Question 1

Which of the following can increase the concentration of a particular gas in a solution?

Accepted Answer

Increasing the partial pressure of a gas above a solution increases the gas's solubility in the solution, according to Henry's Law.

Question 2

What percentage of air is carbon dioxide?

Accepted Answer

Carbon dioxide makes up less than 1% of Earth's atmosphere. The vast majority of the air is nitrogen (about 78%) and oxygen (about 21%), with trace amounts of other gases including carbon dioxide.

Question 3

Which statement best describes the cause of decompression sickness?

Accepted Answer

Decompression sickness occurs when nitrogen gas, which is dissolved in the body's tissues and blood under high pressure, forms bubbles as the pressure decreases during a rapid ascent. These bubbles can cause joint pain, rashes, paralysis, and other symptoms.

Question 4

Which of the following does NOT contribute to the rapid movement of gases into and out of the blood within the lungs?

Accepted Answer

Rapid blood flow actually facilitates the movement of gases by constantly bringing in blood with different concentrations of gases, thus maintaining the concentration gradient that drives gas exchange. The other options (thin membrane, permeability, concentration gradient, and large surface area) directly contribute to efficient gas exchange.

Question 5

What is the partial pressure of oxygen in air at sea level?

Accepted Answer

The partial pressure of oxygen in air at sea level is approximately 160 mm Hg. This is calculated using the fact that oxygen makes up about 21% of air, and the total atmospheric pressure at sea level is about 760 mm Hg. $0.21 \times 760 \approx 160$ mm Hg.

Question 6

At equilibrium, which of the following statements is TRUE when helium and nitrogen are present in a gas at equal partial pressures over water?

Accepted Answer

At equilibrium, the partial pressures of gases in the water are equal to their partial pressures in the gas phase, so if helium and nitrogen have equal partial pressures in the gas, they will also have equal partial pressures in the water.

Question 7

What percentage of air is oxygen?

Accepted Answer

Oxygen makes up approximately 21% of the Earth's atmosphere, with nitrogen being the most abundant gas at about 78%.

Question 8

Movement of oxygen and carbon dioxide between alveoli and blood occurs by what process?

Accepted Answer

The movement of oxygen and carbon dioxide between alveoli and blood occurs through simple diffusion, which is driven by the concentration gradients of these gases across the alveolar-capillary membrane.

Question 9

At sea level, if oxygen is consumed by the body cells at a rate of 300 mL per minute, then how much oxygen diffuses from the alveoli into the blood in the pulmonary capillaries?

Accepted Answer

The amount of oxygen that diffuses from the alveoli into the blood in the pulmonary capillaries matches the rate at which oxygen is consumed by the body cells, which is 300 mL per minute.

Question 10

What is the most abundant gas in the air that we breathe?

Accepted Answer

Nitrogen is the most abundant gas in the Earth's atmosphere, making up about 78% of the air we breathe. Oxygen, the second most abundant gas, constitutes about 21%.

Question 11

Which statement best describes why O₂and CO₂can both be exchanged simultaneously at the alveoli and pulmonary capillaries?

Accepted Answer

Each gas (Oxygen $O_2$ and Carbon Dioxide $CO_2$) diffuses independently down its own partial pressure gradient, allowing for the simultaneous exchange of these gases between the alveoli and the pulmonary capillaries.

Question 12

At equilibrium, the gas molecules that dissolve in solution and those that remain in the gaseous phase are, by definition, at the same

Accepted Answer

At equilibrium, the gas molecules in solution and those in the gaseous phase have the same partial pressure, according to Henry's law.

Question 13

What is the partial pressure of oxygen in a gas mixture that is 40% oxygen, 40% argon, and 20% helium, when the total pressure of the gas is 1000 mm Hg?

Accepted Answer

The partial pressure of a gas in a mixture is calculated by multiplying the total pressure by the fraction (or percentage) of that gas in the mixture. For oxygen, which makes up 40% of the mixture, its partial pressure is 0.40 * 1000 mm Hg = 400 mm Hg.

Question 14

Oxygenated blood is found in which of the following?

Accepted Answer

Oxygenated blood is found in the pulmonary vein, which carries blood from the lungs to the left atrium of the heart.

Question 15

As humidity increases, the partial pressure of oxygen in air

Accepted Answer

As humidity increases, the amount of water vapor in the air increases, which displaces some of the oxygen, leading to a decrease in the partial pressure of oxygen. The total pressure of the air remains the same because it is determined by the atmospheric pressure, not by the composition of the air.

Question 16

The relationship between the concentration of a gas in solution and the partial pressure of that gas can be described by

Accepted Answer

Henry's law describes the relationship between the concentration of a gas in solution and the partial pressure of that gas above the solution. It states that at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

Question 17

In a mixture of gases, the driving force for the movement of an individual gas within that mixture is ultimately the

Accepted Answer

The driving force for the movement of an individual gas within a mixture is its partial pressure. This is because gases move from areas of higher partial pressure to areas of lower partial pressure, according to Dalton's Law of Partial Pressures.

Question 18

At sea level the air pressure which equals 1 atmosphere is

Accepted Answer

At sea level, the standard atmospheric pressure is 760 mm Hg, which is equivalent to 1 atmosphere.

Question 19

The respiratory quotient is calculated as the

Accepted Answer

The respiratory quotient (RQ) is calculated as the ratio of the volume of carbon dioxide produced to the volume of oxygen consumed, which is accurately described in option A.

Question 20

As the air is saturated with water vapor (humidified) upon entry into the conducting pathway, there will be

Accepted Answer

When air is humidified, water vapor is added, which increases its partial pressure. This results in a decrease in the partial pressures of the other gases, including nitrogen, because the total pressure remains constant.

Quiz 17: The Respiratory System: Gas Exchange and the Regulation of Breathing