4.1.1 Photosynthetic reaction

• What happens in photosynthesis?

  1 Light energy is absorbed

  2 By chlorophyll (pigment) in chloroplasts in plant / algal cells

  3 This energy is used to convert carbon dioxide and water into

  glucose (sugar) and oxygen (by-product)
• What type of reaction is photosynthesis and why?

  Endothermic reaction - energy transferred from environment to chloroplast by light
• State the word equation

  carbon dioxide + water → glucose + oxygen
• Why is this statement wrong?

  “Photosynthesis releases energy.”

  Photosynthesis absorbs light energy and uses it to make glucose.
• Why is this statement wrong?

  “Photosynthesis is the term given to

  respiration in plants.”

  Photosynthesis and respiration are two different processes. Both happen in plant cells.
• Why is this statement wrong?

  “Plants photosynthesise to make oxygen.”

  Oxygen is made in photosynthesis, but it is only a by-product. The

  aim of photosynthesis is to make glucose.