View the animation below, then complete the quiz to test your knowledge of the concept.

1	The direction of gas movement is determined by
	A)	temperature.
	B)	size of the gas molecule.
	C)	solubility of the gas in blood.
	D)	partial pressure differences.
	E)	pH.
2	At the arterial end of the pulmonary capillaries,
	A)	O2 diffuses from the alveoli into the blood, while CO2 diffuses from the blood into the alveoli.
	B)	O2 diffuses from the blood into the alveoli, while CO2 diffuses from the alveoli into the blood.
	C)	both O2 and CO2 diffuse from the blood into the alveoli.
	D)	both O2 and CO2 diffuse from the alveoli into the blood.
	E)	O2 diffuses from the alveoli into the blood, but there is no net movement of CO2.
3	At the arterial end of the tissue capillaries,
	A)	O2 diffuses from tissue cells into the blood, while CO2 diffuses from the blood into tissue cells.
	B)	O2 diffuses from the blood into tissue cells, while CO2 diffuses from tissue cells into the blood.
	C)	both O2 and CO2 diffuse from the blood into tissue cells.
	D)	both O2 and CO2 diffuse from tissue cells into the blood.
	E)	O2 diffuses from the blood into tissue cells, but there is no net movement of CO2.
4	The partial pressure of a gas is measured in millimeters of mercury.
	A)	True
	B)	False
5	At the venous end of tissue capillaries, there is no net movement of O2 and CO2.
	A)	True
	B)	False