ACT Past Papers with Answers

Paper 7

ACT June 2023

Form F12 · Science Test · 40 questions

Tools:

Paper 7 · ACT June 2023 · Form F12 · Science Test

The rate at which a ZAMS star fuses hydrogen into helium is directly proportional to the core temperature of that star. Based on the table, is the rate of fusion more likely greater for a 3 Msun ZAMS star or for a 9 Msun ZAMS star? 3 Msun star is higher than that of a 9 Msun star. 3 Msun star is lower than that of a 9 Msun star. 9 Msun star is higher than that of a 3 Msun star. 9 Msun star is lower than that of a 3 Msun star.

AA 3 Msun star, because the core temperature of aBA 3 Msun star, because the core temperature of aCA 9 Msun star, because the core temperature of aDA 9 Msun star, because the core temperature of a

Tools:

Paper 7 · ACT June 2023 · Form F12 · Science Test

Suppose a wet season is any growth season in which there is at least 900 mm of rainfall. Given the region’s average rainfall and the data in Figure 1, how many of the growth seasons, if any, would have been wet seasons? 41 GO ON TO THE NEXT PAGE. ACT-F12 4 4 Passage III Two studies examined how the concentration of Drug M in water affects the accumulation of Drug M in the bodies of a species of planarian (a freshwater flatworm) and the swimming speed of those planarians. Study 1 Each of 24 dishes was prepared as follows: First, 20 mL of a 0.05 mg/L aqueous solution of Drug M was added to the dish. Next, a single 0.04 g planarian was placed in the dish. Finally, the dish was covered with a lid. The dishes were then divided equally into 4 groups. Each group was incubated at 20°C for a different period of time. At the end of a group’s incubation period, a 1-microgram (μg) tissue sample was collected from each planarian in the group. The average biologic Drug M level (BML, micrograms of Drug M per gram of tissue) was determined for each group. These procedures were repeated for a 0.20 mg/L and for a 0.50 mg/L aqueous solution of Drug M (see Figure 1). Figure 1 Study 2 Twelve dishes were prepared using the 0.05 mg/L aqueous solution of Drug M, as in Study 1, and were divided equally into 4 groups. Each group was incubated at 25°C for a different period of time. At the end of a group’s incubation period, each dish in the group was placed on top of a piece of graph paper. The total number of gridlines crossed by each planarian during a 4 min observation period was recorded. The average swimming speed (the number of gridlines crossed per minute) was then determined for each group. These procedures were repeated for a 0.20 mg/L and for a 1.80 mg/L aqueous solution of Drug M (see Figure 2). Figure 2 Figures adapted from Michelle Plusquin, et al., “Physiological and Molecular Characterization of Cadmium Stress in Schmidtea mediterranea.” ©2012 by UBC Press. incubation time (hr) 96 72 48 24 52 48 44 40 36 32 28 24 20 16 12 8 4 0 average BML (μg/g)

A0B1C6D8

Tools:

Paper 7 · ACT June 2023 · Form F12 · Science Test

Consider the samples that were collected from the organisms in Study 1. Do the cells in these samples have nuclei, and do these cells have ribosomes? nuclei ribosomes 43 GO ON TO THE NEXT PAGE. ACT-F12 4 4 Passage IV A Crooke’s radiometer (CR) is a sealed glass bulb, from which most of the air has been removed, that contains 4 metal vanes mounted on a spindle. The same side of each vane is painted black, and the other is silver. See the diagram. diagram When a CR is placed in light, the vanes rotate. For the CR shown in the diagram, four students each provided an explanation for the rotation and predicted the direction— clockwise or counterclockwise—the vanes would rotate. Student 1 Photons (particles of light) exert a greater force when they are absorbed by a material than when they are reflected by a material. This force is weaker than air resis- tance, so it can cause rotation only when enough of the air has been removed from the bulb. Photons are absorbed only by the black side of each vane, exerting a stronger force on that side that causes the vanes to rotate clockwise. The brighter the light in which the CR is placed, the more pho- tons are absorbed by the black sides and the faster the vanes rotate. Student 2 Student 1 is correct except that photons exert a greater force when they are reflected by a material than when they are absorbed by a material. Photons are reflected only by the silver side of each vane, exerting a force that causes the vanes to rotate counterclockwise. Student 3 The forces exerted by photons are too weak to cause rotation of the vanes, even when most of the air has been removed. Instead, photons absorbed by the black side of a vane cause that side to heat up, warming the air molecules in contact with it. Air molecules move from the cooler silver side to the warmer black side. This produces a greater air pressure on the black side and, thus, causes the vanes to rotate clockwise. The brighter the light in which the CR is placed, the greater the temperature difference between the 2 sides of a vane and the faster the vanes rotate. Student 4 Student 3 is correct except that the air molecules move from the warmer black side to the cooler silver side, producing a greater air pressure on the silver side. This causes the vanes to rotate counterclockwise.

Ayes yesByes noCno yesDno no

Form F12 · Science Test · 40 questions

1 / 40