Answer
a.
Work Step by Step
Endotherms have higher metabolic rates than ectotherms. In endotherms, body temperature is kept constant whereas in ectotherms, body temperature fluctuates according to the temperature of their environment. To maintain a constant internal body temperature, an endotherm such as a mouse has to use about thirty times more energy than an ectotherm such as a lizard that has the same body weight. To increase their body temperatures, ectotherms must move themselves to a warmer area rather than raising their metabolic rates.
