ACT Science : How to find research summary in biology

Study concepts, example questions & explanations for ACT Science

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Example Questions

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Example Question #141 : How To Find Research Summary In Biology

In the 1980’s, an epidemic of bovine spongiform encephalopathy, or mad cow disease, swept through cattle herds in the United Kingdom. Scientists and veterinarians were troubled and had a difficult time managing the disease because it spread from one animal to another, and behaved differently than other diseases in the past. 

When infectious material from affected animals was treated with high levels of radiation, for example, the material remained infectious. All known bacteria or viruses that carry disease would have been killed by such a treatment. Additionally, some animals developed the disease without first being exposed to sick animals. Perhaps most frustratingly, among those animals that are exposed before becoming sick, it can take many years after exposure for illness to appear.

There quickly emerged two distinct explanations for the disease. 

Scientist 1:

Mad cow disease is unlike any disease we have handled before. It is increasingly clear that the best explanation for the disease’s dynamics involve proteins, called the protein-only hypothesis. These protein molecules are likely causative of the disease, and they lack any DNA or RNA. It is damage to these DNA or RNA molecules that kills bacteria or viruses when exposed to high levels of radiation. The most important observations that made scientists consider a unique, protein-only model for this disease involved its resistance to radiation. Remarkably, this would be the first example of an infectious agent copying itself without DNA or RNA to mediate the process.

Moreover, some animals develop the disease spontaneously, without physically being infected by another animal. This suggests that internal disorder among protein molecules is a potential route to developing disease, and may be accelerated by exposure to other sick animals.

In fact, this is consistent with the proposed mechanism. It is likely that proteins fold incorrectly, and then influence proteins around them to take on this errant conformation. Some proteins may fold incorrectly by chance, which explains spontaneous disease development. It also explains the long course of disease, as it takes many years for enough proteins to fold incorrectly and result in observable disease.

Scientist 2:

The suggestion that mad cow disease is caused exclusively by protein, in the absence of DNA or RNA, is such a dramatic departure from accepted biological processes that it warrants careful scrutiny. Additionally, other more conventional explanations should be thoroughly investigated before coming to such a conclusion.

Some scientists have shown that very small particles resembling viruses are visible in infectious material under powerful microscopes. Additionally, these viruses are consistent in size and shape with known, highly radiation-resistant viruses called polyomaviruses. It takes much higher-than-typical doses of radiation to cause enough DNA damage to inactivate these viruses.

The observation that mad cow disease occurs spontaneously in some animals is also explained by the viral explanation. Many viruses exist in animals and humans for years, undetected and not causing any observable disease. Sickness or stress can make these viruses reactivate, offering the illusion of spontaneous illness. All of these observations are consistent with the viral hypothesis.

Based on the passage, which of the following is most likely true about RNA & DNA?

I.  They are damaged by radiation

II.  They transmit information

III.  They are not present in polyomaviruses

Possible Answers:

III only

I and II

I and III

I, II, and III

Correct answer:

I and II

Explanation:

The passage is fairly explicit in indicating that options I and II are correct. However, option III may be confusing. Note that the passage indicates that all viruses or bacteria that are known to cause disease are susceptible to radiation-induced killing. Also note that this killing is mediated by DNA or RNA damage.

The passage does indicate that polyomaviruses are radiation resistant, but it makes no suggestion that they are free of DNA or RNA. As viruses, they still contain DNA or RNA.

Example Question #142 : How To Find Research Summary In Biology

If a drug is administered intravenously (i.e. injected into a vein), then the concentration of the drug in the blood will rise and then reach a plateau. After some time, the body will begin to eliminate this drug from the bloodstream. During this elimination phase, ion pumps will actively transport some drugs from the blood into the tubules of the kidneys. Organic anion transporters (OAT) transport acids into the tubules of the kidney while organic cation transporters (OCT) transport bases into the tubules of the kidney. This mechanism, known as secretion, depends entirely on transporters and allows both acidic and basic drugs to be eliminated from the body.

Another process known as reabsorption can also occur in the kidneys. During reabsorption, drugs can be transported from the tubules of the kidney back into the blood. This process depends on the pH of the fluid in kidney tubules (e.g. the urine). At a low pH (i.e. acidic environment), acidic drugs are best reabsorbed. Conversely, at high pH (i.e. basic environment), basic drugs are best reabsorbed.

 

Experiment 1

The same drug was administered to various individuals. After some time elapsed, the rate of renal clearance (i.e. the rate of urine elimination from the body) was measured in each of the individuals. Subsequently, the pH of the urine was measured for each individual. The rate of renal clearance versus urinary pH was then plotted in the provided figure (each black dot represents a different individual).

 

Screen shot 2015 11 12 at 9.57.11 pm

 

Experiment 2

A scientist was able to engineer a mouse kidney that lacked organic anion transporters. She administered various drugs to the mouse and measured the rates of secretion. The data collected is located in the provided table.

 

Screen shot 2015 11 13 at 12.39.18 pm   

 

 

Suppose a third experiment were performed. In this experiment, organic cation transporters (OCT) were inhibited or blocked. Which of the following best explains how the reabsorption of basic drugs would be affected?

Possible Answers:

They would be affected because OCT are involved in reabsorption only.

They would not be affected because OCT are involved in secretion only.

They would not be affected because OCT are involved in reabsorption only.

They would be affected because OCT are involved in secretion only.

Correct answer:

They would not be affected because OCT are involved in secretion only.

Explanation:

OCT are essential for the process of secretion, but not reabsorption. If OCT were inhibited, then the secretion of bases would decrease, but not the reabsorption of bases.

Example Question #143 : How To Find Research Summary In Biology

If a drug is administered intravenously (i.e. injected into a vein), then the concentration of the drug in the blood will rise and then reach a plateau. After some time, the body will begin to eliminate this drug from the bloodstream. During this elimination phase, ion pumps will actively transport some drugs from the blood into the tubules of the kidneys. Organic anion transporters (OAT) transport acids into the tubules of the kidney while organic cation transporters (OCT) transport bases into the tubules of the kidney. This mechanism, known as secretion, depends entirely on transporters and allows both acidic and basic drugs to be eliminated from the body.

Another process known as reabsorption can also occur in the kidneys. During reabsorption, drugs can be transported from the tubules of the kidney back into the blood. This process depends on the pH of the fluid in kidney tubules (e.g. the urine). At a low pH (i.e. acidic environment), acidic drugs are best reabsorbed. Conversely, at high pH (i.e. basic environment), basic drugs are best reabsorbed.

 

Experiment 1

The same drug was administered to various individuals. After some time elapsed, the rate of renal clearance (i.e. the rate of urine elimination from the body) was measured in each of the individuals. Subsequently, the pH of the urine was measured for each individual. The rate of renal clearance versus urinary pH was then plotted in the provided figure (each black dot represents a different individual).

 

Screen shot 2015 11 12 at 9.57.11 pm

 

Experiment 2

A scientist was able to engineer a mouse kidney that lacked organic anion transporters. She administered various drugs to the mouse and measured the rates of secretion. The data collected is located in the provided table.

 

Screen shot 2015 11 13 at 12.39.18 pm   

The pKa of a substance is a measure of its acidity. The lower the pKa, then the more acidic the substance.

Drug X is a strong acid and has the following pKa:

Suppose a new drug has the following pKa:

Both of these drugs were tested under the conditions of Experiment 2. Which of the following would most likely be rate of secretion of the new drug?

Possible Answers:

Correct answer:

Explanation:

This new drug is essentially just as acidic as Drug X; therefore, we should expect a very similar rate of secretion as long as this new drug is tested under the same conditions of Experiment 2.

Example Question #144 : How To Find Research Summary In Biology

If a drug is administered intravenously (i.e. injected into a vein), then the concentration of the drug in the blood will rise and then reach a plateau. After some time, the body will begin to eliminate this drug from the bloodstream. During this elimination phase, ion pumps will actively transport some drugs from the blood into the tubules of the kidneys. Organic anion transporters (OAT) transport acids into the tubules of the kidney while organic cation transporters (OCT) transport bases into the tubules of the kidney. This mechanism, known as secretion, depends entirely on transporters and allows both acidic and basic drugs to be eliminated from the body.

Another process known as reabsorption can also occur in the kidneys. During reabsorption, drugs can be transported from the tubules of the kidney back into the blood. This process depends on the pH of the fluid in kidney tubules (e.g. the urine). At a low pH (i.e. acidic environment), acidic drugs are best reabsorbed. Conversely, at high pH (i.e. basic environment), basic drugs are best reabsorbed.

 

Experiment 1

The same drug was administered to various individuals. After some time elapsed, the rate of renal clearance (i.e. the rate of urine elimination from the body) was measured in each of the individuals. Subsequently, the pH of the urine was measured for each individual. The rate of renal clearance versus urinary pH was then plotted in the provided figure (each black dot represents a different individual).

 

Screen shot 2015 11 12 at 9.57.11 pm

 

Experiment 2

A scientist was able to engineer a mouse kidney that lacked organic anion transporters. She administered various drugs to the mouse and measured the rates of secretion. The data collected is located in the provided table.

 

Screen shot 2015 11 13 at 12.39.18 pm   

An individual's diet can alter urinary pH. Based on the information in the passage, consumption of foods that lower urinary pH would affect which of the following processes?  

Possible Answers:

Both reabsorption and secretion

Reabsorption only

Secretion only

Neither reabsorption nor secretion

Correct answer:

Reabsorption only

Explanation:

The passage states that urinary pH affects reabsorption. The process of secretion is controlled by OAT and OCT, not urinary pH.

Example Question #145 : How To Find Research Summary In Biology

  Species competition is driven by a variety of factors. Resources such as water, food, sunlight, and suitable habitat are among the top contributors that influence interspecific and intraspecific competition. Interspecific is competition between different species and intraspecific competition is between members of the same species.

     One interesting example of interspecific competition is that of two barnacle species that inhabit intertidal zones. Balanus balanoides inhabits the lower intertidal zone and Chthamalus stellatus inhabits the lower intertidal zone. A researcher attempts to study this phenomenon.

     The researcher removes the Balanus species from the lower intertidal zone and observes that theChthamalus species expands its range to inhabit the lower intertidal zone and the upper intertidal zone. The researcher then removes the Chthamalus species from the upper tidal zone of a different area and observes that the Balanus species does not extend its range. The researcher concludes that competition has allowed each species to exist simultaneously by forming specialized niches that promotes survivorship for each species.

An invasive predator has been introduced into the intertidal ecosystem and has begun to encroach on the barnacles' habitats. It directly competes with the Balanus species but cannot reproduce as quickly as the Chthamalus species. What is likely to happen to the Chthamalus population?

Possible Answers:

The population will be forced to a different range.

The population will remain unchanged.

None of the choices are correct.

The population will extend to the lower intertidal region.

Correct answer:

The population will extend to the lower intertidal region.

Explanation:

The population will extend to the lower intertidal region.

The invasive species preys on the Balanus species and decreases its population numbers; however, it cannot compete with the reproduction ratres of the Chthamalus species. It can be assumed that the Chthamalus species will fill the gaps left by the Balanus species and increase its range. None of the other choices are supported by the passage.

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