Understanding:
• Oxygen is produced in photosynthesis from the photolysis of water
• Energy is needed to produce carbohydrates and other carbon compounds from carbon dioxide
Photosynthesis is a two step process:
- The light dependent reactions convert light energy from the Sun into chemical energy (ATP)
- The light independent reactions use the chemical energy to synthesise organic compounds (e.g. carbohydrates)
Step 1: Light Dependent Reactions
- Light is absorbed by chlorophyll, which results in the production of ATP (chemical energy)
- Light is also absorbed by water, which is split (photolysis) to produce oxygen and hydrogen
- The hydrogen and ATP are used in the light independent reactions, the oxygen is released from stomata as a waste product
Step 2: Light Independent Reactions
- ATP and hydrogen (carried by NADPH) are transferred to the site of the light independent reactions
- The hydrogen is combined with carbon dioxide to form complex organic compounds (e.g. carbohydrates, amino acids, etc.)
- The ATP provides the required energy to power these anabolic reactions and fix the carbon molecules together
Summary of the Overall Process of Photosynthesis
