CIE iGCSE Co-Ordinated Science B11. Gas exchange in humans Exam Style Questions Paper 1
Question
Which diagram correctly shows the diffusion of carbon dioxide and oxygen between an alveolus and a capillary?
▶️Answer/Explanation
Answer: C
Explanation: Diagram C correctly shows the diffusion of oxygen from the alveolus into the capillary and carbon dioxide from the capillary into the alveolus. This is because oxygen moves from an area of high concentration (alveolus) to an area of low concentration (capillary), and carbon dioxide moves in the opposite direction.
Question
A child blows into a rubber balloon. What is the percentage of oxygen inside the balloon?
A. 0%
B. 4%
C. 16%
D. 21%
▶️Answer/Explanation
Answer: C
Explanation: When a child blows into a balloon, the air inside is exhaled air, which contains about 16% oxygen, as some oxygen is absorbed by the body during respiration.
Question
The graph shows the volume of air in the lungs at rest and during exercise.
What was the effect of exercise on the rate and depth of breathing?
| Rate of breathing | Depth of breathing |
|---|---|
| A. decrease | decrease |
| B. decrease | increase |
| C. increase | decrease |
| D. increase | increase |
▶️Answer/Explanation
Answer: D. increase (rate of breathing) and increase (depth of breathing)
Explanation: During exercise, the body requires more oxygen, so both the rate and depth of breathing increase to meet this demand.
Question
The diagram shows the main structures in the breathing system of humans.
Which row identifies the larynx, bronchus, trachea and bronchioles?
▶️Answer/Explanation
Ans 😀
Question
When a person exercises for 10 minutes, what is the effect on the depth and rate of their
breathing?
▶️Answer/Explanation
Ans :A
Question
In the diagram of the human breathing system, which structures are correctly labelled?
(A) alveoli and bronchiole
(B) alveoli and trachea
(C) bronchus and bronchiole
(D) bronchus and trachea
▶️Answer/Explanation
Ans : B
Question
What is the expected concentration of oxygen and the water vapour content in expired air?
▶️Answer/Explanation
Ans: A
Question
By which process does oxygen pass from the alveoli to the blood capillaries in the lungs?
(A) diffusion
(B) osmosis
(C) secretion
(D) transpiration
▶️Answer/Explanation
Ans:- A
Question
A person inflates a balloon by breathing into it.
What is the composition of the air in the balloon?
▶️Answer/Explanation
Ans: C
Question
Which statement about the composition of expired air, compared with inspired air, is correct?
(A) The percentage of carbon dioxide is decreased and the percentage of water vapour is increased.
(B) The percentage of carbon dioxide is increased and the percentage of water vapour is increased.
(C) The percentage of oxygen is decreased and the percentage of carbon dioxide is decreased.
(D) The percentage of oxygen is increased and the percentage of carbon dioxide is decreased.
▶️Answer/Explanation
Ans: B
Question
When a person was walking or running, the following measurements were taken:
| Speed (km/h) | Number of breaths per minute | Volume of each breath (dm³) |
|---|---|---|
| 4 | 16 | 1 |
| 6 | 18 | 2 |
| 8 | 20 | 3 |
How many dm³ of air did the person breathe per minute when running at 6 km per hour?
A. 18
B. 36
C. 60
D. 108
▶️Answer/Explanation
Answer: B
Explanation: To calculate the total volume of air breathed per minute, multiply the number of breaths per minute by the volume of each breath. At 6 km/h, the person takes 18 breaths per minute, and each breath is 2 dm³. Therefore, the total volume is 18 × 2 = 36 dm³.
Question
A student breathed gently in and out of the mouthpiece of the apparatus shown.
What were the results after 10 breaths?
▶️Answer/Explanation
Answer: B. P clear, Q milky
Explanation: The apparatus likely contains limewater, which turns milky in the presence of carbon dioxide. As the student exhales, carbon dioxide is released, causing the limewater in Q to turn milky, while P remains clear as it contains inhaled air with less carbon dioxide.
Question
As a molecule of carbon dioxide is removed from the body, in which order does it pass through these structures?
A. pulmonary artery → capillary → alveolus → bronchiole
B. pulmonary artery → capillary → bronchiole → alveolus
C. pulmonary vein → capillary → alveolus → bronchiole
D. pulmonary vein → capillary → bronchiole → alveolus
▶️Answer/Explanation
Answer: A. pulmonary artery → capillary → alveolus → bronchiole
Explanation: Carbon dioxide is carried in the blood to the lungs via the pulmonary artery. It diffuses from the capillaries into the alveoli and is then exhaled through the bronchioles.
Question
Limewater can be used to test for differences in composition between inspired and expired air.
Which row is correct?
| Type of Air | Appearance of Limewater | Conclusion |
|---|---|---|
| A. expired | clear to milky | more carbon dioxide present |
| B. expired | milky to clear | more carbon dioxide present |
| C. inspired | clear to milky | more oxygen present |
| D. inspired | milky to clear | more oxygen present |
▶️Answer/Explanation
Answer: A
Explanation: Expired air contains more carbon dioxide than inspired air. When limewater is exposed to expired air, it turns from clear to milky due to the formation of calcium carbonate, indicating the presence of carbon dioxide.