b3 -2

Question	Answer
Many organ systems are specialised for exchanging materials. The effectiveness of an exchange surface is increased by......	■ having a large surface area ■ being thin, to provide a short diffusion path ■ (in animals) having an efficient blood supply ■ (in animals, for gaseous exchange) being ventilated.
What can effect the ability of organisms to exchange materials?	The size and complexity of an organism increases the difficulty of exchanging materials.
state 2 ways the humans are adapted to exchanging materials	■ the surface area of the lungs is increased by the alveoli ■ the surface area of the small intestine is increased by villi.
Describe how the villi aid absorption	The villi provide a large surface area with an extensive network of capillaries to absorb the products of digestion by diffusion and active transport.
State the function of the breathing system	The breathing system takes air into and out of the body so that oxygen from the air can diffuse into the bloodstream and carbon dioxide can diffuse out of the bloodstream into the air.
Describe the process of ventilation ?	To make air move into the lungs the ribcage moves out and up and the diaphragm becomes flatter. These changes are reversed to make air move out of the lungs. The movement of air into and out of the lungs is known as ventilation.

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	Created by david doran almost 8 years ago