosis
• C. Involvement of ETC
• D. Oxidative phosphorylation

Explanation: In both cyclic and non-cyclic photophosphorylation, the mechanism for ATP synthesis is chemiosmosis, the process that uses membranes to…

• A. Cyclic photophosphorylation
• B. Non-cyclic photophosphorylation
• C. Both cyclic and non-cyclic photophosphorylation
• D. Z-scheme

Explanation: Chemiosmosis is involved in both types of photophosphorylation.

• A. Reduction of CO2
• B. Regeneration of CO2 acceptor
• C. Fixation of CO2
• D. Regeneration of RuBP

Explanation: In first phase CO2 is condensed with RuBP in presence of Rubisco. It is called fixation of CO2.

• A. Alcoholic fermentation
• B. Respiratory electron transport chain
• C. Lactic acid fermentation
• D. Alcoholic and lactic acid fermentation

Explanation: Both alcoholic fermentation and lactic acid fermentation occur in absence of oxygen. It is also called anaerobic respiration.

• A. CO2
• B. CO2 and water
• C. H2O
• D. CO2 and energy

Explanation: These are the end products of aerobic respiration along with energy.

• A. Oxidation process
• B. Redox process
• C. A reduction process
• D. Decarboxylation process

Explanation: Based on the explanations provided, the correct answer to the question is option A) Oxidation process.

• A. ATP to glucose
• B. G3P to ATP
• C. ATP to fructose
• D. ATP to G.3.P

Explanation: As a result Glucose 6-phosphate is formed.

• A. 1
• B. 2
• C. 3
• D. 2, 3

Explanation: Step 2 involves rearrangement i.e. formation of Fructose 6-phosphate from glucose 6-phosphate; and 3 involves ATP phosphorylation.

• A. Phosphoglucokinase
• B. Pyruvate decarboxylase
• C. Phosphofructokinase
• D. Pyruvate dehydrogenase

Explanation: If pyruvate decarboxylase is inhibited acetate formation and subsequently Acetyl Co. A formation will be stopped.

• A. Electron transport chain
• B. Non-cyclic photophosphorylation
• C. Cyclic photophosphorylation
• D. Z - scheme

Explanation: It is respiratory electron transport chain also called oxidative phosphorylation.

• A. Stroma of chloroplast
• B. Grana chloroplast
• C. Matrix of mitochondria
• D. Inner membrane of mitochondria

Explanation: "The explanation for this question will be added soon!".

• A. Water is reduced and CO2 is oxidized
• B. Water is oxidized and CO2 is reduced
• C. Both CO2 and Water are oxidized
• D. Both CO2 and Water are reduced

Explanation: Photosynthesis is an oxidation - reduction process in which water is oxidized and CO2 is reduced.

• A. Reduction
• B. Dehydration
• C. Dephosphorylation
• D. Oxidative decarboxylation

Explanation: The formation of Acetyl-CoA from pyruvic acid is the result of its oxidative decarboxylation.

• A. Cytochrome b
• B. Cytochrome c
• C. Cytochrome a
• D. NADH

Explanation: NADH is a molecule that helps cells produce energy. It is made in the mitochondria, which are tiny organs inside cells.

• A. 2ATP
• B. 3ATP
• C. 4ATP
• D. 6ATP

Explanation: Every molecule of NADH fed into the electron transport chain (ETC) produces 3 ATP.NADH is a coenzyme that carries electrons from the Krebs…

• A. NADPH2
• B. ATP
• C. ATP and NADPH2
• D. RuBP

Explanation: Light energy is converted into chemical energy through the formation of ATP and NADPH.