4 ● ● ● ● ● ● 4 210 GO ON TO THE NEXT PAGE. SCIENCE REASONING TEST 18 Minutes — 18 Questions Directions: There are three passages in this test. Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer sheet. You may refer to the passages as often as necessary. Passage I A series of experiments was performed to study the environmental factors affecting the size and number of leaves on the Cyas plant. Experiment 1 Five groups of 25 Cyas seedlings, all from 2–3 cm tall, were allowed to grow for 3 months, each group at a different humidity level. All of the groups were kept at 75° F and received 9 hours of sunlight a day. The average leaf lengths, widths, and densities are given in Table 1. Table 1 % Humidity Average length (cm) Average width (cm) Average density* (leaves/cm) 15 35 55 75 95 5.6 7.1 9.8 14.6 7.5 1.6 1.8 2.0 2.6 1.7 0.13 0.25 0.56 0.61 0.52 *Number of leaves per 1 cm of plant stalk Experiment 2 Five new groups of 25 seedlings, all from 2–3 cm tall, were allowed to grow for 3 months, each group receiving different amounts of sunlight at a constant humidity of 55%. All other conditions were the same as in Experiment 1. The results are listed in Table 2. Table 2 Sunlight (hrs./day) Average length (cm) Average width (cm) Average density* (leaves/cm) 0 3 6 9 12 5.3 12.4 11.2 8.4 7.7 1.5 2.4 2.0 1.8 1.7 0.32 0.59 0.56 0.26 0.19 *Number of leaves per 1 cm of plant stalk Experiment 3 Five new groups of 25 seedlings, as above, were allowed to grow at a constant humidity of 55% for 3 months at different daytime and nighttime temperatures. All other conditions were the same as in Experiment 1. The results are shown in the following table. Table 3 Day/Night Temperature (˚F) Average length (cm) Average width (cm) Average density* (leaves/cm) 85/85 85/65 65/85 75/75 65/65 6.8 12.3 8.1 7.1 8.3 1.5 2.1 1.7 1.9 1.7 0.28 0.53 0.33 0.45 0.39 *Number of leaves per 1 cm of plant stalk 4 ● ● ● ● ● ● 4 211 GO ON TO THE NEXT PAGE. 1. Which of the following conclusions can be made based on the results of Experiment 2 alone? A. The seedlings do not require long daily periods of sunlight. B. The average leaf density is independent of the humidity the seedlings receive. C. The seedlings need more water at night than during the day. D. The average length of the leaves increases as the amount of sunlight increases. 2. Seedlings grown at a 40% humidity level under the same conditions as in Experiment 1 would have average leaf widths closest to: F. 1.6 cm. G. 1.9 cm. H. 2.2 cm. J. 2.5 cm. 3. According to the experimental results, under which set of conditions would a Cyas seedling be most likely to produce the largest leaves? A. 95% humidity and 3 hours of sunlight B. 75% humidity and 3 hours of sunlight C. 95% humidity and 6 hours of sunlight D. 75% humidity and 6 hours of sunlight 4. According to the results given, Cyas plants are LEAST likely to flourish: F. in deserts. G. in temperate grasslands. H. in tropical jungles. J. at high altitudes. 5. It was assumed in the design of the 3 experiments that all of the Cyas seedlings were: A. more than 5 cm tall. B. equally capable of germinating. C. equally capable of producing flowers. D. equally capable of further growth. 6. As a continuation of the 3 experiments listed, it would be appropriate to next investigate: F. how many leaves over 6.0 cm long there are on each plant. G. which animals consume Cyas seedlings. H. how the mineral content of the soil affects the leaf size and density. J. what time of year the seedlings have the darkest coloring. 4 ● ● ● ● ● ● 4 212 GO ON TO THE NEXT PAGE. Passage II While the focus (point of origin) of most earthquakes lies less than 20 km below the Earth’s surface, certain unusual seismographic readings indicate that some activity originates at considerably greater depths. Below, two scientists discuss the possible causes of deep-focus earthquakes. Scientist 1 Surface earthquakes occur when rock in the Earth’s crust fractures to relieve stress. However, below 50 km, rock is under too much pressure to fracture normally. Deep-focus earthquakes are caused by the pressure of fluids trapped in the Earth’s tectonic plates. As a plate is forced down into the mantle by convection, increases in temperature and pressure cause changes in the crystalline structure of minerals such as serpentine. In adopting a denser configuration, the crystals dehydrate, releasing water. Other sources of fluid include water trapped in pockets of deep sea trenches and carried down with the plates. Laboratory work has shown that fluids trapped in rock pores can cause rock to fail at lower shear stresses. In fact, at the Rocky Mountain Arsenal, the injection of fluid wastes into the Earth accidentally induced a series of shallow-focus earthquakes. Scientist 2 Deep-focus earthquakes cannot result from normal fractures, because rock becomes ductile at the temperatures and pressures that exist at depths greater than 50 km. Furthermore, mantle rock below 300 km is probably totally dehydrated because of the extreme pressure. Therefore, trapped fluids could not cause quakes below that depth. A better explanation is that deep-focus quakes result from the slippage that occurs when rock in a descending tectonic plate undergoes a phase change in its crystalline structure along a thin plane parallel to a stress. Just such a phase change and resultant slippage can be produced in the laboratory by compressing a slab of calcium magnesium silicate. The pattern of deep-quake activity supports this theory. In most seismic zones, the recorded incidence of deep-focus earthquakes corresponds to the depths at which phase changes are predicted to occur in mantle rock. For example, little or no phase change is thought to occur at 400 km, and indeed, earthquake activity at this level is negligible. Between 400 and 680 km, activity once again increases. Although seismologists initially believed that earthquakes could be generated at depths as low as 1,080 or 1,200 km, no foci have been confirmed below 700 km. No phase changes are predicted for mantle rock below 680 km. 7. Scientists 1 and 2 agree on which point? A. Deep-earthquake activity does not occur below 400 km. B. Fluid allows tectonic plates to slip past one another. C. Water can penetrate mantle rock. D. Rock below 50 km will not fracture normally. 8. The graph below shows the pressures that exist at various depths below the Earth’s surface. According to Scientist 2, which point might represent the focus of a deep earthquake? 0.0 0.1 0.2 0.430. pressure (10 dynes/cm ) 12 2 transition zone to lower mantle upper mantle crust M N O P 1000 200 900 800 700 600 500 400 300 100 0 F. M G. N H. O J. P 4 ● ● ● ● ● ● 4 213 GO ON TO THE NEXT PAGE. 9. Which of the following is evidence that would support Scientist 1’s hypothesis? A. The discovery that water can be extracted from mantle-like rock at temperatures and pressures similar to those found below 300 km. B. Seismographic indications that earthquakes occur 300 km below the surface of the Earth. C. The discovery that phase changes occur in the mantle rock at depths of 1,080 km. D. An earthquake underneath Los Angeles that was shown to have been caused by water trapped in sewer lines. 10. Both scientists assume that: F. deep-focus earthquakes are more common than surface earthquakes. G. trapped fluids cause surface earthquakes. H. the Earth’s crust is composed of mobile tectonic plates. J. deep-focus earthquakes cannot be felt on the Earth’s crust without special recording devices. 11. To best refute Scientist 2’s hypothesis, Scientist 1 might: A. find evidence of other sources of underground water. B. record a deep-focus earthquake below 680 km. C. find a substance that doesn’t undergo phase changes even at depths equivalent to 680 km. D. show that rock becomes ductile at depths of less than 50 km. 12. According to Scientist 1, the earthquake at Rocky Mountain Arsenal occurred because: F. serpentine or other minerals dehydrated and released water. G. fluid wastes injected into the Earth compressed a thin slab of calcium magnesium silicate. H. fluid wastes injected into the Earth flooded the remains of a deep-sea trench. J. fluid wastes injected into the Earth lowered the shear stress failure point of the rock. 13. Scientist 2’s hypothesis would be strengthened by evidence showing that: A. water evaporates at high temperatures and pressures. B. deep-focus earthquakes can occur at 680 km. C. stress has the same effect on mantle rock that it has on calcium magnesium silicate. D. water pockets exist at depths below 300 km. 4 ● ● ● ● ● ● 4 214 GO ON TO THE NEXT PAGE. Passage III The resistance (R) of a conductor is the extent to which it opposes the flow of electricity. Resistance depends not only on the conductor’s resistivity (r), but also on the conductor’s length (L) and cross-sectional area (A). The resistivity of a conductor is a physical property of the material which varies with temperature. A research team designing a new appliance had to decide what type of wire to use in a particular circuit. The most important consideration was the wire’s resistance. The team studied the resistance of wires made from four metals — gold (Au), aluminum (Al), tungsten (W), and iron (Fe). Two lengths and two gauges (diameters) of each type of wire were tested at 20° C. The results are recorded in the table below. 10-gauge wire A=5.26mm 2 16-gauge wire A=1.31mm 2 2.59mm 1.29mm Note : Area of a circle = πr 2 Material Resistivity Length Cross- Resistance (mW ◊ cm) (cm) sectional (mW) area (mm 2 ) Au 2.44 1.0 5.26 46.4 Au 2.44 1.0 1.31 186.0 Au 2.44 2.0 5.26 92.8 Au 2.44 2.0 1.31 372.0 Al 2.83 1.0 5.26 53.8 Al 2.83 1.0 1.31 216.0 Al 2.83 2.0 5.26 107.6 Al 2.83 2.0 1.31 432.0 W 5.51 1.0 5.26 105.0 W 5.51 1.0 1.31 421.0 W 5.51 2.0 5.26 210.0 W 5.51 2.0 1.31 842.0 Fe 10.00 1.0 5.26 190.0 Fe 10.00 1.0 1.31 764.0 Fe 10.00 2.0 5.26 380.0 Fe 10.00 2.0 1.31 1,528.0 14. Of the wires tested, resistance increases for any given material as which parameter is decreased? F. Length G. Cross-sectional area H. Resistivity J. Gauge 15. Given the data in the table, which of the following best expresses resistance in terms of resistivity, cross- sectional area, and length? A. A L B. L A C. AL D. AL 16. Which of the following wires would have the highest resistance? F. A 1-cm aluminum wire with a cross-sectional area of 3.31 mm 2 G. A 2-cm aluminum wire with a cross-sectional area of 3.31 mm 2 H. A 1-cm tungsten wire with a cross-sectional area of 0.33 mm 2 J. A 2-cm tungsten wire with a cross-sectional area of 0.33 mm 2 17. According to the information given, which of the following statements is (are) correct? I. 10-gauge wire has a larger diameter than 16-gauge wire. II. Gold has a higher resistivity than tungsten. III. Aluminum conducts electricity better than iron. A. I only B. II only C. III only D. I and III only 4 ● ● ● ● ● ● 4 215 GO ON TO THE NEXT PAGE. 4 ● ● ● ● ● ● 4 STOP! END OF SECTION 4 DO NOT TURN TO ANY OTHER SECTION. 216 18. Which of the following graphs best represents the relationship between the resistivity ( ) of a tungsten wire and its length? F. L G. L H. L J. L . 4 210 GO ON TO THE NEXT PAGE. SCIENCE REASONING TEST 18 Minutes — 18 Questions Directions: There are three passages in this test. Each passage is followed by several questions. After reading a passage,. resistance of wires made from four metals — gold (Au), aluminum (Al), tungsten (W), and iron (Fe). Two lengths and two gauges (diameters) of each type of wire were tested at 20° C. The results are recorded in. Cross- Resistance (mW ◊ cm) (cm) sectional (mW) area (mm 2 ) Au 2.44 1.0 5.26 46.4 Au 2.44 1.0 1.31 186 .0 Au 2.44 2.0 5.26 92.8 Au 2.44 2.0 1.31 372.0 Al 2.83 1.0 5.26 53.8 Al 2.83 1.0 1.31 216.0 Al