The table shows the mass and the oxygen used per gram of body mass per hour for five birds.
| Bird | Body mass / g | Oxygen used / cm³ g⁻¹ h⁻¹ |
|---|---|---|
| Hummingbird | 4 | 12.0 |
| Wren | 10 | 8.0 |
| Robin | 20 | 5.0 |
| Pigeon | 400 | 2.0 |
| Goose | 4000 | 0.8 |
State what is meant by metabolic rate.
[1]
Describe the relationship between body mass and oxygen used per gram, using data from the table.
[2]
Explain this relationship in terms of surface area to volume ratio.
[3]
Suggest why oxygen use is measured per gram of body mass rather than as a total.
[1]