Which of the following are required for the dark reaction of photosynthesis?

A. Light

B. Chlorophyll

C. CO₂

D. ATP

E. NADPH

Choose the correct answer from the options given below:

The correct answer is C, D and E only.

Photosynthesis is broadly divided into two main stages:
1. Light-dependent reactions (Light reactions): These reactions occur in the thylakoid membranes of the chloroplasts. They require direct sunlight and chlorophyll to absorb light energy. The primary products of this stage are chemical energy in the form of ATP (Adenosine Triphosphate) and reducing power in the form of NADPH (Nicotinamide Adenine Dinucleotide Phosphate), along with oxygen gas as a byproduct.
2. Light-independent reactions (Dark reactions / Calvin Cycle): These reactions occur in the stroma of the chloroplasts and do not require direct light. Instead, they use the products of the light reactions to synthesize carbohydrates. The key inputs required for the dark reaction are:
• Carbon dioxide (CO₂): It acts as the source of carbon atoms to build organic molecules (glucose).
• ATP: Provides the energy required for the chemical reactions in the cycle.
• NADPH: Provides the high-energy electrons (reducing power) necessary to reduce carbon dioxide into sugars.

Let us analyze the given options:
• A. Light: Required directly for the light reactions, not the dark reactions.
• B. Chlorophyll: The pigment responsible for trapping light energy during the light reactions.
• C. CO₂: Required as the carbon source in the dark reaction.
• D. ATP: Required to power the dark reaction.
• E. NADPH: Required as the reducing agent in the dark reaction.

Therefore, carbon dioxide (C), ATP (D), and NADPH (E) are the components required for the dark reaction of photosynthesis.