A series of tests performed to determine the diffusion of oxygen and carbon dioxide across the cell membrane in the lungs is called a/an ________.

Diffusion

The process by which molecules move from an area of higher concentration to an area of lower concentration.

Oxygen

A chemical element with symbol O and atomic number 8, essential for most life forms on Earth as part of the process of respiration.

Carbon Dioxide

A colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It is absorbed by plants in photosynthesis.