ACT Science : How to find experimental design in earth and space sciences

Study concepts, example questions & explanations for ACT Science

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Example Question #1 : How To Find Experimental Design In Earth And Space Sciences

Global warming is defined as the slow increase in the temperature of the earth’s atmosphere and is caused by pollutants and carbon dioxide (CO2). While the gradual increase in temperature cannot be refuted, scientists argue over the cause.

 Scientist 1:

Global warming is caused by increases in atmospheric CO2, which is directly created by humans and their consumption of fossil fuels. The natural CO2 released from carbon sinks has a different isotopic ratio from the CO2 released from fossil fuels. Current measurements of the radioactive isotopes of CO2 show that it is from human activity, not from nature. The Earth’s carbon sinks cannot absorb these large amounts of unnatural CO2 emissions. About fifty percent of the CO2 produced by mankind remains in the atmosphere, unable to be absorbed.

Scientist 2:

The rise in atmospheric CO2 levels are a result of global warming, not the cause of it. When the temperature increases, the CO2 in carbon sinks is released. While humans do cause release of CO2, the carbon sinks absorb it. The activity of the carbon sinks increases to allow for higher levels of CO2 absorption. Proponents for human causation of global warming point to the warming and cooling of the stratosphere, however, these temperature fluctuations are caused by changes in the sun’s heat. These proponents also look at the acidity of the ocean as evidence of human causation, however, the rise in ocean acidity is within the normal range of fluctuations over the past ten thousand years.

What new evidence would support the argument made by Scientist 1?

Possible Answers:

An experiment suggesting the ocean acidity level fluctuates with atmospheric temperature changes

An experiment suggesting that 13% of CO2 remaining in the atmosphere is the isotopic CO2 caused by humans

Evidence showing the release of natural CO2 from carbon sinks directly increases the temperature

An experiment suggesting the ocean acidity level has an impact on the atmospheric temperature changes

Evidence showing that use of fossil fuels directly increases the temperature
Correct answer:
Evidence showing that use of fossil fuels directly increases the temperature
Explanation:

Scientist 1 states that "Global warming is caused by increases in atmospheric CO2, which is directly created by humans and their consumption of fossil fuels." An experiment showing that use of fossil fuels directly increases the temperature would support the beliefs of Scientist 1. Scientist 1 does not discuss ocean acidity in his argument, therefore the reader cannot assume any information on this topic would support the argument of Scientist 1.

Example Question #2 : How To Find Experimental Design In Earth And Space Sciences

A scientist observes the motion of stars, planets, and other objects in deep space through a high-powered telescope. She observes that these objects all appear to be moving away from the Earth and graphs her results comparing their velocities, in kilometers per second, and their proper distance, in megaparsecs.

 

 

Hubble_graph

Which of the following is the correct unit for proper distance in this experiment?

Possible Answers:

Meter

Kilometer

Megaparsec

Mile

Correct answer:

Megaparsec

Explanation:

Notice that on the graph, the x-axis (the proper distance) is measured in megaparsecs.

Example Question #3 : How To Find Experimental Design In Earth And Space Sciences

A scientist observes the motion of stars, planets, and other objects in deep space through a high-powered telescope. She observes that these objects all appear to be moving away from the Earth and graphs her results comparing their velocities, in kilometers per second, and their proper distance, in megaparsecs.

 

 

Hubble_graph

Which of the following would be necessary to recreate the experiment?

Possible Answers:

A satellite taking pictures of the distant stars from another location.

A very high mountain to place the telescope on top of.

Infrared imaging of distant stars.

A high-powered telescope.

Correct answer:

A high-powered telescope.

Explanation:

While many of these suggestions would certainly make the experiment easier, the only necessary piece of equipment, as stated in the set up of the experiment, is a high-powered telescope.

Example Question #4 : How To Find Experimental Design In Earth And Space Sciences

Scientists have long debated the origin of organic molecules on Earth.  Organic molecules are those based on the atom carbon, which can form four distinct bonds in contrast to the fewer number allowed in most other non-metals.  As a result of this property, carbon can give rise to the enormously complex molecular shapes necessary for life to arise.

Some scientists argue that organic matter was dissolved in water ice on comets, and brought to Earth early in its history. These comets crashed into the early Earth, and deposited carbon-based molecules in copious quantities to the Earth’s surface as their water melted.

In 2014, the first space probe landed on the comet 67P/Churyumov-Gerasimenko. Suppose that scientists find the following information from 5 distinct samples after landing on the comet. Each sample was taken at a single geographical location, but 5 meters deeper than the last.  Sample 1 was taken at a depth of 1 meter below the surface.

Sample #

Water Ice?

Concentration of Organics

1

No

N/A

2

Yes

1 mg/L

3

No

N/A

4

Yes

4 mg/L

5

Yes

10 mg/L

These samples were compared to 5 similar samples from the surface of Mars.  Scientists posited that this comparison would be meaningful because we know that life does not exist on Mars the same way that it does on Earth.  Thus, they are comparing a known non-biological celestial body, Mars, with another celestial body, the comet, which may be seeding life on suitable plants.

Sample #

Water Ice?

Concentration of Organics

1

No

N/A

2

No

N/A

3

No

N/A

4

No

N/A

5

Yes

1 mg/L

Before sending the probe into space, scientists suggested that organics may be found on celestial bodies like comets.  This suggestion, made in the absence of direct evidence, is most nearly:

Possible Answers:

A law

A theory

A conclusion

Both a theory and a law

A hypothesis

Correct answer:

A hypothesis

Explanation:

Before sending the probe, the scientists had no direct evidence to generate a mature scientific theory.  The passage indicates that the scientists hoped to use the data to mature their hypotheses that organics may exist in space, thus making the statement in the question best characterized as a hypothesis.

Example Question #5 : How To Find Experimental Design In Earth And Space Sciences

Scientists have long debated the origin of organic molecules on Earth.  Organic molecules are those based on the atom carbon, which can form four distinct bonds in contrast to the fewer number allowed in most other non-metals.  As a result of this property, carbon can give rise to the enormously complex molecular shapes necessary for life to arise.

Some scientists argue that organic matter was dissolved in water ice on comets, and brought to Earth early in its history. These comets crashed into the early Earth, and deposited carbon-based molecules in copious quantities to the Earth’s surface as their water melted.

In 2014, the first space probe landed on the comet 67P/Churyumov-Gerasimenko. Suppose that scientists find the following information from 5 distinct samples after landing on the comet. Each sample was taken at a single geographical location, but 5 meters deeper than the last.  Sample 1 was taken at a depth of 1 meter below the surface.

Sample #

Water Ice?

Concentration of Organics

1

No

N/A

2

Yes

1 mg/L

3

No

N/A

4

Yes

4 mg/L

5

Yes

10 mg/L

These samples were compared to 5 similar samples from the surface of Mars.  Scientists posited that this comparison would be meaningful because we know that life does not exist on Mars the same way that it does on Earth.  Thus, they are comparing a known non-biological celestial body, Mars, with another celestial body, the comet, which may be seeding life on suitable plants.

Sample #

Water Ice?

Concentration of Organics

1

No

N/A

2

No

N/A

3

No

N/A

4

No

N/A

5

Yes

1 mg/L

After collecting the data, scientists involved in the study expressed their desire to repeat sampling on another comet.  Based only on the data in the passage, which of the following would suggest that organics would not be present?

I.  No water ice present in the comet

II.  The comet has no composition similarities to Earth

III.  The comet has no composition similarities to Mars

Possible Answers:

I only

I and II

II only

III only

II and III

Correct answer:

I only

Explanation:

I is the best answer here because the data in both tables suggest that no organics are found when there is no water in which they can be dissolved.  The composition similarity to Earth or Mars is less relevant, as no part of the passage suggests this has a bearing on the relative abundance of organics.

Example Question #6 : How To Find Experimental Design In Earth And Space Sciences

Scientists studying historical trends in climate change have a number of tools at their disposal. One method of analyzing paleoclimate data involves the use of fossilized pollen spores embedded in sediment. Pollen spores are specific to the plant that produced them. Because the spores are resilient and are widely-distributed by wind, they provide a snapshot of the vegetation that was widespread at a particular point in time. By identifying the age of a sample and the composition of the various spores, scientists can identify the prominent vegetation and use this information to gain insight into the climate at the time the spores were deposited.

Scientists took sediment samples from various depths of a lakebed. They found that five types of pollen spores make up the majority of spore deposits in each sample. In Table 1, plants are listed along with the respective temperature ranges and levels of precipitation for the areas in which they are commonly found. Table 2 shows the composition of the assortment of spores in each of the four samples taken by the scientists.

Pollen_table_1

Pollen_table_2

In order to replicate the above study, which of the following must be known?

Possible Answers:

The total number of spores in each sample

The time of year the samples were taken

The average precipitation over the year in which the samples were taken

The location and depth from which each sample was taken

Correct answer:

The location and depth from which each sample was taken

Explanation:

The scientists were only concerned with temperature and precipitation as they related to the ideal climate for each plant type. As such, the climate at the time of sample collection is not important. The total number of spores in each sample is also unnecessary information. Total spore count may vary across samples; scientists were more concerned with the percent of the sample for which each plant spore accounted. The locations and depths of each sample are important because each sample represents a particular place and time. Because climate is dependent on location, it is important to sample from the same place in order to replicate the study's results.

Example Question #7 : How To Find Experimental Design In Earth And Space Sciences

Scientists studying historical trends in climate change have a number of tools at their disposal. One method of analyzing paleoclimate data involves the use of fossilized pollen spores embedded in sediment. Pollen spores are specific to the plant that produced them. Because the spores are resilient and are widely-distributed by wind, they provide a snapshot of the vegetation that was widespread at a particular point in time. By identifying the age of a sample and the composition of the various spores, scientists can identify the prominent vegetation and use this information to gain insight into the climate at the time the spores were deposited.

Scientists took sediment samples from various depths of a lakebed. They found that five types of pollen spores make up the majority of spore deposits in each sample. In Table 1, plants are listed along with the respective temperature ranges and levels of precipitation for the areas in which they are commonly found. Table 2 shows the composition of the assortment of spores in each of the four samples taken by the scientists.

Pollen_table_1

Pollen_table_2

In Table 2, what is the most likely explanation for the varying concentrations of spores from Plant 1 across each sample? 

Possible Answers:

Plant A is currently extinct.

Spores are randomly distributed by the wind, so spore count will naturally vary across each sample.

The older the sample, the fewer the spores that are able to survive intact.

Each sample represents the vegetative distribution from a different period of time.

There is no significant difference in spore concentration across each sample.

Correct answer:

Each sample represents the vegetative distribution from a different period of time.

Explanation:

According to the passage, prominent vegetation can indicate the climate in a region over a given time period. Because a plant's prominence can be linked to the climate at that time, the change in spore concentration most likely indicates a change in climate. Climate, by definition, consists of patterns that occur over long periods of time. Therefore, changes in spore concentration are most likely tied to the different eras that each sample is taken from. This is further evidenced by the scientists' decision to take samples from different depths of the lake bed.

Example Question #8 : How To Find Experimental Design In Earth And Space Sciences

Scientists studying historical trends in climate change have a number of tools at their disposal. One method of analyzing paleoclimate data involves the use of fossilized pollen spores embedded in sediment. Pollen spores are specific to the plant that produced them. Because the spores are resilient and are widely-distributed by wind, they provide a snapshot of the vegetation that was widespread at a particular point in time. By identifying the age of a sample and the composition of the various spores, scientists can identify the prominent vegetation and use this information to gain insight into the climate at the time the spores were deposited.

Scientists took sediment samples from various depths of a lakebed. They found that five types of pollen spores make up the majority of spore deposits in each sample. In Table 1, plants are listed along with the respective temperature ranges and levels of precipitation for the areas in which they are commonly found. Table 2 shows the composition of the assortment of spores in each of the four samples taken by the scientists.

Pollen_table_1

Pollen_table_2

In Table 1, what does the range "8 - 15" represent with respect to Plant E?

Possible Answers:

The temperature in degrees Celsius at which Plant E thrives.

The average number of spores from Plant E found in each sample.

The depth at which the majority of Plant E spores were found.

The temperature in degrees Celsius at which Plant E is unable to survive.

The average annual precipitation required for Plant E to thrive.

Correct answer:

The temperature in degrees Celsius at which Plant E thrives.

Explanation:

In Table 1, the range "8 - 15" can be found in the middle column. 

Screenshot_2015-02-16_at_10.13.28_pm

The data label for this column indicates that the range is a measure of temperature in degrees Celsius. The information in the passage states that the temperatures shown are those in which a plant commonly may be found.

Example Question #9 : How To Find Experimental Design In 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

How did the experimental designs of Study 1 and Study 2 differ?

Possible Answers:

Compared to Study 1, Study 2 tested a wider variety of detergents.

Compared to Study 1, Study 2 tested detergents over a longer period of time.

There was no control group in Study 2.

Compared to Study 1, Study 2 took measurements of bacterial colony number more frequently.

Correct answer:

Compared to Study 1, Study 2 tested detergents over a longer period of time.

Explanation:

Study 2 tested detergents over a period of 48 hours, whereas Study 1 tested detergents over a period of 24 hours.

Example Question #10 : How To Find Experimental Design In Earth And Space Sciences

A group of scientists wanted to investigate weather patterns in four cities across the United States. They conducted a series of experiments to look for similarities and differences among the four cities. The scientists measured wind speed and direction, amount of precipitation, and percentage of cloud cover for one week. Further explanation can be found below.

Experiment 1

Scientists measured wind speed using an anemometer at fifteen different locations around each city. Measurements were taken at each location three times a day and then averaged to get a daily wind speed for each city. This was repeated every day for one week, and the results were compiled into Table 1.

Windspeed

Experiment 2 

Scientists set up barometers at five locations in each city. At the end of each day, the precipitation levels in the five barometers were averaged to find the average daily precipitation, and the results are compiled in Table 2.

Precip2

Experiment 3

For the final experiment, scientists placed upward-facing cameras atop the ten tallest buildings in each city. The cameras took one picture per hour. The scientists then used computer software to stitch together the images from all the cameras. The resulting meta-image was then analyzed with another computer program to find the percent of the sky covered by clouds. The results can be found in Table 3.

Ccp3

How many measurements did the scientists take per day in Experiment 1?

Possible Answers:

Correct answer:

Explanation:

The passage states that in Experiment 1, the scientists took measurements three times a day from fifteen locations in each of the four cities. To find the total number of measurements per day, simply multiply those numbers together to get the following:

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