Passage I

    Measles is an extremely contagious viral infection spread by the respiratory route. Figure 1 shows the course of measles from time of exposure to recovery from the infection.

    After recovery from measles, the infected individual develops immunity or resistance to reinfection. Figure 1 shows the development of immunity indicated by the antibody level.

Figure 1 adapted from D. M. McLean, Virology in Health Care. ©1980 by Williams & Wilkins.

     The number of reported cases of measles from 1950 through 1987 is depicted in Figure 2.

Figure 2 adapted from MMWR, "Summary of Notifiable Diseases." ©1986 Communicable Disease Center.
 

Set 3: Science 

Passage I

1. The best answer is C.
Figure 1 indicates where the virus excretion is found. Therefore, Figure 1 should be used to answer this question.

A. Skin
Incorrect. Figure 1 does not indicate an elevated concentration of measles in the skin. Thus there is no evidence to support the claim that on Day 10, the greatest concentration of the measles virus would be in the skin.

B. Mouth
Incorrect. Figure 1 does not indicate an elevated concentration of measles in the mouth. Thus there is no evidence to support the claim that on Day 10, the greatest concentration of the measles virus would be in the mouth.

C. Blood
Correct. Figure 1 indicates that virus excretion is present in the blood between Day 7 and Day 12 of exposure. Figure 1 does not indicate that virus excretion is present in any other part of the body on Day 10. Thus, C is correct.

D. Throat
Incorrect. Figure 1 indicates that virus excretion is present in the throat on Day 12 after exposure, but not before Day 12. Thus, there is no indication of a high concentration of the measles virus in the throat on Day 10.

2. The best answer is H.
Figure 2 indicates that the measles vaccine was introduced during 1963. Figure 2 also indicates the number of reported cases (in thousands) of measles from 1950 through 1987.

F. It completely eradicated measles after 1963.
Incorrect. Figure 2 indicates that cases of measles were reported after 1963. Therefore it is not correct to say that measles were eradicated after 1963.

G. It caused a decrease in the number of measles cases only during 1963.
Incorrect. Figure 2 does show a slight dip in the number of measles cases during 1963, however, the figure also indicates that following the introduction of the measles vaccine, the number of reported cases continued to drop through 1967.

H. It caused a gradual decrease from 400,000 measles cases in 1963 to approximately 1,500 in 1983.
Correct. According to Figure 2, in 1963, there were approximately 400,000 measles cases reported. Following 1963, this number continued to drop, reaching approximately 1,500 in 1985. Thus, H is the correct answer.

J. The introduction of the measles vaccine had no effect on the occurrence of measles after 1963.
Incorrect. According to Figure 2, prior to the introduction of the measles vaccine, the number of reported cases of the measles never fell below 300,000. However, once the measles vaccine was introduced in 1963, the number of reported cases of measles gradually fell.

3. The best answer is A.
Figure 1 depicts the progression of the measles from time of exposure until 10 years after exposure. Figure 1 also indicates the antibody level in the body.

A. Yes; the level of protective antibodies against measles would be elevated 6 months after exposure.
Correct. Figure 1 indicates that 6 months after exposure, the antibody level is elevated. Since this level is not elevated prior to infection, it would be possible to determine that a person had immunity against the measles virus 6 months after exposure by measuring the antibody level and determining that it was elevated.

B. Yes; the virus would still be present in the respiratory tract to protect against reinfection.
Incorrect. Figure 1 indicates that the virus excretion is present in the throat 2 to 3 weeks after exposure. However, the virus excretion is not present in the throat after 6 months.

C. No; the level of protective antibodies against measles would be undetectable 6 months after exposure.
Incorrect. Figure 1 indicates that the antibody level remains elevated for at least 10 years. Thus, the protective antibodies against measles would be detectable 6 months after exposure, making C incorrect.

D. No; the virus would no longer be present in the blood to protect against reinfection.
Incorrect. Even if the virus was no longer present in the blood, other factors could be measured to determine that a person had immunity against the measles virus 6 months after exposure. For example, the antibody level remains elevated for at least 10 years.

4. The best answer is F.
Figure 1 indicates the change in antibody level. It also indicates the presence of a fever, the presence of a rash, the presence of cold symptoms, and when the virus is found in the blood. Therefore, Figure 1 should be used to answer this question.

F. fever vanishes.
Correct. The fever vanishes on Day 2 of exposure. This is also when the antibody level begins to increase. Therefore, one can conclude that there is a rise in the antibody level when the fever vanishes.

G. rash first appears.
Incorrect. The rash first appears on Day 0 of onset. The antibody level remains constant until Day 2 of onset. Thus, the antibody level does not rise when the rash first appears.

H. cold symptoms are most severe.
Incorrect. Cold symptoms are most severe on approximately Day 0 of onset. The antibody level remains constant until Day 2 of onset. Thus, the antibody level does not rise when cold symptoms are most severe.

J. virus is present in the blood.
Incorrect. Figure 1 indicates that the virus excretion is present in the blood between Day 7 of exposure and Day 12 of exposure. Day 12 of exposure is 2 days before onset and 4 days before the antibody level begins to rise.

5. The best answer is D.
Figure 2 indicates the number of measles cases (in thousands) as a function of time.

A. 10.
Incorrect. Between 1981 and 1987, the number of measles cases reported reached a peak in 1986 at approximately 5,000 cases. The lowest number of reported measles cases occurred in 1983 at approximately 1,000 cases. According to the graph, at no time between 1981 and 1987 was the number of measles cases 10 or less.

B. 100.
Incorrect. Between 1981 and 1987, the number of measles cases reported reached a peak in 1986 at approximately 5,000 cases. The lowest number of reported measles cases occurred in 1983 at approximately 1,000 cases. According to the graph, at no time between 1981 and 1987 was the number of measles cases 100 or less.

C. 1,000.
Incorrect. Between 1981 and 1987, the number of measles cases reported reached a peak in 1986 at approximately 5,000 cases. The LOWEST number of reported measles cases occurred in 1983 at approximately 1,000 cases.

D. 5,000.
Correct. Between 1981 and 1987, the number of measles cases reported reached a peak in 1986 at approximately 5,000 cases.

Passage II

6. The best answer is H.

F. The container is insulated in Experiment 2, but not in Experiment 1.
Incorrect. The container is not insulated in either Experiment 1 or Experiment 2.

G. A different gas is used in Experiment 2 than in Experiment 1.
Incorrect. The same gas (helium) is used in both experiments.

H. The initial volume of the gas in Experiment 1 is half that of Experiment 2.
Correct. The initial volume of the gas in Experiment 1 is 1 L and the initial volume of the gas in Experiment 2 is 2 L. Since 1 L is half of 2 L, this is the correct answer.

J. The initial volume of the gas in Experiment 1 is twice that of Experiment 2.
Incorrect. The initial volume of the gas in Experiment 1 is 1 L and the initial volume of the gas in Experiment 2 is 2 L. Since 1 L is not twice 2 L, this is the wrong answer.

7. The best answer is C.
In Experiment 1, helium gas occupied a sealed container. As the pressure of the helium increased (while the temperature of the gas was held constant), the volume of the gas decreased.

A. an identical container made of a different material than the original.
Incorrect. The results of Experiment 1 verified the pressure, volume, and temperature relationship observed by Boyle for one gas (helium). If Experiment 1 were repeated in this manner, the results would be the same as in Experiment 1, and would merely again verify Boyle's observations for the same type of gas.

B. an identical volume of water.
Incorrect. The relationship observed by Boyle pertains to a confined gas, not a confined liquid. If Experiment 1 were repeated in this manner, the results would not be applicable to Boyle's observations.

C. several different gases.
Correct. According to Boyle, the pressure, volume, and temperature relationship for any confined gas is the same as for the confined gas in Experiment 1. To verify this assertion, Experiment 1 should be repeated several times, each time with a different gas.

D. an unsealed container.
Incorrect. The relationship observed by Boyle pertains to a confined gas. If Experiment 1 were repeated in this manner, the helium would not be confined to the container and the results would not be applicable to Boyle's observations.

8. The best answer is F.

F. 0.25 L.
Correct. According to the data in Table 1, as the pressure of the gas increases, the volume of the gas decreases. When the pressure of the gas is 3 atm, the volume of the gas is 0.33 L. Thus, when the pressure of the gas is 4 atm, the volume is less than 0.33 L.

G. 0.33 L.
Incorrect. According to the data in Table 1, when the volume of the gas is 0.33 L, the pressure of the gas is 3 atm, not 4 atm.

H. 0.50 L.
Incorrect. According to the data in Table 1, when the volume of the gas is 0.50 L, the pressure of the gas is 2 atm, not 4 atm.

J. 1.00 L.
Incorrect. According to the data in Table 1, when the volume of the gas is 1.00 L, the pressure of the gas is 1 atm, not 4 atm.

9. The best answer is A.

A. 0.20 L
Correct. The initial volume of the gas at 1 atm in Experiment 1 (1 L) was half the initial volume of the gas at 1 atm in Experiment 2 (2 L). According to the data in Tables 1 and 2, the volume of the gas at 2.5 atm in Experiment 1 (0.40 L) was half the volume of the gas at 2.5 atm in Experiment 2 (0.80 L). Thus, in Experiment 1, if the initial volume of the gas at 1 atm had been half of 1.0 L, or 0.5 L, then the volume of the gas at 2.5 atm would have been half of 0.40 L, or 0.20 L.

B. 0.30 L
Incorrect. Based on the data in Tables 1 and 2, the volume of the gas at 2.5 atm would have been half of 0.40 L, or 0.20 L, not 0.30 L.

C. 0.40 L
Incorrect. Based on the data in Tables 1 and 2, the volume of the gas at 2.5 atm would have been half of 0.40 L, or 0.20 L, not 0.40 L.

D. 0.44 L
Incorrect. Based on the data in Tables 1 and 2, the volume of the gas at 2.5 atm would have been half of 0.40 L, or 0.20 L, not 0.44 L.

10. The best answer is J.

F. The pressure increased, causing the temperature to decrease.
Incorrect. The pressure did not increase, but remained constant at 3 atm.

G. The volume decreased, causing the temperature to decrease.
Incorrect. Although the volume did decrease as the temperature decreased, the decrease in volume did not cause the decrease in temperature.

H. Heat flowed from the surrounding atmosphere, through the container, and into the gas.
Incorrect. Such a heat flow would have resulted in an increase in the temperature of the container.

J. Heat flowed from the gas, through the container, and into the surrounding atmosphere.
Correct. Because the gas and container were hotter than the atmosphere, removal of the insulation resulted in a flow of heat from the gas and container to the atmosphere, resulting in a decrease in the temperature of the gas and container.

11. The best answer is A.

A. They would be the same as those in Experiment 1.
Correct. In the last step of Experiment 3, the gas cooled to room temperature while the gas pressure was maintained at 3.0 atm. Under those conditions (room temperature and a pressure of 3.0 atm), the volume of the gas was 0.33 L. In Experiment 1, under the same conditions, the volume of the gas was the same--0.33 L. Thus, if Experiment 3 were modified so that after each pressure increase, the conditions of Experiment 1 were duplicated, each volume reading would be the same as in Experiment 1.

B. They would be the same as those in Experiment 3.
Incorrect. In the last step of Experiment 3, as the gas cooled to room temperature and the gas pressure was maintained at 3.0 atm, the volume of the gas decreased from 0.52 L to 0.33 L. If Experiment 3 were modified so that after each pressure increase, the gas cooled to room temperature and the pressure of the gas remained constant, each volume reading would be less than in Experiment 3, not the same as in Experiment 3.

C. They would be greater than those in Experiment 2.
Incorrect. In the last step of Experiment 3, the gas cooled to room temperature while the gas pressure was maintained at 3.0 atm. Under those conditions (room temperature and a pressure of 3.0 atm), the volume of the gas was 0.33 L. In Experiment 2, under the same conditions, the volume of the gas was greater--0.67 L. Thus, if Experiment 3 were modified so that after each pressure increase, the gas was cooled to room temperature and the pressure of the gas remained constant, each volume reading would be less than in Experiment 2, not greater than in Experiment 2.

D. They would be smaller than those in Experiment 1.
Incorrect. In the last step of Experiment 3, the gas cooled to room temperature while the gas pressure was maintained at 3.0 atm. Under those conditions (room temperature and a pressure of 3.0 atm), the volume of the gas was 0.33 L. In Experiment 1, under the same conditions, the volume of the gas was the same--0.33 L. Thus, if Experiment 3 were modified so that after each pressure increase, the conditions of Experiment 1 were duplicated, each volume reading would be the same as in Experiment 1, not smaller than in Experiment 1.