AP Biology : Understanding Gas Exchange
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Example Questions
Example Question #1 : Respiratory Physiology
Choose the incorrect statement regarding gas exchange in the alveoli of the lungs.
Gases move between alveoli and blood vessels via passive diffusion
In the lungs, oxygen diffuses from the alveoli into the blood vessels
Carbon dioxide diffuses from the blood vessels into the alveoli for expiration
The partial pressure of oxygen is lower in systemic arteries than in systemic veins
The partial pressure of carbon dioxide is lower in the systemic arteries than it is in the body tissues
The partial pressure of oxygen is lower in systemic arteries than in systemic veins
We know that systemic arteries carry oxygenated blood away from the heart and that these vessels pass through tissues, allowing oxygen to diffuse into the tissues and carbon dioxide to diffuse out into the bloodstream. We also know that veins carry blood back to the heart, which by this time is oxygen-poor due to its gas exchange with the tissues of the body. The partial pressure of oxygen in veins must be lower than it is in arteries, since the veins carry deoxygenated blood.
The remaining statements regarding gas exchange are true.
Example Question #1 : Understanding Gas Exchange
How is oxygen carried after entering the blood of the pulmonary capillaries?
Oxygen diffuses into the cell membranes of red blood cells
Oxygen is carried by white blood cells
Oxygen is free floating in the plasma of the blood
Oxygen is carried by hemoglobin
Oxygen diffuses through all the cells in the body
Oxygen is carried by hemoglobin
Hemoglobin is the main oxygen carrier in the human body. Each hemoglobin protein is able to carry four oxygen molecules. As the hemoglobin travels through the blood vessels of the body, the oxygen is released to tissues and used in the electron transport chain.
If oxygen is unable to bind to hemoglobin, our bodies cannot carry the needed oxygen to the tissues of the body. This can occur when carbon monoxide displaces oxygen from hemoglobin.
Example Question #3 : Understanding Respiratory Functions
Gases diffuse down their concentration gradients, so in order for the body to exchange respiratory gases with the air as needed, air breathed into the lungs must have a __________ concentration of oxygen and a(n) __________ concentration of carbon dioxide compared to the blood in the lungs.
lower . . . higher
higher . . . equal
lower . . . equal
higher . . . lower
higher . . . lower
Oxygen is taken up from the blood by all cells to be used in ATP production. The process of cellular respiration (energy production) creates carbon dioxide as a waste product, which, if accumulated, can cause the blood to become dangerously acidic. Gases in the lungs diffuse passively into or out of the air entirely based on where the concentration is lowest. Thus, oxygen levels in the blood must be lower in concentration than those in the lungs in order for oxygen to enter the blood, and carbon dioxide levels in the blood must be higher than those in the lungs order for carbon dioxide to exit.
Example Question #1 : Understanding Gas Exchange
Mountain climbing at a high altitude can have an affect on one's ability to breath efficiently. At high altitudes, atmospheric pressure can decrease dramatically and result in a lower drive for oxygen into the lungs. The body will try to compensate by increasing the rate of respiration.
How does hyperventilating change the blood chemistry in the human body?
Hyperventilating will retain more 
Hyperventilating will retain more 
Hyperventilating will not affect the blood's pH.
Hyperventilating will release more 
Hyperventilating will release more 
Hyperventilating will release more
Hyperventilation will result in the expiration of more 
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