Page 28 - Q & A STPM 2022 Biology

Biology STPM Chapter 7 Gaseous Exchange

Question 6
The graph below shows the oxygen dissociation curve for haemoglobin and
myoglobin. 100

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Percentage of saturation with oxygen (%) 50 x y

0
Partial pressure
5
10
15
20
of oxygen/ kPa
Semester
Which of the following statements concerning the graph above is correct? 2
A Curve x is for haemoglobin and curve y is for myoglobin.
B Curve x is for myoglobin and curve y is for haemoglobin.
C Curve y shows a higher pigment affinity for oxygen.
D Curve x shows a lower pigment affinity for oxygen.
Answer: B
Myoglobin has a higher affinity for oxygen compared to haemoglobin. This
would displace the curve to the left.

Question 7
The following reaction shows the affinity of haemoglobin towards oxygen in
an animal tissue in the conditions of P and Q.
P
Hb + O HbO
2 Q 2
Which of the following pairs of conditions P and Q are correct?
P Q
A High partial pressure of oxygen Low partial pressure of carbon
dioxide
B High partial pressure of oxygen High partial pressure of carbon
dioxide
C High temperature Low hydrogen ion concentration
D Low temperature Low hydrogen ion concentration

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Chapter 7.indd 153 11/2/21 9:27 AM