An undergraduate biology student working in a lab was reading about the latest health epidemic in the United States concerning obesity. He recently learned in his biology class that an enzyme called fatty acid synthase (FAS) catalyzes the formation of fatty acids. Accumulation of these fatty acids then creates the adipose fatty tissue that individuals typically see in their belly or side-regions. He hypothesizes that by decreasing the rate that this enzyme produces fatty acids by administering an inhibitor will aid in reducing the storage of fats, helping to alleviate obesity. After gaining approval from the university's clinical trials and ethics committee, he gathered a group of 20 test subjects. With the help of his research director, he measured the baseline rate of FAS activity for all test subjects and the averaged rate after oral administrators of a placebo and three types of inhibitors at a concentration of 0.6M to four equally-sized groups. The data is shown in Table 1.                      

Table 1.

The student then wonders if a mixture of different inhibitors were to increase the effect in the subject. He again measured the averaged baseline FAS level of the subjects and then attempted administering a placebo and three different combinations of inhibitors to subjects in a second trial. The results are shown in Table 2.

Table 2. 

A colleague of the researcher interpreted the results from Table 1 and 2 and suggested a third trial which would track the averaged weight change of the subjects over a 6-month period. The results are shown in Table 3.

Table 3.

How might the significance of this study be increased?

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).

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.

Which of the following would be considered as the dependent variable in Experiment 2?

Sleep plays a vital role in defining the daily activities of virtually all animals. During periods of sleep, the parasympathetic nervous system becomes active and induces a relaxed state in response to increased levels of the hormone melatonin. Yet, despite its ubiquity in the animal kingdom, the purpose of sleep and its role in our daily lives has been disputed by scientists. Two scientists discuss their theories about the purpose of sleep.

Scientist 1

During periods of sleep, animals are able to conserve energy that they would otherwise be spending on unnecessary activity. If an animal’s primary food source is most abundant during daylight, it is a waste of precious energy to be moving about at night. For example, many herbivores, such as squirrels, are diurnal (sleep during the night) because their food source is available during the day, while many insectivores, such as bats, are nocturnal (sleep during the day) because their food source is available during the night. Food sources, as an animal’s most valuable resource, dictate their sleep cycles. Many animal traits observable today evolved as a result of the supply and demand of food in their natural habitat.

Scientist 2

During waking hours, it is true that the body utilizes large amounts of energy. However, the role of sleep is to restore biological products that were utilized during periods of wakefulness, rather than simply avoid utilizing energy in the first place. Many types of biological molecules, such as hormones, are released throughout the body while an animal is active. Sleep serves as a period of inactivity during which the body can manufacture and store a supply of these molecules for future use during the next period of activity. Furthermore, sleep allows the body to repair cellular damages that has accumulated during waking hours. Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase. Sleep is necessary for animals to prevent accumulation of damage and to regenerate crucial biomolecules for daily life.

Which of the following best describes how the scientists view the role of sleep?

Sleep plays a vital role in defining the daily activities of virtually all animals. During periods of sleep, the parasympathetic nervous system becomes active and induces a relaxed state in response to increased levels of the hormone melatonin. Yet, despite its ubiquity in the animal kingdom, the purpose of sleep and its role in our daily lives has been disputed by scientists. Two scientists discuss their theories about the purpose of sleep.

Scientist 1

During periods of sleep, animals are able to conserve energy that they would otherwise be spending on unnecessary activity. If an animal’s primary food source is most abundant during daylight, it is a waste of precious energy to be moving about at night. For example, many herbivores, such as squirrels, are diurnal (sleep during the night) because their food source is available during the day, while many insectivores, such as bats, are nocturnal (sleep during the day) because their food source is available during the night. Food sources, as an animal’s most valuable resource, dictate their sleep cycles. Many animal traits observable today evolved as a result of the supply and demand of food in their natural habitat.

Scientist 2

During waking hours, it is true that the body utilizes large amounts of energy. However, the role of sleep is to restore biological products that were utilized during periods of wakefulness, rather than simply avoid utilizing energy in the first place. Many types of biological molecules, such as hormones, are released throughout the body while an animal is active. Sleep serves as a period of inactivity during which the body can manufacture and store a supply of these molecules for future use during the next period of activity. Furthermore, sleep allows the body to repair cellular damages that has accumulated during waking hours. Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase. Sleep is necessary for animals to prevent accumulation of damage and to regenerate crucial biomolecules for daily life.

The scientists agree on which of the following principles:

Dominant alleles (D) produce dominant characteristics; recessive alleles (d) produce recessive characteristics.  Dominant alleles are expressed whenever present (DD, Dd) but recessive alleles are expressed only when the dominant allele is absent (dd) 

A study was done in which the visual traits of two plants and their offspring was tested.  In this study, Plant A, a Tall Purple plant, was mated with Plant B, a Tall Pink plant.  It has been determined that the dominant trait for height is tall (H) and the dominant trait for color is purple (P). 

Breeding both plants will result in offspring that have recessive and dominant traits.  The chart below contains all the possibilities for their offspring. 

Figure 1.

Figure 2.                     HH Pp x Hh pp    Offspring

Is it possible that either plant from Figure 1 had at least one short parent?  

Dominant alleles (D) produce dominant characteristics; recessive alleles (d) produce recessive characteristics.  Dominant alleles are expressed whenever present (DD, Dd) but recessive alleles are expressed only when the dominant allele is absent (dd) 

A study was done in which the visual traits of two plants and their offspring was tested.  In this study, Plant A, a Tall Purple plant, was mated with Plant B, a Tall Pink plant.   It has been determined that the dominant trait for height is tall (H) and the dominant trait for color is purple (P). 

Breeding both plants will result in offspring that have recessive and dominant traits.  The chart below contains all the possibilities for their offspring. 

Figure 1.

Figure 2.                     HH Pp x Hh pp    Offspring

Suppose two distinct tall purple plants had offspring. What is the likelihood that their offspring will also be tall and purple?

Three doctors are discussing the most optimal way to approach cancer treatment. While they all acknowledge that cancer is uncontrolled cell proliferation, they have different opinions on whether chemotherapy is the best treatment method. Chemotherapy is the treatment of cancer with cytotoxic antienoplastic drugs. These drugs are used to kill fast-growing cancerous cells. All three doctors agree that chemotherapy has many associated side effects.

Doctor 1

While the drugs used for chemotherapy can be very strong, they need to be. Cancer, by its very definition, is made up of cells growing at a faster than normal rate. This means the treatment needs to be aggressive. The slower the effects of treatment, the more time the cancer has to spread; therefore, while the chemotherapy can also kill some healthy noncancerous cells in the process, it is still the best option. 

Doctor 2 

Chemotherapy does much more harm than good. Chemotherapy might temporarily destroy the cancer, but it does not cure the cancer. In addition, killing the cancerous cells means poisoning the body with chemicals and toxins. Instead, we should be addressing the reasons cancer exists in the first place, treating it at that step. Cancer is due to toxins in the body, industrial pollutions, and drugs. Avoiding sugar, exercising, and maintaining a healthy lifestyle—free of toxins, processed food, and other containments—is the best approach.

Doctor 3

Chemotherapy is effective in the sense that it kills the cancer cells. The downfall is that chemotherapy also kills the healthy cells in the process; therefore, we should be looking at way to decrease the amount of chemotherapy needed, so that we are only introducing the minimum amount of toxins into the body. Insulin Potentiating Therapy is a type of chemotherapy in which lower doses of chemotherapy are used because they are combined with insulin. Cancer cells have more insulin receptors than non-cancerous cells; therefore, cancer cells will have a biased absorption of such insulin-based chemotherapy when compared with noncancerous cells. In other words, piggybacking chemotherapy onto insulin allows cancer cells to absorb more of the chemotherapy, meaning less chemotherapy is needed and fewer noncancerous cells absorb the chemotherapy.

Which of the following best states the opinion of Doctor 1?

Three doctors are discussing the most optimal way to approach cancer treatment. While they all acknowledge that cancer is uncontrolled cell proliferation, they have different opinions on whether chemotherapy is the best treatment method. Chemotherapy is the treatment of cancer with cytotoxic antienoplastic drugs. These drugs are used to kill fast-growing cancerous cells. All three doctors agree that chemotherapy has many associated side effects.

Doctor 1

While the drugs used for chemotherapy can be very strong, they need to be. Cancer, by its very definition, is made up of cells growing at a faster than normal rate. This means the treatment needs to be aggressive. The slower the effects of treatment, the more time the cancer has to spread; therefore, while the chemotherapy can also kill some healthy noncancerous cells in the process, it is still the best option. 

Doctor 2 

Chemotherapy does much more harm than good. Chemotherapy might temporarily destroy the cancer, but it does not cure the cancer. In addition, killing the cancerous cells means poisoning the body with chemicals and toxins. Instead, we should be addressing the reasons cancer exists in the first place, treating it at that step. Cancer is due to toxins in the body, industrial pollutions, and drugs. Avoiding sugar, exercising, and maintaining a healthy lifestyle—free of toxins, processed food, and other containments—is the best approach.

Doctor 3

Chemotherapy is effective in the sense that it kills the cancer cells. The downfall is that chemotherapy also kills the healthy cells in the process; therefore, we should be looking at way to decrease the amount of chemotherapy needed, so that we are only introducing the minimum amount of toxins into the body. Insulin Potentiating Therapy is a type of chemotherapy in which lower doses of chemotherapy are used because they are combined with insulin. Cancer cells have more insulin receptors than non-cancerous cells; therefore, cancer cells will have a biased absorption of such insulin-based chemotherapy when compared with noncancerous cells. In other words, piggybacking chemotherapy onto insulin allows cancer cells to absorb more of the chemotherapy, meaning less chemotherapy is needed and fewer noncancerous cells absorb the chemotherapy.

What fact do all three doctors seem to agree upon?

Three doctors are discussing the most optimal way to approach cancer treatment. While they all acknowledge that cancer is uncontrolled cell proliferation, they have different opinions on whether chemotherapy is the best treatment method. Chemotherapy is the treatment of cancer with cytotoxic antienoplastic drugs. These drugs are used to kill fast-growing cancerous cells. All three doctors agree that chemotherapy has many associated side effects.

Doctor 1

While the drugs used for chemotherapy can be very strong, they need to be. Cancer, by its very definition, is made up of cells growing at a faster than normal rate. This means the treatment needs to be aggressive. The slower the effects of treatment, the more time the cancer has to spread; therefore, while the chemotherapy can also kill some healthy noncancerous cells in the process, it is still the best option. 

Doctor 2 

Chemotherapy does much more harm than good. Chemotherapy might temporarily destroy the cancer, but it does not cure the cancer. In addition, killing the cancerous cells means poisoning the body with chemicals and toxins. Instead, we should be addressing the reasons cancer exists in the first place, treating it at that step. Cancer is due to toxins in the body, industrial pollutions, and drugs. Avoiding sugar, exercising, and maintaining a healthy lifestyle—free of toxins, processed food, and other containments—is the best approach.

Doctor 3

Chemotherapy is effective in the sense that it kills the cancer cells. The downfall is that chemotherapy also kills the healthy cells in the process; therefore, we should be looking at way to decrease the amount of chemotherapy needed, so that we are only introducing the minimum amount of toxins into the body. Insulin Potentiating Therapy is a type of chemotherapy in which lower doses of chemotherapy are used because they are combined with insulin. Cancer cells have more insulin receptors than non-cancerous cells; therefore, cancer cells will have a biased absorption of such insulin-based chemotherapy when compared with noncancerous cells. In other words, piggybacking chemotherapy onto insulin allows cancer cells to absorb more of the chemotherapy, meaning less chemotherapy is needed and fewer noncancerous cells absorb the chemotherapy.

What is the argument behind Doctor 3's belief that the treatment he discusses is more effective—even though it uses a much lower dosage of chemotherapy?

Three doctors are discussing the most optimal way to approach cancer treatment. While they all acknowledge that cancer is uncontrolled cell proliferation, they have different opinions on whether chemotherapy is the best treatment method. Chemotherapy is the treatment of cancer with cytotoxic antienoplastic drugs. These drugs are used to kill fast-growing cancerous cells. All three doctors agree that chemotherapy has many associated side effects.

Doctor 1

While the drugs used for chemotherapy can be very strong, they need to be. Cancer, by its very definition, is made up of cells growing at a faster than normal rate. This means the treatment needs to be aggressive. The slower the effects of treatment, the more time the cancer has to spread; therefore, while the chemotherapy can also kill some healthy noncancerous cells in the process, it is still the best option. 

Doctor 2 

Chemotherapy does much more harm than good. Chemotherapy might temporarily destroy the cancer, but it does not cure the cancer. In addition, killing the cancerous cells means poisoning the body with chemicals and toxins. Instead, we should be addressing the reasons cancer exists in the first place, treating it at that step. Cancer is due to toxins in the body, industrial pollutions, and drugs. Avoiding sugar, exercising, and maintaining a healthy lifestyle—free of toxins, processed food, and other containments—is the best approach.

Doctor 3

Chemotherapy is effective in the sense that it kills the cancer cells. The downfall is that chemotherapy also kills the healthy cells in the process; therefore, we should be looking at way to decrease the amount of chemotherapy needed, so that we are only introducing the minimum amount of toxins into the body. Insulin Potentiating Therapy is a type of chemotherapy in which lower doses of chemotherapy are used because they are combined with insulin. Cancer cells have more insulin receptors than non-cancerous cells; therefore, cancer cells will have a biased absorption of such insulin-based chemotherapy when compared with noncancerous cells. In other words, piggybacking chemotherapy onto insulin allows cancer cells to absorb more of the chemotherapy, meaning less chemotherapy is needed and fewer noncancerous cells absorb the chemotherapy.

Which doctor could you infer would recommend a preventative approach to cancer as opposed to chemotherapy?