Passage adapted from “The Dead” in Dubliners by James Joyce (1915)

She was fast asleep.

Gabriel, leaning on his elbow, looked for a few moments unresentfully on her tangled hair and half-open mouth, listening to her deep-drawn breath. So she had had that romance in her life: a man had died for her sake. It hardly pained him now to think how poor a part he, her husband, had played in her life. He watched her while she slept as though he and she had never lived together as man and wife. His curious eyes rested long upon her face and on her hair: and, as he thought of what she must have been then, in that time of her first girlish beauty, a strange friendly pity for her entered his soul. He did no like to say even to himself that her face was no longer beautiful but he knew that it was no longer the face for which Michael Furey had braved death.

Perhaps she had not told him all the story. His eyes moved to the chair over which she had thrown some of her clothes. A petticoat string dangled to the floor. One boot stood upright, its limp upper fallen: the fellow of it lay upon its side. He wondered at his riot of emotions of an hour before. From what had it proceeded? From his aunt’s supper, from his own foolish speech, from the wine and dancing, the merry-making when saying good-night in the hall, the pleasure of the walk along the river in the snow. Poor Aunt Julia! She, too, would soon be a shade with the shade of Patrick Morkan and his horse. He had caught that haggard look upon her face for a moment when she was singing Arrayed for the Bridal. Soon, perhaps, he would be sitting in that same drawing-room, dressed in black, his silk hat on his knees. The blinds would be drawn down and Aunt Kate would be sitting beside him, crying and blowing her nose and telling him how Julia had died. He would cast about in his mind for some words that might console her, and would find only lame and useless ones. Yes, yes: that would happen very soon.

The air of the room chilled his shoulders. He stretched himself cautiously along under the sheets and lay down beside his wife. One by one they were all becoming shades. Better pass boldly into that other world, in the full glory of some passion, than fade and wither dismally with age. He thought of how she who lay beside him had locked in her heart for so many years that image of her lover’s eyes when he had told her that he did not wish to live.

Generous tears filled Gabriel’s eyes. He had never felt like that himself towards any woman but he knew that such a feeling must be love. The tears gathered more thickly in his eyes and in the partial darkness he imagined he saw the form of a young man standing under a dripping tree. Other forms were near. His soul had approached that region where dwell the vast hosts of the dead. He was conscious of, but could not apprehend, their wayward and flickering existence. His own identity was fading out into a grey impalpable world: the solid world itself which these dead had one time reared and lived in was dissolving and dwindling.

A few light taps upon the pane made him turn to the window. It had begun to snow again. He watched sleepily the flakes, silver and dark, falling obliquely against the lamplight. The time had come for him to set out on his journey westward. Yes, the newspapers were right: snow was general all over Ireland. It was falling on every part of the dark central plain, on the treeless hills, falling softly upon the hill where Michael Furey lay buried. It lay thickly drifted on the crooked crosses and headstones, on the spears of the little gate, on the barren thorns. His soul swooned slowly as he heard the snow falling faintly through the universe and faintly falling, like the descent of their last end, upon all the living and the dead.

Which of the following inferences about Gabriel's relationship with his wife is the most reasonable to make?

Passage adapted from “The Dead” in Dubliners by James Joyce (1915)

She was fast asleep.

Gabriel, leaning on his elbow, looked for a few moments unresentfully on her tangled hair and half-open mouth, listening to her deep-drawn breath. So she had had that romance in her life: a man had died for her sake. It hardly pained him now to think how poor a part he, her husband, had played in her life. He watched her while she slept as though he and she had never lived together as man and wife. His curious eyes rested long upon her face and on her hair: and, as he thought of what she must have been then, in that time of her first girlish beauty, a strange friendly pity for her entered his soul. He did no like to say even to himself that her face was no longer beautiful but he knew that it was no longer the face for which Michael Furey had braved death.

Perhaps she had not told him all the story. His eyes moved to the chair over which she had thrown some of her clothes. A petticoat string dangled to the floor. One boot stood upright, its limp upper fallen: the fellow of it lay upon its side. He wondered at his riot of emotions of an hour before. From what had it proceeded? From his aunt’s supper, from his own foolish speech, from the wine and dancing, the merry-making when saying good-night in the hall, the pleasure of the walk along the river in the snow. Poor Aunt Julia! She, too, would soon be a shade with the shade of Patrick Morkan and his horse. He had caught that haggard look upon her face for a moment when she was singing Arrayed for the Bridal. Soon, perhaps, he would be sitting in that same drawing-room, dressed in black, his silk hat on his knees. The blinds would be drawn down and Aunt Kate would be sitting beside him, crying and blowing her nose and telling him how Julia had died. He would cast about in his mind for some words that might console her, and would find only lame and useless ones. Yes, yes: that would happen very soon.

The air of the room chilled his shoulders. He stretched himself cautiously along under the sheets and lay down beside his wife. One by one they were all becoming shades. Better pass boldly into that other world, in the full glory of some passion, than fade and wither dismally with age. He thought of how she who lay beside him had locked in her heart for so many years that image of her lover’s eyes when he had told her that he did not wish to live.

Generous tears filled Gabriel’s eyes. He had never felt like that himself towards any woman but he knew that such a feeling must be love. The tears gathered more thickly in his eyes and in the partial darkness he imagined he saw the form of a young man standing under a dripping tree. Other forms were near. His soul had approached that region where dwell the vast hosts of the dead. He was conscious of, but could not apprehend, their wayward and flickering existence. His own identity was fading out into a grey impalpable world: the solid world itself which these dead had one time reared and lived in was dissolving and dwindling.

A few light taps upon the pane made him turn to the window. It had begun to snow again. He watched sleepily the flakes, silver and dark, falling obliquely against the lamplight. The time had come for him to set out on his journey westward. Yes, the newspapers were right: snow was general all over Ireland. It was falling on every part of the dark central plain, on the treeless hills, falling softly upon the hill where Michael Furey lay buried. It lay thickly drifted on the crooked crosses and headstones, on the spears of the little gate, on the barren thorns. His soul swooned slowly as he heard the snow falling faintly through the universe and faintly falling, like the descent of their last end, upon all the living and the dead.

In what season is this passage set?

Passage adapted from “The Dead” in Dubliners by James Joyce (1915)

She was fast asleep.

Gabriel, leaning on his elbow, looked for a few moments unresentfully on her tangled hair and half-open mouth, listening to her deep-drawn breath. So she had had that romance in her life: a man had died for her sake. It hardly pained him now to think how poor a part he, her husband, had played in her life. He watched her while she slept as though he and she had never lived together as man and wife. His curious eyes rested long upon her face and on her hair: and, as he thought of what she must have been then, in that time of her first girlish beauty, a strange friendly pity for her entered his soul. He did no like to say even to himself that her face was no longer beautiful but he knew that it was no longer the face for which Michael Furey had braved death.

Perhaps she had not told him all the story. His eyes moved to the chair over which she had thrown some of her clothes. A petticoat string dangled to the floor. One boot stood upright, its limp upper fallen: the fellow of it lay upon its side. He wondered at his riot of emotions of an hour before. From what had it proceeded? From his aunt’s supper, from his own foolish speech, from the wine and dancing, the merry-making when saying good-night in the hall, the pleasure of the walk along the river in the snow. Poor Aunt Julia! She, too, would soon be a shade with the shade of Patrick Morkan and his horse. He had caught that haggard look upon her face for a moment when she was singing Arrayed for the Bridal. Soon, perhaps, he would be sitting in that same drawing-room, dressed in black, his silk hat on his knees. The blinds would be drawn down and Aunt Kate would be sitting beside him, crying and blowing her nose and telling him how Julia had died. He would cast about in his mind for some words that might console her, and would find only lame and useless ones. Yes, yes: that would happen very soon.

The air of the room chilled his shoulders. He stretched himself cautiously along under the sheets and lay down beside his wife. One by one they were all becoming shades. Better pass boldly into that other world, in the full glory of some passion, than fade and wither dismally with age. He thought of how she who lay beside him had locked in her heart for so many years that image of her lover’s eyes when he had told her that he did not wish to live.

Generous tears filled Gabriel’s eyes. He had never felt like that himself towards any woman but he knew that such a feeling must be love. The tears gathered more thickly in his eyes and in the partial darkness he imagined he saw the form of a young man standing under a dripping tree. Other forms were near. His soul had approached that region where dwell the vast hosts of the dead. He was conscious of, but could not apprehend, their wayward and flickering existence. His own identity was fading out into a grey impalpable world: the solid world itself which these dead had one time reared and lived in was dissolving and dwindling.

A few light taps upon the pane made him turn to the window. It had begun to snow again. He watched sleepily the flakes, silver and dark, falling obliquely against the lamplight. The time had come for him to set out on his journey westward. Yes, the newspapers were right: snow was general all over Ireland. It was falling on every part of the dark central plain, on the treeless hills, falling softly upon the hill where Michael Furey lay buried. It lay thickly drifted on the crooked crosses and headstones, on the spears of the little gate, on the barren thorns. His soul swooned slowly as he heard the snow falling faintly through the universe and faintly falling, like the descent of their last end, upon all the living and the dead.

What is the best evidence for the answer to the previous question querying the season in which the passage is set?

Phosphorus is a key component for life on Earth; it performs essential roles in respiration, photosynthesis, and the decomposition of organic material. Phosphorus is primarily acquired by plants in the inorganic, ionic forms, which are found in soil solutions at concentrations of only a few parts per million. Plants use methods of diffusion and active transport to absorb phosphorus at the surface of their roots.

Phosphorus is abundant in soils; however, it is often unavailable to plants because it forms insoluble complexes with positively charged cations. This occurs when negatively charged phosphorus ions bind to positive cations in the soil (i.e. opposites attract). Enzymes such as acid phosphatases play a critical role in the acquisition and manipulation of phosphorus in plants. It has been found that when soils possess low levels of free phosphorus, plants are stimulated to produce acid phosphatase enzymes, which release inorganic phosphorus in the soil.

Plants need nutrients such as phosphorus to grow and proliferate; therefore, understanding how this species uses phosphorus could lead to conservation practices to limits this invasive species’ impact on the environment. A group of scientists wanted to investigate the relationship between plant enzyme activity and phosphorus levels in aquatic biomes. This investigation was targeted at studying the invasive Eurasian milfoil, Myriophyllum spicatum. In doing so, scientists believed that they could control the spread of the plant into neighboring waters if they were able to limit the nutrients in its environment. A study was performed in order to explore how phosphorus concentration in freshwater ecosystems affects phosphorus cycling and plant enzyme production. In order to determine if there was a relationship between the phosphatase activity and concentration of phosphorus in the sediment and water column of specific sites, researchers measured the respective phosphorus concentrations and enzyme activities. 

In this study, three standing ponds were sampled at six different time periods in the same year from July to December. The phosphorus content of each sample was determined through an ascorbic acid assay. Sediment collections were divided into samples weighing one sixteenth of a gram using coning and quartering techniques. These samples underwent a persulfate digestion and were vacuum filtered to remove excess sediment. Last, the samples were diluted and analyzed for phosphorus content using the ascorbic acid procedure. The solutions’ ability to absorb specific wavelengths of light was measured using a spectrophotometer set at an absorbance of 880 nanometers. After the sediment phosphorus content of each site was determined, scientists decided to determine the concentration of phosphorus releasing enzymes through an alkaline phosphatase assay. One to two milliliters of collected sediment was centrifuged until the sediment formed a pellet. The scientists chemically induced and observed a reaction between the sediment enzymes and insoluble phosphorus compounds present in an artificial substrate. Enzymes speed up chemical reactions by binding to substrates and releasing their constituent parts: in this case phosphorus and an unknown cation. After this reaction was halted, the samples were centrifuged and their absorbance was measured with a spectrophotometer set at 420 nanometers. This identified the concentration of phosphatase enzymes present in each sample. Now, scientists were able to compare the correlation between phosphorus levels and plant enzymes in the soil.

An exponential regression analysis indicated that there was a significant relationship between phosphatase activity and sediment phosphorus concentration (see Figure 1). The trend in the exponential regression analysis showed evidence of an inducible expression between phosphorus substrate and phosphatase enzymes. In other words, phosphorus is often abundant in soils, but is unavailable due to its formation into insoluble complexes with aluminum and iron. As a result, acid phosphatase enzymes break down these insoluble complexes and release phosphorus for plant acquisition and usage; therefore, phosphorus rich environments should possess greater phosphatase activity.

This study supported the expectation that there would be a relationship between phosphatase activities and sediment phosphorus concentration (i.e. higher phosphorus concentrations increase yields of plants, while phosphorus limitation decreases the productivity of invasive species). The scientists hoped to use the findings in this study for the development of bioremediation techniques aimed at controlling invasive species through green management practices.

Figure 1 represents a correlation between phosphorus concentration and phosphatase activity in all the sites across all time periods. 

Which choice provides the best evidence for the answer to the previous question?

Phosphorus is a key component for life on Earth; it performs essential roles in respiration, photosynthesis, and the decomposition of organic material. Phosphorus is primarily acquired by plants in the inorganic, ionic forms, which are found in soil solutions at concentrations of only a few parts per million. Plants use methods of diffusion and active transport to absorb phosphorus at the surface of their roots.

Phosphorus is abundant in soils; however, it is often unavailable to plants because it forms insoluble complexes with positively charged cations. This occurs when negatively charged phosphorus ions bind to positive cations in the soil (i.e. opposites attract). Enzymes such as acid phosphatases play a critical role in the acquisition and manipulation of phosphorus in plants. It has been found that when soils possess low levels of free phosphorus, plants are stimulated to produce acid phosphatase enzymes, which release inorganic phosphorus in the soil.

Plants need nutrients such as phosphorus to grow and proliferate; therefore, understanding how this species uses phosphorus could lead to conservation practices to limits this invasive species’ impact on the environment. A group of scientists wanted to investigate the relationship between plant enzyme activity and phosphorus levels in aquatic biomes. This investigation was targeted at studying the invasive Eurasian milfoil, Myriophyllum spicatum. In doing so, scientists believed that they could control the spread of the plant into neighboring waters if they were able to limit the nutrients in its environment. A study was performed in order to explore how phosphorus concentration in freshwater ecosystems affects phosphorus cycling and plant enzyme production. In order to determine if there was a relationship between the phosphatase activity and concentration of phosphorus in the sediment and water column of specific sites, researchers measured the respective phosphorus concentrations and enzyme activities. 

In this study, three standing ponds were sampled at six different time periods in the same year from July to December. The phosphorus content of each sample was determined through an ascorbic acid assay. Sediment collections were divided into samples weighing one sixteenth of a gram using coning and quartering techniques. These samples underwent a persulfate digestion and were vacuum filtered to remove excess sediment. Last, the samples were diluted and analyzed for phosphorus content using the ascorbic acid procedure. The solutions’ ability to absorb specific wavelengths of light was measured using a spectrophotometer set at an absorbance of 880 nanometers. After the sediment phosphorus content of each site was determined, scientists decided to determine the concentration of phosphorus releasing enzymes through an alkaline phosphatase assay. One to two milliliters of collected sediment was centrifuged until the sediment formed a pellet. The scientists chemically induced and observed a reaction between the sediment enzymes and insoluble phosphorus compounds present in an artificial substrate. Enzymes speed up chemical reactions by binding to substrates and releasing their constituent parts: in this case phosphorus and an unknown cation. After this reaction was halted, the samples were centrifuged and their absorbance was measured with a spectrophotometer set at 420 nanometers. This identified the concentration of phosphatase enzymes present in each sample. Now, scientists were able to compare the correlation between phosphorus levels and plant enzymes in the soil.

An exponential regression analysis indicated that there was a significant relationship between phosphatase activity and sediment phosphorus concentration (see Figure 1). The trend in the exponential regression analysis showed evidence of an inducible expression between phosphorus substrate and phosphatase enzymes. In other words, phosphorus is often abundant in soils, but is unavailable due to its formation into insoluble complexes with aluminum and iron. As a result, acid phosphatase enzymes break down these insoluble complexes and release phosphorus for plant acquisition and usage; therefore, phosphorus rich environments should possess greater phosphatase activity.

This study supported the expectation that there would be a relationship between phosphatase activities and sediment phosphorus concentration (i.e. higher phosphorus concentrations increase yields of plants, while phosphorus limitation decreases the productivity of invasive species). The scientists hoped to use the findings in this study for the development of bioremediation techniques aimed at controlling invasive species through green management practices.

Figure 1 represents a correlation between phosphorus concentration and phosphatase activity in all the sites across all time periods. 

Which of the following identifies the shift in focus of the passage from its beginning to its end?

Phosphorus is a key component for life on Earth; it performs essential roles in respiration, photosynthesis, and the decomposition of organic material. Phosphorus is primarily acquired by plants in the inorganic, ionic forms, which are found in soil solutions at concentrations of only a few parts per million. Plants use methods of diffusion and active transport to absorb phosphorus at the surface of their roots.

Phosphorus is abundant in soils; however, it is often unavailable to plants because it forms insoluble complexes with positively charged cations. This occurs when negatively charged phosphorus ions bind to positive cations in the soil (i.e. opposites attract). Enzymes such as acid phosphatases play a critical role in the acquisition and manipulation of phosphorus in plants. It has been found that when soils possess low levels of free phosphorus, plants are stimulated to produce acid phosphatase enzymes, which release inorganic phosphorus in the soil.

Plants need nutrients such as phosphorus to grow and proliferate; therefore, understanding how this species uses phosphorus could lead to conservation practices to limits this invasive species’ impact on the environment. A group of scientists wanted to investigate the relationship between plant enzyme activity and phosphorus levels in aquatic biomes. This investigation was targeted at studying the invasive Eurasian milfoil, Myriophyllum spicatum. In doing so, scientists believed that they could control the spread of the plant into neighboring waters if they were able to limit the nutrients in its environment. A study was performed in order to explore how phosphorus concentration in freshwater ecosystems affects phosphorus cycling and plant enzyme production. In order to determine if there was a relationship between the phosphatase activity and concentration of phosphorus in the sediment and water column of specific sites, researchers measured the respective phosphorus concentrations and enzyme activities. 

In this study, three standing ponds were sampled at six different time periods in the same year from July to December. The phosphorus content of each sample was determined through an ascorbic acid assay. Sediment collections were divided into samples weighing one sixteenth of a gram using coning and quartering techniques. These samples underwent a persulfate digestion and were vacuum filtered to remove excess sediment. Last, the samples were diluted and analyzed for phosphorus content using the ascorbic acid procedure. The solutions’ ability to absorb specific wavelengths of light was measured using a spectrophotometer set at an absorbance of 880 nanometers. After the sediment phosphorus content of each site was determined, scientists decided to determine the concentration of phosphorus releasing enzymes through an alkaline phosphatase assay. One to two milliliters of collected sediment was centrifuged until the sediment formed a pellet. The scientists chemically induced and observed a reaction between the sediment enzymes and insoluble phosphorus compounds present in an artificial substrate. Enzymes speed up chemical reactions by binding to substrates and releasing their constituent parts: in this case phosphorus and an unknown cation. After this reaction was halted, the samples were centrifuged and their absorbance was measured with a spectrophotometer set at 420 nanometers. This identified the concentration of phosphatase enzymes present in each sample. Now, scientists were able to compare the correlation between phosphorus levels and plant enzymes in the soil.

An exponential regression analysis indicated that there was a significant relationship between phosphatase activity and sediment phosphorus concentration (see Figure 1). The trend in the exponential regression analysis showed evidence of an inducible expression between phosphorus substrate and phosphatase enzymes. In other words, phosphorus is often abundant in soils, but is unavailable due to its formation into insoluble complexes with aluminum and iron. As a result, acid phosphatase enzymes break down these insoluble complexes and release phosphorus for plant acquisition and usage; therefore, phosphorus rich environments should possess greater phosphatase activity.

This study supported the expectation that there would be a relationship between phosphatase activities and sediment phosphorus concentration (i.e. higher phosphorus concentrations increase yields of plants, while phosphorus limitation decreases the productivity of invasive species). The scientists hoped to use the findings in this study for the development of bioremediation techniques aimed at controlling invasive species through green management practices.

Figure 1 represents a correlation between phosphorus concentration and phosphatase activity in all the sites across all time periods. 

What is the main idea of this passage?

Phosphorus is a key component for life on Earth; it performs essential roles in respiration, photosynthesis, and the decomposition of organic material. Phosphorus is primarily acquired by plants in the inorganic, ionic forms, which are found in soil solutions at concentrations of only a few parts per million. Plants use methods of diffusion and active transport to absorb phosphorus at the surface of their roots.

Phosphorus is abundant in soils; however, it is often unavailable to plants because it forms insoluble complexes with positively charged cations. This occurs when negatively charged phosphorus ions bind to positive cations in the soil (i.e. opposites attract). Enzymes such as acid phosphatases play a critical role in the acquisition and manipulation of phosphorus in plants. It has been found that when soils possess low levels of free phosphorus, plants are stimulated to produce acid phosphatase enzymes, which release inorganic phosphorus in the soil.

Plants need nutrients such as phosphorus to grow and proliferate; therefore, understanding how this species uses phosphorus could lead to conservation practices to limits this invasive species’ impact on the environment. A group of scientists wanted to investigate the relationship between plant enzyme activity and phosphorus levels in aquatic biomes. This investigation was targeted at studying the invasive Eurasian milfoil, Myriophyllum spicatum. In doing so, scientists believed that they could control the spread of the plant into neighboring waters if they were able to limit the nutrients in its environment. A study was performed in order to explore how phosphorus concentration in freshwater ecosystems affects phosphorus cycling and plant enzyme production. In order to determine if there was a relationship between the phosphatase activity and concentration of phosphorus in the sediment and water column of specific sites, researchers measured the respective phosphorus concentrations and enzyme activities. 

In this study, three standing ponds were sampled at six different time periods in the same year from July to December. The phosphorus content of each sample was determined through an ascorbic acid assay. Sediment collections were divided into samples weighing one sixteenth of a gram using coning and quartering techniques. These samples underwent a persulfate digestion and were vacuum filtered to remove excess sediment. Last, the samples were diluted and analyzed for phosphorus content using the ascorbic acid procedure. The solutions’ ability to absorb specific wavelengths of light was measured using a spectrophotometer set at an absorbance of 880 nanometers. After the sediment phosphorus content of each site was determined, scientists decided to determine the concentration of phosphorus releasing enzymes through an alkaline phosphatase assay. One to two milliliters of collected sediment was centrifuged until the sediment formed a pellet. The scientists chemically induced and observed a reaction between the sediment enzymes and insoluble phosphorus compounds present in an artificial substrate. Enzymes speed up chemical reactions by binding to substrates and releasing their constituent parts: in this case phosphorus and an unknown cation. After this reaction was halted, the samples were centrifuged and their absorbance was measured with a spectrophotometer set at 420 nanometers. This identified the concentration of phosphatase enzymes present in each sample. Now, scientists were able to compare the correlation between phosphorus levels and plant enzymes in the soil.

An exponential regression analysis indicated that there was a significant relationship between phosphatase activity and sediment phosphorus concentration (see Figure 1). The trend in the exponential regression analysis showed evidence of an inducible expression between phosphorus substrate and phosphatase enzymes. In other words, phosphorus is often abundant in soils, but is unavailable due to its formation into insoluble complexes with aluminum and iron. As a result, acid phosphatase enzymes break down these insoluble complexes and release phosphorus for plant acquisition and usage; therefore, phosphorus rich environments should possess greater phosphatase activity.

This study supported the expectation that there would be a relationship between phosphatase activities and sediment phosphorus concentration (i.e. higher phosphorus concentrations increase yields of plants, while phosphorus limitation decreases the productivity of invasive species). The scientists hoped to use the findings in this study for the development of bioremediation techniques aimed at controlling invasive species through green management practices.

Figure 1 represents a correlation between phosphorus concentration and phosphatase activity in all the sites across all time periods. 

In the study, scientists set the spectrophotometer to __________ in order to measure a sample's absorbance and subsequent phosphorus concentration.

Phosphorus is a key component for life on Earth; it performs essential roles in respiration, photosynthesis, and the decomposition of organic material. Phosphorus is primarily acquired by plants in the inorganic, ionic forms, which are found in soil solutions at concentrations of only a few parts per million. Plants use methods of diffusion and active transport to absorb phosphorus at the surface of their roots.

Phosphorus is abundant in soils; however, it is often unavailable to plants because it forms insoluble complexes with positively charged cations. This occurs when negatively charged phosphorus ions bind to positive cations in the soil (i.e. opposites attract). Enzymes such as acid phosphatases play a critical role in the acquisition and manipulation of phosphorus in plants. It has been found that when soils possess low levels of free phosphorus, plants are stimulated to produce acid phosphatase enzymes, which release inorganic phosphorus in the soil.

Plants need nutrients such as phosphorus to grow and proliferate; therefore, understanding how this species uses phosphorus could lead to conservation practices to limits this invasive species’ impact on the environment. A group of scientists wanted to investigate the relationship between plant enzyme activity and phosphorus levels in aquatic biomes. This investigation was targeted at studying the invasive Eurasian milfoil, Myriophyllum spicatum. In doing so, scientists believed that they could control the spread of the plant into neighboring waters if they were able to limit the nutrients in its environment. A study was performed in order to explore how phosphorus concentration in freshwater ecosystems affects phosphorus cycling and plant enzyme production. In order to determine if there was a relationship between the phosphatase activity and concentration of phosphorus in the sediment and water column of specific sites, researchers measured the respective phosphorus concentrations and enzyme activities. 

In this study, three standing ponds were sampled at six different time periods in the same year from July to December. The phosphorus content of each sample was determined through an ascorbic acid assay. Sediment collections were divided into samples weighing one sixteenth of a gram using coning and quartering techniques. These samples underwent a persulfate digestion and were vacuum filtered to remove excess sediment. Last, the samples were diluted and analyzed for phosphorus content using the ascorbic acid procedure. The solutions’ ability to absorb specific wavelengths of light was measured using a spectrophotometer set at an absorbance of 880 nanometers. After the sediment phosphorus content of each site was determined, scientists decided to determine the concentration of phosphorus releasing enzymes through an alkaline phosphatase assay. One to two milliliters of collected sediment was centrifuged until the sediment formed a pellet. The scientists chemically induced and observed a reaction between the sediment enzymes and insoluble phosphorus compounds present in an artificial substrate. Enzymes speed up chemical reactions by binding to substrates and releasing their constituent parts: in this case phosphorus and an unknown cation. After this reaction was halted, the samples were centrifuged and their absorbance was measured with a spectrophotometer set at 420 nanometers. This identified the concentration of phosphatase enzymes present in each sample. Now, scientists were able to compare the correlation between phosphorus levels and plant enzymes in the soil.

An exponential regression analysis indicated that there was a significant relationship between phosphatase activity and sediment phosphorus concentration (see Figure 1). The trend in the exponential regression analysis showed evidence of an inducible expression between phosphorus substrate and phosphatase enzymes. In other words, phosphorus is often abundant in soils, but is unavailable due to its formation into insoluble complexes with aluminum and iron. As a result, acid phosphatase enzymes break down these insoluble complexes and release phosphorus for plant acquisition and usage; therefore, phosphorus rich environments should possess greater phosphatase activity.

This study supported the expectation that there would be a relationship between phosphatase activities and sediment phosphorus concentration (i.e. higher phosphorus concentrations increase yields of plants, while phosphorus limitation decreases the productivity of invasive species). The scientists hoped to use the findings in this study for the development of bioremediation techniques aimed at controlling invasive species through green management practices.

Figure 1 represents a correlation between phosphorus concentration and phosphatase activity in all the sites across all time periods. 

The underlined portion of the text most likely implies which of the following?

Phosphorus is a key component for life on Earth; it performs essential roles in respiration, photosynthesis, and the decomposition of organic material. Phosphorus is primarily acquired by plants in the inorganic, ionic forms, which are found in soil solutions at concentrations of only a few parts per million. Plants use methods of diffusion and active transport to absorb phosphorus at the surface of their roots.

Phosphorus is abundant in soils; however, it is often unavailable to plants because it forms insoluble complexes with positively charged cations. This occurs when negatively charged phosphorus ions bind to positive cations in the soil (i.e. opposites attract). Enzymes such as acid phosphatases play a critical role in the acquisition and manipulation of phosphorus in plants. It has been found that when soils possess low levels of free phosphorus, plants are stimulated to produce acid phosphatase enzymes, which release inorganic phosphorus in the soil.

Plants need nutrients such as phosphorus to grow and proliferate; therefore, understanding how this species uses phosphorus could lead to conservation practices to limits this invasive species’ impact on the environment. A group of scientists wanted to investigate the relationship between plant enzyme activity and phosphorus levels in aquatic biomes. This investigation was targeted at studying the invasive Eurasian milfoil, Myriophyllum spicatum. In doing so, scientists believed that they could control the spread of the plant into neighboring waters if they were able to limit the nutrients in its environment. A study was performed in order to explore how phosphorus concentration in freshwater ecosystems affects phosphorus cycling and plant enzyme production. In order to determine if there was a relationship between the phosphatase activity and concentration of phosphorus in the sediment and water column of specific sites, researchers measured the respective phosphorus concentrations and enzyme activities. 

In this study, three standing ponds were sampled at six different time periods in the same year from July to December. The phosphorus content of each sample was determined through an ascorbic acid assay. Sediment collections were divided into samples weighing one sixteenth of a gram using coning and quartering techniques. These samples underwent a persulfate digestion and were vacuum filtered to remove excess sediment. Last, the samples were diluted and analyzed for phosphorus content using the ascorbic acid procedure. The solutions’ ability to absorb specific wavelengths of light was measured using a spectrophotometer set at an absorbance of 880 nanometers. After the sediment phosphorus content of each site was determined, scientists decided to determine the concentration of phosphorus releasing enzymes through an alkaline phosphatase assay. One to two milliliters of collected sediment was centrifuged until the sediment formed a pellet. The scientists chemically induced and observed a reaction between the sediment enzymes and insoluble phosphorus compounds present in an artificial substrate. Enzymes speed up chemical reactions by binding to substrates and releasing their constituent parts: in this case phosphorus and an unknown cation. After this reaction was halted, the samples were centrifuged and their absorbance was measured with a spectrophotometer set at 420 nanometers. This identified the concentration of phosphatase enzymes present in each sample. Now, scientists were able to compare the correlation between phosphorus levels and plant enzymes in the soil.

An exponential regression analysis indicated that there was a significant relationship between phosphatase activity and sediment phosphorus concentration (see Figure 1). The trend in the exponential regression analysis showed evidence of an inducible expression between phosphorus substrate and phosphatase enzymes. In other words, phosphorus is often abundant in soils, but is unavailable due to its formation into insoluble complexes with aluminum and iron. As a result, acid phosphatase enzymes break down these insoluble complexes and release phosphorus for plant acquisition and usage; therefore, phosphorus rich environments should possess greater phosphatase activity.

This study supported the expectation that there would be a relationship between phosphatase activities and sediment phosphorus concentration (i.e. higher phosphorus concentrations increase yields of plants, while phosphorus limitation decreases the productivity of invasive species). The scientists hoped to use the findings in this study for the development of bioremediation techniques aimed at controlling invasive species through green management practices.

Figure 1 represents a correlation between phosphorus concentration and phosphatase activity in all the sites across all time periods. 

The figure in the passage is best described as which of the following?

Network theorists attempt to illustrate the social situation of individuals through the observation of their relationships with other people. They note relationships that individuals have with one another and use statistical measures in order to visualize them. Network analysts describe the relationships between individuals and use this information in order to make inferences and conclusions pertaining to the group based upon its observed dynamics. 

There has been debate over the importance of weak and strong ties in regard to an individual’s social situation. Network theorists have described a tie as a relationship between individuals that is characterized by four main components: time, emotional intensity, intimacy, and reciprocal services (i.e. “if you scratch my back, then I’ll scratch yours”). In network sociology, a weak tie is defined as local bridges between two disparate social groups. Some sociologists have argued that weak ties have a greater impact on an individual’s social capital because they are exposed to a group of individuals that are not part of their immediate social network. On the other hand, network theorists have argued that the importance of strong ties has been largely ignored. Sociologists have argued that these tight in-group relations between individuals of social groups are imperative for the transmission of information.

This theory was studied by observing employees in Silicon Valley that were attempting to unionize. Network theorists had individuals in the company write down two names: the name of the person they get advice from (i.e. a weak tie) and the person they consider as a friend (i.e. strong tie). The theorists attempted to understand the differences between whom individuals interact with at work and whom they choose to spend time with outside of the company’s walls. This distinction illustrates the difference between weak and strong ties—that is advice networks at work and friendship networks that extended beyond the physical space of the corporation. Using this information, the researchers were able to create network sociograms that depicted both the friendship and advisory networks of the company.

While sociologists were investigating this information, they were able to observe and apply their data to an attempt to unionize at the company. This group of employees’ attempt to unionize failed and the sociologists were able to use their network data to explain this phenomenon. They concluded that the unionization attempt failed because, while the individuals that were spearheading it were influential in the advice network, they lacked the strong ties in the friends network necessary to form the union. Specifically they did not have ties to influential members of the corporation (i.e. bosses and members of the board). Without the support of influential strong ties in their immediate social networks these individuals were unable to properly form a union. In other words, weak ties in the advisory network introduced them to individuals of power; however, their inability to form strong, friendship bonds with them detrimentally affected their attempts to form a union. 

The passage and the figures are in agreement that strong ties have the ability to transmit information effectively within a social network such as a company. They also agree that these ties can aid in the development of friendship bonds with individuals of power. 

The author would agree that an individual from which of the following regions would be most likely to assist a unionization attempt in the company depicted in the sociogram?