During high-altitude acclimatisation, the human body adapts to lower atmospheric oxygen levels by increasing red blood cell production. A sports scientist monitored a group of endurance runners who spent 25 days at an altitude of 3000 m.
The scientist took blood samples from the runners every 5 days to measure their haemoglobin concentration.
The table shows the average results.
| Time at high altitude (days) | Average (mean) haemoglobin concentration (g dl−1\text{g dl}^{-1}g dl−1) |
|---|---|
| 0 | 12.1 |
| 5 | 12.8 |
| 10 | 13.6 |
| 15 | 14.3 |
| 20 | 14.8 |
| 25 | 15.0 |
Describe how to plot a line graph to show the relationship between time and average haemoglobin concentration, specifying which variable goes on each axis.
Name the dependent variable in this investigation.
Explain how the scientists made sure their results were reliable.
Name two biotic (living) factors of the endurance runners that the scientists should have controlled so their results would be valid.
Runners often report a significant improvement in their aerobic endurance and reduced muscle fatigue after high-altitude training. Explain how the physiological changes shown in the table help to improve performance.
The scientists obtained blood samples using a needle attached to a syringe. Explain which type of blood vessel they should use to obtain the blood samples.
