Photosynthesis

Green plants don't absorb fod from the soil. They make there own food using sunlight, this is photosynthesis.

During photosynthesis, light energy is absored by green chlorophyll, which is found in chloroplasts in some plant cells and algae.

Four things are needed for photosynthesis:

• Light
• Carbon Dioxide
• Water
• Chlorophyll

The light energy is used to convert carbon dioxide from the air and water into glucose. Oxygen is a useful by-product.

The word Equation is : Carbon Dioxide + Water ----> Glucose + Oxygen

The Glucose produced in photosynthesis may be ...

• Changed into insoluble starch and stored in the stem,leaves or roots.
• Used by the plant during respiration to provide energy.

Some glucose in plants and algae is ....

• Used to produce fat and oil and stored
• Used to produce cellulose to strengthen cell walls
• Used to produce Proteins

To produce proteins, plnats also use nitrate ions, which are absorbed from the soil.

There are several factors thath may at any time limit the rate of photosynthesis.

• Temperature
• Carbon dioxide concentration
• Light intensity

As a temperature increases, so does the rate of photosynthesis. However tempertaure can limit photosynthesis as the temp approached 45oC the level of photosynthesis drops to zero because the enzymes controlling the photosynthesis have been denatured.

As the carbon dioxide concentration increase , so does the rate of photosynthesis. After reaching a certain point, an increase in CO2 has no further affect.

As light intensity increase so does the rate of photosynthesis but as with carbon dioxide after a certain point it no longer has an affect on the rate of photosynthesis.