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Photosynthesis

Grades 5-9 · Concept Explainer

Key Points

  • ✓Photosynthesis is how plants make their own food.
  • ✓Plants use sunlight, water, and carbon dioxide.
  • ✓The process happens in chloroplasts.
  • ✓Plants create sugar (glucose) for energy.
  • ✓Oxygen is released as a byproduct.

Photosynthesis is how plants make their own food! Just like we need to eat to get energy, plants use sunlight, water, and carbon dioxide to create their own energy in the form of sugar (glucose). This process happens inside tiny structures called chloroplasts, which are found in plant cells, especially in leaves. As a byproduct, plants release oxygen into the air, which is what we breathe!

Worked Example

A plant absorbs 6 molecules of carbon dioxide and 6 molecules of water. What does it produce?

  1. Step 1: Recall the inputs and outputs of photosynthesis.
  2. Step 2: The inputs are carbon dioxide and water. The outputs are glucose (sugar) and oxygen.
  3. Step 3: Therefore, the plant produces one molecule of glucose and 6 molecules of oxygen.

Answer: One molecule of glucose and 6 molecules of oxygen.

Try It Yourself

1. What are the three things a plant needs for photosynthesis?

2. Where does photosynthesis take place in a plant cell?

3. If a plant is kept in a dark room, will it be able to perform photosynthesis? Explain why or why not.

Watch Out For These Mistakes

  • Thinking that plants only need sunlight to grow.
  • Forgetting that carbon dioxide is needed for photosynthesis.
  • Confusing photosynthesis with respiration (breathing).