chapter24

1) Gas exchange in the aquatic salamander known as the axolotl is correctly described as A) active transport to move oxygen into the salamander from the water. B) carrier-mediated transport to move oxygen into the salamander from the water. C) facilitated diffusion of carbon dioxide from the salamander into the water. D) simple diffusion of oxygen into the salamander from the water. E) active transport of carbon dioxide from the salamander into the water.

D

36) The plasma proteins in humans A) maintain the blood's osmotic pressure. B) transport water-soluble lipids. C) carry out gas exchange. D) undergo aerobic metabolism. E) transport oxygen.

a

45) 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.

a

49) 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.

a

5) 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.

a

55) 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.

a

56) 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.

a

6) 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.

a

65) 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.

a

66) 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.

a

7) Which of the following would increase the amount of oxygen undergoing net diffusion from the lungs into the blood? A) increasing the binding of oxygen to hemoglobin B) increasing the water vapor content of air in the lungs C) increasing the partial pressure of oxygen in the blood D) decreasing the red blood cell count of the blood E) decreasing the partial pressure of oxygen in the lung

a

1) 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.

b

2) 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.

b

2) 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.

b

2) Circulatory systems compensate for A) temperature differences between the lungs and the active tissue. B) the slow rate at which diffusion occurs over large distances. C) the problem of communication systems involving only the nervous system. D) the need to cushion animals from trauma. E) the need fetal organisms have for maintaining an optimal body temperature.

b

34) The hormone that stimulates the production of red blood cells and the organ where this hormone is synthesized are A) growth hormone and pancreas, respectively. B) erythropoietin and kidney, respectively. C) cortisol and adrenal gland, respectively. D) epinephrine and adrenal gland, respectively. E) acetylcholine and bone marrow, respectively.

b

38) The meshwork that forms the fabric of a blood clot is A) chymotrypsin. B) fibrin. C) thrombin. D) prothrombin. E) collagen.

b

4) The circulatory system of bony fishes, rays, and sharks is similar to A) that of birds, with a four-chambered heart. B) the portal systems of mammals, where two capillary beds occur sequentially, without passage of blood through a pumping chamber. C) that of reptiles, with one pumping chamber driving blood flow to a gas-exchange organ, and a different pumping chamber driving blood to the rest of the circulation. D) that of sponges, where gas exchange in all cells occurs directly with the external environment. E) that of humans, where there are four pumping chambers to drive blood flow.

b

40) 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.

b

44) 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 collapse in air.

b

48) 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.

b

53) 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.

b

54) 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.

b

59) Carbon dioxide levels in the blood and cerebrospinal fluid affect their 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.

b

6) Organisms with a circulating body fluid that is distinct from the fluid that directly surrounds the body's cells are likely to have A) an open circulatory system. B) a closed circulatory system. C) a gastrovascular cavity. D) branched tracheae. E) hemolymph.

b

61) 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. Answer: B

b

34.3 End-of-Chapter Questions 1) 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

c

35) Dissolved proteins in human plasma include which of the following? I. fibrinogen II. hemoglobin III. immunoglobulin A) I only B) II only C) I and III only D) II and III only E) I, II, and III

c

37) The production of red blood cells is stimulated by A) low-density lipoproteins. B) immunoglobulins. C) erythropoietin. D) epinephrine. E) platelets.

c

39) When the air in a testing chamber is specially mixed so that its oxygen content is 10% and its overall air pressure is 400 mm Hg, then PO2 is A) 400 mm Hg. B) 82 mm Hg. C) 40 mm Hg. D) 21 mm Hg. E) 4 mm Hg.

c

4) 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

c

42) The epiglottis of a human covers the glottis when he or she is A) talking. B) breathing. C) swallowing. D) yawning. E) sleeping.

c

46) Countercurrent exchange in the fish gill helps to maximize A) endocytosis. B) blood pressure. C) diffusion. D) active transport. E) osmosis.

c

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

c

67) The hemocyanin of arthropods and molluscs differs 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.

c

8) The only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart are the A) amphibians. B) birds. C) fishes. D) mammals. E) reptiles.

c

3) Pulse is a direct measure of A) blood pressure. B) stroke volume. C) cardiac output. D) heart rate. E) breathing rate.

d

33) In a healthy human, the typical life span of a red blood cell is A) 24 hours. B) 1 week. C) 1 month. D) 4 months. E) 80 years or more.

d

47) 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 finest branches of the trachea and cell membranes. E) across all parts of their thin cuticular exoskeleton.

d

50) 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.

d

51) 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.

d

52) 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.

d

57) 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.

d

58) 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.

d

63) 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.

d

7) In which of the following organisms does blood flow from the pulmocutaneous circulation to the heart before circulating through the rest of the body? A) annelids B) molluscs C) fishes D) frogs E) insects

d

3) The fluid that moves around in the circulatory system of a typical arthropod is A) the digestive juices. B) the intracellular fluid. C) the blood plasma. D) the cytosol. E) the interstitial fluid.

e

41) 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.

e

43) 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.

e

60) To become bound to hemoglobin for transport in a mammal, atmospheric molecules of oxygen must cross A) zero membranes—oxygen binds directly to hemoglobin, a protein dissolved in the plasma of the blood. B) one membrane—that of the lining in the lungs—and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood. C) two membranes—in and out of the cell lining the lung—and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood. D) four membranes—in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillary—and then bind directly to hemoglobin, a protein dissolved in the plasma of the blood. E) five membranes—in and out of the cell lining the lung, in and out of the endothelial cell lining an alveolar capillary, and into the red blood cell—to bind with hemoglobin.

e

62) 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.

e

64) 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.

e

68) 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) a decrease in myoglobin concentration in the 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.

e

9) To adjust blood pressure independently in the capillaries of the gas-exchange surface and in the capillaries of the general body circulation, an organism would need a(n) A) open circulatory system. B) hemocoel. C) lymphatic system. D) two-chambered heart. E) four-chambered heart.

e