Question 19M.3.SL.TZ2.3c
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ2.3c |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Outline | Question number | c | Adapted from | N/A |
A study was conducted on 25 healthy, non-smoking males to look at the effect of exercise and altitude on ventilation rate. Subjects were first asked to rest in a sitting position for six minutes. They then pedalled for three periods of six minutes at increasing exercise intensity: at 20 %, 30 % and 40 % of their maximal aerobic power. The entire study was conducted either in normal sea level oxygen conditions or in lower oxygen conditions simulating an altitude of 4000 m. The results are shown in the bar chart.
[Source: E Hermand, et al., (2015), Periodic breathing in healthy humans at exercise in hypoxia,
Journal of Applied Physiology, 118, pages 115–123. https://doi.org/10.1152/japplphysiol.00832.2014]
Outline how ventilation rate could have been monitored in this study.
[2]
a. «data logging» with spirometer
OR
chest belt ✔
b. «tidal» volume recorded for a given period of time
OR
average «tidal» volume found and multiplied by number breaths per minute ✔
Do not accept confusion with respirometer (measuring oxygen consumption or CO2 release).
Must include a reference to time.
Question (c) was poorly answered. Many candidates thought a respirometer would be used to measure ventilation rate while other candidates gave a description of how to measure the number of breaths per minute. This was considered inadequate as the Y axis of the graph indicated that ventilation rate was volume per minute, so reference to volume and time were required in the response.
