HESI A2 Reading Comprehension Practice Test

Whipworms

In the new study, published today (March 14) in the journal Science Advances, the researchers first took samples of whipworms from infected mice. They found that inside the parasites, there were bacteria, which the parasite acquired from its host. (In this case, the parasites acquired the bacteria from the mouse’s gut.) If the parasites were hatched in a bacteria-free environment, they didn’t have any gut bacteria.

What’s more, the parasites needed this gut bacteria to grow and thrive, the researchers said. When the researchers exposed adult whipworms to antibiotics (which have effects on bacteria rather than parasites), the worms died. But when the researchers exposed young whipworms that were free of bacteria to antibiotics, the drugs didn’t have an effect, the researchers said.

In another experiment, the researchers looked at mice that didn’t have any gut bacteria (called germ-free mice), and infected the mice with sterile whipworm larvae (whipworm larvae with no bacteria). Two weeks later, these mice had “barely detectable” levels of worms, while mice with normal gut bacteria had high levels of worms.

Interestingly, the researchers found that the composition of gut bacteria inside the adult whipworms was quite different from that of its host. This finding suggests that the whipworm “selects and maintains its own distinct microbiota regardless of the surrounding bacterial populations,” the researchers said.

The researchers also found that, once a whipworm infection is established inside a host, the infection results in changes to the host’s gut bacteria.This altered gut microbiome reduces the number of new whipworm eggs that can hatch. While this may seem counterproductive for the worm, it keeps amount of the worms from getting too high, and prevents the host’s immune system from removing the worms, the researchers said.

Which of the following is the best paraphrase for the last paragraph?

Whipworms

In the new study, published today (March 14) in the journal Science Advances, the researchers first took samples of whipworms from infected mice. They found that inside the parasites, there were bacteria, which the parasite acquired from its host. (In this case, the parasites acquired the bacteria from the mouse’s gut.) If the parasites were hatched in a bacteria-free environment, they didn’t have any gut bacteria.

What’s more, the parasites needed this gut bacteria to grow and thrive, the researchers said. When the researchers exposed adult whipworms to antibiotics (which have effects on bacteria rather than parasites), the worms died. But when the researchers exposed young whipworms that were free of bacteria to antibiotics, the drugs didn’t have an effect, the researchers said.

In another experiment, the researchers looked at mice that didn’t have any gut bacteria (called germ-free mice), and infected the mice with sterile whipworm larvae (whipworm larvae with no bacteria). Two weeks later, these mice had “barely detectable” levels of worms, while mice with normal gut bacteria had high levels of worms.

Interestingly, the researchers found that the composition of gut bacteria inside the adult whipworms was quite different from that of its host. This finding suggests that the whipworm “selects and maintains its own distinct microbiota regardless of the surrounding bacterial populations,” the researchers said.

The researchers also found that, once a whipworm infection is established inside a host, the infection results in changes to the host’s gut bacteria.This altered gut microbiome reduces the number of new whipworm eggs that can hatch. While this may seem counterproductive for the worm, it keeps amount of the worms from getting too high, and prevents the host’s immune system from removing the worms, the researchers said.

Which of the following can logically be inferred from this passage?

Whipworms

In the new study, published today (March 14) in the journal Science Advances, the researchers first took samples of whipworms from infected mice. They found that inside the parasites, there were bacteria, which the parasite acquired from its host. (In this case, the parasites acquired the bacteria from the mouse’s gut.) If the parasites were hatched in a bacteria-free environment, they didn’t have any gut bacteria.

What’s more, the parasites needed this gut bacteria to grow and thrive, the researchers said. When the researchers exposed adult whipworms to antibiotics (which have effects on bacteria rather than parasites), the worms died. But when the researchers exposed young whipworms that were free of bacteria to antibiotics, the drugs didn’t have an effect, the researchers said.

In another experiment, the researchers looked at mice that didn’t have any gut bacteria (called germ-free mice), and infected the mice with sterile whipworm larvae (whipworm larvae with no bacteria). Two weeks later, these mice had “barely detectable” levels of worms, while mice with normal gut bacteria had high levels of worms.

Interestingly, the researchers found that the composition of gut bacteria inside the adult whipworms was quite different from that of its host. This finding suggests that the whipworm “selects and maintains its own distinct microbiota regardless of the surrounding bacterial populations,” the researchers said.

The researchers also found that, once a whipworm infection is established inside a host, the infection results in changes to the host’s gut bacteria.This altered gut microbiome reduces the number of new whipworm eggs that can hatch. While this may seem counterproductive for the worm, it keeps amount of the worms from getting too high, and prevents the host’s immune system from removing the worms, the researchers said.

What is the writer’s primary purpose in writing this essay?

Quantum Decoherence

Quantum decoherence is the loss of quantum coherence. In quantum mechanics, particles such as electrons are described by a wavefunction, a mathematical description of the quantum state of a system; the probabilistic nature of the wavefunction gives rise to various quantum effects. As long as there exists a definite phase relation between different states, the system is said to be coherent. This coherence is a fundamental property of quantum mechanics, and is necessary for the functioning of quantum computers. However, when a quantum system is not perfectly isolated, but in contact with its surroundings, coherence decays with time, a process called quantum decoherence. As a result of this process, the relevant quantum behavior is lost.

Decoherence can be viewed as the loss of information from a system into the environment (often modeled as a heat bath), since every system is loosely coupled with the energetic state of its surroundings. Viewed in isolation, the system’s dynamics are non-unitary (although the combined system plus environment evolves in a unitary fashion). Thus the dynamics of the system alone are irreversible. As with any coupling, entanglements are generated between the system and environment. These have the effect of sharing quantum information with—or transferring it to—the surroundings.

Decoherence has been used to understand the collapse of the wavefunction in quantum mechanics. Decoherence does not generate actual wave function collapse. It only provides an explanation for the observation of wave function collapse, as the quantum nature of the system “leaks” into the environment. That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. Specifically, decoherence does not attempt to explain the measurement problem. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the “realization” of precisely one state in the “ensemble”.

Decoherence represents a challenge for the practical realization of quantum computers, since such machines are expected to rely heavily on the undisturbed evolution of quantum coherences. Simply put, they require that coherent states be preserved and that decoherence is managed, in order to actually perform quantum computation.

What is the author’s primary purpose in writing this essay?

Quantum Decoherence

Quantum decoherence is the loss of quantum coherence. In quantum mechanics, particles such as electrons are described by a wavefunction, a mathematical description of the quantum state of a system; the probabilistic nature of the wavefunction gives rise to various quantum effects. As long as there exists a definite phase relation between different states, the system is said to be coherent. This coherence is a fundamental property of quantum mechanics, and is necessary for the functioning of quantum computers. However, when a quantum system is not perfectly isolated, but in contact with its surroundings, coherence decays with time, a process called quantum decoherence. As a result of this process, the relevant quantum behavior is lost.

Decoherence can be viewed as the loss of information from a system into the environment (often modeled as a heat bath), since every system is loosely coupled with the energetic state of its surroundings. Viewed in isolation, the system’s dynamics are non-unitary (although the combined system plus environment evolves in a unitary fashion). Thus the dynamics of the system alone are irreversible. As with any coupling, entanglements are generated between the system and environment. These have the effect of sharing quantum information with—or transferring it to—the surroundings.

Decoherence has been used to understand the collapse of the wavefunction in quantum mechanics. Decoherence does not generate actual wave function collapse. It only provides an explanation for the observation of wave function collapse, as the quantum nature of the system “leaks” into the environment. That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. Specifically, decoherence does not attempt to explain the measurement problem. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the “realization” of precisely one state in the “ensemble”.

Decoherence represents a challenge for the practical realization of quantum computers, since such machines are expected to rely heavily on the undisturbed evolution of quantum coherences. Simply put, they require that coherent states be preserved and that decoherence is managed, in order to actually perform quantum computation.

Which of the following statements can logically be inferred from this passage?

Quantum Decoherence

Quantum decoherence is the loss of quantum coherence. In quantum mechanics, particles such as electrons are described by a wavefunction, a mathematical description of the quantum state of a system; the probabilistic nature of the wavefunction gives rise to various quantum effects. As long as there exists a definite phase relation between different states, the system is said to be coherent. This coherence is a fundamental property of quantum mechanics, and is necessary for the functioning of quantum computers. However, when a quantum system is not perfectly isolated, but in contact with its surroundings, coherence decays with time, a process called quantum decoherence. As a result of this process, the relevant quantum behavior is lost.

Decoherence can be viewed as the loss of information from a system into the environment (often modeled as a heat bath), since every system is loosely coupled with the energetic state of its surroundings. Viewed in isolation, the system’s dynamics are non-unitary (although the combined system plus environment evolves in a unitary fashion). Thus the dynamics of the system alone are irreversible. As with any coupling, entanglements are generated between the system and environment. These have the effect of sharing quantum information with—or transferring it to—the surroundings.

Decoherence has been used to understand the collapse of the wavefunction in quantum mechanics. Decoherence does not generate actual wave function collapse. It only provides an explanation for the observation of wave function collapse, as the quantum nature of the system “leaks” into the environment. That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. Specifically, decoherence does not attempt to explain the measurement problem. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the “realization” of precisely one state in the “ensemble”.

Decoherence represents a challenge for the practical realization of quantum computers, since such machines are expected to rely heavily on the undisturbed evolution of quantum coherences. Simply put, they require that coherent states be preserved and that decoherence is managed, in order to actually perform quantum computation.

The tone of this text might best be described as ____.

Quantum Decoherence

Quantum decoherence is the loss of quantum coherence. In quantum mechanics, particles such as electrons are described by a wavefunction, a mathematical description of the quantum state of a system; the probabilistic nature of the wavefunction gives rise to various quantum effects. As long as there exists a definite phase relation between different states, the system is said to be coherent. This coherence is a fundamental property of quantum mechanics, and is necessary for the functioning of quantum computers. However, when a quantum system is not perfectly isolated, but in contact with its surroundings, coherence decays with time, a process called quantum decoherence. As a result of this process, the relevant quantum behavior is lost.

Decoherence can be viewed as the loss of information from a system into the environment (often modeled as a heat bath), since every system is loosely coupled with the energetic state of its surroundings. Viewed in isolation, the system’s dynamics are non-unitary (although the combined system plus environment evolves in a unitary fashion). Thus the dynamics of the system alone are irreversible. As with any coupling, entanglements are generated between the system and environment. These have the effect of sharing quantum information with—or transferring it to—the surroundings.

Decoherence has been used to understand the collapse of the wavefunction in quantum mechanics. Decoherence does not generate actual wave function collapse. It only provides an explanation for the observation of wave function collapse, as the quantum nature of the system “leaks” into the environment. That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings. A total superposition of the global or universal wavefunction still exists (and remains coherent at the global level), but its ultimate fate remains an interpretational issue. Specifically, decoherence does not attempt to explain the measurement problem. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the “realization” of precisely one state in the “ensemble”.

Decoherence represents a challenge for the practical realization of quantum computers, since such machines are expected to rely heavily on the undisturbed evolution of quantum coherences. Simply put, they require that coherent states be preserved and that decoherence is managed, in order to actually perform quantum computation.

Which of the following claims does this detail support: “That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings.”?

Drinking More Coffee May Stave Off Multiple Sclerosis

If you are trying to cut down on your six cups of coffee a day, think again. Research published in the Journal of Neurology, Neurosurgery and Psychiatry indicates that caffeine’s neuroprotective and anti-inflammatory properties may lower the risk of developing multiple sclerosis.

The National Institute of Neurological Diseases and Stroke (NINDS) describes multiple sclerosis (MS) as “an unpredictable disease of the central nervous system,” symptoms of which can range from fairly benign to devastating. MS disrupts communication between the brain and the rest of the body.

Coffee contains over 1,000 biologically active compounds, including the central nervous system (CNS) stimulant, caffeine. Caffeine’s neuroprotective properties can suppress the production of chemicals involved in the inflammatory response.

Previous studies have associated a high coffee intake with lower rates of cardiovascular disease (CVD), stroke and type 2 diabetes. In animal models of Alzheimer’s disease, caffeine has helped to protect against blood-brain barrier leakage.

Two representative population studies provided data for the current research.

Dr. Anna Hedström, of the Institute of Environmental Medicine, Karolinska Institutet in Stockholm, Sweden, and colleagues compared 1,620 Swedish adults with MS with 2,788 healthy subjects, matched for age and sex.

In the US, teams from Johns Hopkins University in Baltimore, MD, the University of California-Berkeley and the Kaiser Permanente Division of Research in Oakland, CA, compared 1,159 people with MS with 1,172 healthy participants.

Six cups a day linked to 31% lower risk of MS

In both studies, participants provided information about their coffee drinking.

The Swedish participants quantified their usual daily intake in cups at different ages, from 15-19 years until they were 40 years and over.

In the US study, participants gave information about their maximum daily consumption. Those who drank one or more cups also recalled at what age they started drinking coffee regularly.

The researchers then estimated coffee consumption at and before the onset of symptoms in those with MS, and they compared the results with those of the healthy groups.

There was a consistently higher risk of MS among those who drank fewer cups of coffee every day in both studies, even after adjusting for factors such as smoking and weight during adolescence.

In the Swedish study, coffee consumption correlated with a lower risk of MS both at the onset of symptoms and 5-10 years beforehand. Those who consumed over six cups (900 ml+) daily had a 28-30% lower risk.

The US study revealed a 26-31% reduction in risk among those who drank above 948 ml daily at least 5 years before and at the start of symptoms, compared with those who never drank coffee.

Findings indicate that the more coffee people consume, the lower their risk of MS.

The authors caution that a causative link cannot be confirmed, since this was an observational study.

What is the main idea of the passage?

Drinking More Coffee May Stave Off Multiple Sclerosis

If you are trying to cut down on your six cups of coffee a day, think again. Research published in the Journal of Neurology, Neurosurgery and Psychiatry indicates that caffeine’s neuroprotective and anti-inflammatory properties may lower the risk of developing multiple sclerosis.

The National Institute of Neurological Diseases and Stroke (NINDS) describes multiple sclerosis (MS) as “an unpredictable disease of the central nervous system,” symptoms of which can range from fairly benign to devastating. MS disrupts communication between the brain and the rest of the body.

Coffee contains over 1,000 biologically active compounds, including the central nervous system (CNS) stimulant, caffeine. Caffeine’s neuroprotective properties can suppress the production of chemicals involved in the inflammatory response.

Previous studies have associated a high coffee intake with lower rates of cardiovascular disease (CVD), stroke and type 2 diabetes. In animal models of Alzheimer’s disease, caffeine has helped to protect against blood-brain barrier leakage.

Two representative population studies provided data for the current research.

Dr. Anna Hedström, of the Institute of Environmental Medicine, Karolinska Institutet in Stockholm, Sweden, and colleagues compared 1,620 Swedish adults with MS with 2,788 healthy subjects, matched for age and sex.

In the US, teams from Johns Hopkins University in Baltimore, MD, the University of California-Berkeley and the Kaiser Permanente Division of Research in Oakland, CA, compared 1,159 people with MS with 1,172 healthy participants.

Six cups a day linked to 31% lower risk of MS

In both studies, participants provided information about their coffee drinking.

The Swedish participants quantified their usual daily intake in cups at different ages, from 15-19 years until they were 40 years and over.

In the US study, participants gave information about their maximum daily consumption. Those who drank one or more cups also recalled at what age they started drinking coffee regularly.

The researchers then estimated coffee consumption at and before the onset of symptoms in those with MS, and they compared the results with those of the healthy groups.

There was a consistently higher risk of MS among those who drank fewer cups of coffee every day in both studies, even after adjusting for factors such as smoking and weight during adolescence.

In the Swedish study, coffee consumption correlated with a lower risk of MS both at the onset of symptoms and 5-10 years beforehand. Those who consumed over six cups (900 ml+) daily had a 28-30% lower risk.

The US study revealed a 26-31% reduction in risk among those who drank above 948 ml daily at least 5 years before and at the start of symptoms, compared with those who never drank coffee.

Findings indicate that the more coffee people consume, the lower their risk of MS.

The authors caution that a causative link cannot be confirmed, since this was an observational study.

What is the writer’s primary purpose in writing this passage?

Drinking More Coffee May Stave Off Multiple Sclerosis

If you are trying to cut down on your six cups of coffee a day, think again. Research published in the Journal of Neurology, Neurosurgery and Psychiatry indicates that caffeine’s neuroprotective and anti-inflammatory properties may lower the risk of developing multiple sclerosis.

The National Institute of Neurological Diseases and Stroke (NINDS) describes multiple sclerosis (MS) as “an unpredictable disease of the central nervous system,” symptoms of which can range from fairly benign to devastating. MS disrupts communication between the brain and the rest of the body.

Coffee contains over 1,000 biologically active compounds, including the central nervous system (CNS) stimulant, caffeine. Caffeine’s neuroprotective properties can suppress the production of chemicals involved in the inflammatory response.

Previous studies have associated a high coffee intake with lower rates of cardiovascular disease (CVD), stroke and type 2 diabetes. In animal models of Alzheimer’s disease, caffeine has helped to protect against blood-brain barrier leakage.

Two representative population studies provided data for the current research.

Dr. Anna Hedström, of the Institute of Environmental Medicine, Karolinska Institutet in Stockholm, Sweden, and colleagues compared 1,620 Swedish adults with MS with 2,788 healthy subjects, matched for age and sex.

In the US, teams from Johns Hopkins University in Baltimore, MD, the University of California-Berkeley and the Kaiser Permanente Division of Research in Oakland, CA, compared 1,159 people with MS with 1,172 healthy participants.

Six cups a day linked to 31% lower risk of MS

In both studies, participants provided information about their coffee drinking.

The Swedish participants quantified their usual daily intake in cups at different ages, from 15-19 years until they were 40 years and over.

In the US study, participants gave information about their maximum daily consumption. Those who drank one or more cups also recalled at what age they started drinking coffee regularly.

The researchers then estimated coffee consumption at and before the onset of symptoms in those with MS, and they compared the results with those of the healthy groups.

There was a consistently higher risk of MS among those who drank fewer cups of coffee every day in both studies, even after adjusting for factors such as smoking and weight during adolescence.

In the Swedish study, coffee consumption correlated with a lower risk of MS both at the onset of symptoms and 5-10 years beforehand. Those who consumed over six cups (900 ml+) daily had a 28-30% lower risk.

The US study revealed a 26-31% reduction in risk among those who drank above 948 ml daily at least 5 years before and at the start of symptoms, compared with those who never drank coffee.

Findings indicate that the more coffee people consume, the lower their risk of MS.

The authors caution that a causative link cannot be confirmed, since this was an observational study.

Which of the following cannot be logically inferred from this passage?