Page 25 - Q & A STPM 2022 Biology

Chapter

Biology STPM Chapter 7 Gaseous Exchange
7 Gaseous Exchange

Penerbitan Pelangi Sdn Bhd. All Rights Reserved.
7.1 Gaseous Exchange in Humans

Section A Multiple-choice Questions

Question 1
The reversible dissociation reaction of oxyhaemoglobin during cellular
respiration is represented by the following equation:
Hb (O )  Hb + 4O 2
2 4
Oxyhaemoglobin Haemoglobin Oxygen
What will happen to the above reaction if the carbon dioxide concentration
Semester
2 in blood increases?
A The reaction shifts to the right
B The reaction shifts to the left
C Carboxyhaemoglobin complex is formed
D Oxyhaemoglobin – CO2 complex is formed

Answer: A
The main function of haemoglobin is to carry oxygen. An increase in partial
pressure of carbon dioxide or a decrease will lower the affinity of haemoglobin
for oxygen. This helps in the unloading of oxygen from oxyhaemoglobin in the
cappilaries of respiring tissues.

Question 2

Which of these statements is about Bohr effect?
A The regulating of constant pH is blood
B The haemoglobin affinity towards carbon dioxide
C The influence of carbon dioxide concentration on the dissociation of
oxyhaemoglobin
D The increase in dissociation rate of carbon dioxide due to the high partial
pressure of oxygen

Answer: C
Bohr effect is the decrease in the oxygen affinity of haemoglobin in response
to decreased blood pH due to increased carbon dioxide concentration in the
blood.

150

Chapter 7.indd 150 11/2/21 9:27 AM