The main gas used in the process of photosynthesis is carbon dioxide (CO₂) , which plants take in from the air through tiny openings in their leaves called stomata. During photosynthesis, plants use carbon dioxide and water, along with light energy, to make glucose (a sugar) and release oxygen as a by- product.

Quick Scoop

  • The key gas used in photosynthesis: carbon dioxide (CO₂).
  • The main gas released during photosynthesis: oxygen (O₂).
  • Simple overall idea: plants take in carbon dioxide and water, use sunlight, and make food (glucose) plus oxygen.

How the gas is used

  • Carbon dioxide enters the leaf through stomata and diffuses into cells that contain chlorophyll, where photosynthesis happens.
  • In the reactions of photosynthesis, the carbon from CO₂ is built into glucose, which stores energy for the plant.

Simple word equation

  • A common way to describe the process is:
    • carbon dioxide + water + light → glucose + oxygen.
  • This shows that carbon dioxide is a reactant (used up), while oxygen is a product (given out).

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