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Photosynthesis MCQs for NEET — Botany Questions with Answers

Practice free Photosynthesis (Botany) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.

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Why do C4 plants generally avoid photorespiration?

A. They lack the RuBisCO enzyme. B. They have a specialized mechanism to concentrate $\text{CO}_2$ at the site of RuBisCO. C. Their RuBisCO has a higher affinity for $\text{O}_2$ than $\text{CO}_2$. D. They perform photosynthesis only during the night.

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Explanation

The NCERT text states: 'Some tropical plants show a special type of photosynthesis called C4 pathway.' It also asks, 'Why do you think RuBisCO carries out more carboxylation in C4 plants?' This implies that C4 plants have adaptations that favor RuBisCO's carboxylation activity, which is indeed the $\text{CO}_2$ concentrating mechanism, minimizing photorespiration.

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The primary cause of photorespiration is the competitive binding of which two molecules to the active site of RuBisCO?

A. $\text{ATP}$ and $\text{NADPH}$ B. Water and Carbon Dioxide C. Carbon Dioxide and Oxygen D. Glucose and Starch

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Explanation

The text highlights that 'RuBisCO also catalyses a wasteful oxygenation reaction' in addition to its role in $\text{CO}_2$ fixation. This 'oxygenation reaction' arises from the competition between $\text{CO}_2$ and $\text{O}_2$ for RuBisCO's active site.

NEET 2023

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How many ATP and NADPH₂ are required for the synthesis of one molecule of Glucose during Calvin cycle?

A. 12 ATP and 12 NADPH₂ B. 18 ATP and 12 NADPH₂ C. 12 ATP and 16 NADPH₂ D. 18 ATP and 16 NADPH₂

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Explanation

Per glucose: 18 ATP + 12 NADPH (6 turns × 3 ATP and 2 NADPH per turn).

NEET 2023

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Which micronutrient is required for splitting of water molecule during photosynthesis?

A. Manganese B. Molybdenum C. Magnesium D. Copper

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Explanation

The OEC of PSII has a Mn₄CaO₅ cluster that oxidises water.

NEET 2023

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The reaction centre in PS II has an absorption maxima at:

A. 680 nm B. 700 nm C. 660 nm D. 780 nm

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Explanation

P680 — PSII reaction centre chlorophyll absorbs at 680 nm.

NEET 2024

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How many molecules of ATP and NADPH are required for every molecule of $CO_2$ fixed in the Calvin cycle?

A. 3 molecules of ATP and 2 molecules of NADPH B. 2 molecules of ATP and 3 molecules of NADPH C. 2 molecules of ATP and 2 molecules of NADPH D. 3 molecules of ATP and 3 molecules of NADPH

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Explanation

Standard NCERT: 3 ATP + 2 NADPH per CO₂ fixed.

NEET 2024

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Which of the following are required for the dark reaction of photosynthesis?

A. Light B. Chlorophyll C. $CO_2$ D. ATP E. NADPH

Choose the correct answer from the options given below:

A. D and E only B. A, B and C only C. B, C and D only D. C, D and E only

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Explanation

Calvin (dark) reactions need CO₂, ATP and NADPH — not light or chlorophyll directly.

NEET 2024

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Given below are two statements:

Statement I: In $C_3$ plants, some $O_2$ binds to RuBisCO, hence $CO_2$ fixation is decreased.

Statement II: In $C_4$ plants, mesophyll cells show very little photorespiration while bundle sheath cells do not show photorespiration.

In the light of the above statements, choose the correct answer from the options given below:

A. Statement I is false but Statement II is true B. Both Statement I and Statement II are true C. Both Statement I and Statement II are false D. Statement I is true but Statement II is false

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Explanation

Both standard NCERT facts about C₃/C₄ photorespiration.

NEET 2025

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Match List I with List II:

List I — A. Chlorophyll a, B. Chlorophyll b, C. Xanthophylls, D. Carotenoids

List II — I. Yellow-green, II. Yellow, III. Blue-green, IV. Yellow to Yellow-orange

Choose the option with all correct matches:

A. A-III, B-IV, C-II, D-I B. A-III, B-I, C-II, D-IV C. A-I, B-II, C-IV, D-III D. A-I, B-IV, C-III, D-II

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Explanation

Chlorophyll a → blue-green (III); Chlorophyll b → yellow-green (I); Xanthophylls → yellow (II); Carotenoids → yellow to yellow-orange (IV).

NEET 2025

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Which of the following statements about RuBisCO is true?

A. It is active only in the dark. B. It has higher affinity for oxygen than carbon dioxide. C. It is an enzyme involved in the photolysis of water. D. It catalyzes the carboxylation of RuBP.

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Explanation

RuBisCO catalyses the carboxylation of RuBP (fixing CO₂) in the Calvin cycle; it actually has a greater affinity for CO₂ than O₂.

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