Aims of this Episode:

  • Describe the process of Photosynthesis;
  • Describe the function of Glucose within a plant;
  • Explain how Active Transport is used in Photosynthesis;
  • Describe the different cells within a leaf.
The back garden of Buckingham Palace.

What is Photosynthesis?

Photosynthesis is the process whereby a plant turns the energy from the sun into a usable form – glucose. In order to do this the plant needs Carbon Dioxide and water as well as the sun light. As Photosynthesis takes place Oxygen is generated as a waste product.

Light, Carbon Dioxide and water are in limited supply in some areas, so there is an element of competition. You can see this in the picture below – small plants don’t grow too close to the larger trees as the sun light is limited and the larger trees have a larger root system to get the water out of the soil.

The Glucose that is created during Photosynthesis is stored in the plant as starch. This is because starch does not dissolve in water, so it cannot be lost through evaporation.

Active Transport

Some of the Glucose is combined with Nitrates from the soil to form Proteins. These Nitrates are pulled into the plant by Active Transport.

What’s the job of the leaf?

The leaves on a plant are responsible for gathering the sun light and the Carbon Dioxide. The Carbon Dioxide enters the base of the leaf, through small holes called Stomata. The opening and closing of these holes is controlled by the Guard Cells. The waste product of Photosynthesis, Oxygen, also comes out through the Stomata.

At the top of the lead are cells that contain a large amount of Chloroplasts – small packets of Chlorophyll, the light absorbing pigment that looks green in colour.

S@S 017: GCSE Photosynthesis
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