ACT Past Papers with Answers

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which of the following factors was held constant during the study? park Table 1 Acorn type Percent of acorns: cached eaten rejected Undamaged red oak Infested red oak Shelled red oak 52 40 32 44 56 60 04 04 08 Undamaged pin oak Infested pin oak Shelled pin oak 24 24 20 64 68 64 12 08 16 Undamaged white oak Infested white oak Shelled white oak 12 24 20 88 76 76 00 00 04 Table 2 Acorn type Average distance traveled (m) before: caching eating Undamaged red oak Infested red oak Shelled red oak

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which of the following statements about pin oak acorns is consistent with the results of the study? than infested pin oak acorns. quently than undamaged pin oak acorns. acorns were cached 24% of the time. the time, and infested pin oak acorns were cached 68% of the time.

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Table 2, before eating shelled red oak acorns, the squirrels traveled an average distance of:

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which of the following statements comparing the dis- tances squirrels traveled before eating infested acorns to the distances they traveled before caching infested acorns is supported by the results in Table 2 ? On aver- age, the distance traveled before: caching for infested red oak acorns. before eating for infested red oak acorns. caching for infested white oak acorns. before eating for infested white oak acorns.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Assume that the more perishable (likely to decay) a given type of acorn, the more likely a squirrel is to eat that acorn rather than cache it. Consider the results in Table 1 for the shelled red oak acorns, infested pin oak acorns, and undamaged white oak acorns. Based on these results, what is the order of these 3 acorn types, from most perishable to least perishable? white oak pin oak pin oak red oak

Paper 18 · ACT December 2020 · Form D03 · Science Test

Of the 1,875 undamaged pin oak acorns tested in the study, the number of those acorns that were cached by squirrels was closest to which of the following? 39 GO ON TO THE NEXT PAGE. ACT-D03 4 4 Passage II In the periodic table, a column of elements is called a group. For each of 5 elements in Group 2A and for each of 5 elements in Group 3A, Table 1 gives the atomic mass (average mass of 1 atom in atomic mass units, amu) and 3 other properties at a temperature of 298 K: • density, • specific heat (amount of heat required to raise the tem- perature of 1 g of a substance by 1 K), • thermal conductivity (ability to conduct heat; the greater the thermal conductivity, the more effectively the sub- stance conducts heat). 40 GO ON TO THE NEXT PAGE. ACT-D03 4 4 Table 1 Group in periodic table Element (symbol) Atomic mass (amu) Density at 298 K (g/cm3 *) Specific heat at 298 K [J/(g·K)† ] Thermal conductivity at 298 K [W/(m·K)‡ ] 2A Beryllium (Be) Magnesium (Mg) Calcium (Ca) Strontium (Sr) Barium (Ba) 20000, 15600, 20000, 3A Boron (B) Aluminum (Al) Gallium (Ga) Indium (In) Thallium (Tl) 23700, *grams per cubic centimeter † joules per gram per kelvin ‡ watts per meter per kelvin Figure 1 shows, for Al and for Mg, how the thermal conductivity varies between 1 K and 100 K. Figure 1 temperature (K) thermal conductivity [W/(m·K)] 25,000 20,000 15,000 10,000 5,000 0 0 20 30 10 40 50 60 70 80 90 100 Key Al Mg

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on Table 1, among the Group 2A elements, as atomic mass increases, the specific heat:

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Table 1, at 298 K, the specific heat of indium is closest in value to the specific heat of which of the following elements?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on the definition of thermal conductivity and on Table 1, does strontium or thallium conduct heat more effectively at 298 K ? greater than that of thallium. less than that of thallium. greater than that of strontium. less than that of strontium.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Neither Table 1 nor Figure 1 gives the thermal conduc- tivity of magnesium at which of the following temperatures?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on Figure 1, at which of the following tempera- tures is the thermal conductivity of Al closest in value to the thermal conductivity of Mg ?

Paper 18 · ACT December 2020 · Form D03 · Science Test

What is the meaning of the value for the density of indium given in Table 1 ? of indium has a mass of 7.31 g. of indium has a volume of 7.31 g. . . 41 GO ON TO THE NEXT PAGE. ACT-D03 4 4 Passage III When viewed from above, the path of a launched object is expected to be a straight line. However, because Earth rotates, the Coriolis effect causes the object to be deflected, either to the right of the expected path in the Northern Hemisphere, or to the left of the expected path in the Southern Hemisphere. The magnitude of deflection (MOD) is a distance that serves as a measure of the Corio- lis effect (see Figure 1). The MOD is the same when mea- sured at the same latitude (for example, 30°) in either hemisphere. Figure 1 Students conducted 3 experiments to study the Corio- lis effect. Experiment 1 The students performed 5 trials, each at a different lat- itude. In each trial, they launched a ball due east at a speed of 25 m/s over a distance of 100 m. They then measured the ball’s MOD, in cm (see Table 1). Experiment 2 The students performed 5 trials, each at 45°N latitude. In each trial, they launched a ball due east at a different speed over a distance of 100 m. They then measured the ball’s MOD (see Table 2). Experiment 3 The students performed 5 trials, each at a different lat- itude. In each trial, they repeatedly launched 2 identical disks, each 4 cm in diameter, directly toward one another at identical speeds across a 200 m long frictionless horizontal plane. The speed was adjusted for each launch until the stu- dents had determined the minimum launch speed required for the disks to just avoid colliding (see Figure 2). Table 3 shows their results. Figure 2

Paper 18 · ACT December 2020 · Form D03 · Science Test

Suppose that in Experiment 2, the students had launched the ball at a speed of 33 m/s. The ball’s MOD at this speed would most likely have been:

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to the results of Experiment 1, as latitude increased, the MOD due to the Coriolis effect: expected path deflected path MOD top view Table 1 Latitude (°N) MOD (cm) 15 0.75 30 1.46 45 2.06 60 2.53 75 2.82 Table 2 Speed (m/s) MOD (cm) 15 3.44 20 2.58 30 1.72 35 1.47 40 1.29 expected path deflected path top view launcher Table 3 Latitude (°N) Minimum speed (m/s) 15 09.44 30 18.23 45 25.78 60 31.58 75 35.22 42 GO ON TO THE NEXT PAGE. ACT-D03 4 4

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on the results of Experiment 3, which of the fol- lowing graphs best shows the relationship between lati- tude and minimum speed required to avoid a collision?

Paper 18 · ACT December 2020 · Form D03 · Science Test

The students made certain to use the same ball in both Experiment 1 and Experiment 2. The students most likely did this to ensure that the ball’s MOD would be: latitude.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on the results of Experiment 2, by how many millimeters did the ball’s MOD decrease when the launch speed was increased from 15 m/s to 20 m/s ?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Suppose that in Experiment 1, a trial had been per- formed in which a ball had been launched at a speed of 25 m/s at 45° South latitude. This trial would most likely have resulted in the ball deflecting to the:

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which of the following statements best summarizes the procedures of Experiment 3 ? The students: the resulting MOD for each disk was slightly larger than 2 cm. were launched until the resulting MOD for each disk was slightly larger than 2 cm. the resulting MOD for each disk was slightly larger than 200 cm. were launched until the resulting MOD for each disk was slightly larger than 200 cm. latitude (°N) 15 30 45 60 75 0 20 10 40 30 latitude (°N) 15 30 45 60 75 0 20 10 40 30 latitude (°N) 15 30 45 60 75 0 20 10 40 30 latitude (°N) 15 30 45 60 75 minimum speed (m/s) minimum speed (m/s) minimum speed (m/s) minimum speed (m/s) 0 20 10 40 30 43 GO ON TO THE NEXT PAGE. ACT-D03 4 4 Passage IV In human blood, calcium (Ca2+ ) concentration is regu- lated by vitamin D3. First, vitamin D3 is converted to cal- cidiol (CD) in the liver. An elevated concentration of CD inhibits further conversion of vitamin D3. Next, CD is con- verted to calcitriol (CT) in the kidneys in a reaction that requires parathyroid hormone (PTH). An elevated concen- tration of CT increases Ca2+ concentration, which in turn inhibits further release of PTH. See Figure 1. Figure 1 Figures 2 and 3, respectively, show how dietary con- sumption of vitamin D3 affects relative blood CD concen- tration and how blood Ca2+ concentration affects relative blood CT concentration. Figure 2 Figure 3 Figures adapted from Hall, John E., Guyton and Hall Textbook of Medical Physiology, 12th ed. ©2011 by Saunders Elsevier.

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Figure 2, if an individual increased dietary consumption of vitamin D3 from 1.0 times the normal RDA to 2.0 times the normal RDA, would the individual’s relative blood CD concentration increase? concentration would decrease. concentration would remain the same. concentration would increase from 0.5 times normal to 1.0 times normal. concentration would increase from 1.0 times normal to 2.0 times normal.

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Figure 3, the relative blood CT concen- tration is between 5 times normal and 6 times normal within which of the following blood Ca2+ concentration ranges? *1.0 0 dietary consumption of vitamin D3 (times normal RDA† ) relative blood CD concentration (times normal) 0 0.5 1.0 1.5 2.0 2.5 *1.0 represents the normal blood calcidiol concentration † recommended daily allowance Note: Assumes minimal exposure to sunlight. *1.0 0 blood Ca2+ concentration (mg/100 mL) relative blood CT concentration (times normal) 0 4 8 12 2 6 10 14 *1.0 represents the normal blood calcitriol concentration Key inhibition activation conversion step vitamin D3 calcidiol (CD) calcitriol (CT) {in liver} {in kidney} PTH increase in blood Ca2+ concentration 44 GO ON TO THE NEXT PAGE. ACT-D03 4 4

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Figure 1, what activates the conversion of CD to CT?

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Figure 3, when an individual’s blood CT concentration is at a normal value, the individual’s blood Ca2+ concentration is closest to which of the fol- lowing values?

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Figure 2, the greatest variation in relative blood CD concentration occurs when the dietary con- sumption of vitamin D3 is within which of the follow- ing ranges? RDA normal RDA normal RDA normal RDA

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to the given information, the inhibition of the conversion of vitamin D3 to CD is caused by: 45 GO ON TO THE NEXT PAGE. ACT-D03 4 4 Passage V The Atwood machine shown in Figure 1 was used as part of 2 studies on objects moving with constant acceleration. Figure 1 Study 1 In each of 10 trials, the following procedure was performed:

Paper 18 · ACT December 2020 · Form D03 · Science Test

The speed (in m/s) of Block Y can be obtained using the equation: speed = (acceleration) × (time) The speed of Block Y at the time it struck the platform in Trial 2 is correctly represented by which of the fol- lowing expressions? ) × (0.78 s) ) × (0.96 s) ) × (0.78 s) ) × (0.96 s)

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which of the following statements is consistent with the available information about the design or proce- dures of the studies? performed in Study 1. equal to the mass of Block Y. of Study 1. of equal mass.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Suppose that in Study 1, a trial had been performed in which Block Y was pulled down and then released when Block X was 1.5 m above the platform. Further suppose that in this trial, mX was 0.8 kg and mY was

Paper 18 · ACT December 2020 · Form D03 · Science Test

Suppose that in Step 3, Block X had been pulled down and held in place so that Block Y was 100 centimeters (NOT meters) above the platform. Would the values of t recorded in Study 1 more likely have been greater than or less than those shown in Table 1 ? longer distance. shorter distance. distance. distance.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on the results of the studies, for a given value of mX, as mY was increased, which of the variables F, t, and a also increased?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on the description of Study 1, was mY a depen- dent variable or an independent variable? intentionally set to one of several chosen values. obtained as the result of taking a measurement. intentionally set to one of several chosen values. obtained as the result of taking a measurement.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Consider any trial in which the block masses were NOT equal. In this trial, once Block X had been released, the gravitational potential energy of Block Y immediately began to: 47 GO ON TO THE NEXT PAGE. ACT-D03 4 4 Passage VI Demonstration A science teacher poured 400 mL of water into a beaker and heated the beaker with a Bunsen burner. After a few minutes, bubbles began to form in the water and float to the surface. Four students were asked to explain how the bubbles were formed and also to describe the composition of the bubbles. Student 1 The chemical formula of water is H2O. As H2O is heated, the chemical bonds between the hydrogen (H) and oxygen (O) atoms break, leaving individual H and O atoms. The H atoms dissolve in the remaining water, while the O atoms combine to form oxygen molecules (O2). The breakdown of water and the formation of O2 can be summarized by the following balanced chemical equations: H2O → 2H + O O + O → O2 Because O2 is a gas, it forms bubbles in the water, and the bubbles contain O2 only. Student 2 Student 1 is correct about how the chemical bonds in H2O break down and how O2 molecules are formed. How- ever, the H atoms do not dissolve in the remaining water; rather, they combine to form hydrogen molecules (H2), as shown in the following equation: H + H → H2 Because both O2 and H2 are gases, bubbles are formed in the water, and the bubbles contain a mixture of O2 and H2 only. Student 3 The chemical bonds in water do not break when water is heated. Instead, water molecules form new chemical bonds—called hydrogen bonds—with other water mole- cules. As more and more hydrogen bonds form, a thin cir- cular sheet of hydrogen-bonded water molecules is formed. When this sheet comes in contact with the surface of the water, air pressure pushes down on the center of the sheet, causing it to bow in the middle and close up on itself, forming a spherical bubble (see Figure 1). The bubbles contain air (a mixture of gases) only. Figure 1 Student 4 As the water is heated, chemical bonds are neither broken nor formed. Instead, the water molecules absorb the heat energy, and this energy is converted into kinetic energy. Once the kinetic energy reaches a certain threshold, the water begins to change from the liquid phase to the gas phase, forming bubbles that contain water vapor only.

Paper 18 · ACT December 2020 · Form D03 · Science Test

Based on the description of the demonstration, were the bubbles that formed more dense than the surround- ing water, or less dense than the surrounding water? formation. the beaker after formation. formation. formation.

Paper 18 · ACT December 2020 · Form D03 · Science Test

During the demonstration, bubbles were observed to form well below the water’s surface. This information directly contradicts the explanation given by which student?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which students stated or implied that the bubbles con- tain gas molecules?

Paper 18 · ACT December 2020 · Form D03 · Science Test

According to Students 1, 2, and 3, the process of bubble formation (in water) involves which of the fol- lowing changes? thin circular sheet closed bubble bowing of sheet air pressure 48 GO ON TO THE NEXT PAGE. ACT-D03 4 4

Paper 18 · ACT December 2020 · Form D03 · Science Test

Suppose that after the students gave their responses, the teacher filled a balloon with a mixture of H2 and O2. Further suppose that she held a lit candle to the balloon and then the balloon exploded. Based on this information, which of Student 2 and Student 4, if either, would be more likely to claim that an explosion would have occurred during the original demonstration if the teacher had held a lit candle above the surface of the water being heated?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which student’s explanation is the most scientifically accurate?

Paper 18 · ACT December 2020 · Form D03 · Science Test

Which of the following balanced chemical equations 49 ACT-D03 4 4 END OF TEST 4 STOP! DO NOT RETURN TO ANY OTHER TEST. 50 Scoring Keys for Form D03 Use the scoring key for each test to score your answer document for the multiple-choice tests. Mark a “1” in the blank for each question you answered correctly. Add up the numbers in each reporting category and enter the total number correct for each reporting category in the blanks provided. Also enter the total number correct for each test in the blanks provided. The total number correct for each test is the sum of the number correct in each reporting category. Test 1: English—Scoring Key Number Correct (Raw Score) for: Production of Writing (POW) _______ (23) Knowledge of Language (KLA) _______ (12) Conventions of Standard English (CSE) _______ (40) Total Number Correct for English Test _______ (POW + KLA + CSE) (75) Key Reporting Category* POW KLA CSE