Question
(a) Fig. 1.1 shows the human head, neck and thorax.
Complete Table 1.1 by writing one letter from Fig. 1.1 to identify the named structures.
The first one has been done for you.
(b) In an investigation, a student breathed in and out of the apparatus shown in Fig. 1.2.
Valve X opens to allow atmospheric air in while valve Y is closed.
When the student breathes out, valve X is closed and valve Y opens to allow breathed
out air into the bag.
The student breathed in and out four times. The bag was sealed and the volume of air
inside the bag was measured.
A sample of air from the bag was analysed for the percentage composition of oxygen,
carbon dioxide and nitrogen.
The student then did some vigorous exercise for five minutes. After the exercise, the
student repeated the procedure.
The results of the investigation are shown in Table 1.2.
(i) Calculate the mean volume of air per breath after exercise.
Write your answer in Table 1.2.
Show your working.
[1]
(ii) Suggest one way, not shown in Table 1.2, in which the student’s breathing
changed after exercise.
(iii) The figures in Table 1.2 for the percentage composition of air in each sample do
not add up to 100 %.
Name one other gas that would be present in both samples of air.
(iv) The results for oxygen and carbon dioxide in the samples of breathed out air taken
before and after exercise are different.
Describe and explain these differences.
Answer/Explanation
Ans:
Question
The ribcage and diaphragm are involved in the breathing mechanism to ventilate the lungs.
Fig. 3.1 is a flow chart that shows the changes that take place when breathing in.
(a) Complete Fig. 3.1 by writing appropriate words in the spaces provided. [6]
(b) Fig. 3.2 shows part of the epithelium that lines the trachea.
Explain how the cells labelled A and B in Fig. 3.2 protect the gas exchange system.
Answer/Explanation
Ans:
