ACT Past Papers with Answers

Paper 37 · ACT September 2015 · Form 72C · Science Test

During Studies 1 and 2, why did the size of the fruit fly population in each tube decrease rather than increase? contained only males. contained only virgin females. tion contained only males. tion contained only virgin females.

Paper 37 · ACT September 2015 · Form 72C · Science Test

Study 1 differed from Study 2 in which of the follow- ing ways? male fruit flies were tested in Study 2. female fruit flies were tested in Study 2. lower percent of sugar than did the SY medium tested in Study 2. higher percent of sugar than did the SY medium tested in Study 2.

Paper 37 · ACT September 2015 · Form 72C · Science Test

Suppose that an additional trial in Study 3 had been performed using a 12% SY medium (a diet with 12% sugar and 12% killed yeast). The average life span of the Strain X fruit flies in this trial would most likely have been:

Paper 37 · ACT September 2015 · Form 72C · Science Test

The researchers had predicted that decreasing a fruit fly’s ability to detect odors would increase its life span. Are the results of Study 3 consistent with this prediction? span of Strain X fruit flies was longer than the average life span of Strain N fruit flies. span of Strain N fruit flies was longer than the average life span of Strain X fruit flies. span of Strain X fruit flies was longer than the average life span of Strain N fruit flies. span of Strain N fruit flies was longer than the average life span of Strain X fruit flies.

Paper 37 · ACT September 2015 · Form 72C · Science Test

Suppose the researchers wanted to determine whether a defect in the ability to detect odors would change the life span of fruit flies fed 15% SY medium when live yeast is added to the diet or when additional odors from live yeast are added to the diet. Which of the fol- lowing experiments should be performed?

Paper 37 · ACT September 2015 · Form 72C · Science Test

The results for which 2 tubes should be compared to determine how a reduced calorie diet affects life span in the absence of live yeast and additional odors from live yeast? Table 1 Strain SY medium Average life span (days) % sugar % killed yeast Strain N 030, 030, 50.1 050, 050, 50.1

Paper 37 · ACT September 2015 · Form 72C · Science Test

Which hypothesis, if any, asserts that monarch butter- flies store lipids during 2 distinct periods?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Which hypothesis, if any, asserts that monarch butter- flies require energy from stored lipids neither for migration nor during the overwintering period?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Hypothesis 3, which of the following figures best depicts the change in the lipid mass of a monarch butterfly from the beginning of migration to the end of migration? (Note: In each figure, B represents the beginning of migration and E represents the end of migration.) lipid mass time B E lipid mass time B E lipid mass time B E lipid mass time B E GO ON TO THE NEXT PAGE. 4 4

Paper 37 · ACT September 2015 · Form 72C · Science Test

Assume that changes in the body mass of a monarch butterfly are caused only by changes in the mass of the butterfly’s stored lipids. The statement “The percent of a monarch butterfly’s body mass that is made up of lipids is greater at the beginning of migration than at the end of migration” is supported by which of the hypotheses?

Paper 37 · ACT September 2015 · Form 72C · Science Test

To store lipids, monarch butterflies convert sugar from nectar they have consumed into lipids. A supporter of which hypothesis, if any, would be likely to claim that to ensure the butterflies can store lipids for the over- wintering period, nectar must be present at the butter- flies’ overwintering sites?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Which of the following statements about lipids in monarch butterflies is consistent with all 3 hypotheses? the overwintering period. migration. during the overwintering period. migration.

Paper 37 · ACT September 2015 · Form 72C · Science Test

When the monarch butterflies use their stored lipids, the lipids must be broken down to produce energy-rich molecules that can be readily used by cells. Which of the following molecules is produced as a direct result of the breakdown of the lipids? GO ON TO THE NEXT PAGE. 4 4 Passage III Greenhouse gases such as methane (CH4) warm Earth’s climate. Figure 1 shows the concentration of CH4 in Earth’s atmosphere and the solar radiation intensity at Earth’s surface for tropical Europe and Asia over the past 250,000 years. As the figure shows, the CH4 concentration and the solar radiation intensity have increased and decreased at the same times over most of this period. Figure 2 shows the same types of data for the same region over the past 11,000 years. This figure is consistent with the hypothesis that the greenhouse gases from human activities may have begun warming Earth’s climate thou- sands of years earlier than once thought. GO ON TO THE NEXT PAGE. 4 4 Figure 1 solar radiation intensity (watts/m 2 ) concentration of CH 4 in Earth’s atmosphere (ppb*) 540 520 500 480 460 440 900 800 700 600 500 400 300 200 thousands of years ago 250 200 150 100 50 0 (present) solar radiation CH4 concentration Key *ppb = parts per billion Figure 2 Figures adapted from William Ruddiman, Plows, Plagues & Petro- leum. ©2005 by Princeton University Press.

Paper 37 · ACT September 2015 · Form 72C · Science Test

According to Figure 2, the solar radiation intensity 8,000 years ago was closest to which of the following?

Paper 37 · ACT September 2015 · Form 72C · Science Test

According to Figure 2, if the trend in the CH4 concen- tration had continued to match the trend in the solar radiation intensity, the CH4 concentration at present would most likely be:

Paper 37 · ACT September 2015 · Form 72C · Science Test

Suppose that whenever the CH4 concentration increases, a corresponding, immediate increase in average global temperature occurs, and that whenever the CH4 concentration decreases, a corresponding, immediate decrease in average global temperature occurs. Based on Figure 2, which of the following graphs best represents a plot of average global temper- ature over the past 11,000 years?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Figure 1, the average solar radiation intensity over the past 250,000 years was closest to which of the following?

Paper 37 · ACT September 2015 · Form 72C · Science Test

One solar radiation cycle is the time between a maxi- mum in the solar radiation intensity and the next maxi- mum in the solar radiation intensity. According to Figure 1, the average length of a solar radiation cycle during the past 250,000 years was:

Paper 37 · ACT September 2015 · Form 72C · Science Test

Which of the following statements best describes the primary effect of CH4 on Earth’s climate? Earth’s climate. ing Earth’s climate. from space, cooling Earth’s climate. face, warming Earth’s climate. solar radiation intensity (watts/m 2 ) concentration of CH 4 in Earth’s atmosphere (ppb) thousands of years ago solar radiation CH4 concentration Key 505 500 495 490 485 480 475 10 5 0 (present) 750 700 650 600 550 500 450 average global temperature 11 thousands of years ago 0 average global temperature11 thousands of years ago 0 average global temperature 11 thousands of years ago 0 average global temperature 11 thousands of years ago 0 GO ON TO THE NEXT PAGE. 4 4 Passage IV In 2 experiments, a student pulled each of 3 blocks in a straight line across a flat, horizontal surface. In Experiment 1, the student measured the pulling force (the force required to move each block at a constant speed) and plotted the pulling force, in newtons (N), versus block mass, in kilograms (kg). The results are shown in Figure 1. Figure 1 In Experiment 2, the student measured the speed versus time of a 2.00 kg block, a 2.50 kg block, and a

Paper 37 · ACT September 2015 · Form 72C · Science Test

If a block was pulled toward the east, the frictional force exerted on the block by the surface was directed toward the:

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Figure 2, what is the order of the 3 blocks, from the block that required the shortest time to reach 15 m/sec to the block that required the longest time to reach 15 m/sec ?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Figure 2, what was the approximate value of the acceleration of the 3.00 kg block?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Figure 1, the results of Experiment 1 are best modeled by which of the following equations? 0 . 0 0 block mass (kg) 1 . 0 0 1 . 5 0 2 . 5 0 3 . 5 0 0 . 5 0 2 . 0 0 3 . 0 0 4 . 5 0 4 . 0 0 pulling force (N) time (sec)

Paper 37 · ACT September 2015 · Form 72C · Science Test

At each of the times plotted in Figure 2 (except

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Figure 1, an applied force of 30.00 N would most likely have been required to maintain the constant speed of a block having a mass of: GO ON TO THE NEXT PAGE. 4 4 Passage V A typical acid-base indicator is a compound that will be one color over a certain lower pH range but will be a different color over a certain higher pH range. In the small range between these pH ranges—the transition range—the indicator’s color will be an intermediate of its other 2 colors. Students studied 5 acid-base indicators using colorless aqueous solutions of different pH and a well plate (a plate containing a matrix of round depressions—wells—that can hold small volumes of liquid). Experiment 1 The students added a pH = 0 solution to 5 wells in the first column of the well plate, then added a pH = 1 solution to the 5 wells in the next column, and so on, up to pH = 7. Next, they added a drop of a given indicator (in solution) to each of the wells in a row, and then repeated this process, adding a different indicator to each row. The color of the resulting solution in each well was then recorded in Table 1 (B = blue, G = green, O = orange, P = purple, R = red, Y = yellow). Experiment 2 Experiment 1 was repeated with solutions that had a pH of 8 or greater (see Table 2). Experiment 3 Students were given 4 solutions (Solutions I−IV) of unknown pH. The well plate was used to test samples of each solution with 4 of the 5 indicators (see Table 3). Tables adapted from David R. Lide, ed., CRC Handbook of Chem- istry and Physics, 78th ed. ©1997 by CRC Press LLC. Table 3 Indicator Color in Solution: I II III IV Metanil yellow Y Y Y O Resorcin blue B B R R Curcumin R R Y Y Indigo carmine B Y B B Table 1 Indicator Color in solution with a pH of: 0 1 2 3 4 5 6 7 Metanil yellow R R O Y Y Y Y Y Resorcin blue R R R R R P P B Curcumin Y Y Y Y Y Y Y Y Hessian bordeaux B B B B B B B B Indigo carmine B B B B B B B B Table 2 Indicator Color in solution with a pH of: 8 9 10 11 12 13 14 Metanil yellow Y Y Y Y Y Y Y Resorcin blue B B B B B B B Curcumin O R R R R R R Hessian bordeaux B R R R R R R Indigo carmine B B B B G Y Y GO ON TO THE NEXT PAGE. 4 4

Paper 37 · ACT September 2015 · Form 72C · Science Test

One way Experiment 2 differed from Experiment 3 was that in Experiment 2: of known pH. of unknown pH.

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on the description of the well plate and how it was used, the empty well plate would most likely have been which of the following colors?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on the results of Experiments 1 and 2, which of the following is a possible transition range for curcumin?

Paper 37 · ACT September 2015 · Form 72C · Science Test

A chemist has 2 solutions, one of pH = 1 and one of pH = 6. Based on the results of Experiments 1 and 2, could indigo carmine be used to distinguish between these solutions? pH = 6. at pH = 6. pH = 6. at pH = 6.

Paper 37 · ACT September 2015 · Form 72C · Science Test

The indicator propyl red has a transition range of pH = 4.6 to pH = 6.8. If propyl red had been included in Experiments 1 and 2, it would have produced results most similar to those produced by which of the 5 indicators?

Paper 37 · ACT September 2015 · Form 72C · Science Test

A student claimed that Solution III has a pH of 7.3. Are the results of Experiments 1−3 consistent with this claim? yellow. yellow.

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on the results of Experiments 1−3, which of Solutions I−IV has the lowest pH ? GO ON TO THE NEXT PAGE. 4 4 Passage VI Drilling mud (DM) is a suspension of clay particles in water. When a well is drilled, DM is injected into the hole to lubricate the drill. After this use, the DM is brought back up to the surface and then disposed of by spraying it on adjacent land areas. A cover of DM on plants and soil can affect the albedo (proportion of the total incoming solar radiation that is reflected from a surface), which in turn can affect the soil temperature. The effect of a cover of DM on the albedo and the soil temperature of an unsloped, semiarid grassland area was studied from July 1 to August 9 of a particular year. On June 30, 3 plots (Plots 1−3), each 10 m by 40 m, were established in the grassland area. For all the plots, the types of vegetation present were the same, as was the den- sity of the vegetation cover. At the center of each plot, a soil temperature sensor was buried in the soil at a depth of

Paper 37 · ACT September 2015 · Form 72C · Science Test

Albedo was measured at noon because that time of day is when solar radiation reaching the ground is:

Paper 37 · ACT September 2015 · Form 72C · Science Test

Why was the study designed so that the 3 plots had the same types of vegetation present and the same density of vegetation cover? These conditions ensured that any variations in albedo and soil temperature would most likely be attributable only to variations among the plots in the: albedo June 30 July 5 July 10 July 15 July 20 July 25 July 30 Aug. 4 Aug. 9 Key Plot 1 Plot 2 Plot 3 daily average soil temperature (°C) 28 26 24 22 20 18 June 30 July 5 July 10 July 15 July 20 July 25 July 30 Aug. 4 Aug. 9 Key Plot 1 Plot 2 Plot 3 GO ON TO THE NEXT PAGE. 4 4 4 4 36. On one day of the study period, a measurable rainfall occurred in the study area. The albedo calculated for the cloudless day just after the rainy day was lower than the albedo calculated for the cloudless day just before the rainy day. On which day did a measurable rainfall most likely occur in the study area?

Paper 37 · ACT September 2015 · Form 72C · Science Test

Source question 36. Refer to the source image.

Paper 37 · ACT September 2015 · Form 72C · Science Test

For each plot, the number of temperature readings recorded by the soil temperature sensor every minute was closest to which of the following?

Paper 37 · ACT September 2015 · Form 72C · Science Test

According to Figure 1 and the description of the study, was July 20 a cloudless day? day. day. that day. day.

Paper 37 · ACT September 2015 · Form 72C · Science Test

According to the results of the study, did the presence of a cover of DM increase or decrease the albedo, and did the presence of a cover of DM increase or decrease the soil temperature? albedo soil temperature

Paper 37 · ACT September 2015 · Form 72C · Science Test

Based on Figure 1, on August 3, what percent of incoming solar radiation was NOT reflected from Plot 2 ? END OF TEST 4 STOP! DO NOT RETURN TO ANY OTHER TEST.