For instance, a shrew has a higher metabolic rate and a greater surface area-to-volume ratio than a horse, which means that the shrew generates more internal heat per gram of body weight
Trang 1BIOLOGY TOPICAL:
Respiratory and Skin Systems
Test 1
Time: 21 Minutes*
Number of Questions: 16
* The timing restrictions for the science topical tests are optional
If you are using this test for the sole purpose of content
reinforcement, you may want to disregard the time limit
Trang 2DIRECTIONS: Most of the questions in the following
test are organized into groups, with a descriptive passage preceding each group of questions Study the passage, then select the single best answer to each question in the group Some of the questions are not based on a descriptive passage; you must also select the best answer to these questions If you are unsure of the best answer, eliminate the choices that you know are incorrect, then select an answer from the choices that remain Indicate your selection
by blackening the corresponding circle on your answer sheet A periodic table is provided below for your use with the questions
PERIODIC TABLE OF THE ELEMENTS
1
H
1.0
2
He
4.0 3
Li
6.9
4
Be
9.0
5
B
10.8
6
C
12.0
7
N
14.0
8
O
16.0
9
F
19.0
10
Ne
20.2 11
Na
23.0
12
Mg
24.3
13
Al
27.0
14
Si
28.1
15
P
31.0
16
S
32.1
17
Cl
35.5
18
Ar
39.9 19
K
39.1
20
Ca
40.1
21
Sc
45.0
22
Ti
47.9
23
V
50.9
24
Cr
52.0
25
Mn
54.9
26
Fe
55.8
27
Co
58.9
28
Ni
58.7
29
Cu
63.5
30
Zn
65.4
31
Ga
69.7
32
Ge
72.6
33
As
74.9
34
Se
79.0
35
Br
79.9
36
Kr
83.8 37
Rb
85.5
38
Sr
87.6
39
Y
88.9
40
Zr
91.2
41
Nb
92.9
42
Mo
95.9
43
Tc
(98)
44
Ru
101.1
45
Rh
102.9
46
Pd
106.4
47
Ag
107.9
48
Cd
112.4
49
In
114.8
50
Sn
118.7
51
Sb
121.8
52
Te
127.6
53
I
126.9
54
Xe
131.3 55
Cs
132.9
56
Ba
137.3
57
La *
138.9
72
Hf
178.5
73
Ta
180.9
74
W
183.9
75
Re
186.2
76
Os
190.2
77
Ir
192.2
78
Pt
195.1
79
Au
197.0
80
Hg
200.6
81
Tl
204.4
82
Pb
207.2
83
Bi
209.0
84
Po
(209)
85
At
(210)
86
Rn
(222) 87
Fr
(223)
88
Ra
226.0
89
Ac †
227.0
104
Unq
(261)
105
Unp
(262)
106
Unh
(263)
107
Uns
(262)
108
Uno
(265)
109
Une
(267)
*
58
Ce
140.1
59
Pr
140.9
60
Nd
144.2
61
Pm
(145)
62
Sm
150.4
63
Eu
152.0
64
Gd
157.3
65
Tb
158.9
66
Dy
162.5
67
Ho
164.9
68
Er
167.3
69
Tm
168.9
70
Yb
173.0
71
Lu
175.0
†
90
Th
232.0
91
Pa
(231)
92
U
238.0
93
Np
(237)
94
Pu
(244)
95
Am
(243)
96
Cm
(247)
97
Bk
(247)
98
Cf
(251)
99
Es
(252)
100
Fm
(257)
101
Md
(258)
102
No
(259)
103
Lr
(260)
GO ON TO THE NEXT PAGE.
Trang 3Passage I (Questions 1–5)
All birds and mammals are able to maintain
relatively constant body temperatures despite fluctuations
in external temperature These animals have evolved
thermoregulatory mechanisms that help them adapt to
their environments One such mechanism involves
metabolic rates A plot of the rate of oxygen consumption
versus body weight for various mammals reveals that
metabolic rate is inversely proportional to body weight
(Figure 1) However, metabolic rate and the transfer of
heat to the environment are directly proportional to the
surface area-to-volume ratio of the animal For instance, a
shrew has a higher metabolic rate and a greater surface
area-to-volume ratio than a horse, which means that the
shrew generates more internal heat per gram of body
weight and loses more heat to the environment This
makes it especially difficult for small animals to maintain
a constant body temperature in cold weather
A thermoregulatory mechanism often used by
mammals to lose excess body heat in hot weather is
sweating, but this requires a large supply of readily
available water Mammals inhabiting environments that
are both hot and dry have had to evolve alternative means
of handling the heat generated by metabolism For
example, gazelles possess retia, vascular structures that
enable them to maintain organ-specific temperatures
Gazelles have been found to have brain temperatures as
much as 2.9°C lower than their body core temperatures
The existence of a vascular structure that thermally
isolates the head from the rest of the animal means that
scarce water is used only to cool the head, while body
temperature is allowed to rise Local cooling of the head
occurs via panting
Body weight (kilograms)
Shrew
0 0.01 0.1 1 10 100 1,000
Harvest mouse Cactus mouse House mouse Flying squirrel RatRabbitCat Dog Horse Human
Figure 1
1 It has often been observed that small animals, such
as baby penguins, huddle together when it is cold outside What is the most likely explanation for this phenomenon?
A Huddling increases the effective surface
area-to-volume ratio, thereby decreasing the loss of body heat
B Huddling decreases the effective surface
area-to-volume ratio, thereby decreasing the loss of body heat
C Huddling decreases the effective surface
area-to-volume ratio, thereby increasing the loss of body heat
D Huddling increases the effective surface
area-to-volume ratio, thereby increasing the loss of body heat
2 Based on the information in the passage, it can be
reasonably inferred that:
A gazelles have evolved beyond the need for
thermoregulation
B the primary object of thermoregulation in
gazelles is the maintenance of a constant brain temperature
C gazelles have not successfully adapted to their
environment
D gazelles tolerate large water losses.
3 Which of the following is most likely true of an
animal that must keep all of its vital organs at approximately the same temperature?
A It could not survive in a desert environment.
B It sweats excessively and becomes dehydrated in
hot weather
C Its body temperature is dictated by the most
temperature-sensitive organ
D It must always have a large supply of water.
GO ON TO THE NEXT PAGE.
Trang 44 The main advantage that the gazelle has over
mammals (inhabiting the same environment) that
cool themselves primarily by sweating is:
A the ability to maintain a lower brain temperature.
B the ability to tolerate higher external
temperatures
C lower metabolic requirements.
D more efficient water conservation.
5 Many Arctic animals have a countercurrent heat
exchange mechanism in their extremities that
prevents excessive heat loss from dissipation Veins
returning from the extremities with cold venous blood
are in direct contact with arteries carrying warm blood
to the extremities By which of the following
mechanisms is heat transferred from the arteries to the
veins?
A Conduction
B Convection
C Radiation
D Evaporation
GO ON TO THE NEXT PAGE.
Trang 5Passage II (Questions 6–11)
Emphysema is a lung disease characterized by
marked destruction of the alveolar walls, leading to the
permanent enlargement of the alveoli The condition arises
most commonly as a consequence of heavy cigarette
smoking Smoking irritates the bronchi and bronchioles,
resulting in chronic infection Furthermore, it causes
partial paralysis of the cilia of the epithelial lining of the
respiratory tract, disabling the mechanism for mucus
removal from the passageways Finally, it stimulates
mucus secretion and inhibits the alveolar macrophages
The resulting infection and excess mucus, along with
inflammatory edema (accumulation of fluid in the
epithelial tissue), lead to obstruction of many of the
smaller airways, making it difficult for the patient to
move air out of the lungs The subsequent entrapment of
air stretches the alveoli and contributes to the destruction
of the alveolar walls
Expiration becomes difficult in emphysematous
patients because bronchiolar obstruction increases airway
resistance This resistance is already elevated during
expiration due to the compressive force on the outside of
the lung Slowing of forced expiration is the most reliable
indicator of chronic emphysema
The significant loss of functional lung tissue that
often results from chronic emphysema has two important
physiological effects First, it causes a decrease in the
diffusion capacity of the lung, which is the ability of the
respiratory membrane to exchange gases between the
alveoli and the pulmonary capillaries Second, it decreases
the number of pulmonary capillaries through which blood
can pass As a result, the pulmonary vascular resistance
increases markedly, causing pulmonary hypertension
6 The inhibitory effect of cigarette smoking on the
alveolar macrophages will most directly contribute to
which of the following?
A Increase in bacteria and solid particles in the
alveoli
B Increase in the number of paralyzed cilia
C Decrease in the destruction of alveolar walls
D Decrease in the amount of functional lung tissue
7 Oxygen moves from the alveoli into the pulmonary
capillaries and carbon dioxide moves from the pulmonary capillaries into the alveoli via:
A active transport.
B facilitated diffusion.
C simple diffusion.
D osmosis.
8 The decrease in the number of pulmonary capillaries
due to the loss of functional lung tissue will most likely cause a pressure overload in the:
A right atrium.
B right ventricle.
C left atrium.
D left ventricle.
9 A clinical test for emphysema is the forced
expiratory vital capacity maneuver, in which the person first inspires to total lung capacity and then expires as rapidly as possible Which of the following graphs best illustrates the difference in test results between a normal individual and one with emphysema?
B
A
seconds
seconds
lung volume
C
D
seconds
seconds
lung volume
lung volume
lung volume
normal emphysema
GO ON TO THE NEXT PAGE.
Trang 61 0 Based on the information in the passage a patient
with severe emphysema who is breathing at a normal
rate will exhibit:
A low PCO2 and high PO2 in the blood
B low PCO2 and low PO2 in the blood
C high PCO2 and high PO2 in the blood
D high PCO2 and low PO2 in the blood
1 1 In an individual with emphysema, new, larger
alveolar chambers are formed as the walls of the
original alveoli dissolve and the alveoli coalesce
However, the diffusing capacity of the lung is greatly
reduced What best accounts for this phenomenon?
A The total volume of the alveolar chambers is
decreased
B The total surface area of the respiratory
membrane is decreased
C The total number of alveolar chambers available
during respiration is decreased
D The thickness of the respiratory membrane is
increased
GO ON TO THE NEXT PAGE.
Trang 7Questions 12 through 16 are
NOT based on a descriptive
passage
1 2 Air entering the lungs of a tracheotomy patient
through a tracheostomy (a tube inserted directly into
the trachea) is colder and dryer than normal, which
often causes lung crusting and infection This occurs
primarily because the air:
A enters the respiratory system too rapidly to be
filtered
B is not properly humidified by the larynx.
C does not flow through the nasal passageways.
D does not flow past the mouth and tongue.
1 3 The graph below shows the relationship between O2
consumption and total alveolar ventilation (the rate at
which air reaches the alveoli) during exercise What is
the net effect of exercise on arterial PO2?
O2 consumption (L/min)
Total
alveolar
ventilation
(L/min)
1.0 2.0 3.0 4.0 20
40
60
80
100
110
A PO 2 remains the same, because ventilation
increases as metabolism increases
B PO2 increases markedly, because ventilation
increases as metabolism decreases
C PO2 decreases, because oxygen consumption
increases
D PO 2 initially decreases and then rebounds,
because ventilation increases
1 4 When an animal pants, it breathes rapidly in and out,
causing large quantities of new air to come into contact with the upper portions of the respiratory passages The function of this mechanism is to:
A rapidly increase CO2 expiration
B moisten the mucosa of the respiratory passages.
C minimize the movement of respiratory muscles.
D decrease body heat via evaporation.
1 5 Heat conduction to the skin is controlled by the
degree of vasoconstriction of the arterioles that supply blood to the skin Which of the following controls the vasoconstriction of these arterioles?
A Autonomic nervous system
B Sensory nervous system
C Somatic nervous system
D Spinal cord
1 6 A person unacclimatized to hot weather will often
lose as much as 15 – 30 g of salt each day for the first few days due to profuse sweating After 4 to 6 weeks of acclimatization, however, the same person will lose only 3 – 5 g of salt per day This decrease in salt loss is caused by:
A increased ADH secretion.
B decreased ADH secretion.
C increased aldosterone secretion.
D decreased aldosterone secretion.
END OF TEST
Trang 8ANSWER KEY:
Trang 9RESPIRATORY AND SKIN SYSTEMS TEST 1 TRANSCRIPT
Passage I (Questions 1-5)
1 Choice B is the correct answer An animal's primary "goal" when it's cold outside is to keep warm It wants
to limit the amount of heat lost to the environment, because the more heat it loses, the colder the animal feels Realizing that, you should have eliminated choices C and D immediately, since the last part of both statements says, "thereby
increasing the loss of body heat." So now you've narrowed it down to either choice A or B The amount of heat transferred
from a body to its external environment is directly proportional to the amount of surface area (a.k.a skin) exposed to the external environment If you couldn't recall this, the information was provided for you in the passage If heat is lost through exposed surface area, then it follows that the more surface area exposed, the greater the amount of heat lost According to the passage, smaller animals have a tougher time than larger ones trying to maintain a constant internal body temperature, because smaller animals have a greater surface area-to-volume ratio and a higher metabolic rate than large ones Therefore, smaller animals generate more heat and lose more heat to their environment
When the external temperature is lower than the animal's internal temperature, heat is transferred to the external
environment via radiation Radiation is defined as the transfer of heat between objects that are not in direct contact So, as I
already said, it follows that the more surface area exposed, the more heat lost This means that if a group of small animals can somehow decrease their collective surface area-to-volume ration, then they will lose less heat as a unit Huddling accomplishes this when a group of small animals huddle together in the cold, they are decreasing the total surface area exposed, as a group, to the environment In other words, huddling decreases the effective surface area-to-volume ration,
thereby decreasing the loss of body heat per individual baby penguin So, choice A is wrong and the correct answer is
choice B
2 Choice B is the correct answer It's apparent from the question stem that this is a reading comprehension-type
question, obviously dealing with gazelles, since that's the subject that all four answer choices deal with According to the passage, gazelles have evolved structures called retia, which are vascular structures that allow them to maintain organ-specific
temperatures Thus, right off the bat, you should have eliminated choice A, because we know that the gazelle has evolved specific adaptations for thermoregulation; it has not evolved beyond the need for thermoregulation no animal has The
gazelle's retia are located in the carotid arteries, which are located in the next region, and afford the gazelle the luxury of having a brain temperature almost 3 degrees cooler than its body core temperature This also means that the gazelle doesn't lose valuable water trying to cool down its head, so water is conserved which is a particularly useful adaptation in a hot, arid climate From this, it can reasonably be inferred from the passage that one of the primary objects of thermoregulation in gazelles is the maintenance of a constant brain temperature So, choice B is the right answer According to the passage, the gazelle's head is cooled by panting, which involves rapid, short, shallow breaths that allow air to pass over the tongue and evaporate saliva Unlike sweating, panting does not incur a great loss of water, salt, and other essential ions So choice D is wrong And this also makes it clear that choice C is not a valid conclusion, because the evolution of such complex and
unique thermoregulatory mechanisms implies that the gazelle has successfully adapted to its desert-like environment Again,
choice B is the right answer
3 Choice C is the correct answer You're being asked to draw a conclusion about what it means for all organs,
including the brain, to have a single body temperature In the passage you're told that gazelles evolved retia to deal with a climate that is both hot and dry Water loss is kept at a minimum by only cooling the head, while body temperature is allowed to rise This seems to imply that the gazelle brain is a temperature-sensitive organ that must be maintained at a particular temperature for proper functioning, regardless of external temperature and the temperature of the rest of the body Now, if an animal must keep ALL of its vital organs at the same temperature, and if one particular organ, such as the brain,
is the most temperature-sensitive organ, then the animal is obligated to maintain its body temperature at the temperature required by that organ So choice C is the right answer Let's look at the remaining choices You don't know at what temperature the most temperature-sensitive organ in this hypothetical animal must be maintained, so you can't conclude that this animal can't survive in a desert, or that it will sweat very heavily in hot weather So choice A and B can be ruled out As for choice D all animals need water to survive, including humans But whether or not the animal needs a large supply of water depends on how efficient its thermoregulatory mechanisms are; for instance, camels don't need much water even though they live in a hot, dry environment Again, choice C is the correct answer
4 Choice D is the correct answer This is another question about the gazelle, and it requires you to infer what
advantage the gazelles with their retia have over other mammals in the same or similar habitat a hot dry environment According to the passage, the main advantage to retia is water conservation An animal that sweats in hot weather begins to
do so when internal heat production rises When the sweat evaporates, it cools the body, but at the expense of a great water loss Gazelles, on the other hand, cool themselves by panting, and by allowing their body temperature to rise, thereby
Trang 10or the question stem for you to conclude any of these things Hence, choices A, B, and C are all incorrect Again, choice D is the right answer
5 Choice A is the correct answer This is one of those questions that is peripherally related to the passage
topic, which is thermoregulation, but that can really be answered without reading the passage at all To answer it you have to rely entirely on your outside knowledge of the methods by which heat is transferred from one object or surface to another So let's discuss the answer choices one by one Conduction, choice A, is the transfer of thermal energy, or heat, between the molecules of two bodies that are in direct physical contact and differ in temperature Heat is transferred from the warmer body
to the colder body In the countercurrent heat exchange mechanism found in animals inhabiting cold environments, such as the Arctic fox, the warm arteries are in direct physical contact with the cold veins, allowing for the transfer of heat from the arteries to the veins So choice A is the answer to this question Choice B, convection, is the movement of air or water in currents to or from the body's surface For example, when a person sweats on a breezy day, the evaporation of the sweat warms the air above the skin; when air is warmed, it rises, and new, colder air now comes into contact with the surface of the skin Radiation, choice C, refers to the transfer of energy between objects that are NOT in direct physical contact by way of electromagnetic waves All objects with temperatures above absolute zero produce radiation Thermal radiation occurs when an animal's body temperature is warmer or colder than air temperature Heat is exchanged between the animal and the air as electromagnetic waves Choice D, evaporation, is the loss of heat from the surface of a liquid as liquid molecules evaporate into gaseous molecules Every gram of water that evaporates dissipates over 500 calories, thus cooling the surface from which
it evaporates Again, the correct answer is choice A
Passage II (Questions 6-11)
6 The correct choice is A The alveolar macrophages, which are present in the alveolar walls, engulf bacteria,
dead cells, and particles that become trapped in the alveoli The alveolar macrophages are white blood cells that fight to prevent infection and are, therefore an integral component of the lung's defense system Since, according to the passage, smoking inhibits the alveolar macrophages and prevents them from doing their job, the amount of bacteria and the number of solid particles in the alveoli will increase, and so choice A is correct Even if you weren't familiar with the role macrophages play in the alveoli, you could have deduced the right answer It can be inferred from the passage that inhibition of the alveolar macrophages promotes infection Among the choices, the only one that would lead directly to infection is choice A
While it is true that smoking causes an increase in the number of paralyzed cilia of the lung epithelium (choice B)
and a decrease in the amount of functional lung tissue (choice D), these effects are not the direct consequence of the inhibition
of macrophages Choice C makes no sense because smoking causes an increase, not a decrease, in the destruction of alveolar walls Again, choice A is the right answer
7 The correct answer is choice C First, let's review each of the mechanisms of transport Active transport,
choice A, is the net movement of dissolved particles against their concentration gradient with the help of carrier molecules Active transport requires energy in the form of ATP An example of active transport is the sodium-potassium pump You can eliminate active transport right away because the passage refers to the "diffusion capacity" of the lung Facilitated diffusion, choice B, is the net movement of dissolved particles along their concentration gradient with the help of carrier molecules It
does not require energy input An example of facilitated diffusion is glucose transport in the nephron Simple diffusion,
choice C, is the net movement of dissolved particles down their concentration gradient Diffusion is a passive process An excellent example of simple diffusion is gas exchange in the lungs Oxygen diffuses from the alveoli, where it is highly concentrated, into the pulmonary capillaries, where there is a low concentration of oxygen, without the help of carrier molecules; carbon dioxide diffuses from the pulmonary capillaries into the alveoli, down its concentration gradient Thus choice C is the correct answer Choice D, osmosis, is the simple diffusion of water from a region of lower solute
concentration to a region of higher solute concentration since we are obviously not talking about the movement of water in
this question, you can eliminate choice D right away as well Again, choice C is the right answer
8 The correct answer is choice B The right ventricle of the heart pumps deoxygenated blood into the lungs via the pulmonary arteries Remember, arteries carry blood away from the heart When the loss of functional lung tissue reduces
the number of pulmonary capillaries through which blood can flow, the resulting pressure overload leads to right ventricular enlargement, a condition known as cor pulmonale The right atrium, choice A, pumps deoxygenated blood returning from the body into the right ventricle The left atrium, choice C, receives oxygenated blood from the lungs via the pulmonary veins, and pumps the blood into the left ventricle, choice D Again, choice B is the right answer
9 The correct answer is choice A The passage stresses than an emphysematous patient has a great deal of
difficulty with expiration, or exhaling In fact, we're told that "slowing of forced expiration is the most reliable indicator of chronic emphysema." We can therefore predict that the graph of an emphysematous patient performing the forced expiratory