Final answer:
The respiration rate of a small mouse would likely be higher than that of a small lizard at 10°C because mice are endothermic with consistently high metabolic rates regardless of ambient temperature, while lizards are ectothermic and slow down their metabolism in the cold.
Step-by-step explanation:
At a temperature of 10°C, the rate of respiration for a small lizard and a small mouse would differ due to their differing thermoregulatory mechanisms. Lizards, being ectothermic animals, rely heavily on the ambient temperature to regulate their body temperature, which means their metabolic rate and, consequently, their respiration rate would be slower in cold conditions. On the other hand, mice are endothermic, maintaining a constant body temperature through internal metabolic processes, resulting in a comparatively higher rate of respiration even at low temperatures.
When measuring respiration with a respirometer, the volume of oxygen consumed is typically recorded. To ensure accuracy, since respiration also produces carbon dioxide, a substance such as soda lime should be added to absorb the CO2. This keeps the volume measurements reflective of oxygen consumption alone. The readings might illustrate that even at a cold temperature of 10°C, the mouse, with its higher metabolic rate, would show a greater volume of O2 consumption per gram of body weight than the lizard, which would slow down its metabolism significantly in response to the cold.