AP BIOLOGY

Detailed explanation-1: -The partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. As a result, oxygen diffuses across the respiratory membrane from the alveoli into the blood. In contrast, the partial pressure of carbon dioxide is high in the pulmonary capillaries and low in the alveoli.

Detailed explanation-2: -Partial pressure of oxygen will be highest in whole blood. plasma and serum are the components of whole blood where only dissolved oxygen is present in negligible amount. Whole blood contains RBCs which are the main carriers of oxygen.

Detailed explanation-3: -Diffusion of gases always takes place from higher concentration to lower concentration. So, for the movement of oxygen from alveoli to blood the partial pressure of oxygen is higher in blood than in the alveoli of the lungs.

Detailed explanation-4: -Alveoli are the site of gaseous exchange and have a higher partial pressure of oxygen than that of blood. Blood is rich in carbon dioxide at cell and tissue levels due to cellular respiration. The higher partial pressure of oxygen in alveoli allow diffusion of oxygen into the blood.

Detailed explanation-5: -Approximately 21 percent of atmospheric gas is oxygen. Carbon dioxide, however, is found in relatively small amounts (0.04 percent); therefore, the partial pressure for oxygen is much greater than that of carbon dioxide. The partial pressure of any gas can be calculated by: P = (Patm) (percent content in mixture).