Question 1

Which condition would increase the amount of oxygen diffusing from the lungs into the blood?

Accepted Answer

A)  An increase in the binding rate of O2 to hemoglobin 
B)  A decrease in the partial pressure of O2 in the lungs 
C)  An increase in the partial pressure of O2 in the blood 
D)  A decrease in the red blood cell count 
E)  An increase in the water vapor of air in the lungs 
A)  An increase in the binding rate of O2 to hemoglobin 
B)  A decrease in the partial pressure of O2 in the lungs 
C)  An increase in the partial pressure of O2 in the blood 
D)  A decrease in the red blood cell count 
E)  An increase in the water vapor of air in the lungs A

Question 2

In human lungs, the gas exchange surface area provided by _______ is enormous.

Accepted Answer

A)  trachea 
B)  gills 
C)  parabronchi 
D)  bronchi 
E)  alveoli 
A)  trachea 
B)  gills 
C)  parabronchi 
D)  bronchi 
E)  alveoli E

Question 3

Which statement about 2,3-bisphosphoglyceric acid (BPG) is true?

Accepted Answer

A)  It is a breakdown product of hemoglobin. 
B)  A higher level in the red blood cells makes it harder for hemoglobin to release O2 to tissues. 
C)  It causes a left-shifted O2-binding/dissociation curve in adult hemoglobin. 
D)  Its production increases with altitude. 
E)  Its production decreases with exercise. 
A)  It is a breakdown product of hemoglobin. 
B)  A higher level in the red blood cells makes it harder for hemoglobin to release O2 to tissues. 
C)  It causes a left-shifted O2-binding/dissociation curve in adult hemoglobin. 
D)  Its production increases with altitude. 
E)  Its production decreases with exercise. D

Question 4

Which characterizes the situation faced by a water-breathing ectotherm as water temperature drops?

Accepted Answer

A)  Decreased oxygen content of water 
B)  Increased body temperature 
C)  Increased need for oxygen 
D)  Increased metabolic rate 
E)  Decreased energy expenditure for ventilation 
A)  Decreased oxygen content of water 
B)  Increased body temperature 
C)  Increased need for oxygen 
D)  Increased metabolic rate 
E)  Decreased energy expenditure for ventilation

Question 5

In patients with pulmonary fibrosis, excess fibrous connective tissue thickens the walls of the lungs, making the lung tissue less elastic.Why would this lowered elasticity decrease the ability of these patients to exercise?

Accepted Answer

If the lung tissue is less elastic, the

Question 6

A human's basic breathing rhythm is generated in the _______ and modified by neurons in or above the _______.

Accepted Answer

A)  pons; medulla 
B)  medulla; pons 
C)  lungs; brainstem 
D)  brainstem; lungs 
E)  lungs; larynx 
A)  pons; medulla 
B)  medulla; pons 
C)  lungs; brainstem 
D)  brainstem; lungs 
E)  lungs; larynx

Question 7

During tidal breathing, respiratory _______ neurons in the medulla _______ just before the start of an _______.

Accepted Answer

A)  motor; increase their firing rate; exhalation 
B)  motor; decrease their firing rate; inhalation 
C)  motor; increase their firing rate; inhalation 
D)  sensory; stop firing; exhalation 
E)  sensory; stop firing; inhalation 
A)  motor; increase their firing rate; exhalation 
B)  motor; decrease their firing rate; inhalation 
C)  motor; increase their firing rate; inhalation 
D)  sensory; stop firing; exhalation 
E)  sensory; stop firing; inhalation

Question 8

In fish gas exchange systems, blood flows through gill lamellae in a direction opposite to water flow, a phenomenon known as _______.

Accepted Answer

countercur

Question 9

Which feature characterizes the lungs of mammals?

Accepted Answer

A)  Air sacs 
B)  Tidal ventilation 
C)  Complete emptying in exhalation 
D)  Crosscurrent air flow 
E)  Countercurrent air flow 
A)  Air sacs 
B)  Tidal ventilation 
C)  Complete emptying in exhalation 
D)  Crosscurrent air flow 
E)  Countercurrent air flow

Question 10

Refer to the figure showing the O2-binding/dissociation curves for human and llama hemoglobins.   South American camelids (i.e., llamas, alpacas, guanacos, and vicuñas) are native to the Andes Mountains.In the natural habitat of these mammals, more than 5,000 meters above sea level, the PO2 is below 85 mm Hg, and the PO2 in the camelids' lungs is about 50 mm Hg.The hemoglobins of these camelids are different from that of humans.Why would llama hemoglobin be advantageous at high altitudes?

Accepted Answer

Atmospheric pressure is lower at high al

Question 11

Which statement about how breathing is regulated is true?

Accepted Answer

A)  Mammals are quite sensitive to decreasing levels of O2 in their arterial blood. 
B)  The brainstem posterior to the medulla regulates breathing. 
C)  Fishes are very sensitive to decreasing levels of O2 in their arterial blood. 
D)  In mammals, a small increase in arterial PCO2 prompts no change in ventilation. 
E)  Severing the spinal cord does not stop breathing in mammals. 
A)  Mammals are quite sensitive to decreasing levels of O2 in their arterial blood. 
B)  The brainstem posterior to the medulla regulates breathing. 
C)  Fishes are very sensitive to decreasing levels of O2 in their arterial blood. 
D)  In mammals, a small increase in arterial PCO2 prompts no change in ventilation. 
E)  Severing the spinal cord does not stop breathing in mammals.

Question 12

Refer to the graph showing several different O2-binding/dissociation curves for hemoglobin.   Curve _______ would most likely represent a normal adult human, curve _______ would most likely represent an adult human exposed to high altitude, and curve _______ would most likely represent a human fetus.

Accepted Answer

A)  A; B; C 
B)  A; C; B 
C)  B; A; C 
D)  B; C; A 
E)  C; B; A 
A)  A; B; C 
B)  A; C; B 
C)  B; A; C 
D)  B; C; A 
E)  C; B; A

Question 13

Refer to the figure showing the hemoglobin-oxygen binding/dissociation curve.   Which statement about hemoglobin's O2-binding/dissociation curve is true?

Accepted Answer

A)  At rest, our body's hemoglobin activity can be illustrated by only the upper one-fourth of its O2-binding/dissociation curve. 
B)  A smaller decrease in PO2 is required for hemoglobin to drop from 100 to 75% saturation than for hemoglobin to drop from 75 to 50% saturation. 
C)  Our blood normally carries a small reserve of O2. 
D)  The steepest part of the O2-binding/dissociation curve results in a small release of O2 for a large drop in PO2. 
E)  The PO2 of our blood drops well below 40 mm Hg during light exertion. 
A)  At rest, our body's hemoglobin activity can be illustrated by only the upper one-fourth of its O2-binding/dissociation curve. 
B)  A smaller decrease in PO2 is required for hemoglobin to drop from 100 to 75% saturation than for hemoglobin to drop from 75 to 50% saturation. 
C)  Our blood normally carries a small reserve of O2. 
D)  The steepest part of the O2-binding/dissociation curve results in a small release of O2 for a large drop in PO2. 
E)  The PO2 of our blood drops well below 40 mm Hg during light exertion.

Question 14

If a new air pollutant were to destroy the surfactant in people's lungs, one likely result would be

Accepted Answer

A)  decreased surface tension of the fluid lining their alveoli. 
B)  increased uptake of CO2 from the environment. 
C)  increased effort needed to breathe. 
D)  decreased levels of hydrogen bonding in the fluid of their alveoli. 
E)  decreased amounts of CO2 carried in their blood. 
A)  decreased surface tension of the fluid lining their alveoli. 
B)  increased uptake of CO2 from the environment. 
C)  increased effort needed to breathe. 
D)  decreased levels of hydrogen bonding in the fluid of their alveoli. 
E)  decreased amounts of CO2 carried in their blood.

Question 15

The carotid and aortic bodies

Accepted Answer

A)  are blood vessels. 
B)  respond to significant declines in PO2. 
C)  decrease respiration when blood volumes drop. 
D)  are electrosensors. 
E)  are found on the surface of the medulla. 
A)  are blood vessels. 
B)  respond to significant declines in PO2. 
C)  decrease respiration when blood volumes drop. 
D)  are electrosensors. 
E)  are found on the surface of the medulla.

Question 16

Which statement about CO2 is true?

Accepted Answer

A)  CO2 is less soluble in water than is O2. 
B)  The amount of CO2 in the atmosphere is extremely large. 
C)  PCO2 is lower in stagnant water than in fast-flowing water. 
D)  For air-breathing animals, CO2 readily diffuses from the body to the environment at sea level and at high altitude. 
E)  Aquatic ectotherms typically face challenges in CO2 exchange. 
A)  CO2 is less soluble in water than is O2. 
B)  The amount of CO2 in the atmosphere is extremely large. 
C)  PCO2 is lower in stagnant water than in fast-flowing water. 
D)  For air-breathing animals, CO2 readily diffuses from the body to the environment at sea level and at high altitude. 
E)  Aquatic ectotherms typically face challenges in CO2 exchange.

Question 17

Which feature characterizes myoglobin?

Accepted Answer

A)  It is present in low concentrations in diving mammals. 
B)  It facilitates diffusion of O2 in muscle cells. 
C)  It can bind two O2 molecules. 
D)  It is unable to hold an O2 reserve. 
E)  It has a lower affinity for O2 than does hemoglobin. 
A)  It is present in low concentrations in diving mammals. 
B)  It facilitates diffusion of O2 in muscle cells. 
C)  It can bind two O2 molecules. 
D)  It is unable to hold an O2 reserve. 
E)  It has a lower affinity for O2 than does hemoglobin.

Question 18

Which statement about gill circulation in fishes is true?

Accepted Answer

A)  Efferent blood vessels bring low-oxygen blood to the gills. 
B)  Blood flow during perfusion is bidirectional. 
C)  O2 diffuses from water into blood along the entire length of lamellae due to the high PO2 gradient between water and blood. 
D)  Afferent blood vessels carry high-oxygen blood to the gills. 
E)  The direction of blood flow through the lamellae is the same as that of water flowing over the lamellae. 
A)  Efferent blood vessels bring low-oxygen blood to the gills. 
B)  Blood flow during perfusion is bidirectional. 
C)  O2 diffuses from water into blood along the entire length of lamellae due to the high PO2 gradient between water and blood. 
D)  Afferent blood vessels carry high-oxygen blood to the gills. 
E)  The direction of blood flow through the lamellae is the same as that of water flowing over the lamellae.

Question 19

Refer to the figure showing models of concurrent and countercurrent gas exchange.   If you did an experiment in which you measured the oxygen saturation of the blood and water going through a gill in goldfish, your results would look most like panel _______, because _______.

Accepted Answer

A)  A; fish have an efficient concurrent flow pattern of blood and water through their gills 
B)  B; fish have an efficient concurrent flow pattern of blood and water through their gills 
C)  A; fish have a flow pattern through their gills that optimizes the PO2 gradient between water and blood 
D)  B; fish have a flow pattern through their gills that optimizes the PO2 gradient between water and blood 
E)  B; fish have a countercurrent flow pattern of blood and water through their gills 
A)  A; fish have an efficient concurrent flow pattern of blood and water through their gills 
B)  B; fish have an efficient concurrent flow pattern of blood and water through their gills 
C)  A; fish have a flow pattern through their gills that optimizes the PO2 gradient between water and blood 
D)  B; fish have a flow pattern through their gills that optimizes the PO2 gradient between water and blood 
E)  B; fish have a countercurrent flow pattern of blood and water through their gills

Question 20

Chemosensors on the surface of the medulla are sensitive to

Accepted Answer

A)  O2. 
B)  N2. 
C)  surfactant. 
D)  the pH of the cerebrospinal fluid. 
E)  the O2-saturation level of hemoglobin. 
A)  O2. 
B)  N2. 
C)  surfactant. 
D)  the pH of the cerebrospinal fluid. 
E)  the O2-saturation level of hemoglobin.

Exam 48: Gas Exchange

Which condition would increase the amount of oxygen diffusing from the lungs into the blood?

In human lungs, the gas exchange surface area provided by _______ is enormous.

Which statement about 2,3-bisphosphoglyceric acid (BPG) is true?

Which characterizes the situation faced by a water-breathing ectotherm as water temperature drops?

In patients with pulmonary fibrosis, excess fibrous connective tissue thickens the walls of the lungs, making the lung tissue less elastic.Why would this lowered elasticity decrease the ability of these patients to exercise?

A human's basic breathing rhythm is generated in the _______ and modified by neurons in or above the _______.

During tidal breathing, respiratory _______ neurons in the medulla _______ just before the start of an _______.

In fish gas exchange systems, blood flows through gill lamellae in a direction opposite to water flow, a phenomenon known as _______.

Which feature characterizes the lungs of mammals?

Which statement about how breathing is regulated is true?

Refer to the graph showing several different O2-binding/dissociation curves for hemoglobin. Curve _______ would most likely represent a normal adult human, curve _______ would most likely represent an adult human exposed to high altitude, and curve _______ would most likely represent a human fetus.

Refer to the figure showing the hemoglobin-oxygen binding/dissociation curve. Which statement about hemoglobin's O2-binding/dissociation curve is true?

If a new air pollutant were to destroy the surfactant in people's lungs, one likely result would be

The carotid and aortic bodies

Which statement about CO2 is true?

Which feature characterizes myoglobin?

Which statement about gill circulation in fishes is true?

Refer to the figure showing models of concurrent and countercurrent gas exchange. If you did an experiment in which you measured the oxygen saturation of the blood and water going through a gill in goldfish, your results would look most like panel _______, because _______.

Chemosensors on the surface of the medulla are sensitive to

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Filters

A human's basic breathing rhythm is generated in the _ and modified by neurons in or above the _.

During tidal breathing, respiratory ___ neurons in the medulla _ just before the start of an _____.

Refer to the graph showing several different O₂-binding/dissociation curves for hemoglobin. Curve ___ would most likely represent a normal adult human, curve _ would most likely represent an adult human exposed to high altitude, and curve _____ would most likely represent a human fetus.

Refer to the figure showing the hemoglobin-oxygen binding/dissociation curve. Which statement about hemoglobin's O₂-binding/dissociation curve is true?

Which statement about CO₂ is true?

Refer to the figure showing models of concurrent and countercurrent gas exchange. If you did an experiment in which you measured the oxygen saturation of the blood and water going through a gill in goldfish, your results would look most like panel _, because _.