ACT Science : Biology

Study concepts, example questions & explanations for ACT Science

varsity tutors app store varsity tutors android store varsity tutors amazon store varsity tutors ibooks store

Example Questions

1 2 61 62 63 64 65 66 67 69 Next →

Example Question #681 : Biology

Vaccinations have become a controversial topic in the United States. Currently the US Food and Drug Administration (FDA) regulates all vaccines. The federal government does not mandate vaccinations for any individual; however, all states require vaccinations for children entering public school. There are several types of vaccines—live attenuated vaccines, inactivated vaccines, subunit vaccines, toxoid vaccines, and conjugate vaccines, just to name a few. All of these vaccines have the shared purpose of exposing the host body to antigens of a specific disease. When the body receives the antigens, the immune system is activated, remembering the antigens. The next time the individual is exposed to the disease, the body will remember the antigen and have a better probability of not getting infected. Two scientists below discuss their belief on vaccines.

Scientist 1

Vaccines have saved many lives. The risks of not being vaccinated far outweigh the risks of adverse vaccine reactions. Reports linking autism to vaccines have been evaluated by the CDC, which states there is no scientific link between autism and vaccines. The second leading cancer killer in women is cervical cancer. The HPV vaccine protects against the two most common strains causing cancer. This is an example of a vaccine that does much more good than bad. Vaccines also reduce the amount of money spent on healthcare, because the preventative cost of a vaccine is much cheaper than the cost of treating an infected person. The only time a vaccine should not be administered is if the chance of the individual coming into contact with the disease is so rare it is not worth the potential of adverse reactions.

 Scientist 2

Many vaccines nowadays are extraneous. Vaccines for diseases like whooping cough and scarlet fever were once necessary but now outdated. Modern updates on hygiene, waste management, and water filtration have resulted in significantly decreased chances of infection. In addition, diseases like rotavirus have an infection period of a few days, and the main symptom is dehydration. Modern medicine can easily treat severe dehydration, and the risk of rotavirus infection is very slim; therefore, the results of infection are far milder than the results of an adverse reaction. Vaccines for children can cause extremely dangerous adverse reactions. This includes anaphylactic shock, paralysis, and death. While scientists have not been able to conclusively prove this, many believe that these reactions are related to the age of the host and the lack of a developed immune systemor neural network. Vaccines suppress the immune system, which can lead to autoimmune disorders. In addition, vaccines can congest the lymphatic system with proteins molecules from the vaccines; therefore, I would recommend requirements for vaccination to take place at a later stage in a child’s development.

What statement would Scientist 2, but not Scientist 1, agree with? 

Possible Answers:

Vaccines expose the host body to antigens of a specific disease. 

Vaccines should not be administered to young children. 

The risks of not being vaccinated far outweigh the risks of adverse vaccine reactions.

All states require vaccinations for children entering public school.

Correct answer:

Vaccines should not be administered to young children. 

Explanation:

Scientist 2 concludes his argument by stating that he would recommend requirements for vaccination to take place at a later stage in a child’s development. He also discusses why he believes vaccinations at a young age can cause more damage. Scientist 1 does not address children specifically, but only mentions one exceptional case where the vaccines should not be administered.

Example Question #681 : 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.

Assume that Scientist 2's hypothesis is correct. Which of the following would be most likely?

Possible Answers:

No amount of radiation ever renders material non-infectious.

Trace amounts of DNA or RNA are eventually found in infectious material.

Many other diseases are ultimately found that are transmitted by proteins without DNA or RNA.

Polyomaviruses are found to be less radiation-resistant than previously thought.

Correct answer:

Trace amounts of DNA or RNA are eventually found in infectious material.

Explanation:

If Scientist 2 is correct, the viral hypothesis is true. If the viral hypothesis is true, we would expect that DNA or RNA exists somewhere in the infectious material, but has not yet been discovered.

Example Question #682 : 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.

With which of the following statements would both Scientist 1 and Scientist 2 most likley agree?

Possible Answers:

The protein-only hypothesis is not the simplest explanation, but is the most likely.

Many more transmissible diseases are caused by viruses or bacteria than proteins.

Many more transmissible diseases are caused by proteins than viruses or bacteria.

The protein-only hypothesis is not the most-likley explanation, but is the simplest.

Correct answer:

Many more transmissible diseases are caused by viruses or bacteria than proteins.

Explanation:

Despite being on opposite sides of the protein-only hypothesis for mad cow disease, Scientist 1 and 2 are likely to agree that many more diseases are caused by either viruses or bacteria than proteins. Scientist 1 would argue that proteins are causative in this case, but would likely appreciate that this is a unique case relative to most other diseases studied.

1 2 61 62 63 64 65 66 67 69 Next →
Learning Tools by Varsity Tutors