대교 ACT

DIRECTIONS: The passage in this test is followed by several questions. After reading the passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passage as often as necessary. You are NOT permitted to use a calculator on this test.

Passage I

The following table represents the concentration of ions and dissolved gases in the sediment at the bottom of an ocean. A depth of 0 centimeters (cm) represents the top of the sediment. The concentrations are expressed in parts per million (ppm). The acidity of a solution is represented on a scale known as pH. A pH of 1 is very acidic, a pH of 7 is neutral, and a pH of 14 is very basic.

Depth
(cm) Temperature
(^oC) pH Concentration in sediment (ppm)

SO₄^2- S^2- CO₂ Fe³⁺ Fe²⁺ O₂

0 4 7.0 7.0 0.0 1.0 4.0 0.5 2.0

5 5 6.5 5.0 2.0 1.5 3.0 1.5 1.0

10 7 6.0 3.5 3.5 2.0 2.0 2.0 0.0

15 9 5.5 3.3 3.8 3.0 0.8 3.8 0.0

20 10 5.0 3.0 4.0 1.0 0.5 4.0 0.0

Table adapted from R.M. Atlas and R. Bartha, Microbial Ecology: Fundamentals and Applications.
©1981 by Addison-Wesley Publishing Company.

1. According to the information provided in the table, the concentration of which of the following ions and dissolved gases is constant for sediment depths of 10 cm or more?
A. Sulfide (S^2-)
B. Carbon dioxide (CO₂)
C. Ferric iron (Fe³⁺)
D. Oxygen (O₂)

2. The graph below best represents the relationship between concentration and sediment depth for which of the following ions and dissolved gases?

F. Ferrous iron (Fe²⁺)
G. Oxygen (O₂)
H. Carbon dioxide (CO₂)
J. Sulfate (SO₄^2-)

3. If the trends indicated in the table were to continue, one would predict the pH of the sediments at a depth of 35 cm to be:
A. 1.5.
B. 3.5.
C. 4.5.
D. 6.0.

4. A certain type of bottom-dwelling microorganism thrives under the following environmental conditions: low concentrations of Fe²⁺, high concentrations of O₂, and a neutral pH. Based on the table, at which of the following sediment depths would one most likely find this microorganism?
F.  0 cm
G.  5 cm
H. 10 cm
J.  15 cm

5. A researcher wants to determine whether an unidentified sediment sample was drawn from a depth of 15 cm or 20 cm. Based on the information in the table, which of the following would NOT confirm the depth of the sample?
A. O₂ concentration
B. Fe³⁺ concentration
C. S^2- concentration
D. pH

Passage II
    The Sun's path from sunrise to sunset varies with the time of year. A student performed the following experiments on three clear, sunny days at three- or four-month intervals throughout the course of a year to study the path of the Sun through the sky.
Experiment 1
    At a chosen Northern Hemisphere location, the student placed a stick vertically into the ground so that 1 meter of its length was left above ground. The student knew that the length of the shadow was related to the height of the Sun above the horizon and that the shadow would point away from the direction of the Sun. The length in meters (m) and direction of the shadow cast by the stick were measured one hour after sunrise (Shadow A), at mid-morning (B), at noon (C), at mid-afternoon (D), and one hour before sunset (E) on each of the three days. The direction of each shadow was determined by placing a magnetic compass at the base of the stick and aligning the north arrow with the north mark on the compass. The direction of each shadow was then determined by a comparison with the compass face markings. The results are recorded in Table 1.

Table 1

Shadow Day 1 Day 2 Day 3

Length
(m) Shadow
direction Length
(m) Shadow
direction Length
(m) Shadow
direction

A 5.0 SW 8.6 NW 6.8 W

B 1.2 W 2.9 NNW 1.7 NW

C 0.3 N 2.3 N 0.9 N

D 1.2 E 3.0 NNE 1.8 NE

E 5.0 SE 8.6 NE 6.9 E

Experiment 2
The following year, the student repeated Experiment 1 at a chosen location in the Southern Hemisphere. The results are in Table 2.

Table 2

Shadow Day 1 Day 2 Day 3

Length
(m) Shadow
direction Length
(m) Shadow
direction Length
(m) Shadow
direction

A 9.0 SW 5.0 NW 6.9 W

B 3.2 SSW 1.1 W 1.8 SW

C 2.5 S 0.3 S 1.0 S

D 3.2 SSE 1.1 E 1.8 SE

E 9.1 SE 5.0 NE 6.9 E

6. Which of the following was a constant in both experiments?
F. Length of vertical stick exposed
G. Shadow direction
H. Day of the year
J. Shadow length

7. If the experiments were repeated after pounding the stick farther into the ground so that only 0.5 m was exposed, how would this affect the shadow lengths?
A. They would be twice as long as those in the original experiments.
B. They would be one-and-one-half times as long as those in the original experiments.
C. They would be one-half as long as those in the original experiments.
D. They would be one-fourth as long as those in the original experiments.

8. Which of the following graphs best represents the relationship between the length of the stick's shadow and the time of day?
F. H.
G. J.

9. When the Sun is at an altitude 45^o above the horizon, a vertical object will cast a shadow with a length equal to the object's height. Which of the following days included a measurement taken when the Sun was at an altitude of 45^o ?
A. Day 1 in Experiment 1
B. Day 1 in Experiment 2
C. Day 2 in Experiment 1
D. Day 3 in Experiment 2

10. Which of the following statements is best supported by the direction of Shadow A on each of the three days in Experiment 1 ?
F. The direction of sunrise along the horizon varies throughout the year.
G. Shadows never point due south in the Northern Hemisphere.
H. Shadows never point due north in the Northern Hemisphere.
J. The Sun's brightness varies throughout the year.

11. Based on the shadow directions in these experiments, which of the following best describes the difference between the apparent path of the Sun as seen from the observation points in the Northern and Southern Hemispheres?
A. The Sun travels a more southerly path in the Southern Hemisphere than in the Northern Hemisphere.
B. The Sun travels a more northerly path in the Southern Hemisphere than in the Northern Hemisphere.
C. The Sun rises in the East and sets in the West in the Northern Hemisphere, but the opposite is true in the Southern Hemisphere.
D. The Sun rises in the West and sets in the East in the Northern Hemisphere, but the opposite is true in the Southern Hemisphere.

Set 2: Science

Passage I

1. The best answer is D.

A. Sulfide (S^2–) Incorrect. Sulfide increases from 3.5 to 4.0 ppm as depth increases from 10 cm to 20 cm.

B. Carbon dioxide (CO₂) Incorrect. CO₂ increases from 2.0 to 3.0 ppm and then decreases from 3.0 to 1.0 ppm as depth increases from 10 cm to 20 cm.

C. Ferric iron (Fe³⁺) Incorrect. Ferric iron decreases from 2.0 to 0.5 ppm as depth increases from 10 cm to 20 cm.

D. Oxygen (O₂) Correct. Oxygen level is constant at 0.0 ppm at depths of 10 cm or more.

2. The best answer is H.

According to the figure, concentration of the key quantity is 1.0 ppm both at 0 and 20 cm.

F. Ferrous iron (Fe²⁺) Incorrect. Ferrous iron's concentration is 0.5 ppm at 0 depth and 4.0 ppm at 20 cm.

G. Oxygen (O₂) Incorrect. Oxygen's concentration is 2.0 ppm at 0 depth and 0.0 ppm at 20 cm.

H. Carbon dioxide (CO₂) Correct. Carbon dioxide's concentration increases from 1 ppm at 0 depth to 3 ppm at 15 cm, then decreases to 1 ppm at 20 cm.

J. Sulfate (SO₄^2–) Incorrect. Sulfate's concentration is 7.0 ppm at 0 depth and 3.0 ppm at 20 cm.

3. The best answer is B. According to the table, pH decreases linearly at the rate of 0.5 units for every 5 cm decrease in depth.

A. 1.5. Incorrect. Given that pH decreases linearly at the rate of 0.5 units for every 0.5 cm decrease in depth, a depth of 55 cm would be required before the pH was 1.5.

B. 3.5. Correct. At 20 cm, pH = 5.0; 35 cm is three 5-cm increments below 20 cm. At 35 cm, pH would be 5.0 – (3 0.5) = 5.0 - 1.5 = 3.5.

C. 4.5. Incorrect. Given that pH decreases linearly at the rate of 0.5 units for every 0.5 cm decrease in depth, a depth of 25 cm-not 35 cm-would have a pH of 4.5.

D. 6.0. Incorrect. At a depth of 10 cm, the pH is 6. Given that pH decreases as depth increases, at a depth of 35 cm the pH would be less than 6.

4. The best answer is F. By inspection, one can see that, at a depth of 0, the concentration of Fe²⁺ is lowest (0.5 ppm), the concentration of O₂ is highest (2.0), and pH is neutral (7.0).

F. 0 cm Correct. By inspection, one can see that the concentration of Fe²⁺ is the lowest available (0.5 ppm), the concentration of O₂ is the highest available (2.0), and pH is neutral (7.0) at a depth of 0.

G. 5 cm Incorrect. The concentration of Fe²⁺ (1.5 ppm) is higher than at 0 depth, the concentration of O₂ (1.0 ppm) is lower than at 0 depth, and pH (6.5) is below neutral.

H. 10 cm Incorrect. Oxygen level at this depth (0.0 ppm) is clearly the least favorable of all the choices, and iron level is significantly higher than at 0.

J. 15 cm Incorrect. Oxygen level at this depth (0.0 ppm) is clearly the least favorable of the choices, iron is close to its maximum listed level, and pH is distinctly acidic.

5. The best answer is A. The quantity tested must have different values at 15 cm and 20 cm to confirm; thus, the answer will have the same value at 15 cm and 20 cm.

A. O₂ concentration Correct. O₂ levels are the same at 15 cm and 20 cm, so the oxygen test could NOT be used for confirmation.

B. Fe³⁺ concentration Incorrect. Fe³⁺ levels are different at 15 cm (0.8 ppm) and 20 cm (0.5 ppm), so the ferric iron test COULD be used for confirmation.

C. S^2– concentration Incorrect. S^2– levels are different at 15 cm (3.8 ppm) and 20 cm (4.0 ppm), so the sulfide test COULD be used for confirmation.

D. pH Incorrect. pH levels are different at 15 cm (5.5) and 20 cm (5.0), so the pH test COULD be used for confirmation.

Passage II

6. The best answer is F. The experimental design description states a stick of a given dimension was used to create shadows of various lengths.

F. Length of vertical stick exposed Correct. The experimental description states that, in all cases, 1.0 meter of the stick was left above ground. This was constant in both experiments.

G. Shadow direction Incorrect. The experimental results show that shadow direction varied throughout both experiments.

H. Day of the year Incorrect. The experiments were performed on six different days.

J. Shadow length Incorrect. The experimental results show that shadow length varied throughout both experiments.

7. The best answer is C. According to the experiments, the length of stick exposed above ground was related to the lengths of shadows measured.

A. They would be twice as long as those in the original experiments. Incorrect. If half as much stick was exposed above ground compared to the original experiments, the shadows would be half as long as the shadows in the original experiments. It would take a length of stick twice as long exposed above ground for the shadow to be twice as long.

B. They would be one-and-one-half times as long as those in the original experiments. Incorrect. The shadows would be half as long. It would take a length of stick one-and-a-half times as long exposed above ground for the shadow to be one-and-one-half times as long.

C. They would be one-half as long as those in the original experiment. Correct. If half as much stick was exposed above ground compared to the original experiments, the shadows would be half as long as the shadows in the original experiments.

D. They would be one-fourth as long as those in the original experiments. Incorrect. The shadows would be half as long. It would require a length of stick one-fourth as long exposed above ground for the shadow to be one-fourth as long.

8. The best answer is J. Shadows F–J represent measurements taken in chronological order at various times during a day starting one hour after sunrise and going until one hour before sunset. The data from both experiments show that at a given site, on a given day, the shadow length is longest just after sunrise, decreases to a minimum length at noon, then increases again until it reaches a maximum one hour before sunset.

F. Incorrect. This graph shows a constant increase from sunrise to sunset, which is not consistent with the data.

G. Incorrect. The correct graph would show maxima near sunrise and sunset and a minimum around noon. This graph represents an initial increase, then a leveling off, from sunrise to sunset, which is not consistent with the data.

H. Incorrect. This graph represents a constant shadow length throughout the day and not a maxima near sunrise and sunset and a minimum around noon.

J. Correct. The data from both experiments show that at a given site, on a given day, the shadow length is longest just after sunrise, decreases to a minimum length at noon, then increases again until it reaches a maximum one hour before sunset. The data are represented best in this figure.

9. The best answer is D. Since 1.0 meter of the stick was exposed above ground in the experiments, one would look for a set of measurements that included a shadow length of exactly 1.0 meter.

A. Day 1 in Experiment 1 Incorrect. None of the Day 1 measurements in Experiment 1 were 1.0 meter long.

B. Day 1 in Experiment 2 Incorrect. None of the Day 1 measurements in Experiment 2 were 1.0 meter long.

C. Day 2 in Experiment 1 Incorrect. None of the Day 2 measurements in Experiment 1 were 1.0 meter long.

D. Day 3 in Experiment 2 Correct. Shadow C on this day was exactly 1.0 meter long.

10. The best answer is F. According to the data in Experiment 1, Shadow A is pointing in a SW direction on Day 1, a NW direction on Day 2, and a W direction on Day 3. The three study days were spaced at three- to four-month intervals throughout the course of a year.

F. The direction of sunrise along the horizon varies throughout the year. Correct. Shadow A was measured one hour after sunrise. The shadow points away from the direction of the Sun. Since the Shadow A direction is different on each day, the direction of sunrise at the study location must be different on each day. This indicates the direction of sunrise varies throughout the year.

G. Shadows never point due south in the Northern Hemisphere. Incorrect. The data only provides evidence about shadow direction on three days during a year at ONE Northern Hemisphere location. These data are not enough to support a statement that shadows never point due south in the Northern Hemisphere.

H. Shadows never point due north in the Northern Hemisphere. Incorrect. The data only provides evidence about shadow direction on three days during a year at ONE Northern Hemisphere location. These data are not enough to support a statement that shadows never point due north in the Northern Hemisphere.

J. The Sun's brightness varies throughout the year. Incorrect. No data about the Sun's brightness was taken directly in either experiment.

11. The best answer is B. Comparing the data for the two hemispheres, 9 of the 15 shadows measured in the Southern Hemisphere point S, SW, or SE. This indicates that the Sun appeared north of that location at the time the shadows were measured. At the same time, the corresponding Northern Hemisphere measurements indicate the Sun was occasionally north of that location, but more often south of it.

A. The Sun travels a more southerly path in the Southern Hemisphere than in the Northern Hemisphere. Incorrect. It is physically impossible for the Sun to appear further south to an observer in the Southern Hemisphere than it does to an observer in the Northern Hemisphere.

B. The Sun travels a more northerly path in the Southern Hemisphere than in the Northern Hemisphere. Correct. More shadows in the Southern Hemisphere location pointed south than did shadows in the Northern Hemisphere location.

C. The Sun rises in the East and sets in the West in the Northern Hemisphere, but the opposite is true in the Southern Hemisphere. Incorrect. The Sun rises in the East (or NE or SE) and sets in the West (or NW or SW) in BOTH hemispheres.

D. The Sun rises in the West and sets in the East in the Northern Hemisphere, but the opposite is true in the Southern Hemisphere. Incorrect. The Sun rises in the East (or NE or SE) and sets in the West (or NW or SW) in BOTH hemispheres.