During the light reactions of photosynthesis ______ is oxidized and ______ is reduced.

Question

BlackTom AI · Accepted Answer

During the light reactions of photosynthesis, electron flow is initiated by splitting water and ultimately reducing carrier molecules. 
Option 1: 'Oxygen and water' would imply oxygen is oxidized and water is reduced, which contradicts the known direction of electron flow where water loses electrons (is oxidized) and NADP+ gains electrons (is reduced).
Option 2: 'CO2 and Water' suggests carbon dioxide is the oxidized species and water is reduced, which does not reflect the events of the light reactions where CO2 is fixed later in the Calvin cycle and not involved in the direct oxidation-reduction steps of the light reactions.
Option 3: 'NADPH and CO2' states that NADPH is oxidized and CO2 is reduced, but in the light reactions NADP+ is reduced to NADPH, not NADPH being oxidized, so this reverses the actual redox changes.
Option 4: 'Water and NADP+' correctly identifies water as the substance that is oxidized (splitting to release electrons and protons) and NADP+ as the electron acceptor that is reduced to NADPH, which matches the standard depiction of the Z-scheme of photosystem I/II. The oxidation of water provides electrons, while the reduction of NADP+ stores energy in NADPH for the carbon-fixing steps downstream.
Option 5: 'Water and CO2' would imply CO2 is involved as the oxidized partner, which is not correct for the light reactions where CO2 is not directly oxidized or reduced.

In summary, only option 4 aligns with the fundamental redox changes of the light reactions: water is oxidized, and NADP+ is reduced to NADPH, while O2 is released as a byproduct.

Dashboard TEST 1 2025 T3

During the light reactions of photosynthesis is oxidized and is reduced.

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Dashboard TEST 1 2025 T3

During the light reactions of photosynthesis ______ is oxidized and ______ is reduced.

View Explanation

Log in for full answers

Similar Questions

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

Green plants release oxygen into the atmosphere during

NADPH is generated during the ________ reactions, only through _____ electron flow.

Order the flow of electrons in the light-dependent reactions of photosynthesis. 1: Splitting of water 2: Photons + Photosystem II 3: Photons + Photosystem I 4: Cytochrome b6-f complex 5: NADP Reductase

What are the 2 main products of the light reactions? (Choose ONE correct answer)

During the light reactions, a water molecule is split, supplying the missing electrons in PSI and PSII. (True or False)

Where does the light reactions occur? (Choose ONE correct answers)

More Practical Tools for Students Powered by AI Study Helper

Making Your Study Simpler

During the light reactions of photosynthesis is oxidized and is reduced.

NADPH is generated during the ____ reactions, only through _ electron flow.