Question

Which of the following is true of vertebrates with four-chambered hearts?

There is a partial gas exchange in one chamber of the heart.


There is a partial mixing of oxygen-rich and oxygen-poor blood.


There is no mixing of oxygen-rich and oxygen-poor blood.


There is a complete mixing of oxygen-rich and oxygen-poor blood.

Answer 1

There is no mixing of oxygen-rich and oxygen-poor blood.

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The right atrium and right ventricle of the human heart pump oxygen-poor blood to the lungs and the left atrium receives oxygen-rich blood. They never mix.