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.
Photosynthesis is the process in plants in which
carbon dioxide and water is converted into
glucose and 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) with oxygen is released as a by-product.
The rate of photosynthesis may be limited
by shortage of light, low temperature and
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.
For optimum growth and saving time, energy
and money, farmers use light intensity,
temperature and concentration of carbon
dioxide to to create the best conditions in
greenhouses for crops to grow.
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.