AP BIOLOGY

Detailed explanation-1: -Gas exchange during respiration occurs primarily through diffusion. Diffusion is a process in which transport is driven by a concentration gradient.

Detailed explanation-2: -Once in the lungs, the air travels through a series of increasingly smaller structures called bronchioles. It eventually reaches tiny sacs called alveoli. From the alveoli, the oxygen from the air you breathe enters your blood in nearby blood vessels. This is a process called oxygen diffusion.

Detailed explanation-3: -This exchange of oxygen and carbon dioxide is called respiration.

Detailed explanation-4: -Diffusion is the spontaneous movement of gases, without the use of any energy or effort by the body, between the alveoli and the capillaries in the lungs. Perfusion is the process by which the cardiovascular system pumps blood throughout the lungs.