Question 19M.3.SL.TZ2.b
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ2.b |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Compare and contrast | Question number | b | 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]
Compare and contrast the effect of increasing exercise intensity at sea level and at an altitude of 4000 m.
[2]
a. in both sea level and 4000m ventilation rate while exercising «at all intensities» is «significantly» more than at rest
OR
both sea level and 4000m show an increase in ventilation rate «dm3 min–1» as exercise intensity increased ✔
b. ventilation rate at 4000m «slightly» higher than at sea level for all conditions
OR
higher ventilation rate at 4000m not «significantly» different as error bars overlap ✔
Accept positive correlation.
In this question the candidates were asked to look at data on the effect of exercise and altitude on ventilation rate. Most candidates could state one other variable that should have been controlled in this study and could compare and contrast the effect of increasing exercise intensity in the two groups.
