Water that has large amounts of dissolved calcium and magnesium is referred to as hard water. Calcium and magnesium naturally occur in Earth materials such as limestone, magnesite, gypsum, and other minerals groundwater comes into contact with. Calcium is a vital component of bones and teeth. Calcium is also necessary for proper muscle action, blood clotting, and regulating the heartbeat. Magnesium is necessary for more than 300 biochemical processes in the body, such as regulating heartbeat and blood sugar levels, helping maintain normal blood pressure, and facilitating protein synthesis. The health benefits of drinking hard water have been well documented since the 1920s. One study investigated the effects of different amounts of dietary magnesium on rat survival rates. The first table shows the summary data from this study. Softening water has become a common practice in many homes. Soft water is water that has had the calcium and magnesium ions and other minerals removed to prevent the buildup of a residue called scale in pipes and appliances. Soft water also increases the effectiveness of soaps and detergents. Research around the health benefits of drinking hard water suggests that people may be at higher risk for certain diseases when their water lacks dissolved calcium and magnesium. The second table summarizes data from two human population studies that examined the role of dietary magnesium and cardiovascular health.
Which statement explains the central idea of the passage?
- A. People should consume as much magnesium as possible to ensure good cardiovascular health.
- B. People may experience health benefits from drinking hard water because it contains magnesium.
- C. People who live in rural environments are healthier than people who live in urban environments.
- D. People should stop the practice of softening water because it removes minerals that are necessary for good health.
Correct Answer & Rationale
Correct Answer: B
Option B accurately reflects the central idea by highlighting the potential health benefits of magnesium found in hard water. This aligns with the passage's focus on the relationship between magnesium intake and cardiovascular health. Option A is misleading as it suggests an excessive intake of magnesium is necessary, while the passage likely emphasizes balance rather than maximum consumption. Option C incorrectly generalizes health comparisons between rural and urban populations without specific evidence from the passage. Option D misrepresents the passage's message by implying a complete cessation of water softening, rather than discussing the importance of maintaining essential minerals like magnesium.
Option B accurately reflects the central idea by highlighting the potential health benefits of magnesium found in hard water. This aligns with the passage's focus on the relationship between magnesium intake and cardiovascular health. Option A is misleading as it suggests an excessive intake of magnesium is necessary, while the passage likely emphasizes balance rather than maximum consumption. Option C incorrectly generalizes health comparisons between rural and urban populations without specific evidence from the passage. Option D misrepresents the passage's message by implying a complete cessation of water softening, rather than discussing the importance of maintaining essential minerals like magnesium.
Other Related Questions
The roller coaster diagram shows a set of cars moving downward from position 1 to position 2. As the cars travel from position 1 toward position 2, their...
- A. gravitational potential energy; total energy
- B. kinetic energy; gravitational potential energy
- C. total energy; kinetic energy
- D. gravitational potential energy; kinetic energy
Correct Answer & Rationale
Correct Answer: A
As the roller coaster cars move from position 1 to position 2, they descend, resulting in a decrease in gravitational potential energy due to their lower height. However, their total energy—comprising both kinetic and potential energy—remains constant, assuming negligible friction. Option B incorrectly suggests that kinetic energy increases while gravitational potential energy decreases, but it does not address total energy. Option C misrepresents the relationship by stating total energy changes, which it does not. Option D also fails, as it inaccurately implies that gravitational potential energy is the only energy type being discussed.
As the roller coaster cars move from position 1 to position 2, they descend, resulting in a decrease in gravitational potential energy due to their lower height. However, their total energy—comprising both kinetic and potential energy—remains constant, assuming negligible friction. Option B incorrectly suggests that kinetic energy increases while gravitational potential energy decreases, but it does not address total energy. Option C misrepresents the relationship by stating total energy changes, which it does not. Option D also fails, as it inaccurately implies that gravitational potential energy is the only energy type being discussed.
Based on the table, use the drop-down menus to make the following statement correct. _ experiences the least warming effect from CO2 because it has the _ of CO2 in its atmosphere.
- A. smallest amount
- B. largest amount
- C. Mars
- D. Planet L
Correct Answer & Rationale
Correct Answer: A,C
The statement highlights that Mars experiences the least warming effect from CO2 due to its atmospheric composition. Mars has a small amount of CO2 compared to other planets, which limits its greenhouse effect and consequently its warming. Option B, "largest amount," is incorrect as it contradicts the premise that a larger CO2 presence would lead to more warming. Option D, "Planet L," is not a recognized celestial body in this context and does not provide relevant information regarding CO2 levels. Thus, the combination of Mars with the smallest amount of CO2 accurately reflects the relationship between atmospheric composition and warming effects.
The statement highlights that Mars experiences the least warming effect from CO2 due to its atmospheric composition. Mars has a small amount of CO2 compared to other planets, which limits its greenhouse effect and consequently its warming. Option B, "largest amount," is incorrect as it contradicts the premise that a larger CO2 presence would lead to more warming. Option D, "Planet L," is not a recognized celestial body in this context and does not provide relevant information regarding CO2 levels. Thus, the combination of Mars with the smallest amount of CO2 accurately reflects the relationship between atmospheric composition and warming effects.
Sommer's research concludes that cheetahs have sufficient genetic diversity to respond to common diseases, but may still be at risk of new diseases. Which statement from the passage supports this conclusion?
- A. Major histocompatibility complex (MHC) genes are used by the body to identify self from non-self...
- B. The variation in MHC genes in cheetahs is still smaller than that for other big cat species but appears to be sufficient...
- C. If any of the genetic factors are different, then the immune system of the individual...
- D. Sommer's research determined how many alleles are present on two different types of MHC genes...
Correct Answer & Rationale
Correct Answer: B
Option B directly supports Sommer's conclusion by highlighting that the variation in MHC genes among cheetahs, while less than in other big cats, is adequate for their immune response to common diseases. This indicates sufficient genetic diversity for disease management, aligning with the research's findings. Option A discusses the function of MHC genes but does not address their variation in cheetahs, making it less relevant. Option C mentions genetic factors affecting immune response but lacks specific information about cheetah genetic diversity. Option D focuses on the number of alleles without linking it to the implications for disease response, thus failing to support the conclusion effectively.
Option B directly supports Sommer's conclusion by highlighting that the variation in MHC genes among cheetahs, while less than in other big cats, is adequate for their immune response to common diseases. This indicates sufficient genetic diversity for disease management, aligning with the research's findings. Option A discusses the function of MHC genes but does not address their variation in cheetahs, making it less relevant. Option C mentions genetic factors affecting immune response but lacks specific information about cheetah genetic diversity. Option D focuses on the number of alleles without linking it to the implications for disease response, thus failing to support the conclusion effectively.
Based on these results and assuming that whenever two materials are present their remaining energy is averaged, what would the scientist best conclude to be the composition of Saturn's rings?
- A. equal amounts of loose rocks and loose snow
- B. equal amounts of ice and bedrock
- C. a small amount of bedrock and a large amount of carbon rock
- D. large amounts of ice and smaller amounts of carbon rock
Correct Answer & Rationale
Correct Answer: D
The conclusion about Saturn's rings is supported by the composition of ice and carbon rock. Large amounts of ice are consistent with observations of Saturn’s rings, which are primarily composed of water ice particles. Smaller amounts of carbon rock align with the presence of darker materials found in the rings. Options A and B suggest equal amounts of materials that do not reflect the observed predominance of ice. Option C overestimates the presence of bedrock, which is not supported by scientific data. Thus, option D accurately captures the dominant composition of Saturn's rings.
The conclusion about Saturn's rings is supported by the composition of ice and carbon rock. Large amounts of ice are consistent with observations of Saturn’s rings, which are primarily composed of water ice particles. Smaller amounts of carbon rock align with the presence of darker materials found in the rings. Options A and B suggest equal amounts of materials that do not reflect the observed predominance of ice. Option C overestimates the presence of bedrock, which is not supported by scientific data. Thus, option D accurately captures the dominant composition of Saturn's rings.