Question

At the site of gas exchange in the lungs, where does the oxygen move?

O2 moves from the alveoli to the white blood cells.
O2 moves from the white blood cells to the alveoli.
O2 moves from the alveoli to the red blood cells.
O2 moves from the red blood cells to the alveoli.

Answer 1

O2 moves from the alveoli to the red blood cells.

Explanation: Oxygen diffuses down its partial pressure gradient from the alveolar air into the pulmonary capillary blood, where it is taken up primarily by hemoglobin inside red blood cells (not white blood cells).