Question

Which of the following statements comparing the circulatory systems in mammals and birds is true?

a. Birds have far smaller hearts per gram.
b. Mammals have, on average, higher systolic blood pressures.
c. Birds have a smaller cross-sectional area of capillaries per gram.
d. Mammals have a higher pressure systemic circuit.
e. Birds and mammals have essentially identical circulatory systems.

Answer 1

Both mammals and birds have a four-chambered heart and double circulation, which efficiently separates oxygenated and deoxygenated blood.

Step-by-step explanation:

The correct statement comparing the circulatory systems in mammals and birds is that mammals and birds both have a four-chambered heart and double circulation. This means that their hearts completely separate oxygenated and deoxygenated blood, allowing for an efficient circulatory system. It is also important to note that the systemic circuit in both mammals and birds is responsible for pumping oxygenated blood throughout the body, which is not necessarily at a higher pressure than in birds. Therefore, the options suggesting that birds have much smaller hearts per gram, as well as statements about blood pressure and capillary size, are generally not accurate comparisons. Additionally, birds and mammals do not have identical circulatory systems due to species-specific differences, but they do share the key feature of double circulation.