Question 1

The genetic disorder sickle-cell anemia develops because the hemoglobin molecule is deformed.Afflicted individuals often suffer muscle pain,even at low levels of exertion.A reasonable hypothesis for the symptoms is that the deformed hemoglobin

Accepted Answer

The deformed hemoglobin in sickle-cell anemia does not carry oxygen effectively, leading to a shortage of oxygen in the affected tissues, including muscle. This oxygen shortage can result in muscle pain and fatigue, especially during exertion.

Question 2

As a compensation for high altitude,it would be common to observe all of the following EXCEPT an

Accepted Answer

The increased binding affinity between hemoglobin and oxygen is a compensatory mechanism that does occur at high altitude. Therefore, this is not something that would be uncommon to observe. The other three options are all typical compensatory responses to high altitude.

Question 3

Patients with the respiratory disease emphysema lose the elasticity of their alveoli;their efforts to exhale can collapse the bronchioles and cause the alveoli to rupture.How might this disease affect the carbon dioxide content of their blood?

Accepted Answer

Emphysema affects the surface area available for diffusion of gases in the lungs, including carbon dioxide (CO2), because the alveoli lose their elasticity and can rupture. Consequently, the lungs have a reduced capacity to remove CO2 from the blood during exhalation, leading to an accumulation of CO2 in the blood (hypercapnia), which can cause respiratory acidosis. Therefore, the carbon dioxide content of the blood would increase in patients with emphysema.

Question 4

How does an actively respiring mitochondrion gain the oxygen it needs to continue its metabolism?

Accepted Answer

Because the mitochondrion is consuming oxygen in its metabolic reactions, the oxygen concentration around the mitochondrion is lower than the surrounding environment. Therefore, oxygen diffuses from high concentration (outside the cell) to low concentration (inside the cell) through the cell membrane to reach the mitochondrion.

Question 5

There are actually two gas exchange events: one occurs in the lung and the other occurs when the blood is in a capillary surrounded by active cells.Which statement best summarizes this second exchange?

Accepted Answer

The second gas exchange event occurs at the systemic capillaries, where oxygen diffuses out of the blood and into the tissues, while carbon dioxide diffuses from the tissues into the blood.

Question 6

Carbon dioxide

Accepted Answer

Carbon dioxide is converted to the highly soluble bicarbonate ion and dissolves in the plasma for its journey to the lung. This is known as the bicarbonate buffer system, which helps to regulate the pH of the blood. Carboxy-carotenoid is not involved in carrying carbon dioxide in the blood. Carbon dioxide does not move from regions of cellular respiration to the alveoli dissolved in the cytoplasm of red blood cells. It also does not attach to hemoglobin and cause structural changes that strengthen oxygen binding.

Question 7

Considering that oxygen is a polar molecule and that its solubility is inversely proportional to temperature,it is most likely that the habitat with the lowest concentration of oxygen would be

Accepted Answer

The solubility of oxygen in water decreases as the temperature increases. Therefore, a pond during summer, which would have a higher temperature compared to the other options, would have the lowest concentration of oxygen.

Question 8

When blood flowing in a pulmonary capillary first arrives at an alveolus,the concentration of

Accepted Answer

When blood first arrives at an alveolus, it is coming from the body where it has collected carbon dioxide (a waste product of metabolism). Therefore, the concentration of carbon dioxide will be greater in the blood plasma than in the alveolus, facilitating its diffusion out of the blood and into the alveolar air to be exhaled.

Question 9

Examine the table below.

Because swimming requires large amounts of ATP and ATP synthesis requires oxygen,which fish is most likely to be the fastest swimmer?

Accepted Answer

The rudderfish is most likely to be the fastest swimmer as it has the highest value for hematocrit, which indicates a higher oxygen-carrying capacity and therefore more efficient ATP synthesis.

Question 10

Which statement accurately describes the pathway an oxygen molecule follows as it moves through the lung to the blood?

Accepted Answer

An oxygen molecule travels from a bronchiole (a small airway) to an alveolus (a small sac in the lung where gas exchange occurs) to a capillary (a small blood vessel) to a red blood cell (where the oxygen binds to hemoglobin, a protein within the red blood cell). Therefore, option C is the accurate description of the pathway.

Question 11

Oxygen molecules are polar and dissolve so poorly in blood plasma that there is NOT enough oxygen to meet the metabolic demands of a vertebrate.However,red blood cells contain ________,which greatly increases the oxygen content of blood.

Accepted Answer

Hemoglobin is a protein found in red blood cells that binds oxygen molecules. Each hemoglobin molecule can bind up to four oxygen molecules, greatly increasing the oxygen content of blood. This allows oxygen to be delivered efficiently to tissues throughout the body. Carbon dioxide, alveoli, and nodules do not increase the oxygen content of blood.

Question 12

The figure below illustrates distance and diffusion time;note that the time required is NOT directly proportional to the distance.Why,for the insect and mouse,might an increase in distance of 20-fold require an increase in time of 60-fold?

Accepted Answer

As oxygen disperses into a large area, its concentration declines, which can result in a slower rate of diffusion over longer distances. The concentration gradient between two locations plays a significant role in determining the rate of diffusion. As the distance increases, the concentration gradient becomes weaker, slowing down the diffusion process. Therefore, an increase in distance of 20-fold might require an increase in time of 60-fold for the insect and mouse, as the oxygen concentration declines over the larger distance. Options A, B, and D are not relevant to the given scenario.

Question 13

Which of the following statements about the oxygen-binding pigments in mammals is INCORRECT?

Accepted Answer

The oxygen-binding pigments in mammals are not dissolved in the plasma portion of the blood. Rather, they are contained within specialized cells, such as red blood cells (hemoglobin) or muscle cells (myoglobin).

Question 14

Blood in a capillary leaving a nearby cell would contain

Accepted Answer

A capillary leaving a nearby cell would contain a higher concentration of carbon dioxide than when it arrived because the cell has metabolized oxygen and produced carbon dioxide as a waste product, which is then released into the bloodstream to be carried away.

Question 15

Whether sleeping or exercising,the rate of gas exchange is precisely matched to the body's immediate respiratory needs;gas exchange during exercise,for example,increases because

Accepted Answer

During exercise, there is an increased demand for oxygen and an increased production of carbon dioxide by the active cells. This results in a higher concentration gradient between the alveoli and the blood, which leads to an increase in the rate of diffusion and gas exchange. The rate of diffusion is directly proportional to the concentration gradient between the two regions. Therefore, choice C is the best answer. Choices A, B, and D are incorrect because they do not accurately explain the mechanism behind the increase in gas exchange during exercise.

Question 16

At altitudes above 10,000 feet the thinner air and reduced concentration of atmospheric gases begin to have an effect on many individuals,who may feel light-headed or nauseated because

Accepted Answer

The correct answer is D because at higher altitudes, the reduced atmospheric pressure decreases the oxygen gradient between the atmosphere and blood plasma, making it harder for the blood to become fully oxygenated. This can lead to symptoms like light-headedness or nausea due to lower oxygen levels in the body.

Question 17

Hemoglobin

Accepted Answer

Hemoglobin is a protein found in red blood cells that binds to oxygen in the lungs and releases it near cells undergoing cellular respiration. This allows for efficient delivery of oxygen to the body's tissues. Hemoglobin is not an enzyme and does not transport oxygen from cells. It also does not make the blood more acidic.

Question 18

The concentration of oxygen in normal exhaled air

Accepted Answer

The answer of The concentration of oxygen in normal exhaled...

Question 19

Although often drawn symmetrically,the wall of the right ventricle is actually much thinner than that of the left and is able to generate only about one-quarter of the pressure.Why might this still be physiologically acceptable?

Accepted Answer

The thin-walled right ventricle is acceptable because the resistance to blood flow in the lungs is much less than in the body's other organs. This means that the right ventricle does not need to generate as much pressure in order to push blood through the lungs. Therefore, the thinner wall of the right ventricle is physiologically acceptable in the context of pulmonary circulation.

Question 20

It's very rare for two sets of capillaries to occur in sequence;what physiological challenge could occur in such a situation?

Accepted Answer

The answer of It's very rare for two sets of...

Quiz 28: Circulation and Gas Exchange