49) The sun shining on a tidal pool during a hot day heats the water. As some water evaporates, the pool
becomes saltier, causing
A) a decrease in its carbon dioxide content.
B) a decrease in its oxygen content.
C) an increase in its ability to sustain aerobic organisms.
D) a decrease in the water’s density.
E) a decrease in the movement of the water molecules.
50) Sponges, cnidarians, and flatworms lack a specialized gas exchange surface because
A) they are too large for a circulatory system to operate well.
B) they live without need for oxygen.
C) they do not produce carbon dioxide.
D) countercurrent exchange mechanisms cannot function well in their living conditions.
E) nearly all of their cells are in direct contact with the external environment.
51) Flying insects do all of the following except
A) increase metabolism as much as 200-fold during flight.
B) switch from diffusion of tracheal gases to active transport during flight.
C) utilize high numbers of mitochondria in flight muscles.
D) produce water molecules from oxygen in mitochondria.
E) generate carbon dioxide from catabolism of fuel molecules.
52) The epiglottis of a human covers the glottis when he or she is
A) talking.
B) breathing.
C) swallowing.
D) yawning.
E) sleeping.
53) In mammals, most gas exchange between the atmosphere and the pulmonary blood occurs in the
A) trachea.
B) larynx.
C) bronchi.
D) bronchioles.
E) alveoli.
54) Gas exchange is more difficult for aquatic animals with gills than for terrestrial animals with lungs
because
A) water is less dense than air.
B) water contains much less O2 than air per unit volume.
C) gills have less surface area than lungs.
D) gills allow only unidirectional transport.
E) gills allow water to flow in one direction.
55) Countercurrent exchange is evident in
A) the flow of water across the gills of a fish and that of blood within those gills.
B) the flow of blood in the dorsal vessel of an insect and that of air within its tracheae.
C) the flow of air within the primary bronchi of a human and that of blood within the pulmonary veins.
D) the flow of water across the skin of a frog and that of blood within the ventricle of its heart.
E) the flow of fluid out of the arterial end of a capillary and that of fluid back into the venous end of the
same capillary.
56) Countercurrent exchange in the fish gill helps to maximize
A) endocytosis.
B) blood pressure.
C) diffusion.
D) active transport.
E) osmosis.
57) Air-breathing insects carry out gas exchange
A) in their specialized external gills.
B) in their specialized internal gills.
C) in the alveoli of their lungs.
D) across the membranes of their cells.
E) across all parts of their thin cuticular exoskeleton.
58) An oil-water mixture works as an insecticidal spray against mosquitoes and other insects because it
A) coats their lungs.
B) blocks the openings into the tracheal system.
C) interferes with gas exchange across the capillaries.
D) clogs their bronchi.
E) prevents gases from leaving the atmosphere.
59) Atmospheric pressure at sea level is equal to a column of 760 mm Hg. Oxygen makes up 21% of the
atmosphere by volume. The partial pressure of oxygen (PO2) in such conditions is
A) 160 mm Hg.
B) 16 mm Hg.
C) 120/75.
D) 21/760.
E) 760/21.
60) Some human infants, especially those born prematurely, suffer serious respiratory failure because of
A) the sudden change from the uterine environment to the air.
B) the overproduction of surfactants.
C) the incomplete development of the lung surface.
D) lung collapse due to inadequate production of surfactant.
E) mutations in the genes involved in lung formation.
61) Of the following choices, impairment of a mammal’s breathing cycle is most likely following neural
damage in
A) the cerebrum and cerebellum.
B) the medulla oblongata and the pons.
C) the adrenal medulla and the adrenal cortex.
D) the thalamus and the hypothalamus.
E) the frontal lobe and the temporal lobe.
62) Air rushes into the lungs of humans during inhalation because
A) the rib muscles and diaphragm contract, increasing the lung volume.
B) the volume of the alveoli increases as smooth muscles contract.
C) gas flows from a region of lower pressure to a region of higher pressure.
D) pulmonary muscles contract and pull on the outer surface of the lungs.
E) a positive respiratory pressure is created when the diaphragm relaxes.
63) The exhalation of air from human lungs is driven by
A) a decrease in the volume of the thoracic cavity.
B) a decrease in the residual volume of the lungs.
C) the contraction of the diaphragm.
D) the closure of the epiglottis.
E) the expansion of the rib cage.
64) As a person goes from rest to full-effort exercise, there is an increase in the
A) tidal volume.
B) vital capacity.
C) residual volume.
D) total lung capacity.
E) All of the above would be different.
65) A person with a tidal volume of 450 mL, a vital capacity of 4,000 mL, and a residual volume of
1,000 mL would have a potential total lung capacity of
A) 1,450 mL.
B) 4,000 mL.
C) 4,450 mL.
D) 5,000 mL.
E) 5,450 mL.
66) During most daily activities, the human respiration rate is most closely linked to the blood levels of
A) nitric acid.
B) nitrogen.
C) oxygen.
D) carbon dioxide.
E) carbon monoxide.
67) Breathing is usually regulated by
A) erythropoietin levels in the blood.
B) the concentration of red blood cells.
C) hemoglobin levels in the blood.
D) CO2 and O2 concentration and pH-level sensors.
E) the lungs and the larynx.
68) At an atmospheric pressure of 870 mm Hg of 21% oxygen, the partial pressure of oxygen is
A) 100 mm Hg.
B) 127 mm Hg.
C) 151 mm Hg.
D) 182 mm Hg.
E) 219 mm Hg.
69) At sea level, atmospheric pressure is 760 mm Hg. Oxygen gas is approximately 21% of the total
gases in the atmosphere, so the approximate partial pressure of oxygen is
A) 0.2 mm Hg.
B) 20.0 mm Hg.
C) 76.0 mm Hg.
D) 160.0 mm Hg.
E) 508.0 mm Hg.
70) At the summit of a high mountain, the atmospheric pressure is 380 mm Hg. If the atmosphere is still
composed of 21% oxygen, then the partial pressure of oxygen at this altitude is
A) 0 mm Hg.
B) 80 mm Hg.
C) 160 mm Hg.
D) 380 mm Hg.
E) 760 mm Hg.
71) Carbon dioxide levels in the blood and cerebrospinal fluid affect its pH. This enables the organism
to sense a disturbance in gas levels as
A) the brain directly measures and monitors carbon dioxide and causes breathing changes accordingly.
B) the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this
measure to control breathing.
C) the brain alters the pH of the cerebrospinal fluid to force the animal to retain more or less carbon
dioxide.
D) stretch receptors in the lungs cause the medulla oblongata to speed up or slow breathing.
E) the medulla oblongata is able to control the concentration of bicarbonate ions in the blood.
72) An increase from pH 7.2 to pH 7.4 around hemoglobin causes
A) hemoglobin to release all bound oxygen molecules.
B) an increase in the affinity of hemoglobin to bind oxygen molecules.
C) hemoglobin to denature.
D) an increase in the binding of H+ by hemoglobin.
E) hemoglobin to more readily give up its oxygen molecules.
73) An “internal reservoir” of oxygen in rested muscle is found in oxygen molecules bound to
A) hemoglobin.
B) bicarbonate ions.
C) carbonic acid.
D) actin and myosin.
E) myoglobin.
74) Hemoglobin and hemocyanin
A) are both found within blood cells.
B) are both red in color.
C) are both freely dissolved in the plasma.
D) both transport oxygen.
E) are both found in mammals.
75) The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in
A) the partial pressure of oxygen.
B) the partial pressure of carbon monoxide.
C) hemoglobin concentration.
D) temperature.
E) pH.
76) Most of the carbon dioxide produced by humans is
A) converted to bicarbonate ions by an enzyme in red blood cells.
B) bound to hemoglobin.
C) transported in the erythrocytes as carbonic acid.
D) simply dissolved in the plasma.
E) bicarbonate ions bound to hemoglobin.
77) Hydrogen ions produced within human red blood cells are prevented from significantly lowering
plasma pH because they bind to
A) hemoglobin.
B) plasma proteins.
C) carbon dioxide.
D) carbonic acid.
E) plasma buffers.
78) The hemocyanin of arthropods and molluscs differ from the hemoglobin of mammals in that
A) the oxygen dissociation curve for hemocyanin is linear.
B) hemocyanin carries appreciably more carbon dioxide.
C) hemocyanin has protein coupled to copper rather than iron.
D) the protein of hemocyanin is not bound to metal.
E) hemocyanin includes cyanic acid.
79) In an animal species known for endurance running rather than fast sprinting, you would expect to
find
A) a slower rate of oxygen consumption so that its breathing will not have to be accelerated.
B) an increase of storage of oxygen in myoglobin of its muscles.
C) a relatively slow heart rate in order to lower oxygen consumption.
D) a lower pressure of oxygen in the alveoli.
E) a much higher rate of oxygen consumption for its size.
Art Questions
Blood entering a capillary bed of an unusual vertebrate was measured for the pressures exerted by
various factors, as shown in Figure 42.1.
Figure 42.1
80) For this unusual capillary bed,
A) the pH is lower on the arterial side than on the venous side.
B) oxygen is taken up by the erythrocytes within the capillaries.
C) the osmotic pressure remains constant due to carbon dioxide compensation.
D) the hydrostatic pressure declines from the arterial side to the venous side because oxygen is lost.
E) fluids will leave the capillaries on the arterial side of the bed and re-enter on the venous side.
Scenario Questions
81) An anthropologist discovers the fossilized heart of an extinct animal. The evidence indicates that the
organism’s heart was large, well-formed, and had four chambers, with no connection between the right
and left sides. A reasonable conclusion supported by these observations is that the
A) animal had evolved from birds.
B) animal was endothermic and had a high metabolic rate.
C) animal was most closely related to alligators and crocodiles.
D) animal was likely an invertebrate animal.
E) species had little to no need to regulate blood pressure.
21
82) A group of students was designing an experiment to test the effect of smoking on grass frogs. They
hypothesized that keeping the frogs in a smoke-filled environment for defined periods would result in
the animals developing lung cancer. However, when they searched for previously published information
to shore up their hypothesis, they discovered they were quite wrong in their original assessment. Even
though they were never going to go ahead with their experiment (so as not to harm frogs needlessly),
they knew that a more likely outcome of putting carcinogens in the air would be the development of
A) the amphibian equivalent of hypertension.
B) skin cancer.
C) gill abnormalities in the next generation of tadpoles.
D) tracheal tube abnormalities.
E) diminished absorption of oxygen.
End-of-Chapter Questions
The following questions are from the end-of–chapter “Test Your Understanding” section in Chapter 42
of the textbook.
83) Which of the following respiratory systems is not closely associated with a blood supply?
A) the lungs of a vertebrate
B) the gills of a fish
C) the tracheal system of an insect
D) the skin of an earthworm
E) the parapodia of a polychaete worm
84) Blood returning to the mammalian heart in a pulmonary vein drains first into the
A) vena cava.
B) left atrium.
C) right atrium.
D) left ventricle.
E) right ventricle.
85) Pulse is a direct measure of
A) blood pressure.
B) stroke volume.
C) cardiac output.
D) heart rate.
E) breathing rate.
86) When you hold your breath, which of the following blood gas changes first leads to the urge to
breathe?
A) rising O2
B) falling O2
C) rising CO2
D) falling CO2
E) rising CO2 and falling O2
87) One feature that amphibians and humans have in common is
A) the number of heart chambers.
B) the type of gas exchange tissues.
C) a complete separation of circuits for circulation.
D) the number of circuits for circulation.
E) a low blood pressure in the systemic circuit.
88) If a molecule of CO2 released into the blood in your left toe is exhaled from your nose, it must pass
through all of the following except
A) the pulmonary vein.
B) an alveolus.
C) the trachea.
D) the right atrium.
E) the right ventricle.
89) Compared with the interstitial fluid that bathes active muscle cells, blood reaching these cells in
arteries has a
A) higher PO2.
B) higher PCO2.
C) greater bicarbonate concentration.
D) lower pH.
E) lower osmotic pressure.
90) Which of the following reactions prevails in red blood cells traveling through alveolar capillaries?
(Hb = hemoglobin)
A) Hb + 4 O2 → Hb(O2)4
B) Hb(O2)4 → Hb + 4 O2
C) CO2 + H2O → H2CO3
D) H2CO3 → H+ + HCO3–
E) Hb + 4 CO2 → Hb(CO2)4