Question

Oxygen and carbon dioxide cross from the alveoli through the capillary walls and into the blood by what transport mechanism?.

Answer 1

Diffusion

Step-by-step explanation:

Since there’s is an existing partial pressure gradient along with the fact that O2 and CO2 are small and nonpolar molecules, such molecules can pass through capillary walls into the blood without help from transport proteins.

Answer 2

By simple diffusion.