IGCSE Biology Gas exchange & respiration topical questions

Name each part of the breathing system described.

1. (a)The windpipe, held open by rings of cartilage.[1]
2. (b)The two tubes branching from the windpipe, one to each lung.[1]
3. (c)The tiny air sacs where gas exchange happens.[1]
4. (d)The sheet of muscle below the lungs.[1]

Complete the table comparing inspired and expired air.

1. (a)Complete the oxygen row and the carbon dioxide row.[2]
2. (b)Name the test and its positive result for carbon dioxide.[1]
3. (c)State which gas water vapour is higher in, and why.[1]

Write the word equation for each reaction.

1. (a)Aerobic respiration in a liver cell.[1]
2. (b)Anaerobic respiration in yeast.[1]
3. (c)Anaerobic respiration in a muscle during vigorous exercise.[1]

Air travels from the nose to the alveoli through several structures.

1. (a)Name the tube that carries air down the neck, and its two branches into the lungs.[2]
2. (b)State the function of the cartilage rings in the wall named in (a).[1]
3. (c)Name the cells that sweep mucus upwards in the airways.[1]
4. (d)Name the structures where gas exchange takes place.[1]

A student investigates whether exercise changes breathing.

1. (a)Describe how she could measure her breathing rate and depth before and after exercise.[2]
2. (b)State the expected results.[1]
3. (c)Explain the increase in breathing rate and depth. (Extended)[2]

Describe and explain the mechanism of exhalation. (Extended)

1. (a)Describe what the diaphragm and intercostal muscles do when you breathe out.[2]
2. (b)Explain how these movements push air out of the lungs.[2]
3. (c)Name the muscles used in a forced exhalation that are relaxed during quiet exhalation.[1]

A yeast and glucose mixture is held at different temperatures with the gas bubbling through limewater.

1. (a)Name the gas produced and the positive limewater result.[2]
2. (b)Describe how the rate of bubbling changes between 10 °C and 40 °C, and between 40 °C and 60 °C.[1]
3. (c)Explain both parts of the pattern.[2]

A student’s breathing rate was measured before, during and after three minutes of skipping.

1. (a)Calculate the percentage increase in breathing rate from rest to the end of skipping. Show your working.[2]
2. (b)Describe what happens to breathing rate after the exercise stops.[1]
3. (c)Explain why breathing rate rises during exercise.[2]

Compare inspired and expired air, and explain the differences. (Supplement)

1. (a)State the approximate percentages of oxygen and of carbon dioxide in inspired and in expired air.[2]
2. (b)Explain why the oxygen percentage falls.[1]
3. (c)Explain why the carbon dioxide percentage rises.[1]
4. (d)Explain why expired air contains more water vapour and is warmer.[2]

Yeast is mixed with glucose solution in a flask. A layer of oil is poured on top of the mixture, and a tube leads from the flask to a beaker of limewater.

1. (a)Name the gas that bubbles into the limewater, and state the result of the test.[2]
2. (b)Why is the layer of oil added?[1]
3. (c)Write the word equation for the respiration happening in the flask.[1]
4. (d)The flask feels slightly warm. Explain why.[1]
5. (e)The experiment is repeated at 60 °C instead of 30 °C. Predict the result and explain.[1]

Explain how the alveoli are adapted for efficient gas exchange. (Extended)

1. (a)Describe three structural features of the alveoli and link each to faster exchange.[3]
2. (b)Explain why oxygen moves from the alveolus into the blood.[2]
3. (c)Name the process by which both gases cross the alveolar wall.[1]

A sprinter finishes a 400 m race breathing very fast with a high pulse rate. Her legs ache. (Extended)

1. (a)Name the type of respiration her leg muscles used during the sprint and write its word equation.[2]
2. (b)Explain why this respiration released much less energy than aerobic respiration.[1]
3. (c)Explain why her breathing and pulse remained high after the race.[4]

After a race, a runner’s oxygen consumption stays high: at rest she uses 0.25 dm³ per minute; during the first 3 minutes of recovery she uses 2.0 dm³ per minute. (Supplement)

1. (a)Calculate the extra oxygen used above resting level during the 3-minute recovery. Show your working.[2]
2. (b)Explain why oxygen consumption stays high after exercise stops.[2]
3. (c)Name the organ that removes lactic acid from the blood.[1]
4. (d)Write the word equation for the removal of lactic acid.[1]
5. (e)State why her heart rate also remains high during recovery.[1]

Explain fully how movements of the diaphragm, ribs and intercostal muscles bring air into and out of the lungs. (Supplement)

1. (a)Explain the mechanism of inhalation.[3]
2. (b)Explain the mechanism of exhalation.[3]