Deck 42: Gas Exchange and Circulation

Question 1

Why is it more difficult to obtain enough oxygen via respiration from water than from air?

A) The density of water makes ventilating the respiratory tissues more difficult.
B) The viscosity of water is less than that of air.
C) The solubility of oxygen in water is less than in air.
D) All of the above answers apply.
E) Only A and C apply.

Answer 1

Only A and C apply.

Question 2

When you are jogging, your muscles are using more oxygen and releasing more carbon dioxide into the blood than when you are at home on the couch. Which of the following would occur during your jog?

A) The concentration of bicarbonate ions HCO₃^- ) in the blood would decrease.
B) Blood pH would increase by at least 1 pH unit.
C) The medullary respiratory center would increase the rate of breathing.
D) All of the above answers apply.

Answer 2

The medullary respiratory center would increase the rate of breathing.

Question 3

Which of the following is NOT a feature of gas exchange in the respiratory system of birds?

A) The flow of air through the lungs is one way.
B) Gas exchange occurs during both inhalation and exhalation.
C) The exchange of gases between parabronchi and blood is in a countercurrent direction.
D) The dead space within the respiratory system is small compared to that in mammals.

Answer 3

C

Question 4

The sun shining on a tidal pool during a hot day heats the water. As some water evaporates, the pool becomes saltier, causing which of the following?

A) a decrease in the water's oxygen content
B) a decrease in the water's density
C) an increase in the water's ability to sustain aerobic organisms
D) an increase in the water's carbon dioxide content
E) an increase in photosynthesis by the tidal pool plants

Question 5

You prop open the gill covers of a fish, tie a string around its tail, and tow it backward through the water. This action forces water to flow in the back of the gill covers, from back to front over the gills, and out through the fish's mouth. What effect would this backward movement have on gas exchange?

A) The only effect would be the fish's discomfort from this treatment.
B) It would increase efficiency of gas exchange.
C) It would reduce efficiency of gas exchange.

Question 6

The air pressure in Denver, Colorado, is about 83% of the air pressure in Miami Beach, which is about sea level. Given that the air pressure in Miami Beach is 760 mm Hg and oxygen makes up 21% of the air in Miami Beach, what is the percentage of oxygen and the partial pressure of oxygen in Denver, respectively?

A) 17.4%; 21 mm Hg
B) 21%; 21 mm Hg
C) 21%; 132 mm Hg
D) 17.4%; 132 mm Hg

Question 7

Which of the following best describes the process of ventilation?

A) the movement of oxygen gas through the blood of the circulatory system
B) the diffusion of gases into and out of tissues where cellular respiration occurs
C) the movement of air through lungs or gills
D) the diffusion of gases into and out of the circulatory system
E) the movement of carbon dioxide gas through the blood of the circulatory system

Question 8

What is the rate of diffusion in the gas- exchange organ of an air- breathing animal where the area for gas exchange in the lung is 200 mm², the diffusion constant is 0.08, the PO₂ partial pressure of oxygen) of the air in the lung is 140 mm Hg, the PO₂ in blood flowing into the lung is 90 mmHg, and the thickness of the gas exchange membrane is 0.001 mm?

A) 00032
B) 800,000
C) 125
D) 10,000,000

Question 9

Which of the following events would be predicted by the Bohr shift effect as the amount of carbon dioxide released from your tissues into the blood capillaries increases?

A) The amount of oxygen in arterial blood would increase.
B) The amount of oxygen in venous blood would increase.
C) The amount of oxygen in venous blood would decrease.
D) The amount of oxygen in arterial blood would decrease.
E) More than one of the above is true.

Question 10

Fick's law of diffusion describes the factors that influence the diffusion of respiratory gases across biological membranes like gills and lungs. Diffusion rate = k × A × P₂ - P₁)/D. Natural selection is least likely to act upon which variable in Fick's law?

A) A
B) D
C) P₂ - P₁
D) k

Question 11

A rabbit taken from a meadow near sea level and moved to a meadow high on a mountainside would have some trouble breathing. Why?

A) The partial pressure of oxygen in the air at high elevations is higher than at sea level.
B) The partial pressure of oxygen in the air at high elevations is lower than at sea level.
C) The percentage of oxygen in the air at high elevations is higher than at sea level.
D) The percentage of oxygen in the air at high elevations is lower than at sea level.

Question 12

Carbon dioxide levels in the blood and in cerebrospinal fluid affect the pH of these fluids. Which of the following mechanisms does an organism use to sense a disturbance in gas?

A) Neurons in contact with cerebrospinal fluid monitor pH and use this measure to control breathing.
B) Stretch receptors in the lungs cause the medulla oblongata to speed up or slow breathing.
C) The brain alters the pH of the cerebrospinal fluid to force the animal to retain more or less carbon dioxide.
D) The medulla oblongata is able to control the concentration of bicarbonate ions in the blood.
E) The brain directly measures and monitors oxygen levels and causes breathing changes accordingly.

Question 13

In midsummer, you are fishing at a lake. You catch the most fish at the inlet of a stream into the lake, where logs and branches are creating turbulent flow and mixing deep water with the shallow water near the surface of the lake. What is the probable reason the fish are congregating in this area?

A) This area is cooler, which stimulates metabolism.
B) This area has higher oxygen content, aiding gill oxygen uptake.
C) This area is warmer, which stimulates metabolism.
D) This area has a lower oxygen content, which helps to transfer oxygen into the fish's gills.
E) None of the above apply.

Question 14

In what way does hemoglobin act as a buffer against changes in blood pH?

A) Subsequent binding of oxygen is drastically reduced after the first one is bound.
B) Hemoglobin binds some of the excess protons released by carbonic acid.
C) Hemoglobin removes excess protons from the red blood cells so that they can be excreted through the kidneys.
D) Hemoglobin produces protons or hydroxide ions as needed to alter the blood pH.
E) All of the above answers apply.

Question 15

If other factors are equal, which of the following environments would have the highest level of dissolved oxygen?

A) warm, fresh water at high elevation
B) cool, fresh water at high elevation
C) cool, salty water at low elevation
D) cool, fresh water at low elevation
E) warm, salty water at low elevation

Question 16

Marine crabs have internal gills covered by an exoskeleton, and, because their whole body is covered by exoskeleton, they cannot expand their body enough to generate much negative pressure within the gill chambers to draw water in over their gills. Which of the following would serve to increase the efficiency of gas exchange by marine crabs?

A) a countercurrent exchange system
B) oxygen- carrying molecules in the blood
C) movement of limbs or other structures to create a current over the gills
D) all of the above
E) only B and C

Question 17

Which of the following statements supports the hypothesis that the bidirectional gas flow occurring in humans air goes in and out through the same passages) is less efficient than the unidirectional flow in fish?

A) Bidirectional flow in humans does not take advantage of countercurrent exchange.
B) About one- third of the air in human lungs is trapped in "dead space" where gas exchange with the circulation cannot occur.
C) None of the above are true.
D) Both A and B are true.

Question 18

The oxygen content of water increases linearly with an increase in oxygen partial pressure, while the oxygen content of blood increases in a sigmoidal S- shaped) fashion. Why?

A) The Bohr shift is stronger in water than in blood.
B) Carbonic anhydrase contributes to CO₂ release in blood, but not water.
C) Hemoglobin shows cooperative oxygen binding.
D) All of the above answers apply.

Question 19

What is the main difference between respiration in terrestrial insects and in terrestrial vertebrates?

A) Insects rely on the blood in their circulatory system to deliver oxygen from the air to their tissues, whereas terrestrial vertebrates rely on their lungs to deliver oxygen in air to their tissues.
B) Insects have a lower metabolic rate than terrestrial vertebrates do, so they tend to rely more heavily on their circulatory system than their tracheal system for oxygen transport.
C) Insects rely on their tracheal system to deliver oxygen in air to their tissues, whereas terrestrial vertebrates rely on their lungs to deliver oxygen to their tissues through the blood in their circulatory system.
D) Insects use their tracheal system to transfer oxygen from air into blood, whereas terrestrial vertebrates use their lungs to transfer oxygen from air into blood.

Question 20

A mutation results in a form of hemoglobin with binding sites for four molecules of oxygen but does not exhibit cooperative binding. Which of the following would result?

A) Each hemoglobin molecule would bind only one molecule of oxygen.
B) Oxygen would be delivered to the tissues more readily than in a normal individual.
C) The oxygen- hemoglobin dissociation curve would be unaffected.
D) Both A and C would occur.
E) None of the above would result.

Question 21

Which of the following mechanisms play a role in regulating heart rate?
Which of the following mechanisms play a role in regulating heart rate?

A) chemical messengers in the blood, such as epinephrine
B) nerves originating from the medulla lower part of the brain)
C) pacemaker cells within the heart
D) all of the above A to C)
E) only A and C

Question 22

Which of the following is the normal sequence of signal conduction in the human heart?

A) neural and chemical messengers -AV node -atria -SA node -ventricles
B) neural but not chemical messengers -AV node -ventricles -SA node - atria
C) neural and chemical messengers -ventricles -SA node -atria -AV node
D) neural and chemical messengers -SA node -atria -AV node -ventricles
E) chemical but not neural messengers -atria -SA node -ventricles -AV node

Question 23

You are a physician, and see a patient who complains of abnormal fatigue during exercise. You find that the immediate problem is a buildup of carbon dioxide in the tissues. What is the most likely cause?

A) abnormally shaped platelets
B) abnormal carbonic anhydrase
C) not enough hemoglobin
D) abnormal hemoglobin

Question 24

Which of the following conditions would be the most likely result of an abnormally high blood pressure in an animal, like a reptile, possessing a closed circulatory system?

A) reversal of normal blood flow direction in the veins
B) hemorrhage in the capillary beds
C) hemorrhage in the aorta
D) all of the above

Question 25

In a cross section through an artery and vein running parallel in your leg, which would be the artery?

A) The vessel with more muscle tissue in the wall.
B) The vessel lined with endothelium.
C) The vessel with the largest interior diameter.
D) The vessel with valves to prevent backflow.
E) All of the above answers apply.

Question 26

Complete the statement correctly. Fetal hemoglobin

A) is better able to release oxygen than is adult hemoglobin.
B) has a higher affinity for carbon dioxide than does adult hemoglobin.
C) binds more carbon dioxide molecules than adult hemoglobin.
D) has a higher affinity for oxygen than does adult hemoglobin.
E) is better able to release carbon dioxide than is adult hemoglobin.

Question 27

Birds generate a lot of heat, especially during flight. Yet the adipose tissue under their skin and the feathers atop their skin make it difficult to eliminate excess heat across the skin. Which of the following can absorb body heat and eliminate it from the bird most effectively?

A) lymph in the lymphatic vessels
B) blood in the heart
C) blood in the vessels
D) urine in the bladder
E) air in the air sacs

Question 28

Use the following information when answering the corresponding questions).
Lymph hearts are pumping structures that drive lymph through the lymphatic system, returning it to the circulatory system a large veins entering the heart. Researchers examined rate and strength of pumping of lymph hearts in two species of amphibi toad Bufo marinus) and a frog Rana catesbiana). During hemorrhage or dehydration, the volume of blood in the circulatory system falls. A hormone, arginine vasotocin AVT), is released in these situations. The researchers examined the effect of AVT on lymph heart function. They found that AVT increased pressure at the lymph heart, but did not affect the rate of lymph heart pumping. They also examined the effect of atrial natriuretic peptide ANP), a hormone that is released when blood volume is higher than normal. E. A. DeGrauw and S. S. Hillman. 2004. General function and endocrine control of the posterior lymph hearts in Bufo marinus and Rana catesbiana. Physiological and Biochemical Zoology 774):594- 600.)

-What is a diagnosis of hypertension in adults based on?

A) blood pressure being greater than 140/90 mm Hg systolic/diastolic)
B) percentage of blood volume made up of platelets
C) measurement of fatty deposits on the endothelium of arteries
D) measurement of the LDL/HDL ratio in peripheral blood
E) number of leukocytes per cubic millimetre of blood

Question 29

Which of the four muscular chambers of the human heart directly propels blood into the pulmonary circulation?

A) left ventricle
B) right atrium
C) right ventricle
D) left atrium

Question 30

Blood is pumped at high pressures in arteries from the heart to ensure that all parts of the body receive adequate blood flow. Capillary beds, however, would hemorrhage under direct arterial pressures. How does the design of the circulation network contribute to reducing blood pressure to avoid this scenario?

A) Fluid loss from the arteries is high enough that pressure drops off significantly by the time blood reaches the capillaries.
B) Blood flow through the capillaries is essentially frictionless, and this reduces the amount of pressure on their walls.
C) The total cross- sectional diameter of the arterial circulation increases with progression from artery to arteriole to capillary, leading to a reduced blood pressure.
D) All of the above answers apply.

Question 31

Which of the following result, either directly or indirectly, when carbonic anhydrase is functioning properly?

A) The amount of oxygen released by hemoglobin decreases.
B) The amount of carbon dioxide diffusing into red blood cells increases.
C) The pH of capillary blood decreases.
D) Only A and B are true.
E) Only B and C are true.

Question 32

Which of the following functions is not a function of insect hemolymph?

A) transport of carbon dioxide
B) transport of hormones
C) transport of wastes
D) transport of cells involved in the immune response

Question 33

Use the following information when answering the corresponding questions).
Lymph hearts are pumping structures that drive lymph through the lymphatic system, returning it to the circulatory system a large veins entering the heart. Researchers examined rate and strength of pumping of lymph hearts in two species of amphibi toad Bufo marinus) and a frog Rana catesbiana). During hemorrhage or dehydration, the volume of blood in the circulatory system falls. A hormone, arginine vasotocin AVT), is released in these situations. The researchers examined the effect of AVT on lymph heart function. They found that AVT increased pressure at the lymph heart, but did not affect the rate of lymph heart pumping. They also examined the effect of atrial natriuretic peptide ANP), a hormone that is released when blood volume is higher than normal. E. A. DeGrauw and S. S. Hillman. 2004. General function and endocrine control of the posterior lymph hearts in Bufo marinus and Rana catesbiana. Physiological and Biochemical Zoology 774):594- 600.)

-What effect would increasing lymph heart pressure have?

A) Blood volume would increase.
B) Hemorrhage would decrease.
C) Blood volume would decrease.
D) Hemorrhage would increase.
E) None of the above answers apply.

Question 34

A significant increase in the amount of interstitial fluid surrounding the capillary beds of a human's lungs will cause

A) a decrease in the amount of work needed for effective ventilation of the lungs.
B) an increase of pressure that would cause the capillary beds to burst.
C) an increase in the amount of oxygen moving from the lungs into the blood.
D) a decrease in the amount of oxygen moving from the lungs into the blood.
E) an increase in the amount of carbon dioxide moving from the blood to the lungs.

Question 35

Which of the following mechanisms are used to regulate blood pressure in the closed circulatory system of vertebrates?

A) constricting and relaxing sphincters in the walls of arterioles
B) changing the force of heart contraction
C) adjusting the volume of blood contained in the veins
D) all of the above

Question 36

Use the following information when answering the corresponding questions).
Lymph hearts are pumping structures that drive lymph through the lymphatic system, returning it to the circulatory system a large veins entering the heart. Researchers examined rate and strength of pumping of lymph hearts in two species of amphibi toad Bufo marinus) and a frog Rana catesbiana). During hemorrhage or dehydration, the volume of blood in the circulatory system falls. A hormone, arginine vasotocin AVT), is released in these situations. The researchers examined the effect of AVT on lymph heart function. They found that AVT increased pressure at the lymph heart, but did not affect the rate of lymph heart pumping. They also examined the effect of atrial natriuretic peptide ANP), a hormone that is released when blood volume is higher than normal. E. A. DeGrauw and S. S. Hillman. 2004. General function and endocrine control of the posterior lymph hearts in Bufo marinus and Rana catesbiana. Physiological and Biochemical Zoology 774):594- 600.)
Many organs have adaptations to increase the rate of diffusion of a gas or solute. How are fish gills adapted to optimize oxygen absorption?

A) Continual flow of water across the gills
B) Co- current flow of water across the gills and blood within the gill capillaries
C) Countercurrent flow of water across the gills and blood within the gill capillaries
D) Bidirectional flow of water across the gills

Question 37

Baroreceptors are specialized pressure- sensing nerve cells that are important in circulatory homeostasis. Where are these nerve cells located in humans?

A) cells in brain
B) arteries entering the neck region
C) arteries leaving the heart
D) all of the above
E) only B and C

Question 38

Insect trachea come in direct contact with the internal organs to which they deliver oxygen. What parameter of Fick's Law does this optimize?

A) A
B) P
C) K
D) D

Question 39

An animal has a cardiac output of 40 mL/min and a stroke volume of 5 mL. What is its heart rate?

A) 12.5 beats/minute
B) 8 beats/minute
C) 200 beats/minute
D) Heart rate cannot be determined with only these two variables.

Question 40

Some animals have no gills when young but then develop gills that grow larger as the animal grows larger. What is the reason for this increase in gill size?

A) Relative to their surface area, the young have more body volume in which they can store oxygen for long periods of time.
B) The young of these animals are much more active than the adult, which leads to a higher BMR basal metabolic rate) and, therefore, a higher need for oxygen.
C) The young have a higher basal metabolic rate.
D) Relative to their volume, the young have more surface area across which they can transport all the oxygen they need.

Question 41

Where does the blood within the pulmonary vein travel next?

A) left atrium of the heart
B) pulmonary artery
C) alveolar capillaries
D) right atrium of the heart

Question 42

Figure 42.1
On the ECG above, within which waveform would atrial relaxation occur?

A) 1
B) 2
C) 3

Question 43

Figure 42.1
On the ECG above, which waveform represents ventricular electrical activity?

A) 1
B) 2
C) 3

Question 44

Figure 42.1
On the ECG above, which waveform represents ventricular relaxation?

A) 1
B) 2
C) 3

Question 45

Which of the following is a function of the insect tracheal system?

A) transport of cells involved in the immune response
B) transport of carbon dioxide
C) transport of wastes
D) transport of hormones

Question 46

Figure 42.1
On the ECG above, which waveform represents electrical activity within the atria?

A) 1
B) 2
C) 3