An investigator studied the rate of aerobic respiration in the marine polychaete Nereis virens at different environmental temperatures using a flow-through respirometer system.
The investigator measured the rate of oxygen consumption (mm3 O2 g−1 h−1\text{mm}^3\ \text{O}_2\ \text{g}^{-1}\ \text{h}^{-1}mm3 O2 g−1 h−1) for polychaetes of different body masses at three constant temperatures: 12 ∘C12\ ^\circ\text{C}12 ∘C, 17 ∘C17\ ^\circ\text{C}17 ∘C, and 22 ∘C22\ ^\circ\text{C}22 ∘C.
The results are shown in the table below:
| Body mass (g\text{g}g) | Rate of oxygen consumption (mm3 O2 g−1 h−1\text{mm}^3\ \text{O}_2\ \text{g}^{-1}\ \text{h}^{-1}mm3 O2 g−1 h−1) at 12 ∘C12\ ^\circ\text{C}12 ∘C | Rate of oxygen consumption (mm3 O2 g−1 h−1\text{mm}^3\ \text{O}_2\ \text{g}^{-1}\ \text{h}^{-1}mm3 O2 g−1 h−1) at 17 ∘C17\ ^\circ\text{C}17 ∘C | Rate of oxygen consumption (mm3 O2 g−1 h−1\text{mm}^3\ \text{O}_2\ \text{g}^{-1}\ \text{h}^{-1}mm3 O2 g−1 h−1) at 22 ∘C22\ ^\circ\text{C}22 ∘C |
|---|---|---|---|
| 2.02.02.0 | 142142142 | 210210210 | 315315315 |
| 4.04.04.0 | 124124124 | 181181181 | 268268268 |
| 6.06.06.0 | 110110110 | 159159159 | 232232232 |
| 8.08.08.0 | 989898 | 141141141 | 204204204 |
Suggest how the investigator could ensure that the water temperature remains stable inside the respirometer chamber during the measurements.
Explain why maintaining a constant, continuous flow of water past the animals in the respirometer is essential for ensuring the validity of the respiration measurements.
Use the formula:
Q10=(R2R1)10T2−T1 Q_{10} = \left(\frac{R_2}{R_1}\right)^{\frac{10}{T_2 - T_1}} Q10=(R1R2)T2−T110To calculate the temperature coefficient (Q10Q_{10}Q10) for respiration in the smallest group of polychaetes (2.0 g2.0\text{ g}2.0 g) between 12 ∘C12\ ^\circ\text{C}12 ∘C and 22 ∘C22\ ^\circ\text{C}22 ∘C. Show your working and give your answer to 3 significant figures.
Based on the data, evaluate the claim that increasing the temperature from 12 ∘C12\ ^\circ\text{C}12 ∘C to 22 ∘C22\ ^\circ\text{C}22 ∘C has a greater relative effect on the metabolic rate of smaller polychaetes compared to larger polychaetes.
