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Practice Test 10 - ACT Science

20 questions. Answer them in any order, then submit to see your score and every explanation.

  1. Scientist 1 suggests that renewable energy sources are the key to reducing global warming. Scientist 2 argues that reducing overall consumption is more effective. Which statement is consistent with Scientist 2's viewpoint but not Scientist 1's?
  2. In a study on how different cooking oils affect food crispiness, the type of oil was varied while keeping cooking temperature and time constant. The crispiness of the food was assessed. Which variable was held constant?
  3. A public health team studies why flu outbreaks peak in winter in many regions. Researchers propose different causes. Scientist 1: Scientist 1 argues low humidity in winter increases virus survival and transmission. Dry air allows respiratory droplets to remain airborne longer and may preserve viral particles. Scientist 1 predicts that in indoor environments where humidity is artificially raised, transmission rates should decrease. Scientist 2: Scientist 2 proposes human behavior is the main driver. In winter, people spend more time indoors in close contact, increasing transmission opportunities. Scientist 2 predicts that regions with similar indoor crowding patterns will show similar seasonality even if outdoor humidity differs. Scientist 3: Scientist 3 argues reduced sunlight in winter lowers vitamin D levels, weakening immune responses. Scientist 3 predicts supplementation that raises vitamin D levels will reduce infection rates, even if humidity and behavior are unchanged. Both Scientist 1 and Scientist 2 would agree that:
  4. Researchers studied how the concentration of a pollutant affects fish respiration rates. Pollutant levels were varied, while water temperature and fish species were kept constant. The respiration rate was recorded. The experimenter manipulated [blank] and measured [blank].
  5. If the drink is left on the bench for several hours, its temperature will be closest to which of the following?
  6. In a biology lab, a student measures leaf surface area using a grid. If the grid is not properly aligned, the surface area measurements would most likely:
  7. Based on the data in both studies, which of the following combinations of light intensity and relative humidity would likely produce the highest overall transpiration rate for a Spathiphyllum plant?
  8. A student measured the concentration of a sugar solution using a hydrometer. Steps: (1) Pour solution into a tall cylinder. (2) Lower the hydrometer gently until it floats freely. (3) Read the scale at the liquid surface and record specific gravity. (4) Repeat for three solutions. The student read the scale from slightly above the meniscus, and bubbles sometimes stuck to the hydrometer stem. The solutions were at different temperatures because some were freshly mixed with warm water. Expected pattern: higher sugar concentration gives higher specific gravity. Which procedural error would have the greatest effect on the results?
  9. Consider the data for the Mouse at 35°C in Figure 1. If the temperature were increased further to 45°C, which of the following predictions is most biologically likely?
  10. A biologist conducted an experiment to test the effect of different fertilizer types on crop yield. Three types of fertilizers were used on three separate fields, and the crop yield was measured after 3 months. Which hypothesis is being tested?
  11. A lab group tracked the concentration of dissolved oxygen (DO) in a stream across one day. Figure 1 shows DO concentration versus time. At what time is DO at its minimum value? The curve decreases from about 9.0 at 0 h to 7.2 at 6 h, reaches a lowest point near 6.5 at 10 h, then rises to about 10.0 at 18 h and ends near 9.2 at 24 h. Caption: DO was measured periodically; the minimum corresponds to the lowest point on the plotted curve.
  12. In an experiment to determine the effect of sugar concentration on yeast fermentation, sugar concentration was varied while keeping temperature and yeast type constant. The amount of carbon dioxide produced was measured. In this experiment, the dependent variable is:
  13. A hydrology study measured nitrate concentration in a stream upstream and downstream of a farm. Samples were taken on three dates. Between Date 1 and Date 2, the farm applied fertilizer. Between Date 2 and Date 3, a large storm occurred. Based on the data, which conclusion is most strongly supported?
  14. A chemistry class tested whether the surface area of calcium carbonate affects reaction rate with hydrochloric acid. Hypothesis: powdered CaCO3_3 reacts faster than a single large chunk of the same mass. Procedure: (1) Measure 2.00 g of CaCO3_3 as either powder or one intact chip. (2) Add 50.0 mL of 1.0 M HCl to a 250 mL flask. (3) Add CaCO3_3, immediately seal the flask with a stopper connected to a gas syringe, and start a timer. (4) Record CO2_2 volume in the syringe every 10 s for 120 s. (5) Repeat 3 trials per CaCO3_3 form, using fresh acid each time. The class compared CO2_2 volume vs. time curves. Which hypothesis is being tested?
  15. Which of the following statements best describes the relationship between depth and density within the Mantle (0-2,900 km), according to Figure 2?
  16. An experiment measures the growth rate of plants under different light conditions. Which factor is the most significant source of error in this procedure?
  17. Suppose a new survey of the Milky Way's halo reveals a vast population of billions of rogue planets and brown dwarfs, totaling 5 times the mass of all visible stars. This finding would strictly support the hypothesis of:
  18. How do Scientist 1 and Scientist 2 interpret the growth patterns of dinosaurs differently?
  19. A nutrition student tested whether the concentration of vitamin C solution affects how quickly it reduces a blue dye (DCPIP) to colorless. She prepared vitamin C solutions at 0.10%, 0.20%, 0.30%, and 0.40% (mass/volume). For each trial, she added 5.0 mL of a vitamin C solution to 5.0 mL of DCPIP in the same type of test tube, gently swirled for 5 seconds, and measured the time (s) until the mixture became colorless. The dye volume, total liquid volume, swirl time, and room lighting were kept constant. To isolate the effect of vitamin C concentration, the experimenter controlled:
  20. According to Figure 1, at 80 km/h the wet-road braking distance is approximately how many times the dry-road braking distance?

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