Human Gas Exchange
100 questions· page 1 of 10
The percentages of each of the gases in inspired and expired air are measured when a student is resting and when a student is exercising.
The results are shown.
| gas | percentage in inspired air | percentage in expired air when resting | percentage in expired air when exercising |
|---|---|---|---|
| nitrogen | 78 | 78 | 78 |
| oxygen | 21 | 16 | 14.5 |
| carbon dioxide | 0.04 | 5.04 | 6.54 |
From the data, which statement is not correct?
Options
A The difference between the percentages of carbon dioxide in expired air when exercising and in expired air when resting is 1.5.
B When resting, the difference between the percentage of oxygen in inspired and expired air is due to oxygen being used by respiration in the body.
C Inspired air contains 52.5 times more oxygen than carbon dioxide.
D The percentage of oxygen taken from inspired air is the same as the percentage of carbon dioxide added to expired air when exercising.
Which sets of muscles contract to cause the body to breathe in?
Options
A diaphragm and external intercostal muscles
B diaphragm and internal intercostal muscles
C diaphragm muscles only
D external and internal intercostal muscles
Four people do exactly the same physical exercise.
The graph shows their breathing rate in breaths per minute before, during and after the exercise.
One person is a professional athlete.
Which line shows the results for the professional athlete?
Options
A A
B B
C C
D D
Villi and alveoli have certain common features.
What is not a feature of villi and alveoli?
Options
A a rich capillary network
B a single-celled layer of epithelium
C lacteals connected to the lymphatic system
D a very large total surface area
Which cells in the gas exchange system produce mucus?
Options
A ciliated cells
B goblet cells
C lymphocyte cells
D red blood cells
The diagram shows an alveolus and a blood capillary.
Which row identifies the letters P, Q and R?
Options
| P | Q | R | |
|---|---|---|---|
| A | carbon dioxide | oxygen | red blood cell |
| B | carbon dioxide | oxygen | white blood cell |
| C | oxygen | carbon dioxide | red blood cell |
| D | oxygen | carbon dioxide | white blood cell |
The table shows the changes that occur in the thorax during breathing.
Which changes occur during inspiration?
Options
| diaphragm | external intercostal muscles | internal intercostal muscles | pressure in thorax | |
|---|---|---|---|---|
| A | contracts | contract | relax | falls and then rises |
| B | relaxes | relax | contract | rises and then falls |
| C | relaxes | contract | relax | rises and then falls |
| D | contracts | relax | contract | falls and then rises |
When the volume of the thorax increases, the pressure in the thorax is lowered. This results in air being taken into the body.
How is the volume of the thorax increased so that air is breathed in?
Options
A by the diaphragm and the external intercostal muscles contracting
B by the diaphragm relaxing and the external intercostal muscles contracting
C by the diaphragm and the internal intercostal muscles contracting
D by the diaphragm relaxing and the internal intercostal muscles contracting
Some students were each given the apparatus shown.
They placed the mouthpieces in their mouths and then gently breathed in and out through the apparatus ten times.
Which statement describes what happened when they breathed in and out?
Options
A When they breathed in, air from the room bubbled through test-tube U and the limewater became cloudy in test-tube U.
B When they breathed out, air from their lungs bubbled through test-tube T and the limewater became cloudy in test-tube T.
C When they breathed in, air from the room bubbled through test-tube T and the limewater remained clear in test-tube T.
D When they breathed out, air from their lungs bubbled through test-tube U and the limewater remained clear in test-tube U.
The graph shows the changes in lung volume during breathing when a person was at rest and then when they began to exercise.
From resting to exercise, the volume of air breathed in at each breath increased from ......x...... to ......y...... .
Looking at the graph, which numbers correctly complete the gaps in the sentence?
Options
| x | y | |
|---|---|---|
| A | 0.5 | 3.0 |
| B | 0.5 | 5.0 |
| C | 2.0 | 5.0 |
| D | 2.0 | 5.0 |