Question
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What is the step-by-step process of photosynthesis?

Verified Answer

Photosynthesis is a multi-stage biochemical process through which green plants convert light energy into chemical energy in the form of glucose.

It occurs in two main stages: light reactions and dark reactions (Calvin cycle).

Step-by-step process of photosynthesis:

1. Absorption of light energy
Chlorophyll present in chloroplasts absorbs sunlight, mainly in the blue and red wavelengths.

2. Light reactions (in thylakoid membranes)

  • Light energy is used to split water molecules (photolysis).

  • Oxygen is released as a by-product.

  • Energy carriers ATP (adenosine triphosphate) and NADPH are produced.

3. Formation of oxygen
The splitting of water releases oxygen (O₂), which diffuses out through stomata.

4. Dark reactions / Calvin Cycle (in stroma)

  • Carbon dioxide (CO₂) is fixed into organic molecules.

  • ATP and NADPH (from light reactions) are used to convert CO₂ into glucose.

5. Glucose formation and storage
Glucose is synthesized and either:

  • Used immediately for energy

  • Stored as starch

  • Converted into other organic compounds

Overall chemical equation:

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

Key points:

  • Light reactions require sunlight; dark reactions do not directly require light but depend on products of light reactions.

  • Occurs in chloroplasts of plant cells.

In simple terms: Photosynthesis uses sunlight to generate energy, which is then used to convert carbon dioxide and water into glucose and oxygen.