ACT science practice test 85

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.


Students conducted experiments to determine what factors affect the period of a pendulum. A pendulum is a swinging weight, or bob, attached to a string (see Figure 1). When released from an angle, a pendulum will move back and forth. One complete back-and-forth movement is called a period.

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Figure 1

Three variables may affect the period of a pendulum: swing amplitude, measured as the angle at which the bob is released; the length of the string; and the mass of the bob. Students created pendulums by attaching a string to the ceiling and then tying a bob onto the other end of the string. They conducted three experiments. In each experiment all variables except the one tested were kept constant.

Experiment 1

In this experiment students varied the mass of the bob. Bobs of 20g, 100g, and 200g were tested for three trials each. The string length was 1m and the amplitude was 45 degrees. The results are shown in Table 1.

Table 1

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Experiment 2

The second variable tested was amplitude. Bobs were dropped from 15-, 45-, and 75-degree angles for three trials each. The string length was 1 m and the bobs used were 100 g. Figure 2 displays the average results.

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Figure 2

Experiment 3

Next the students tested the effect of varying the string length. Strings of 1 m, 0.6 m, and 0.3 m were tested in three trials each; 100 g bobs were used and the amplitude was 45 degrees. The results are displayed in Table 2 and Figure 3.

Table 2

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Figure 3

1. Based on the results of Experiment 1, the average period for a bob of 100 g was:

A. 1.79 s.
B. 1.83 s.
C. 1.89 s.
D. 1.91 s.

2. If an additional trial had been conducted in Experiment 3 with the length of the string being 1.4 m, the average period would most likely have been:

F. 2.21.
G. 1.75.
H. 1.33.
J. 0.87.

3. For each trial in Experiment 1, as the mass of the bob increased, the time of the period:

A. stayed the same.
B. increased.
C. decreased.
D. increased and then decreased.

4. Based on the information presented in Figure 2, which of the following pendulums would have the longest average period? Assume that the string length and bob weight are equal.

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F. Pendulum A
G. Pendulum B
H. The average period would be about the same.
J. It is impossible to determine from the information given.

5. In Experiment 3, Trial 2, how long did it take the pendulum with the string length of 0.6 m to complete one back-and-forth movement?

A. 1.06 s
B. 1.44 s
C. 1.47 s
D. 1.84 s

6. Which of the following variables was NOT tested during the experiments conducted by the students?

F. Mass of the bob
G. Length of string
H. Size of bob
J. Swing amplitude

Scientists conducted a series of experiments to determine the effect of changes in temperature on the intertidal rocky shore crab, Petrolisthes granulsus (P. granulosus). Several fitness-related traits, such as body size and reproductive capacity in P. granulosus individuals from three sites were compared after the crabs were exposed to various temperatures. In addition, metabolic rate experiments were conducted to determine the energetic cost associated with crab exposure to high temperatures.

Table 1 displays the temperatures (°C) used in the experiments. Thermal category TC1 refers to the maximum temperature registered at each site, while TC2 refers to the average of maximum temperatures recorded every day. The Control thermal category is defined as the average temperature experienced by the crabs during the acclimation period.

Table 1

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Figure 1 displays the average size (cephalothorax length) of P. granulosus in the 3 populations, while Figure 2 displays the average egg volume in the 3 populations.

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Figure 1

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Figure 2

Figure 3 shows the average standard metabolic rates (SMR) of male crabs from the 3 populations exposed to 3 thermal categories.

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Figure 3

7. According to Table 1, crabs from which site were exposed to the highest temperatures during the experiments?

A. Iquique
B. Coquimbo
C. Concepcion
D. Crabs at all of the locations were exposed to the same maximum temperatures.

8. Based on the information in Figure 2, the average eggs of crabs from the Coquimbo site were found to be closest to which size?

F. 0.1 mm
G. 0.17 mm
H. 0.2 mm
J. 0.25 mm

9. According to Figure 3, adult male crabs from which category were found to have the highest average standard metabolic rates?

A. TC1 from Concepcion
B. Control from Coquimbo
C. TC1 from Iquique
D. TC2 from Concepcion

10. Based on the information provided, which of the following best describes the effect that average maximum temperature has on the average size of the crabs?

F. As the average maximum temperature increased, the average size of the crabs stayed the same.
G. As the average maximum temperature increased, the average size of the crabs increased.
H. As the average maximum temperature decreased, the average size of the crabs decreased.
J. As the average maximum temperature decreased, the average size of the crabs increased.

11. Suppose the scientists had measured the average egg volume of crabs in the control groups. Based on the information in Table 1 and Figure 2, the average egg volume of crabs at the Concepcion site would have been closest to:

A. 0.05 mm.
B. 0.1 mm.
C. 0.2 mm.
D. 0.3 mm.

12. The scientists started this experiment with the theory that crabs exposed to higher temperatures would develop higher standard metabolic rates. Do the results of the experiment support this theory?

F. Yes. The crabs at Iquique in the thermal category TC2 were exposed to the highest temperatures and were found to have the highest SMR.
G. Yes. At all locations the crabs from thermal category TC1 were found to have the highest SMR.
H. No. At all locations the crabs from thermal category TC1 were found to have the lowest SMR.
J. No. The results were mixed. At two locations the crabs from thermal category TC1 were found to have the highest SMR, but at one location the crabs from the control group had the highest SMR.