Table 1 shows readings made by a student using a peak-flow meter during an experiment on breathing. The student made three attempts before exercise and thre...
Question 1 Report
Table 1 shows readings made by a student using a peak-flow meter during an experiment on breathing. The student made three attempts before exercise and three attempts immediately after climbing stairs. Fig. 1 shows the mouthpiece of the apparatus used to measure the rate at which air can be forced from the lungs.
| Condition | Peak flow reading / dm3 min-1 |
|---|---|
| Before exercise, attempt 1 | 420 |
| Before exercise, attempt 2 | 440 |
| Before exercise, attempt 3 | 430 |
| After exercise, attempt 1 | 485 |
| After exercise, attempt 2 | 500 |
| After exercise, attempt 3 | 495 |
(a) Calculate the mean peak flow reading before exercise. Show your working. [2]
(b) Describe the change in the peak flow readings after exercise. [2]
(c) Explain why the student should use a clean mouthpiece for each person. [2]
Answer Details
(a)
\[420+440+430=1290\]
\[1290\div3=430\text{ dm}^3\text{ min}^{-1}\]
The mean peak flow before exercise is 430 dm3 min-1 [2].
(b) All readings are higher after exercise [1]. The mean rises from 430 to approximately 493 dm3 min-1, an increase of about 60 to 65 dm3 min-1 [1].
(c) A clean mouthpiece prevents transfer of microorganisms and disease between people [1]. It is also hygienic and gives a fair comparison because one person's contamination cannot affect another person's test [1].
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