Multiple choice

In humans gas exchange occurs between

  1. Arteries and body cells

  2. Alveoli and veins

  3. Alveoli and capillaries

  4. Skin and air

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gas exchange occurs in the lungs between the alveoli (air sacs) and the surrounding pulmonary capillaries. Oxygen enters the blood and carbon dioxide leaves it.