Photosynthesis

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Green plants and algae use light energy to make their own food. They obtain the raw materials they need to make this food from the air and the soil. The conditions in which plants are grown can be changed to promote growth

light energy carbon dioxide + water glucose + oxygen

light energy is absorbed by a green substance called chlorophyll, which is found in chloroplasts in some plant cells and algae

this energy is used by converting carbon dioxide (from the air) and water (from the soil) into sugar (glucose)

oxygen is released as a by-product

Limiting Factors

The rate of photosynthesis may be limited by:

■ shortage of light

■ low temperature

■ shortage of carbon dioxide.

Light, temperature and the availability of carbon dioxide interact and in practice any one of them may be the factor that limits photosynthesis.

Uses of Glucose

The glucose produced in photosynthesis may be converted into insoluble starch for storage. Plant cells use some of the glucose produced during photosynthesis for respiration. Some glucose in plants and algae is used:

■ to produce fat or oil for storage

■ to produce cellulose, which strengthens the cell wall

■ to produce proteins.

To produce proteins, plants also use nitrate ions that are absorbed from the soil

Uses of Glucose

The glucose produced in photosynthesis may be converted into insoluble starch for storage. Plant cells use some of the glucose produced during photosynthesis for respiration. Some glucose in plants and algae is used:

■ to produce fat or oil for storage

■ to produce cellulose, which strengthens the cell wall

■ to produce proteins.

To produce proteins, plants also use nitrate ions that are absorbed from the soil

Limiting Factors

The rate of photosynthesis may be limited by:

■ shortage of light

■ low temperature

■ shortage of carbon dioxide.

Light, temperature and the availability of carbon dioxide interact and in practice any one of them may be the factor that limits photosynthesis.

What is photosynthesis?

Limiting Factors

Uses of Glucoose