HORTICULTURE

Detailed explanation-1: -Gas exchange is the physical process by which gases move passively by diffusion across a surface.

Detailed explanation-2: -Adaptations of the alveoli: Moist walls-gases dissolve in the moisture helping them to pass across the gas exchange surface. Permeable walls-allow gases to pass through. Extensive blood supply-ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.

Detailed explanation-3: -Adaptations of exchange surfaces Most gas exchange surfaces are extremely thin (sometimes just one cell thick), ensuring a short diffusion pathway across the exchange surface. They will also have a large surface area to volume ratio which provides more space for the diffusion of gases.

Detailed explanation-4: -the membranes of cells. the flattened shape of structures such as leaves. the walls of blood capillaries are one cell thick. the epithelia of alveoli in the respiratory system and the villi in the small intestine are only one cell thick.