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

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.

Which of the following best describes the relationship between time and the number of bacterial colonies on Plate 2 in Study 1?

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

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.

Which of the following is a reasonable conclusion to draw from the graph associated with Study 2?

Adapted from "What is Ocean Acidification?" NOAA Pacific Marine Environmental Laboratory Carbon Program. NOAA. Web. 22 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F>.

The Chemistry

When carbon dioxide  is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The Biological Impacts

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher  conditions in the ocean, as they require  to live just like plants on land. On the other hand, studies have shown that a more acidic environment has a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies in the U.S. and around the world depend on the fish and shellfish in our oceans.

Ocean Acidification: An Emerging Global Problem

Ocean acidification is an emerging global problem. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. Since sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food chain and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision making and action.

Which of the following graphs shows the general relationship between pH and acidity as described in the passage?

Adapted from "What is Ocean Acidification?" NOAA Pacific Marine Environmental Laboratory Carbon Program. NOAA. Web. 22 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F>.

The Chemistry

When carbon dioxide  is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The Biological Impacts

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher  conditions in the ocean, as they require  to live just like plants on land. On the other hand, studies have shown that a more acidic environment has a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies in the U.S. and around the world depend on the fish and shellfish in our oceans.

Ocean Acidification: An Emerging Global Problem

Ocean acidification is an emerging global problem. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. Since sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food chain and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision making and action.

When the authors use the term "calcifying species," they most nearly mean __________.

Adapted from "What is Ocean Acidification?" NOAA Pacific Marine Environmental Laboratory Carbon Program. NOAA. Web. 22 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F>.

The Chemistry

When carbon dioxide  is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The Biological Impacts

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher  conditions in the ocean, as they require  to live just like plants on land. On the other hand, studies have shown that a more acidic environment has a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies in the U.S. and around the world depend on the fish and shellfish in our oceans.

Ocean Acidification: An Emerging Global Problem

Ocean acidification is an emerging global problem. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. Since sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food chain and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision making and action.

According to the passage, why would some species benefit from ocean acidification?

Adapted from "What is Ocean Acidification?" NOAA Pacific Marine Environmental Laboratory Carbon Program. NOAA. Web. 22 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F>.

The Chemistry

When carbon dioxide  is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The Biological Impacts

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher  conditions in the ocean, as they require  to live just like plants on land. On the other hand, studies have shown that a more acidic environment has a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies in the U.S. and around the world depend on the fish and shellfish in our oceans.

Ocean Acidification: An Emerging Global Problem

Ocean acidification is an emerging global problem. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. Since sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food chain and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision making and action.

Photosynthetic algae differ from shelled organisms with respect to the effect of ocean acidification primarily because __________.

Adapted from "What is Ocean Acidification?" NOAA Pacific Marine Environmental Laboratory Carbon Program. NOAA. Web. 22 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F>.

The Chemistry

When carbon dioxide  is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The Biological Impacts

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher  conditions in the ocean, as they require  to live just like plants on land. On the other hand, studies have shown that a more acidic environment has a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies in the U.S. and around the world depend on the fish and shellfish in our oceans.

Ocean Acidification: An Emerging Global Problem

Ocean acidification is an emerging global problem. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. Since sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food chain and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision making and action.

Over time, if ocean acidification continues at the rate projected in the passage, what would you expect to happen to the concentration of calcium carbonate in the ocean?

Adapted from "What is Ocean Acidification?" NOAA Pacific Marine Environmental Laboratory Carbon Program. NOAA. Web. 22 Apr. 2015. <http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F>.

The Chemistry

When carbon dioxide  is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. These chemical reactions are termed "ocean acidification" or "OA" for short. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with respect to calcium carbonate minerals. This means there are abundant building blocks for calcifying organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells.

Since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity. Future predictions indicate that the oceans will continue to absorb carbon dioxide and become even more acidic. Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.

The Biological Impacts

Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher  conditions in the ocean, as they require  to live just like plants on land. On the other hand, studies have shown that a more acidic environment has a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. When shelled organisms are at risk, the entire food web may also be at risk. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Many jobs and economies in the U.S. and around the world depend on the fish and shellfish in our oceans.

Ocean Acidification: An Emerging Global Problem

Ocean acidification is an emerging global problem. Over the last decade, there has been much focus in the ocean science community on studying the potential impacts of ocean acidification. Since sustained efforts to monitor ocean acidification worldwide are only beginning, it is currently impossible to predict exactly how ocean acidification impacts will cascade throughout the marine food chain and affect the overall structure of marine ecosystems. With the pace of ocean acidification accelerating, scientists, resource managers, and policymakers recognize the urgent need to strengthen the science as a basis for sound decision-making and action.

According to the passage, where in the marine food web do shelled organisms sit?

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. 

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.

What can you reasonably concluded about the presence of brown chert in the sediments found in the alpine lake?

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. 

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.

If, in the year 2020, the percent of brown chert found in the alpine lake increases to 20 percent, what would you conclude about the glacier?