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 Vaccines for diseases like whooping cough and scarlet fever were once necessary but now outdated.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.

Scientist 2 states that many vaccines are now outdated because of: 

An experiment was done to test the antibiotic resistance of the bacteria Pseudomonas flourescens and Escherichia coli by using the antibiotic disk sensitivity method. Four different antibiotics were tested on each bacterium. Media were prepared with each type of bacterium and a drop of each antibiotic was added to each corner of the plates, a different antibiotic in each corner. The cultures were observed for eighteen hours. After this period of time, the zones of inhibition (where the bacteria was not able to grow due to the antibiotic) were measured. The table below shows the results of the four antibiotics on the two bacteria, Pseudomonas flourescens and Escherichia coli.

According to the results of this test, which of the following is true of the observed antibiotic resistance trends?

A group of scientists wanted to test the effects of Nitra-Grow, a chemical additive that can be given to plants to help them grow. 3 test groups of plants were given all the same time of sunlight, the same type of soil, and the same amount of water. Plant A was given no extra chemicals. Plant B was given 5g of Nitra-Grow. Plant C was given 5g of Ammonia to see if Nitra-Grow worked any better than a basic nitrogen-based household product. The plants are then measured on 5 consecutive days to find their average height (in cm).

What is the general relationship between plant height and the amount of days?

A group of scientists wanted to test the effects of Nitra-Grow, a chemical additive that can be given to plants to help them grow. 3 test groups of plants were given all the same time of sunlight, the same type of soil, and the same amount of water. Plant A was given no extra chemicals. Plant B was given 5g of Nitra-Grow. Plant C was given 5g of Ammonia to see if Nitra-Grow worked any better than a basic nitrogen-based household product. The plants are then measured on 5 consecutive days to find their average height (in cm).

Suppose that the scientists repeated the experiment with Plant D. Plant D was given 15g of Nitro-Grow and 15g of Ammonia. What would be the expected results?

     Chemical reactions involve two main components, reactants and products. The reactants, often referred to as substrates, interact with each other and rearrange in order to be converted into products. The speeds of these reactions are often defined by substrate concentration and the presence of enzymes. Enzymes are referred to as catalysts. Peroxidase is traditionally derived from turnips; however, it is commonly found in many plant and animal cells. This enzyme helps plant cells by removing hydrogen peroxide from cells in the form of tetraguaiacol.

Study 1

     A scientist wants to observe the production of tetraguaiacol by observing a reaction between hydrogen peroxide and guaiacol. The product of this reaction is orange-brown in color. The scientist measures the intensity of color in each sample using a spectrophotometer. In the control experiment, the scientist mixed the substrates together and measured the reaction rate. In the test experiment, a peroxidase enzyme was added to a new set of substrates and rate of reaction was measured. The results of these reactions are plotted in Figure 1.

Figure 1

Study 2

     A research team decides to study the effects of the peroxidase facilitated reaction in the presence of heat. Reaction rates are known to speed up when heat is applied; however, at a certain point enzymes, such as peroxidase, denature and the reaction slows. The scientists perform a control trial at room temperature  and test trials at , , and . The results are plotted in Figure 2.

Figure 2

In Figure 1 of Study 1, why does the control reaction occur at a different rate than the enzyme reaction?

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 no 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.

An effective treatment is developed for mad cow disease that is known to disrupt DNA or RNA structure, but leave proteins intact.  Which of the following is most likely to also be true?

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 no 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.

Suppose that a scientist discovers a different protein that is decisively shown to be able to cause disease in the absence of DNA or RNA.  However, this protein is only present in non-mammals and does not cause disease in mammals.  Which of the following is most accurate?

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 no 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.

Scientist 1 introduces the observation that infectious material is radiation resistant to:

Clostridium botulinum is a bacterial organism that can cause disease in people after eating improperly canned foods. As a result of this risk, canning foods involves bringing contents to high pressures and temperatures, thus killing the inactive form of Clostridium, called a spore.

Table 1 shows the ability of a scientist to detect spores as a function of the peak temperature and pressure reached during the process used for canning green beans.

Table 2 shows the infectious dose of spores per cubic millimeter necessary to cause illness in four populations. 

A scientist discovers that, despite adhering to appropriate canning methods as described above, an outbreak of disease due to Clostridium botulinum has taken place in a Minnesota school. She visits the school and collects food samples to determine the cause of the outbreak. While compiling data at the school, she discovers that there are an increasing number of cases of a new strain of Clostridium botulinum. Upon investigation, the scientist finds that all children who attend the school are older than 5 years of age.

According to the data in Table 1, Clostridium botulinum spores are most likely:

Clostridium botulinum is a bacterial organism that can cause disease in people after eating improperly canned foods. As a result of this risk, canning foods involves bringing contents to high pressures and temperatures, thus killing the inactive form of Clostridium, called a spore.

Table 1 shows the ability of a scientist to detect spores as a function of the peak temperature and pressure reached during the process used for canning green beans.

Table 2 shows the infectious dose of spores per cubic millimeter necessary to cause illness in four populations. 

A scientist discovers that, despite adhering to appropriate canning methods as described above, an outbreak of disease due to Clostridium botulinum has taken place in a Minnesota school. She visits the school and collects food samples to determine the cause of the outbreak. While compiling data at the school, she discovers that there are an increasing number of cases of a new strain of Clostridium botulinum. Upon investigation, the scientist finds that all children who attend the school are older than 5 years of age.

According to table 1, which of the following changes to a canning procedure is likely to have the greatest impact on reducing the number of active spores?