Q40.4-5ITD. - Campbell Biology

Question

Which animal expends the most kilocalories per year on thermoregulation?

 

Step-by-Step Solution

Answer

The penguin expends the most energy annually on thermoregulation. 

Step 1: Thermoregulation

The word thermo means heat; thus, thermoregulation refers to maintaining heat or temperature in the body. Birds and mammals adapt to the process of thermoregulation. Hence, they are called warm-blooded or homeothermic organisms. They are capable of regulating body temperature through metabolic processes. 

Step 2: Energy expenditure in penguin, mouse, and python

The annual energy expenditures of penguins, mice, and pythons are 340,000 kcal/ year, 4000 kcal/year, and 8000 kcal/year, respectively. The most energy expenditure is found in penguins because their body mass is more than other organisms. It is less in mice due to the body size. 

Step 3: Energy expenditure on thermoregulation

As per the graph, energy expenditure on thermoregulation is more in the mouse. However, mouse’s annual energy expenditure is much less than penguin’s annual energy expenditure. It is calculated by dividing the energy expenditure of penguins and mice. That is  $\frac{340,000}{4000}=85$. 

Therefore, penguins expend 85 times more energy than mice. Thus, the amount of energy expended by a mouse is much less than a penguin.