11. Gas exchange in humans
A section of Biology, 0610
Listing 10 of 291 questions
For Examiner's Use shows the human head, neck and thorax. A B C D K J H G F E Complete Table 1.1 by writing one letter from to identify the named structures. The first one has been done for you. Table 1.1 structure letter from left lung D bronchus diaphragm intercostal muscle rib trachea For Examiner's Use In an investigation, a student breathed in and out of the apparatus shown in . 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. atmospheric air valve X valve Y bag for collection of breathed out air breathed out air air breathed out 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. Table 1.2 sample of breathed out air before exercise after exercise total volume of air collected in bag / cm3 2 000 15 000 mean volume of air per breath / cm3 percentage of oxygen / % 17.2 15.3 percentage of carbon dioxide / % 3.6 5.5 percentage of nitrogen / % 74.9 74.7 For Examiner's Use Calculate the mean volume of air per breath after exercise. Write your answer in Table 1.2. Show your working. Suggest one way, not shown in Table 1.2, in which the student’s breathing changed after exercise. 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. 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.
0610_s13_qp_31
THEORY
2013
Paper 3, Variant 1
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291