ZIMSEC O Level Combined Science: Photosynthesis
- Green plants are the food and oxygen producers of the living world.
- They manufacture organic molecules from inorganic raw materials.
- Animals rely on green plants to make food that provides them with energy and oxygen.
- Green plants are thus known as producers and animals are in turn known as consumers.
- Only green plants can make food.
- The process by which green plants make food from inorganic materials is known as photosynthesis.
- Photosynthesis- is the process by which green plants use light energy to combine carbon dioxide and water into carbohydrates and releasing oxygen as a by product.
- The word equation for photosynthesis is:
- \text{Carbon Dioxide+Water}\xrightarrow[light]{chlorophyll}\text{Carbohydrates+Oxygen}
- There are two types of carbohydrates made during the process of photosynthesis:
- sugars and starch.
- Testing for either of these molecules in plants will show whether plants are making food.
- Most plants produce although others like cereals (e.g. maize) produce sugars first.
- The simple sugar compound (glucose) is converted into starch for storage in the leaves.
- Chlorophyll is the green pigment found in plants.
- It is commonly found in plant leaves.
- It absorbs light energy from the sun and converts it into chemical energy.
- It absorbs light energy from the usn which can then be used to manufacture food.
To access more topics go to the Combined Science Notes page.