Exchange And Transport

Question 1

Why do single celled organism use diffusion?

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Answer 1

Thin cell surface membrane, short diffusion distance
Large SA:V ratio
Respire at lower rate

Question 2

Why can’t multicellular organisms use diffusion?

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Answer 2

Small SA:V ratio
High metabolic rate
Cells deep within body, large diffusion distance
Diffusion is too slow across membrane

Question 3

3 features of exchange surfaces?

Answer 3

Large SA

Very thin

Good blood supply / ventilation

Question 4

Inspiration features 
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Answer 4

External intercostal muscle and diaphragm contracts

Rib cage moves upwards and outwards

Volume of thorax increases

Pressure in lungs decrease

Question 5

Expiration features 
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Answer 5

External intercostal muscle and diaphragm relax

Rib cage moves downwards and inwards

Thorax volume decreases

Lung pressure increases

Question 6

Define vital capacity

Answer 6

Max volume breathed in or out

Question 7

Define tidal volume

Answer 7

Volume of air in each breath

Question 8

How does air enter insects?

Answer 8

Through spiracles in trachea