ACT Past Papers with Answers

Paper 14 · ACT December 2021 · Form E23 · Science Test

According to Table 2, which compounds have observed i values less than 2.50 at all the concentrations listed?

Paper 14 · ACT December 2021 · Form E23 · Science Test

According to Table 2, at which of the following con- centrations is the observed i value for KCl the lowest ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Based on Tables 1 and 2, which ionic compound has the largest deviation from its theoretical i value at a concentration of 2.0 mol/kg H2O ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Consider the following substances: sodium chloride, potassium chloride, magnesium chloride, ammonium sulfate, and water. Which of these substances would be classified as a solvent in the solutions represented in Table 2 ? sium chloride only nesium chloride, and ammonium sulfate

Paper 14 · ACT December 2021 · Form E23 · Science Test

Sucrose (C12H22O11) is a molecular compound and remains intact when it dissolves in water. Based on this information and the passage, would the theoretical i value for C12H22O11 more likely be less than that of KCl or greater than that of KCl ? likely 1. likely 4 or greater. most likely 1. most likely 4 or greater. 39 GO ON TO THE NEXT PAGE. ACT-E23 4 4 Passage II Some mutations in Escherichia coli allow the bacteria to survive exposure to an antibiotic. These antibiotic- resistant bacteria may have a different relative fitness (a measure of survival and reproductive success) than E. coli without mutations. Scientists conducted a study to deter- mine the relative fitness of 5 E. coli strains—1 nonmutated (Strain U) and 4 mutated (Strains W, X, Y, and Z)—when the strains were exposed for 24 hr to each of 5 different concentrations of the antibiotic streptomycin (see Table 1). The effect of the mutation in each of Strains W−Z is listed in Table 2. Table 1 adapted from Viktória Lázár et al., “Bacterial Evolution of Antibiotic Hypersensitivity.” ©2013 by EMBO and Macmillan Pub- lishers Limited.

Paper 14 · ACT December 2021 · Form E23 · Science Test

Based on Table 1, as streptomycin concentration increased, the relative fitness of Strain Y:

Paper 14 · ACT December 2021 · Form E23 · Science Test

Based on Table 1, if Strain X had been exposed for 24 hr to a streptomycin concentration of 3 μg/mL, its relative fitness would most likely have been:

Paper 14 · ACT December 2021 · Form E23 · Science Test

According to Table 2, which of the following state- ments best describes the effect of the mutation in Strain X cells? Compared to nonmutated E. coli cells, Strain X cells move streptomycin:

Paper 14 · ACT December 2021 · Form E23 · Science Test

Suppose an equal number of Strain W cells and Strain X cells were exposed for 24 hr to a streptomycin concentration of 2 μg/mL. Based on Table 1, which of Strain W or Strain X would more likely have the greater number of cells survive and reproduce? and Strain X had a relative fitness of 0.8. and Strain X had a relative fitness of 0.9. Strain W had a relative fitness of 0.3. Strain W had a relative fitness of 1.2. Table 1 Strain Relative fitness of E. coli exposed for 24 hr to a streptomycin concentration (in μg/mL*) of: 0 2 4 6 8 U 1.0 0.5 0.0 0.0 0.0 W 1.2 0.3 0.1 0.0 0.0 X 0.9 0.8 0.5 0.2 0.0 Y 0.7 0.8 0.7 0.5 0.3 Z 1.0 0.1 0.9 0.8 1.5 *micrograms per milliliter Note: A relative fitness of 0.0 indicates no surviving bacteria. Table 2 Strain Effect of mutation W Increased rate of cell division X Increased rate of streptomycin removal from the cell Y Decreased rate of streptomycin entry into the cell Z Decreased rate of DNA damage repair 40 GO ON TO THE NEXT PAGE. ACT-E23 4 4

Paper 14 · ACT December 2021 · Form E23 · Science Test

Consider the mutated strain with an increased rate of cell division. According to Table 1, what was the rela- tive fitness of this strain when it was exposed for 24 hr to a streptomycin concentration of 4 μg/mL ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

In the study, the relative fitness of a nonmutated strain that was grown for 24 hr in the absence of an antibiotic was set to 1.0. Was this strain more likely Strain U or Strain Z, and was this strain grown for 24 hr at a strep- tomycin concentration of 0 μg/mL or at a streptomycin concentration of 8 μg/mL ? 41 GO ON TO THE NEXT PAGE. ACT-E23 4 4 Passage III Antimony trioxide (Sb2O3) is a chemical compound that is used as a flame retardant in manufacturing plastic bottles made of polyethylene terephthalate (PET). PET bot- tles can retain some Sb2O3 after manufacturing, and small amounts of the antimony ion (Sb3+ ) can be absorbed out of the plastic by water stored in those bottles. Two experi- ments were performed to study the absorption of Sb3+ by water stored in clear plastic bottles made of PET. Experiment 1 The following steps were performed:

Paper 14 · ACT December 2021 · Form E23 · Science Test

How many times in Experiment 2 was a bottle placed into the box when the box was maintained at 10°C ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Suppose that in Experiment 2 the bottle containing water stored at 50°C had been reused 35 times. At that reuse number, the approximate concentration of Sb3+ in the water would have been:

Paper 14 · ACT December 2021 · Form E23 · Science Test

Assume that the maximum acceptable concentration of Sb3+ in drinking water is 6,000 ng/L. This concentra- tion of Sb3+ is how many times as great as the concen- tration of Sb3+ in water stored at 50°C in a bottle that was reused 21 times in Experiment 2 ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Which set of experimental conditions resulted in an Sb3+ concentration of 140 ng/L in water stored in a bottle that had been reused 14 times?

Paper 14 · ACT December 2021 · Form E23 · Science Test

The substance composing the bottles tested in the exper- iments is best classified as which of the following?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Suppose that in Experiment 1 a temperature of 20°C had been tested. At a reuse number of 21, the Sb3+ con- centration would most likely have been between:

Paper 14 · ACT December 2021 · Form E23 · Science Test

Did Experiment 1 and Experiment 2, respectively, take more than 1 day or less than 1 day to complete? Experiment 1 Experiment 2 43 GO ON TO THE NEXT PAGE. ACT-E23 4 4 Passage IV Introduction During the early Earth period (the first 2 billion years after Earth formed), the Sun produced only about 70% of the light and heat that it does today. Consequently, if early Earth’s atmosphere had been identical to Earth’s atmo- sphere today, the average surface temperature would have been well below the freezing point of water. However, geo- logic evidence indicates that a large amount of liquid water was present on the surface. Two hypotheses were proposed to explain how 3 heat-absorbing greenhouse gases—carbon dioxide (CO2), ammonia (NH3), and methane (CH4)—in early Earth’s atmosphere contributed to the presence of liquid water on the surface. Hypothesis 1 During the early Earth period, volcanic eruptions released both CO2 and NH3 into the atmosphere. In addi- tion, microbes produced CH4 by metabolizing hydrogen (H2) gas. Compared with atmospheric greenhouse gas con- centrations at present day, those on early Earth were consid- erably greater: the CO2 concentration was about 100 times as great, the NH3 concentration was about 20 times as great, and the CH4 concentration was about 1,000 times as great. These higher-than-present atmospheric concentrations of CO2, NH3, and CH4 absorbed enough heat to maintain an average surface temperature that allowed for liquid water. Hypothesis 2 The only source of atmospheric CO2, NH3, and CH4 on early Earth was volcanic eruptions. Compared with atmospheric CO2 and NH3 concentrations at present day, those on early Earth were somewhat greater: the CO2 con- centration was about 40 times as great and the NH3 concen- tration was about 10 times as great. The CH4 concentration was about the same as its present value. At those concen- trations, the 3 gases by themselves would not have absorbed enough heat to raise the average surface tempera- ture above freezing. However, atmospheric concentrations of both nitrogen (N2) and H2 were approximately twice what they are today. These higher-than-present concentra- tions of N2 and H2 greatly enhanced the heat-absorbing effects of the 3 greenhouse gases, maintaining an average surface temperature that allowed for liquid water.

Paper 14 · ACT December 2021 · Form E23 · Science Test

A supporter of Hypothesis 1 and a supporter of Hypothesis 2 would be likely to agree that, during the early Earth period, magma from beneath Earth’s crust contained:

Paper 14 · ACT December 2021 · Form E23 · Science Test

Suppose that the current atmospheric CO2 concentra- tion on Earth is approximately 395 parts per million (ppm). Based on Hypothesis 2, the atmospheric CO2 concentration on early Earth was most likely closest to which of the following values?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Which of the hypotheses, if either, indicated that 2 additional gases were necessary for CO2, NH3, and CH4 to absorb enough heat for liquid water to exist on early Earth’s surface?

Paper 14 · ACT December 2021 · Form E23 · Science Test

In regard to the source of CH4 in early Earth’s atmo- sphere, which of the following statements describes a difference between Hypothesis 1 and Hypothesis 2 ? According to Hypothesis 1, CH4 was: ing to Hypothesis 2, CH4 was produced by micro- bial metabolism. ing to Hypothesis 2, CH4 was produced by chemi- cal reactions between CO2 and H2O. according to Hypothesis 2, CH4 was released from volcanic eruptions. according to Hypothesis 2, CH4 was produced by chemical reactions between CO2 and H2O. 44 GO ON TO THE NEXT PAGE. ACT-E23 4 4

Paper 14 · ACT December 2021 · Form E23 · Science Test

The metabolism of the microbes referred to in Hypoth- esis 1 is most likely represented by which of the fol- lowing balanced chemical equations?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Hypothesis 1 would be best supported by which of the following findings involving CO2 or CH4 ? of CO2 was 20 times the present concentration of CH4 was 20 times the present concentration dence of CO2 produced by microbes dence of CH4 produced by microbes

Paper 14 · ACT December 2021 · Form E23 · Science Test

Suppose that if Earth’s atmospheric N2 concentration were increased from its present value, the atmosphere would scatter a higher percentage of incoming sun- light, resulting in cooler surface temperatures. This information would weaken which of the hypotheses, if either? 45 GO ON TO THE NEXT PAGE. ACT-E23 4 4 Passage V Viscous fluid flow occurs when various parts of a fluid interact with each other to produce forces that inhibit flow and generate heat. Students performed 3 studies of viscous fluid flow using the experimental setup shown in Figure 1 below. Figure 1 In each trial of the studies, the students sent a fluid through a tube such that the fluid completely filled the tube. The fluid had a viscosity η; the tube had a radius R and was fitted with 2 pressure gauges, Gauge G and Gauge H, that were a distance D apart. The pressure of the fluid at Gauge G minus the pressure of the fluid at Gauge H always equaled 5 kilopascals. (A kilopascal, kPa, is a unit of pres- sure, which is defined as force per unit area.) Using a flow meter, the students measured the fluid’s flow rate through the tube, F, in milliliters per second (mL/sec). Study 1 The students measured F for various fluids, each having a different η, that flowed, one at a time, through a tube having an R of 5.00 mm and a D of 1.00 m (see Table 1). Study 2 The students measured F for a fluid having an η of

Paper 14 · ACT December 2021 · Form E23 · Science Test

Suppose that a sixth trial had been performed in Study 1 for which the fluid’s flow rate had equaled 920 mL/sec. In that trial, the viscosity of the fluid would most likely have been: Pa·sec. Pa·sec and 2.00 × 10−3 Pa·sec. Pa·sec and 3.00 × 10−3 Pa·sec. Pa·sec. Table 2 R (mm) F (mL/sec)

Paper 14 · ACT December 2021 · Form E23 · Science Test

In Study 2, which variables were held constant?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Based on the information given, if the pressure at Gauge G was 105 kPa, what was the pressure at Gauge H ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Based on the information given, in what direction was the fluid flowing? sure at Gauge G was greater than the pressure at Gauge H. sure at Gauge G was less than the pressure at Gauge H. sure at Gauge H was greater than the pressure at Gauge G. sure at Gauge H was less than the pressure at Gauge G.

Paper 14 · ACT December 2021 · Form E23 · Science Test

The viscosity of each fluid investigated in the studies resulted from which of the following types of inter- action between parts of the fluid?

Paper 14 · ACT December 2021 · Form E23 · Science Test

In Study 3, when D was equal to 2.50 m, approxi- mately what volume of fluid flowed past either gauge in 1 minute ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

The pressure gradient between any 2 points lying on a horizontal line inside a tube equaled the absolute value of the difference in pressure between the 2 points divided by the distance between the 2 points. What was the pressure gradient between Gauges G and H during Study 1 ? 47 GO ON TO THE NEXT PAGE. ACT-E23 4 4 Passage VI Wheat growth is negatively affected by higher-than- normal salt (NaCl) concentrations in the soil. Scientists investigated whether the negative effects are countered by adding to the soil either a species of bacteria (Species R) or a mixture of proteins from marine algae (PMA). Study 1 First, 240 identical 2 L pots were each filled with

Paper 14 · ACT December 2021 · Form E23 · Science Test

According to the results of Study 1, from 3 days after treatment through 9 days after treatment, the average number of seeds that had germinated per pot for Group 4:

Paper 14 · ACT December 2021 · Form E23 · Science Test

Based on the results of Study 2, how many of the groups had an average plant height greater than 1 meter ?

Paper 14 · ACT December 2021 · Form E23 · Science Test

The presence of more than 1 plant in a pot can nega- tively affect the growth of all the plants in the pot, due to competition among the plants. What action was taken in Study 2 to prevent competition among the plants? one were removed from each pot that had multiple seeds. except one were removed from each pot that had multiple seedlings.

Paper 14 · ACT December 2021 · Form E23 · Science Test

Consider the claim “The average height of the plants in a group was affected by the number of days that the pots in that group were irrigated.” Can this claim be evaluated on the basis of the results of Study 2 ? the same for all the groups. different for each group. the same for all the groups. different for each group.

Paper 14 · ACT December 2021 · Form E23 · Science Test

Consider the statement “Treatment with Species R was more effective at promoting seed germination in soil with a higher-than-normal NaCl concentration than was treatment with PMA.” Are the results of Study 1 for 5, 7, and 9 days after treatment consistent with this statement? seeds germinated per pot was greater for Group 3 than for Group 4. seeds germinated per pot was greater for Group 4 than for Group 3. seeds germinated per pot was greater for Group 3 than for Group 4. seeds germinated per pot was greater for Group 4 than for Group 3.

Paper 14 · ACT December 2021 · Form E23 · Science Test

Let x represent the number of days after treatment until germination was first observed among the Group 2 pots in Study 1. Based on the results of Study 1, x is given by which of the following expressions?

Paper 14 · ACT December 2021 · Form E23 · Science Test

Consider the statement “On average, plant height was greater for the plants treated with H2O containing PMA and NaCl than it was for the plants treated with either H2O containing NaCl only or H2O containing Species R and NaCl.” Do the results of Study 2 support this statement? greater than the average plant height in Groups 2 and 4. greater than the average plant height in Groups 2 and 3. greater than that in Group 2 but less than that in Group 4. greater than that in Group 2 but less than that in Group 3. 49 ACT-E23 4 4 END OF TEST 4 STOP! DO NOT RETURN TO ANY OTHER TEST. 50 Scoring Keys for Form E23 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) _______ (24) Knowledge of Language (KLA) _______ (11) Conventions of Standard English (CSE) _______ (40) Total Number Correct for English Test _______ (POW + KLA + CSE) (75) Key Reporting Category* POW KLA CSE