Calculate the Q10 (see introduction) for the change in heart rate between 0°C–10°C; 10°C–20°C and 20°C–30°C of Daphnia magna. Use the mean heart rate from all the Daphnia measured in the class at each temperature for your calculations.

Question 1 (10 marks)

1. Desert animals experience large daily variation in environmental temperature, with high temperatures during the day and low temperatures during the night. What effect do you expect a drop in temperature from 25°C to 0°C would have on the heart rate of an ectotherm (e.g. a lizard) compared with an endotherm (e.g. a fox)? Explain your reasoning.

Question 2 (10 marks) 2a. Calculate the Q10 (see introduction) for the change in heart rate between 0°C–10°C; 10°C–20°C and 20°C–30°C of Daphnia magna. Use the mean heart rate from all the Daphnia measured in the class at each temperature for your calculations. Clearly show your working.

2b. Between which temperatures did the smallest change in heart rate occur? Why?