AP BIOLOGY

Detailed explanation-1: -Oxygen is diffusing from the air inside the alveoli within the lungs into the erythrocytes and blood plasma. Diffusion is a type of passive transport, where molecules move from high concentration to low concentration. This means that the concentration of oxygen in the air must be higher than it is in the blood.

Detailed explanation-2: -Each air sac is surrounded by a network of fine blood vessels (capillaries). The oxygen in inhaled air passes across the thin lining of the air sacs and into the blood vessels. This is known as diffusion. The oxygen in the blood is then carried around the body in the bloodstream, reaching every cell.

Detailed explanation-3: -In a process called diffusion, oxygen moves from the alveoli to the blood through the capillaries (tiny blood vessels) lining the alveolar walls.

Detailed explanation-4: -Oxygen diffuses through the cell membrane and is transported in blood plasma by free diffusion and by convection.

Detailed explanation-5: -Since there is no energy required in this movement of particles, it is termed as a passive transport. Movement of oxygen across the cell membrane is an example of diffusion as the concentration of oxygen is greater outside the cell than the inside.