Photosynthesis (Cambridge (CIE) O Level Biology): Revision Note

Photosynthesis

• Photosynthesis can be defined as:

The process by which plants manufacture carbohydrates from raw materials using energy from light

• Green plants make glucose from the raw materials carbon dioxide and water

• At the same time, oxygen is made and released as a waste product

• The green pigment chlorophyll absorbs light energy from the sun, providing the energy needed for the reaction to occur

Photosynthesis Equations

• The word equation for photosynthesis can be represented as follows:

Photosynthesis word equation diagram

The word equation for photosynthesis shows the raw materials and products. Here the additional requirements for light energy and chlorophyll are also indicated

• The raw materials required by plants are taken up by different plant organs from the plant's environment:

Photosynthesis raw materials diagram

Plants gain the materials required for photosynthesis from their surroundings

• Light energy from the sun is converted into chemical energy in the bonds holding the atoms in the glucose molecules together

• The balanced chemical equation for photosynthesis is:

Photosynthesis balanced chemical equation diagram

The chemical symbol for glucose is C₆H₁₂O₆; to provide enough atoms of carbon, hydrogen and oxygen to produce glucose, 6 molecules of carbon dioxide and 6 molecules of water need to enter the reaction