ACT Past Papers with Answers

Paper 3

ACT September 2024

Form H11 · Science Test · 40 questions

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Paper 3 · ACT September 2024 · Form H11 · Science Test

Which 2 types of diesel fuel were made from the same type of plant?

ATypes W and XBTypes X and YCTypes X and ZDTypes Y and Z

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Paper 3 · ACT September 2024 · Form H11 · Science Test

Consider only the biodiesel fuel types listed in Table 1. Based on Table 2, which of the biodiesel fuel types caused the temperature of the water in the can to increase the most? 40 GO ON TO THE NEXT PAGE. ACT-H11 4 4 Passage II The roots of soybean plants can produce structures called root nodules. Root nodules have been found to con- tain a certain species of bacteria. Four students each pre- dicted the function of root nodules and the effect of the bacteria on the soybean plants. Then the students con- ducted an experiment to test their predictions. Student 1 The function of root nodules is to house the bacteria. Root nodules form only when the bacteria are present. The bacteria convert nitrogen (N2) in the atmosphere to ammo- nia (NH3), which can be more readily used as a nutrient by plants. Thus, the plants will grow larger when the bacteria are present. Student 2 The function of root nodules is to house the bacteria. Root nodules form regardless of whether the bacteria are present. The bacteria convert N2 in the atmosphere to NH3, which can be more readily used as a nutrient by plants. Thus, the plants will grow larger when the bacteria are present. Student 3 The function of root nodules is to protect the plants from the bacteria. Root nodules form only when the bacte- ria are present. If the bacteria infect a plant’s roots, root nodules grow around the bacteria to keep the bacteria from spreading. The bacteria are harmful to the plants, so the plants will grow larger when the bacteria are absent. Student 4 The function of root nodules is to protect the plants from the bacteria. Root nodules form regardless of whether the bacteria are present. If the bacteria infect a plant’s roots, the plant transports the bacteria to the root nodules to keep the bacteria from spreading. The bacteria are harm- ful to the plants, so the plants will grow larger when the bacteria are absent. Experiment In each of 200 identical pots filled with a sterile soil, a single soybean seed was planted. The bacteria were added to half of the pots, and then all the pots were placed in a greenhouse where they experienced identical growing con- ditions for 45 days. Then, the average number of root nod- ules and the average plant dry mass, in the presence of and in the absence of the bacteria, were determined (see Fig- ures 1 and 2, respectively). 30 25 20 15 10 5 0 average number of root nodules no bacteria bacteria Figure 1 average plant dry mass (g) no bacteria bacteria Figure 2

AType WBType XCType YDType Z 4.0 3.5 3.0 2.0 1.0 0.0 2.5 1.5 0.5

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Paper 3 · ACT September 2024 · Form H11 · Science Test

Suppose that the core samples had included sediment taken from a depth of 21 cm. Based on Figure 2, the average Se content of the tidal flat sediment taken from that depth would most likely have been: 46 GO ON TO THE NEXT PAGE. ACT-H11 4 4 Passage V Spectrophotometry is a method used to determine the amount of light that is absorbed by a substance in a solu- tion. The method involves adding a sample of a solution to a cuvette (a small vial), placing the cuvette into a spectro- photometer, and then sending a beam of light at a particu- lar wavelength through the cuvette (see Figure 1). The absorbance (A) of the solution is a measure of the portion of light that does not reach the detector and depends on light wavelength, solution concentration, and cuvette width. light source detector beam of light solution in cuvette width Figure 1 Two experiments were performed to determine the A of samples of aqueous nickel (Ni2+ ) solutions at various concentrations in grams/liter (g/L). The A for each sample was determined at a wavelength of 710 nanometers (nm; 1 nm = 1 × 10−9 m). During both experiments, just before each trial was run, the spectrophotometer was calibrated with a sample that has zero absorbance by passing light through a cuvette that contained only distilled water. Experiment 1 For each of Trials 1−6, a sample of an aqueous solu- tion having a different Ni2+ concentration was placed into a new cuvette. All the cuvettes were identical in each trial. The A of each solution was measured, and the results are shown in Table 1. Table 1 Trial Ni2+ concentration (g/L) A 1 2.3 0.048 2 4.7 0.098 3 9.4 0.195 4 14.1 0.274 5 18.8 0.369 6 23.5 0.444 Experiment 2 Samples of a 5.9 g/L aqueous Ni2+ solution were placed into 4 separate cuvettes (Trials 7−10). Each cuvette had a different width in millimeters (mm). The A of each solution was measured, and the results are shown in Table 2. Table 2 Trial Cuvette width (mm) A 7 10.0 0.112 8 15.0 0.168 9 20.0 0.224 10 30.0 0.336

Aless than 0.55 mg/kg.Bbetween 0.55 mg/kg and 0.65 mg/kg.Cbetween 0.65 mg/kg and 0.75 mg/kg.Dgreater than 0.75 mg/kg.

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Paper 3 · ACT September 2024 · Form H11 · Science Test

Based on the results of Experiments 1 and 2, did a greater amount of light reach the detector in Trial 3 or in Trial 10? Trial 10. Trial 10. for Trial 3. for Trial 3. 48 GO ON TO THE NEXT PAGE. ACT-H11 4 4 Passage VI Certain strains of bacteria can communicate by releas- ing and detecting the molecule VAI. When the released VAI reaches a certain concentration in the environment, the bacteria respond by producing light. Scientists con- ducted 2 experiments to examine the relationship between the number of bacteria present and the production of light in 3 bacteria strains (Strains P, Q, and R) that differed only in their ability to release or to detect VAI (see Table 1). Table 1 Strain Release VAI? Detect VAI? P yes yes Q no yes R yes no Experiment 1 The scientists placed 1 L of a growth medium without VAI into a flask. Then, they added 1 × 106 cells of Strain P to the flask. The flask was placed in a 28°C incubator that rotated at a rate of 500 rotations per minute for 24 hr. These procedures were repeated for each of Strains Q and R. Every 4 hr during the incubation period, a 1 mL sample was removed from each flask and was used to determine the optical density (OD; a measurement directly proportional to the number of bacteria cells in a sample) for each strain (see Table 2). Table 2 Strain OD at time (hr): 4 8 12 16 20 24 P 0.6 1.0 1.4 1.3 1.3 1.3 Q 0.4 1.1 1.2 1.2 1.2 1.2 R 0.3 0.8 1.1 1.1 1.2 1.2 A detector inside the incubator continuously recorded the relative light units (RLU) produced by the cells in each flask. Figure 1 shows the RLU values recorded for each strain over the 24 hr incubation. 6,000 5,000 4,000 3,000 2,000 1,000 0 RLU time (hr) 0 4 8 12 16 20 24 Key Strain P Strain Q Strain R Figure 1 Experiment 2 Experiment 1 was repeated except that the growth medium in each flask contained VAI at a concentration of 5 nanograms per liter. The OD values for each strain were identical to those in Table 2. The RLU values recorded for each strain over the 24 hr incubation are shown in Figure 2. 25,000 20,000 15,000 10,000 5,000 0 RLU time (hr) 0 4 8 12 16 20 24 Key Strain P Strain Q Strain R Figure 2 Figures adapted from K. E. Eboigbodin and G. K. Robinson, “Monitoring Bacterial Cell-to-Cell Communication ‘Quorum Sensing’ Using FLUOstar OPTIMA.” ©2009 by BMG LABTECH GmbH. 49 ACT-H11 4 4 34. Which of the following conditions was different in Experiment 1 than in Experiment 2?

ATrial 3; the A for Trial 3 was higher than the A forBTrial 3; the A for Trial 3 was lower than the A forCTrial 10; the A for Trial 10 was higher than the ADTrial 10; the A for Trial 10 was lower than the AENumber of cells added to each flask6Rotations per minute during incubation7Amount of VAI added to the growth medium8Temperature at which the flasks were incubated

Form H11 · Science Test · 40 questions

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