Question

What is the source of electrons in photosynthesis?

• A. Carbohydrates
• B. Water
• C. CO2
• D. NADH

Hint:

In photosynthesis, water is split to release electrons, protons, and oxygen during the light-dependent reactions.

Answer 1

The Correct Option is B

Step 1: Understanding Photosynthesis.
During photosynthesis, water molecules are split into oxygen, protons, and electrons through the light-dependent reactions. The electrons are then used in the electron transport chain.

Step 2: Analyzing the options.
(A) Carbohydrates: Incorrect — Carbohydrates are produced by photosynthesis but do not provide electrons.
(B) Water: Correct — Water is the source of electrons in photosynthesis, specifically in the light-dependent reactions.
(C) CO2: Incorrect — Carbon dioxide is used in the Calvin cycle but does not provide electrons.
(D) NADH: Incorrect — NADH is an energy carrier but does not donate electrons in the light-dependent reactions.

Step 3: Conclusion.
The correct answer is (B) Water, as water molecules provide electrons in the light reactions of photosynthesis.