exchange and transport in animals sample exam questions and answers

Question 1

Where does gas exchange take place in the lungs? [1 mark]

Answer 1

Alveolus

Question 2

Oxygen is involved with aerobic respiration in cells.

What is the equation for aerobic respiration?

Answer 2

glucose + oxygen → carbon dioxide + water

Question 3

A person had emphysema. This reduces the number of alveoli in the lungs.

Explain how emphysema would affect the amount of oxygen carried in the bloodstream. [2 marks]

Answer 3

• emphysema will reduce the amount of oxygen carried into the bloodstream
• because there is reduced alveoli, which are the gas exchange surface between the lungs and blood capillaries

Question 4

Give one reason why it is important that human lungs have a high surface area to volume ratio. [1 mark]

Answer 4

To maximise gas exchange/maximise oxygen uptake

Question 5

Give one reason why the wall of the left ventricle of the heart is thicker than the right. [1 mark]

Answer 5

To pump blood around the body under higher pressure

Question 6

Valves in the human heart may become damaged and no longer function.

Describe what would happen to the flow of blood in the left side of the heart if the valve between the left atrium and ventricle did not function effectively. [2 marks]

Answer 6

• blood would flow backwards from the ventricle to the atrium/blood will leak through
• less (oxygenated) blood would be pumped to the body

Question 7

Calculate the rate of oxygen consumption per second for the results in respirometer A. [2 marks]

Answer 7

2.4 ÷ (30 × 60)

= 0.0013 ml/second

Or 1.6 ÷ (20 × 60) = 0.0013 ml/second

Or 0.8 ÷ (10 × 60) = 0.0013 ml/second

Question 8

Describe how the circulatory system transports substances around the body. [6 marks]

Answer 8

• the heart/ventricle pumps blood
• blood passes through blood vessels/arteries/veins/capillaries
• the blood travels to the lungs and then to the rest of the body
• arteries transport blood away from the heart
• veins transport blood to the heart
• valves prevent backflow
• capillaries exchange materials with tissues/cells
• red blood cells carry oxygen
• plasma transports nutrients/waste/hormones

Question 9

A reduced cardiac output would affect the performance of an athlete.

Explain the effects that a reduced cardiac output would have on the muscle cells of an athlete. [6 marks]

Answer 9

• there will less blood flow (to the muscles)
• less blood leaves the heart
• less oxygen reaches muscle
• less glucose reaches muscle
• reduced rate of aerobic respiration
• less energy released
• less carbon dioxide removed
• greater rate of anaerobic respiration
• glucose broken down without oxygen
• reduced muscle contraction
• build up of lactic acid in muscle cells

-lactic acid causes cramp/fatigue

Question 10

Describe how digested food molecules move from the small intestine to the heart. [2 marks]

Answer 10

A description linking two of the following things:

• food molecules are absorbed/diffuse
• into blood/plasma
• into capillaries
• in veins (to the heart)

Question 11

Yeast use both aerobic and anaerobic respiration to release energy.

Which organelle in the yeast cell is the site of aerobic respiration? [1 mark]

Answer 11

mitochondrion/mitochondria

Question 12

Yeast use both aerobic and anaerobic respiration to release energy.

The word equation for anaerobic respiration in yeast is:

glucose → alcohol + carbon dioxide

Describe how aerobic respiration is different from anaerobic respiration in yeast. [2 marks]

Answer 12

A description including any two from the following:

Aerobic respiration:

• uses oxygen
• produces water
• releases more energy
• does not produce/release alcohol
• anaerobic respiration occurs in the cytoplasm