How are the lungs adapted to increase the rate of diffusion? 3 Marks

Increase in surface area, which is provided by the many alveoli that are located at the end of the bronchioles. These can number in the thousands.
The alveoli have a thin wall, one cell thick, so diffusion can happen at a rapid rate as the gases (oxygen in to body and carbon dioxide out) pass through
Good blood supply is the last one. The alveoli are lined with capillaries that are constantly bringing deoxygenated blood towards the lungs and oxygenated away from lungs. This creates a concentration gradient.