Question

Which of the following is not a product of light reaction of photosynthesis ?

• A. ATP
• B. NADPH
• C. NADH
• D. Oxygen

Answer 1

The Correct Option is C

In photosynthesis, the light reaction (also known as the photochemical phase) takes place in the thylakoid membranes of the chloroplasts. During this process, light energy is captured and converted into chemical energy, resulting in the formation of certain products. Let's break down the options given and determine which of them is not a product of the light reaction:

1. ATP (Adenosine Triphosphate): During the light reaction, ATP is synthesized from ADP and inorganic phosphate through a process known as photophosphorylation. ATP acts as an energy carrier.
2. NADPH (Nicotinamide Adenine Dinucleotide Phosphate): NADP⁺ is reduced to NADPH, which serves as a reducing agent and is used in the Calvin cycle (light-independent reactions) for the synthesis of glucose.
3. Oxygen: Oxygen is produced as a by-product when water molecules are split by photolysis (light-induced water splitting). This process releases oxygen gas into the atmosphere.
4. NADH: This is a reducing agent that is typically involved in cellular respiration. It is not produced during the light reaction of photosynthesis.

Therefore, among the given options, NADH is not a product of the light reaction of photosynthesis.

To summarize, the primary products of the light reactions are ATP, NADPH, and Oxygen. The correct answer is NADH as it is associated with mitochondrial electron transport during cellular respiration, not photosynthesis.