GCSE biology unit 3

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Active Transport

Substances being absorbed against the concentration gradient (low --> high) requires energy from respiration.

Villi in the small intestine

Adaptations: - large surface area, lots of capillaries. Absorb the products of digestion by diffusion and active transport.


Adaptations: - large surface area, moist, good blood supply. They are air sacs in the lungs, they have a thin cell wall so diffusion of carbon dioxide and oxygen takes place easily.

The leaf

Adaptations: - have lots of surface area, flat and chlorophlly (chloroplasts). They have stomata to let carbon dioxide in and oxygen out. This also leads to loss of water vapour which is called transpiration. The stomata are protected by guard cells which controls the rate of photosynthesis, with the amount of oxygen out and carbon dioxide in.

Circulation system

The bodies transport system, carrying the blood from the heart to all the other cells in the body. This provides them with food and blood. This blood is oxygenated blood and takes away the waste products in the deoxygenated blood.

Blood vessels

Blood is taken away from the heart by the arteries.

Blood returns back to the heart by the veins.

Blood is taken around the organs by the capillaries.

The heart has a double pump the left side pumps to your whole body, but the right side only goes


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