Plants, unlike animals, can make their own food. They do this using a process called photosynthesis. The food that plants produce is important, not only for the plants themselves, but for the other organisms that feed on the plants. Getting optimum rates of photosynthesis produces maximum plant yields.
The word and symbol equations for photosynthesis are:
Photosynthesis requires energy in the form of light to drive the chemical reaction. Photosynthesis is an endothermic reaction.
The light energy required is absorbed by a green pigment called chlorophyll in the leaves. Chlorophyll is located in chloroplasts in plant cells, particularly the palisade and spongy mesophyll cells. Revise plant cells and their part in photosythesis here.
Plant leaves are the main photosynthetic organ, but any part of the plant exposed to the light will develop chlorophyll and photosynthesise.
Oxygen is formed as the waste product. Some is used for the plant's respiration, and also released, which makes it available for respiration to animals and many microorganisms. During the day, provided the rate of photosynthesis is sufficiently high, plant leaves and water plants give out oxygen.
Some of the glucose produced by photosynthesis is used for respiration.
Glucose is also the starting point for the biosynthesis of materials that plants need to live.
The glucose not used for respiration is used in the following ways:
There are four major uses of glucose produced in photosynthesis: