1
1 mark
1 markWhat makes the alveoli suitable as a gas exchange surface in mammals?
| a dense capillary network | large total surface area |
A | X | X |
B | ✔ | X |
C | X | ✔ |
D | ✔ | ✔ |
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Gas Exchange in Humans (Cambridge (CIE) IGCSE Biology)
Exam Questions
3 hours28 questions21 mark
1 markWhich of the following sequences show the correct path of oxygen as it enters the lungs?
trachea → bronchiole → bronchus → alveolus
trachea → bronchus → bronchiole → alveolus
alveolus → bronchus → bronchiole → trachea
alveolus → bronchiole → bronchus → trachea
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31 mark
1 markWhat is the approximate percentage of carbon dioxide in expired air?
16 %
0.04 %
4 %
21 %
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41 mark
1 markExtended
The image below shows some cells found in the trachea.
What is the function of the part labelled K?
Increasing surface area
Gas exchange
Moving mucus
Trapping bacteria
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51 mark
1 markName the structures shown in the diagram.
| W | X | Y | Z |
A | larynx | trachea | bronchi | bronchioles |
B | trachea | larynx | bronchioles | bronchi |
C | bronchi | trachea | bronchioles | larynx |
D | larynx | bronchi | larynx | bronchioles |
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11 mark
1 markThe diagram below shows a cross-section through an alveolus and a capillary.
Why does oxygen move from P to Q?
The concentration of carbon dioxide is lower in the alveolus than in the blood.
The concentration of oxygen in the blood is lower than in the air in the capillary.
Oxygen must replace carbon dioxide.
The concentration of oxygen in the blood is lower than the air in the alveolus.
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21 mark
1 markSome amphibians, such as frogs, can use their skin as a gas exchange surface.
What are the most likely characteristics of the surface of the skin in these amphibians?
| surface area | type of skin |
A | small | thick |
B | large | thick |
C | small | thin |
D | large | thin |
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31 mark
1 markExtended
When the diaphragm relaxes and internal intercostal muscles contract, how does the volume and pressure inside the thorax change?
| pressure | volume |
A | decreases | decreases |
B | decreases | increases |
C | increases | decreases |
D | increases | increases |
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41 mark
1 markCompared to the composition of atmospheric air, the air exhaled by a man contains:
more water vapour, more carbon dioxide.
more water vapour, less carbon dioxide.
less water vapour, more carbon dioxide.
less water vapour, less carbon dioxide.
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51 mark
1 markExtended
The diagram shows the composition of four samples of air (O2 = oxygen, CO2 = carbon dioxide, N2 = nitrogen).
Which sample is inspired air and which sample is expired air?
| inspired air | expired air |
A | R | S |
B | P | R |
C | Q | P |
D | S | R |
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11 mark
1 markExtended
Which of the following correctly describes the actions of the intercostal muscles and the diaphragm when we breathe in?
| external intercostal muscles | internal intercostal muscles | diaphragm |
A | contract | relax | domed |
B | contract | relax | flat |
C | relax | contract | domed |
D | relax | contract | flat |
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21 mark
1 markThe diagram shows part of the structure of a human lung.
Where would the concentration of carbon dioxide be highest?
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31 mark
1 markExtended
The diagram below illustrates the changes in air pressure taking place inside the lungs during a complete cycle of breathing. Atmospheric pressure is 101 kPa.
At which point on the diagram does the process of inhalation start?
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41 mark
1 markExtended
A person exhales, and the air from their lungs is collected and placed in a gas jar. A second gas jar contains normal atmospheric air. A candle is set alight and is placed inside each gas jar as shown. The time taken for each flame to go out is measured with a stopwatch.
The table shows the results of this experiment.
gas jar | time for candle flame to go out /s |
1 | 7 |
2 | 12 |
Which of the following is a correct explanation for the difference between the results in jars 1 and 2?
Jar 1 contains atmospheric air which has less oxygen than exhaled air.
Jar 1 contains exhaled air which has less oxygen compared to atmospheric air.
Jar 2 contains atmospheric air which has more carbon dioxide than exhaled air.
Jar 2 contains exhaled air which has more carbon dioxide than oxygen in it.
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51 mark
1 markWhich of the following helps carbon dioxide to be excreted rapidly into the alveoli from the blood in the lungs?
Inhaled air has a lower concentration of carbon dioxide than the blood constantly pumping through the lungs.
Alveoli have thick walls and a large surface area.
Alveoli have thin walls and a large surface area.
The concentration of carbon dioxide in the blood is lower than in the alveoli.
1, 2 & 4 only
3 only
1 & 3 only
3 & 4 only
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61 mark
1 markExtended
The graph shows changes in the volume of air in the lungs of a person at rest, over a period of 30 seconds.
Which graph below shows the changes in the volume of air in the lungs for the same person immediately after they have done a few minutes of vigorous exercise?
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