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Photosynthesis NEET Questions — Free MCQ Practice

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The first product of C3 and C4 cycle are:

A.

PGA, PGAL

B.

PGA, OAA

C.

PGAL, RuBP

D.

PGAL, OAA

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Explanation

P-216, para1, 2nd last line

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PEP is present in which cells?

A.

Only Mesophyll cells

B.

Bundle Sheath cells

C.

both a and b

D.

Passage cells

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Explanation

P-219, Para 2

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The binding of RuBisCO for O2 and CO2 is –

A.

Non- competitive

B.

Competitive

C.

Uncompetitive

D.

Mixed

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Explanation

P-220; Photorespiration; Para 2

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Temperature will affect which process more sensitively?

A.

Dark process

B.

Non Cyclic Process

C.

Cyclic Process

D.

Splitting of water

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Explanation

P-223 Factors Affecting Photosynthesis- Temperature; Para 1

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Which of the following processes is directly responsible for creating a proton gradient across the thylakoid membrane during the light reaction?

A. Splitting of water molecules B. Synthesis of ATP by ATPase C. Fixation of CO2 in the Calvin cycle D. Movement of electrons from PS I to NAD

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Explanation

According to the NCERT text, 'Splitting of water molecules is associated with PS II resulting in the release of O2, protons and transfer of electrons to PS II.' The release of protons ($H^+$) into the thylakoid lumen directly contributes to the proton gradient.

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What is the primary role of the F0 part of the ATPase enzyme in chemiosmosis?

A. To bind ADP and inorganic phosphate B. To act as a channel for proton movement across the membrane C. To catalyse the reduction of NADP+ to NADPH D. To absorb light energy and excite electrons

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Explanation

The NCERT states, 'The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.' The F0 part functions as the transmembrane channel allowing protons to flow down their electrochemical gradient.

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The energy released from the proton gradient is primarily utilized for:

A. Regenerating RuBP B. Synthesizing carbohydrates in the stroma C. Driving the synthesis of ATP D. Splitting water molecules

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Explanation

The NCERT explicitly mentions, 'The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.' This highlights the direct link between the proton gradient and ATP production.

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Where does the chemiosynthetic pathway (generation of ATP and NADPH) primarily occur within the chloroplast?

A. Stroma B. Inner membrane C. Thylakoid membrane D. Outer membrane

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Explanation

The NCERT states, 'Within the chloroplasts, the membranes are sites for the light reaction, while the chemosynthetic pathway occurs in the stroma.' However, in the summary, it clarifies that 'a proton gradient is created across the membrane of the thylakoid. The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP.' This implies that the chemiosmosis, leading to ATP synthesis, occurs across the thylakoid membrane. The question refers to the 'chemosynthetic pathway' which in the summary is referred to as the process involving ATP and NADPH synthesis following the light reaction across the thylakoid membrane. If it means 'carbon fixation' then it is stroma. Given the context of the question following proton gradient, it refers to ATP synthesis part of light reaction, which happens on thylakoid membrane.

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Which of the following is NOT a consequence of the proton gradient across the thylakoid membrane?

A. Movement of $H^+$ through ATPase B. Synthesis of ATP C. Release of oxygen D. Formation of NADPH

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Explanation

The NCERT states that 'Splitting of water molecules is associated with PS II resulting in the release of O2, protons and transfer of electrons to PS II.' The release of oxygen occurs before and independently of the proton gradient breakdown for ATP synthesis. The proton gradient facilitates ATP synthesis via ATPase and its formation is related to electron transport which ultimately leads to NADPH formation.

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A crucial event in chemiosmotic hypothesis is the accumulation of protons ($H^+$) in which specific compartment of the chloroplast?

A. Stroma B. Cytosol C. Thylakoid lumen D. Intermembrane space

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Explanation

The proton (hydrogen ion) gradient is created across the thylakoid membrane, meaning protons accumulate within the thylakoid lumen.

Photosynthesis MCQs for NEET — Botany Questions with Answers

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