ACT Science : Earth and Space Sciences

Study concepts, example questions & explanations for ACT Science

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Example Questions

Example Question #161 : Earth And Space Sciences

Study 1

A student wishes to study the effects of various household detergents on the mortality of a certain type of bacteria over an extended period of time. She introduces that type of bacteria to four separate agar plates (labeled Plate 1, Plate 2, Plate 3, and Plate 4), and then allows the bacteria to grow for three days. After this period, she treats Plate 1 with water, Plate 2 with Detergent X, Plate 3 with Detergent Y, and Plate 4 with Detergent Z. She then counts the number of bacterial colonies on each plate every eight hours for the next twenty-four hours.

Table 1

 Screen_shot_2015-03-12_at_6.12.46_pm

Study 2

The student now wishes to compare the effects of Detergent X and Detergent Y on the same type of bacteria as she used in Study 1. The student introduces that type of bacteria to three separate plates (labeled Plate I, Plate II, and Plate III), and then allows the bacteria to grow for 3 days. After this period, she treats Plate I with water, Plate II with Detergent X, and Plate III with Detergent Y. She then counts the number of bacterial colonies on each plate every eight hours for the next forty-eight hours.

Screen_shot_2015-03-12_at_6.12.32_pm

In Study 1, which detergent killed the greatest number of bacteria in total during the twenty-four hours of the experiment?

Possible Answers:

All of the detergents killed the same number of bacteria.

Detergent Z

Detergent Y

Detergent X

Correct answer:

Detergent Y

Explanation:

Looking at the table, if we subtract the final number of colonies from the initial number of colonies for each plate, we find that Plate 3 has the largest difference. Plate 3 corresponds to Detergent Y, so Detergent Y killed the greatest number of bacteria in total during the experiment involved in Study 1.

Example Question #162 : Earth And Space Sciences

Study 1

A student wishes to study the effects of various household detergents on the mortality of a certain type of bacteria over an extended period of time. She introduces that type of bacteria to four separate agar plates (labeled Plate 1, Plate 2, Plate 3, and Plate 4), and then allows the bacteria to grow for three days. After this period, she treats Plate 1 with water, Plate 2 with Detergent X, Plate 3 with Detergent Y, and Plate 4 with Detergent Z. She then counts the number of bacterial colonies on each plate every eight hours for the next twenty-four hours.

Table 1

 Screen_shot_2015-03-12_at_6.12.46_pm

Study 2

The student now wishes to compare the effects of Detergent X and Detergent Y on the same type of bacteria as she used in Study 1. The student introduces that type of bacteria to three separate plates (labeled Plate I, Plate II, and Plate III), and then allows the bacteria to grow for 3 days. After this period, she treats Plate I with water, Plate II with Detergent X, and Plate III with Detergent Y. She then counts the number of bacterial colonies on each plate every eight hours for the next forty-eight hours.

Screen_shot_2015-03-12_at_6.12.32_pm

In Study 1, what was the most likely number of bacterial colonies on Plate 4 at 12 hours after the start of the experiment?

Possible Answers:

59

42

50

70

Correct answer:

50

Explanation:

From inspection of the table, we see that the number of bacterial colonies on Plate 4 decreases linearly—roughly 20 colonies are killed every eight hours. Knowing this, we can reason that the number of colonies at twelve hours is roughly 50 (about halfway between 42 and 60).

Example Question #163 : Earth And Space Sciences

Study 1

A student wishes to study the effects of various household detergents on the mortality of a certain type of bacteria over an extended period of time. She introduces that type of bacteria to four separate agar plates (labeled Plate 1, Plate 2, Plate 3, and Plate 4), and then allows the bacteria to grow for three days. After this period, she treats Plate 1 with water, Plate 2 with Detergent X, Plate 3 with Detergent Y, and Plate 4 with Detergent Z. She then counts the number of bacterial colonies on each plate every eight hours for the next twenty-four hours.

Table 1

 Screen_shot_2015-03-12_at_6.12.46_pm

Study 2

The student now wishes to compare the effects of Detergent X and Detergent Y on the same type of bacteria as she used in Study 1. The student introduces that type of bacteria to three separate plates (labeled Plate I, Plate II, and Plate III), and then allows the bacteria to grow for 3 days. After this period, she treats Plate I with water, Plate II with Detergent X, and Plate III with Detergent Y. She then counts the number of bacterial colonies on each plate every eight hours for the next forty-eight hours.

Screen_shot_2015-03-12_at_6.12.32_pm

A student obtains a mystery detergent of unknown identity and decides to perform an experiment with it. He starts with 80 bacterial colonies on a single plate, and observes that only 2 colonies remain at 40 hours following treatment with the detergent. What is the most likely identity of this detergent?

Possible Answers:

Cannot be determined

Detergent Y

Detergent X

Neither Detergent X nor Detergent Y

Correct answer:

Detergent X

Explanation:

From the graph associated with Study 2, we see that about 2 colonies remain on Plate II roughly 40 hours following treatment. Plate II contains Detergent X. 

Example Question #11 : How To Find Data Representation In Earth And Space Sciences

Glaciers move, on average, 1 meter per day, although many are known to move faster or slower depending on their size. Whether they are alpine glaciers, which form high in the mountains, or continental glaciers that cover huge areas of land near the poles, glaciers are responsible for breaking up rock and moving sediment as they move across the land. 

Below is a chart of average speed of movement of an alpine glacier per year, as well the amount of sediment displaced by the glacier. 

Year

Average Glacial Movement

Sediment movement per year (tons)

1995

1.1 m/day

2.2

1996

1.3 m/day

2.6

1997

1.5 m/day

3.0

1998

1.3 m/day

2.2

2000

1.1 m/day

1.8

2005

1.0 m/day

1.6

2010

0.9 m/day

1.5

Two scientists have done research on an alpine lake that lies in the path of the glacier. Each took five samples of sediment from the lake.

Scientist 1 believes that the glacier is beginning to melt as it moves lower in elevation, releasing some of the sediment it has carried into mountain streams and springs, causing the makeup of sediments in the lake to change. He notes that the sediment from the lake bed contains brown chert, a rock that can only be found in elevations higher than that of the lake. Scientist 1 took his sample from the sediments that washed ashore on the beach of the lake.

Scientist 2 believes the glacier is not melting, but displacing rock beds so that the sediment loosens and breaks free of the bedrock and then is carried by wind and other erosive elements to the lake. He notes that the sediment from the lake bed contains only trace amounts of the brown chert, not enough to suggest the glacier is melting. Scientist 2 took his samples from sediment deposits at the bottom of the lake. 

Below is a chart of the sediment collection samples and the percentage of brown chert found in each.

Sample #

Scientist 1: % Brown Chert

Scientist 2: % Brown Chert

1

5.2

0.9

2

7.1

1.2

3

6.3

0.4

4

6.5

0.8

5

5.8

1.0

 

If there are 2000 pounds per ton, how many pounds of sediment, approximately, did the glacier move per day in 1997?

Possible Answers:

4.0

4000

21.4

165

16.5

Correct answer:

16.5

Explanation:

In 1997, the glacier moved 3.0 tons of sediment, or 6000 pounds. Simply convert the answer to days instead of years like thus: 

6000lbs per year/ 365 days per year = 16.44 pounds per day. The closest answer is 16.5

Example Question #161 : Earth And Space Sciences

Glaciers move, on average, 1 meter per day, although many are known to move faster or slower depending on their size. Whether they are alpine glaciers, which form high in the mountains, or continental glaciers that cover huge areas of land near the poles, glaciers are responsible for breaking up rock and moving sediment as they move across the land. 

Below is a chart of average speed of movement of an alpine glacier per year, as well the amount of sediment displaced by the glacier. 

Year

Average Glacial Movement

Sediment movement per year (tons)

1995

1.1 m/day

2.2

1996

1.3 m/day

2.6

1997

1.5 m/day

3.0

1998

1.3 m/day

2.2

2000

1.1 m/day

1.8

2005

1.0 m/day

1.6

2010

0.9 m/day

1.5

Two scientists have done research on an alpine lake that lies in the path of the glacier. Each took five samples of sediment from the lake.

Scientist 1 believes that the glacier is beginning to melt as it moves lower in elevation, releasing some of the sediment it has carried into mountain streams and springs, causing the makeup of sediments in the lake to change. He notes that the sediment from the lake bed contains brown chert, a rock that can only be found in elevations higher than that of the lake. Scientist 1 took his sample from the sediments that washed ashore on the beach of the lake.

Scientist 2 believes the glacier is not melting, but displacing rock beds so that the sediment loosens and breaks free of the bedrock and then is carried by wind and other erosive elements to the lake. He notes that the sediment from the lake bed contains only trace amounts of the brown chert, not enough to suggest the glacier is melting. Scientist 2 took his samples from sediment deposits at the bottom of the lake. 

Below is a chart of the sediment collection samples and the percentage of brown chert found in each.

Sample #

Scientist 1: % Brown Chert

Scientist 2: % Brown Chert

1

5.2

0.9

2

7.1

1.2

3

6.3

0.4

4

6.5

0.8

5

5.8

1.0

 

What could account for the slow decrease in average movement per year since 1998?

Possible Answers:

All of the answers could be true.

The ground could be leveling out, causing the glacier to slow down. 

There could be a mountain in the path of the glacier, slowing it down.

The glacier could be freezing more, therefore adding more mass and slowing down.

The glacier could be melting, therefore decreasing the mass and slowing down. 

Correct answer:

The glacier could be melting, therefore decreasing the mass and slowing down. 

Explanation:

All of the answers are possibilties, but the idea that the glacier could be melting is the best. Glaciers move so slowly and are so heavy that objects in the way or leveling of the ground would not affect movement. The only thing that would would be a change in the mass of the glacier itself and melting would decrease the mass and therefore the momentum of the glacier.

Example Question #12 : How To Find Data Representation In Earth And Space Sciences

Glaciers move, on average, 1 meter per day, although many are known to move faster or slower depending on their size. Whether they are alpine glaciers, which form high in the mountains, or continental glaciers that cover huge areas of land near the poles, glaciers are responsible for breaking up rock and moving sediment as they move across the land. 

Below is a chart of average speed of movement of an alpine glacier per year, as well the amount of sediment displaced by the glacier. 

Year

Average Glacial Movement

Sediment movement per year (tons)

1995

1.1 m/day

2.2

1996

1.3 m/day

2.6

1997

1.5 m/day

3.0

1998

1.3 m/day

2.2

2000

1.1 m/day

1.8

2005

1.0 m/day

1.6

2010

0.9 m/day

1.5

Two scientists have done research on an alpine lake that lies in the path of the glacier. Each took five samples of sediment from the lake.

Scientist 1 believes that the glacier is beginning to melt as it moves lower in elevation, releasing some of the sediment it has carried into mountain streams and springs, causing the makeup of sediments in the lake to change. He notes that the sediment from the lake bed contains brown chert, a rock that can only be found in elevations higher than that of the lake. Scientist 1 took his sample from the sediments that washed ashore on the beach of the lake.

Scientist 2 believes the glacier is not melting, but displacing rock beds so that the sediment loosens and breaks free of the bedrock and then is carried by wind and other erosive elements to the lake. He notes that the sediment from the lake bed contains only trace amounts of the brown chert, not enough to suggest the glacier is melting. Scientist 2 took his samples from sediment deposits at the bottom of the lake. 

Below is a chart of the sediment collection samples and the percentage of brown chert found in each.

Sample #

Scientist 1: % Brown Chert

Scientist 2: % Brown Chert

1

5.2

0.9

2

7.1

1.2

3

6.3

0.4

4

6.5

0.8

5

5.8

1.0

 

What do you predict will be the average movement per year of the glacier in 2020?

Possible Answers:

1.7 m/day

1.1 m/day

0.7 m/day

1.3 m/day

0.9 m/day

Correct answer:

0.7 m/day

Explanation:

The speed of the glacier has steadily been decreasing for over a decade. Following the pattern of an approximately 0.1 m/day decrease every five years or so, the speed of the glacier in 2020 would be around 0.7 m/day

Example Question #161 : Earth And Space Sciences

Glaciers move, on average, 1 meter per day, although many are known to move faster or slower depending on their size. Whether they are alpine glaciers, which form high in the mountains, or continental glaciers that cover huge areas of land near the poles, glaciers are responsible for breaking up rock and moving sediment as they move across the land. 

Below is a chart of average speed of movement of an alpine glacier per year, as well the amount of sediment displaced by the glacier. 

Year

Average Glacial Movement

Sediment movement per year (tons)

1995

1.1 m/day

2.2

1996

1.3 m/day

2.6

1997

1.5 m/day

3.0

1998

1.3 m/day

2.2

2000

1.1 m/day

1.8

2005

1.0 m/day

1.6

2010

0.9 m/day

1.5

Two scientists have done research on an alpine lake that lies in the path of the glacier. Each took five samples of sediment from the lake.

Scientist 1 believes that the glacier is beginning to melt as it moves lower in elevation, releasing some of the sediment it has carried into mountain streams and springs, causing the makeup of sediments in the lake to change. He notes that the sediment from the lake bed contains brown chert, a rock that can only be found in elevations higher than that of the lake. Scientist 1 took his sample from the sediments that washed ashore on the beach of the lake.

Scientist 2 believes the glacier is not melting, but displacing rock beds so that the sediment loosens and breaks free of the bedrock and then is carried by wind and other erosive elements to the lake. He notes that the sediment from the lake bed contains only trace amounts of the brown chert, not enough to suggest the glacier is melting. Scientist 2 took his samples from sediment deposits at the bottom of the lake. 

Below is a chart of the sediment collection samples and the percentage of brown chert found in each.

Sample #

Scientist 1: % Brown Chert

Scientist 2: % Brown Chert

1

5.2

0.9

2

7.1

1.2

3

6.3

0.4

4

6.5

0.8

5

5.8

1.0

 

What is the approximate relationship between the speed of the glacier and the amount of sediment displaced each year? 

Possible Answers:

inverse

logarithmic

direct

indirect

exponential

Correct answer:

direct

Explanation:

On average, as the speed of the glacier increases or decreases, so does the amount of sediment displaced, indicating that the amount of sediment displaced is directly related to the speed of the glacier. 

Example Question #162 : Earth And Space Sciences

 

Displaying FotorPhoto.jpg

Above is the deer population of Routt County National Forest between 1905 and 2005. The First White-tail deer were introduced to the forest for hunting in 1905. They are not native to the area, though they thrived in the environment.

White tailed deer eat the seeds of coniferous trees, berries, and an assortment of other plants. They tend to roam in small family herds and stick to areas where water is abundant and is unlikely to freeze completely in the winter.

In 1995, an environmental scientist watched a small herd of deer for ten days, recording their movements and taking note of herd size and stopping place. Below is a chart of his results.

 

Day

Travel distance (mi)

Herd size

Stopping place

1

21

13

Bear Creek

2

15

13

Yampa Valley

5

19

13

Bear Creek

8

11

10

Gilpin Lake

10

22

10

Yampa Valley

 

     

Yampa Valley

What could have caused the sudden spike in population after the deer were introduced?

Possible Answers:

Quick breeding and acclimation to the environment.

Over-hunting and acclimation to the environment. 

Quick breeding and over-hunting. 

Acclimation to the environment and a cold winter. 

Correct answer:

Quick breeding and acclimation to the environment.

Explanation:

For the population to grow so rapidly, there had to have been both quick breeding as well as a lack of environmental hazards which only would have come from acclimation to the environment. Population growth relies on a stability in te environment that would allow for safe breeding as well as a low infant death rate among the animals. There must also, though, be breeding in quick enough cycles to replace the animals lost to age, diease and predators. Over-hunting and cold winters would only hinder population growth

Example Question #163 : Earth And Space Sciences

 

Displaying FotorPhoto.jpg

Above is the deer population of Routt County National Forest between 1905 and 2005. The First White-tail deer were introduced to the forest for hunting in 1905. They are not native to the area, though they thrived in the environment.

White tailed deer eat the seeds of coniferous trees, berries, and an assortment of other plants. They tend to roam in small family herds and stick to areas where water is abundant and is unlikely to freeze completely in the winter.

In 1995, an environmental scientist watched a small herd of deer for ten days, recording their movements and taking note of herd size and stopping place. Below is a chart of his results.

 

Day

Travel distance (mi)

Herd size

Stopping place

1

21

13

Bear Creek

2

15

13

Yampa Valley

5

19

13

Bear Creek

8

11

10

Gilpin Lake

10

22

10

Yampa Valley

 

The deer population could have declined after 15 years because of

Possible Answers:

an increase in the wolf population. 

the melting of snow into lakes and streams.

a large and sudden wildfire.

a decade of long springs and summers.

Correct answer:

an increase in the wolf population. 

Explanation:

An increase in the wolf population, a predator to deer, would cause the deer to be preyed on in larger numbers, decreasing their population. It is not a wildfire because that would cause a sudden drop in population. The population decline is gradual, suggesting some element is causing a few more deer each season to be lost. Being hunted by wolves would account for this greater loss better than the other options, which would show a sudden decline but, ultimately, recovery.

Example Question #21 : How To Find Data Representation In Earth And Space Sciences

 

Displaying FotorPhoto.jpg

Above is the deer population of Routt County National Forest between 1905 and 2005. The First White-tail deer were introduced to the forest for hunting in 1905. They are not native to the area, though they thrived in the environment.

White tailed deer eat the seeds of coniferous trees, berries, and an assortment of other plants. They tend to roam in small family herds and stick to areas where water is abundant and is unlikely to freeze completely in the winter.

In 1995, an environmental scientist watched a small herd of deer for ten days, recording their movements and taking note of herd size and stopping place. Below is a chart of his results.

 

Day

Travel distance (mi)

Herd size

Stopping place

1

21

13

Bear Creek

2

15

13

Yampa Valley

5

19

13

Bear Creek

8

11

10

Gilpin Lake

10

22

10

Yampa Valley

 

Which of the following statements could be correct, given the graph above?

Possible Answers:

In 2000 deforestation reached its peak in Routt National Forest, affecting wildlife. 

from 1955 to 1965 the winters were too cold and too long to allow plants to grow properly, especially berries.

In 1955 the Parks Service issued a protection notice allowing hunters to hunt wolves out of season but disallowed the hunting of white-tailed deer entirely. 

From 1955 to 2005 hunting in Routt National Forest grew more popular and the Parks Serivce issued more hunting licenses for white-tailed deer. 

Correct answer:

In 1955 the Parks Service issued a protection notice allowing hunters to hunt wolves out of season but disallowed the hunting of white-tailed deer entirely. 

Explanation:

The statement must match the changes in population that occured during that time. The only statement that correctly connects to the population change is the statement concerning hunting changes for deer and wolves, which would decrease the wolf population and account, then, for the rise in deer population.

You must consider first the year in question and then acount for the particular trend occuring in that year. From 1955-1965, the population is increasing, which would not correlate with a harsh winter. The same is true for 1955-2005; more deer hunting would not see an increase in population. 

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