NEET Biology: photophosphorylation Practice Questions
15 free multiple-choice questions on photophosphorylation (Photosynthesis and Respiration) for NEET Biology, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. What molecule acts as the immediate electron acceptor from Photosystem II as electrons move down the chain?
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Correct answer: A — Plastoquinone (PQ)
Following light absorption in PSII, the excited electrons are passed to the primary electron acceptor, which is typically Plastoquinone (PQ), which then carries the electrons to the next complex.
Q2. Which molecule acts as the initial electron donor for the light-dependent reactions during photophosphorylation in oxygenic photosynthesis?
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Correct answer: D — H₂O
Water (H₂O) is split during the light reactions, releasing electrons, protons, and oxygen. The electrons replace those lost by Photosystem II, initiating the flow of electrons that drives photophosphorylation.
Q3. Where does the process of photophosphorylation primarily occur in photosynthetic organisms like plants and cyanobacteria?
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Correct answer: D — Thylakoid membrane
Photophosphorylation occurs across the thylakoid membrane, which is embedded within the chloroplasts. This membrane contains the photosystems and electron transport chain components necessary for light-dependent reactions.
Q4. Which molecule is directly synthesized during photophosphorylation to power the Calvin cycle?
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Correct answer: D — ATP
The primary goal of the light reactions is to generate energy carriers, mainly ATP (energy) and NADPH (reducing power), which are necessary for the subsequent Calvin cycle.
Q5. What is the immediate energy molecule synthesized during photophosphorylation that drives the synthesis of sugars?
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Correct answer: A — ATP
ATP (Adenosine Triphosphate) is the energy currency produced during photophosphorylation and is used to provide the necessary energy for the reduction and fixation steps in the Calvin cycle.
Q6. The energy captured from light is initially absorbed by pigment molecules located in which part of the thylakoid membrane?
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Correct answer: B — The thylakoid membrane itself
Light energy is absorbed by chlorophyll and other pigments embedded within the thylakoid membrane structures.
Q7. The establishment of the proton gradient across the thylakoid membrane is crucial for which subsequent step?
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Correct answer: D — ATP synthesis
The proton gradient (proton motive force) is essential for driving the synthesis of ATP by the ATP synthase enzyme during chemiosmosis.
Q8. What is the primary final product generated during the photophosphorylation stage of photosynthesis?
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Correct answer: B — NADPH
The photophosphorylation process, driven by the proton gradient, results in the synthesis of ATP and the reduction of NADP⁺ to NADPH.
Q9. Which component of the thylakoid membrane is essential for establishing the proton gradient necessary for chemiosmosis during photophosphorylation?
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Correct answer: A — Photosystem II
The electron transport chain (ETC) embedded in the thylakoid membrane pumps protons (H⁺) from the stroma into the thylakoid lumen, creating a high proton concentration gradient.
Q10. The process of photophosphorylation is directly dependent on the presence of which of the following?
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Correct answer: A — Chlorophyll
Photophosphorylation requires light energy to excite electrons. Chlorophyll absorbs this light energy, initiating the process.
Q11. What is the role of the excitation of electrons by light in the initial phase of photophosphorylation?
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Correct answer: C — To excite electrons to a higher energy level
Light energy is absorbed by photosystem components, which excites electrons to a higher energy level, initiating the flow through the electron transport chain.
Q12. What is the immediate energy-carrying molecule produced directly by photophosphorylation?
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Correct answer: A — ATP
Photophosphorylation is the process that generates ATP (adenosine triphosphate) using a proton gradient.
Q13. Which molecule is the direct source of electrons for the process of photophosphorylation?
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Correct answer: D — Water (H₂O)
Water is split in Photosystem II (PSII) to release electrons, protons, and oxygen, making it the ultimate source of electrons for the subsequent photophosphorylation process.
Q14. Which electron transport chain (ETC) is directly involved in the photophosphorylation process?
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Correct answer: B — ETC associated with Photosystem I and II
The ETC embedded in the thylakoid membrane, involving Photosystem I and II, is responsible for creating the proton gradient necessary for ATP synthesis.
Q15. Where does photophosphorylation primarily take place in photosynthetic organisms?
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Correct answer: C — Thylakoid membrane
Photophosphorylation occurs across the thylakoid membranes within the chloroplasts, where the photosystems and electron transport chain are embedded.
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