Page 39 - Q & A STPM 2022 Biology

Biology STPM Chapter 7 Gaseous Exchange
7.2 Breathing Cycle

Section A Multiple-choice Questions

Penerbitan Pelangi Sdn Bhd. All Rights Reserved.
Question 1
During breathing movements of a human, which of the following causes a
change from inspiration to expiration?
A The arrival of deoxygenated blood in the lungs.
B The stimulation of stretch receptors of the inflated alveoli.
C A low partial pressure of CO detected by the chemoreceptors of the
2
carotid bodies and aortic bodies.
D A high pH of the arterial blood.

Answer: B
During inspiration, as the lungs expand, stretch receptors on the wall of the
Semester
2 alveoli and bronchioles are stimulated. Nerve impulses are sent via vagus nerve
to expiratory centre in the medulla. This causes a change from inspiration to
expiration.

Question 2

The increase in concentration of carbon dioxide is detected by the
chemoreceptors located in the
A intercostal muscles
B carotid and aortic bodies
C diaphragm
D bronchiole tubes

Answer: B
The peripheral chemoreceptors are located in the carotid and aortic bodies,
which are sensitive to high CO concentration and low arterial blood pH.
2

Question 3
Which of the following factors is the most effective in increasing the breathing
rate in a mammal?
A A lack of oxygen in the tissues.
B A lack of oxygen in the blood.
C An excess of carbon dioxide in the lungs.
D An excess of carbon dioxide in the blood.

164

Chapter 7.indd 164 11/2/21 9:27 AM