imone/ARB huggingface dataset:
Question: Osteomyelitis is a bone infection often caused by the bacterium Staphylococcus aureus, which spreads through the blood to the bones. The infection is quite common after surgeries when soft tissues become infected and the infection moves to the adjacent bones. The long bones of children are particularly susceptible as they have excellent circulation to them during the growth period. In adults, the best circulation is to the vertebrae, and these are the bones that are most likely to develop osteomyelitis.
Osteomyelitis is treated with various antibiotics, but some patients have chronic infections that are not eradicated by antibiotic therapy due to a unique feature of S. aureus. S. aureus can be internalized by osteoblasts where the bacteria can continue to survive in the intracellular environment. Inside the osteoblasts, bacteria can induce apoptosis, killing their host cell. Surgical debridement is often required to remove the damaged and dead bone tissue created by the infection.
A major research question deals with how an S. aureus infection induces apoptosis in the host osteoblasts. In order for apoptosis to initiate in osteoblasts, the enzyme capsase-8 must be activated. This enzyme serves as a protease that cleaves critical proteins in the cell, causing cell death. Capsase-8 is only expressed under certain circumstances. In the case of osteomyelitis, the S. aureus bacteria cause the induction of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in the osteoblasts. Then TRAIL activates capsase-8, which triggers a series of events leading to apoptosis and death of osteoblasts.
Which of the following potential drugs might be helpful in preventing the death of osteoblasts caused by S. aureus infection?

Options:
A. one that increases capsase-8 activity
B. one that increases TRAIL activity
C. one that is an antagonist to TRAIL
D. all of the above
Answer: Death of osteoblasts due to S. aureus infection is the result of induction of apoptosis. Apoptosis is triggered by capsase-8, so increasing the activity of capsase-8 would increase the rate of apoptosis and osteoblast death. Further, capsase-8 is activated by TRAIL made by S. aureus, so increasing the TRAIL activity would also increase osteoblast death rates. A drug that is antagonistic to TRAIL would decrease capsase-8 activity and decrease the rate of apoptosis in osteoblasts. The correct answer is C.
Question: Osteomyelitis is a bone infection often caused by the bacterium Staphylococcus aureus, which spreads through the blood to the bones. The infection is quite common after surgeries when soft tissues become infected and the infection moves to the adjacent bones. The long bones of children are particularly susceptible as they have excellent circulation to them during the growth period. In adults, the best circulation is to the vertebrae, and these are the bones that are most likely to develop osteomyelitis.
Osteomyelitis is treated with various antibiotics, but some patients have chronic infections that are not eradicated by antibiotic therapy due to a unique feature of S. aureus. S. aureus can be internalized by osteoblasts where the bacteria can continue to survive in the intracellular environment. Inside the osteoblasts, bacteria can induce apoptosis, killing their host cell. Surgical debridement is often required to remove the damaged and dead bone tissue created by the infection.
A major research question deals with how an S. aureus infection induces apoptosis in the host osteoblasts. In order for apoptosis to initiate in osteoblasts, the enzyme capsase-8 must be activated. This enzyme serves as a protease that cleaves critical proteins in the cell, causing cell death. Capsase-8 is only expressed under certain circumstances. In the case of osteomyelitis, the S. aureus bacteria cause the induction of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in the osteoblasts. Then TRAIL activates capsase-8, which triggers a series of events leading to apoptosis and death of osteoblasts.
Many strains of $S$. aureus that cause osteomyelitis are termed methicillin-resistant Staphylococcus aureus (MRSA). These strains have developed resistance to the antibiotic methicillin as well as to other antibiotics. The mechanism by which this antibiotic resistance occurs is by:

Options:
A. the overuse of antibiotics, which causes patients to become resistant to the antibiotics
B. the overuse of antibiotics, which selects for bacteria that have mutations that allow them to survive in the presence of the antibiotics
C. mutations, which occur as the bacteria are exposed to antibiotics that can serve as mutagens
D. all of the above
Answer: Bacteria spontaneously mutate in order to produce diversity in the population. Some bacteria have spontaneous mutations, usually on plasmids, that allow them to survive in the presence of certain antibiotics. If the bacterial population is repeatedly exposed to that antibiotic due to overuse, it exerts selective pressure where only the resistant bacteria survive. These resistant bacteria multiply, and in the next generation a higher frequency of resistance is observed. Antibiotic resistance has nothing to do with people becoming resistant to antibiotics-it is all about the bacterial mutations. The correct answer is B.
Question: A scientist suspects that the food in an ecosystem may have been contaminated with radioactive phosphates over a period of months. Which of the following substances could be examined for radioactive phosphate to test the hypothesis?

Options:
A. the carbohydrates produced by plants in the area
B. the DNA of the organisms in the area
C. the lipids produced by organisms living in the area
D. all of the above
Answer: This question relies on a knowledge of the basic chemical composition of the biologically important molecules. Carbohydrates and lipids are composed of C, O, and H. However, DNA is a nucleic acid and contains phosphate groups. The correct answer is B.
Question: At the end of the electron transport chain in aerobic cellular respiration, the final acceptor of the electrons is which will then produce a molecule

Options:
A. $\mathrm{CO}_{2} ; \mathrm{O}_{2}$
B. $\mathrm{NAD}^{+} ; \mathrm{NADH}$
C. $\mathrm{O}_{2} ; \mathrm{H}_{2} \mathrm{O}$
D. ADP; ATP
Answer: During the electron transport chain, oxygen serves as the terminal electron acceptor during aerobic respiration. In addition to serving as an electron acceptor, the oxygen also gathers protons from the electron transport chain, producing water in the process. The correct answer is C.
Question: Endothelin is a vasoactive peptide involved in a variety of processes, including the control of blood flow. Endothelin is capable of binding to two different receptors. There are receptors for endothelin located on smooth muscle (ETA) and receptors for endothelin located on vascular endothelium (ETB). When endothelin binds to ETA, it initiates vasoconstriction by narrowing blood vessels. However, when endothelin binds to ETB, vasodilation occurs due to the widening of blood vessels. The activity of the ETB receptor seems to counterregulate the ETA effects and prevents excessive vasoconstriction.
Drug $X$ is a selective receptor antagonist for endothelin. It is designed to bind preferentially to certain endothelin receptors. Drug $\mathrm{Y}$ is another selective receptor antagonist for endothelin. It is also designed to preferentially bind to one of the endothelin receptors. Researchers are hopeful that drugs $\mathrm{X}$ and $\mathrm{Y}$ will be of value in the treatment of conditions such as pulmonary arterial hypertension (PAH). In PAH, excess endothelin is produced, which causes an increase in blood pressure within the pulmonary arteries. Normal pressure in the pulmonary arteries is expected to be about $14 \mathrm{~mm} \mathrm{Hg}$, and pressure at or above $25 \mathrm{~mm}$ Hg constitutes PAH. Both drugs have been tested in patients with PAH. There were five patients in each group. At the end of the study, the percent decrease in mean pulmonary artery pressure was measured for each patient and reported in the table.
\begin{tabular}{cccc}
\hline Patient & Drug X & DrugY & Placebo \\
\hline 1 & $+10 \%$ & $-10 \%$ & $+5 \%$ \\
2 & $+3 \%$ & $-5 \%$ & $0 \%$ \\
3 & $-5 \%$ & $+2 \%$ & $+13 \%$ \\
4 & $+2 \%$ & $0 \%$ & $-4 \%$ \\
5 & $0 \%$ & $-7 \%$ & $-2 \%$ \\
Average decrease & $+2 \%$ & $-4 \%$ & $+2.4 \%$ \\
\hline
\end{tabular}
Which endothelin receptor is drug X selectively binding to?

Options:
A. ETA only
B. ETB only
C. both ETA and ETB
D. neither ETA nor ETB
Answer: The results from the drug $\mathrm{X}$ group indicate that the treatment caused an increase in mean pulmonary artery pressure. This helps us to eliminate choice $\mathrm{A}$, which suggests that drug $\mathrm{X}$ is binding to ETA. If this were the case, the drug would be bound to ETA so that endothelin could only bind to ETB. When endothelin binds to ETB, vasodilation occurs, implying a decrease in pressure. This was not seen in the drug $\mathrm{X}$ group. Choice $\mathrm{B}$ suggests that drug $\mathrm{X}$ is selectively binding to the ETB receptor. This would mean that endothelin could only bind to ETA, which does in fact cause an increase in pressure. This would be the correct choice. Answers and Explanations Passage V MCAT The correct answer is B.
Question: The one principal effect not attributed to the hormone insulin is:

Options:
A. glycogen formation and storage
B. conversion of glycogen into glucose
C. carbohydrate oxidation
D. inhibition of gluconeogenesis
Answer: The pancreas is the source for two hormones: insulin and glucagon. Among its principal effects, insulin stimulates glycogen formation and storage, stimulates carbohydrate oxidation, and inhibits gluconeogenesis. All of these effects are described in choices A, C, and D. The other hormone, glucagon, stimulates conversion of glycogen into glucose. So choice B is the correct answer. The correct answer is B.
Question: Human immunodeficiency virus (HIV) is known to infect T cells and macrophages possessing the CD4 receptor. In addition to the CD4 receptor, there are a variety of coreceptors that are also needed for certain strains of HIV to infect cells. One of these coreceptors is called CCR5 and is needed for the most common strains of HIV (called R5) to infect their host cells. The more CCR5 receptors a cell has, the greater the rate of infection for the cell. Some individuals have the delta-32 allele of CCR5 that leads to a decreased risk of HIV infection.
Women are at a much higher risk for contracting HIV from a male partner than a male is for contracting HIV from a female partner. Some of the increased risk for women is dependent on sex hormones. It has been hypothesized that women have different risks of contracting HIV at different points in their reproductive cycles. For example, women may be at a greater risk of contracting HIV following ovulation during the last 2 weeks of their cycle as opposed to the first 2 weeks of their cycle prior to ovulation. The difference between risk of infection before and after ovulation relates to sex hormones produced at various points in the reproductive cycle. It seems that the estrogen that is produced prior to ovulation provides a somewhat protective, although certainly not absolute, role against HIV infection. For women who do become infected with HIV, studies have shown that women in the first 3 to 5 years after HIV infection carry lower HIV viral loads than men, perhaps due to the influence of estrogen. This suggests a major role for sex hormones in the infection and progression of HIV.
Drugs such as AZT and ddI are nucleoside analogs used in HIV-infected patients. Both are chemically modified versions of the nucleotides that make up DNA and RNA. These modified nucleosides interfere with normal replication and transcription. The MOST important goal of these drugs would be:

Options:
A. to prevent the replication of host cell DNA so that the host cell cannot function
B. to prevent the transcription of host cell RNA so that no proteins can be expressed
C. to prevent the viral nucleic acid from entering the host cells
D. to prevent replication of the viral genome
Answer: The question explains that AZT and ddI interfere with replication and transcription. During a viral infection, the ideal situation would be to interfere with viral processes while leaving host cell processes unaffected. Choice A suggests that host cell DNA replication should be prevented in order to keep the host cell from functioning and mentions nothing about how this would affect the virus. Choice B is similar in that it does not mention how the virus would be affected. Choice $\mathrm{C}$ is not appropriate because it discusses preventing infection. If the patient is already confirmed as infected, then this choice wouldn't make sense. If a person is infected with HIV, then the viral genetic material has already entered the host cells. If replication of the viral genome can be prevented as suggested by choice $\mathrm{D}$, then the progression of the infection can be slowed. The correct answer is D.
Question: The discovery and development of various types of anesthesia have revolutionized modern medicine, allowing many medical procedures to be performed with minimal discomfort to the patient. Local anesthesia is used to induce loss of sensation in a particular area, while general anesthesia is used to induce loss of sensation along with loss of consciousness. Both procaine (also known as novocaine) and lidocaine are drugs used for local anesthesia, and they have similar mechanisms of action. The drugs affect neurons in the local areas to which they are applied by preventing the opening of $\mathrm{Na}^{+}$gated channels in the neurons.
Procaine and lidocaine have their own advantages and disadvantages. For example, procaine has the ability to cause vasoconstriction in addition to its analgesic properties. However, lidocaine induces anesthesia faster and for a longer period of time than procaine. In addition to being used as an anesthetic, lidocaine is often used in the treatment of ventricular fibrillation, a condition where the cardiac muscle displays rapid, uncoordinated, and weak rhythms. The drug causes decreased excitability of the ventricles by blocking $\mathrm{Na}^{+}$gated channels, while the sinoatrial node in the right atrium is unaffected by the drug.
Procaine has a half-life of up to $0.5$ hours in patients. When procaine is metabolized in the body, it is converted to para-aminobenzoic acid (PABA) in the plasma by the enzyme pseudocholinesterase, and PABA is then excreted by the kidneys. Lidocaine is twice as potent as procaine, but lidocaine is also twice as toxic. The half-life of lidocaine in patients is typically between $1.5$ and 2 hours. Lidocaine is metabolized in the liver by two enzymes that produce the metabolites monoethylglycinexylidide and glycinexylidide. The passage states that when lidocaine is given for ventricular fibrillation the sinoatrial node is unaffected. The sinoatrial node normally functions as:

Options:
A. a valve in the heart
B. the pacemaker of the heart
C. the barricade between the right and left side of the heart that keeps oxygenated and deoxygenated blood from mixing
D. a regulator of blood pressure in the heart
Answer: This question relies on your knowledge of the anatomy of the heart and the conducting system of the heart. The sinoatrial node (SA node) is a group of conducting cells located in the right atrium. Recall that the valves of the heart are atrioventricular (AV) and semilunar valves. The barricade that divides the right and left side of the heart is the septum. The SA node generates electrical signals that control cardiac muscle contractions and serves as the pacemaker for the heart. The correct answer is B.
Question: Leukemia is a term that describes a wide variety of blood cell cancers. Most leukemia cases involve elevated leukocyte counts. In acute cases of leukemia, immature leukocytes proliferate quickly, which leads to many abnormal immature cells in the bone marrow. This inhibits the ability of the bone marrow to produce healthy new leukocytes. This form of the cancer progresses rapidly, and the cells metastasize easily as they move into the bloodstream from the bone marrow. It can be fatal within weeks or months if not treated promptly. In contrast, chronic cases of leukemia typically involve the proliferation of abnormal mature leukocytes. This form of the disease progresses more slowly, and treatment need not always be immediate.
Once classified as acute or chronic, leukemia can be further subdivided into lymphocytic or myelogenous. This distinction depends on which type of leukocyte is abnormal in the patient. In lymphocytic leukemia, the lymphoid cells, such as the lymphocytes, are abnormal. In the myelogenous form, the myeloid cells, such as basophils, neutrophils, and eosinophils, are affected.
Chemotherapy drugs are often used in the management of leukemia cases. There are numerous categories of these drugs, and they have varied mechanisms of action. In treatment, several drugs are used in combination because some of the drugs are cell-cycle specific while others are not. Alkylating agents are capable of disrupting the function of DNA. Tubulin-binding agents are designed to interfere with microtubule formation. Other drugs are designed to interfere with DNA polymerase, DNA repair mechanisms, or protein synthesis, or to act as purine analogs. Many of these drugs cannot enter into the brain when injected or ingested, so if the cancer has spread to
this area, special methods must be used to introduce the drugs to the brain.
What is the most logical explanation for why certain drugs may NOT be able to reach the brain if they have been ingested or injected?

Options:
A. These drugs have a chemical nature that does not allow them to cross the blood-brain barrier.
B. These drugs are so toxic that they are broken down before they reach the brain.
C. Most of these drugs target only cancerous cells that normally would not be in the brain.
D. The drugs that have been ingested have likely been denatured by the acids in the stomach.
Answer: The blood-brain barrier is a change in the permeability of blood vessels leading to the brain. Depending on the chemical composition, some drugs can cross and some cannot. Of the choices listed, it seems that if the drugs cannot reach the brain, then they have not crossed the blood-brain barrier. While choice D might seem plausible if a drug was ingested, it would not make sense for a drug that was injected. The correct answer is A.
Question: Osteomyelitis is a bone infection often caused by the bacterium Staphylococcus aureus, which spreads through the blood to the bones. The infection is quite common after surgeries when soft tissues become infected and the infection moves to the adjacent bones. The long bones of children are particularly susceptible as they have excellent circulation to them during the growth period. In adults, the best circulation is to the vertebrae, and these are the bones that are most likely to develop osteomyelitis.
Osteomyelitis is treated with various antibiotics, but some patients have chronic infections that are not eradicated by antibiotic therapy due to a unique feature of S. aureus. S. aureus can be internalized by osteoblasts where the bacteria can continue to survive in the intracellular environment. Inside the osteoblasts, bacteria can induce apoptosis, killing their host cell. Surgical debridement is often required to remove the damaged and dead bone tissue created by the infection.
A major research question deals with how an S. aureus infection induces apoptosis in the host osteoblasts. In order for apoptosis to initiate in osteoblasts, the enzyme capsase-8 must be activated. This enzyme serves as a protease that cleaves critical proteins in the cell, causing cell death. Capsase-8 is only expressed under certain circumstances. In the case of osteomyelitis, the S. aureus bacteria cause the induction of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in the osteoblasts. Then TRAIL activates capsase-8, which triggers a series of events leading to apoptosis and death of osteoblasts.
Osteoblasts are normally involved in building new bone matrix. Their activity is stimulated by the hormone made by the

Options:
A. calcitonin; thyroid
B. parathyroid hormone; parathyroid glands
C. osteotonin; bone marrow
D. none of the above
Answer: Knowledge of the endocrine structures and hormones is needed to answer this question. The hormone calcitonin stimulates the storage of calcium in bone matrix. Its target is the osteoblasts that build new bone matrix. The calcitonin hormone is made by the thyroid gland. Parathyroid hormone is antagonistic to calcitonin and stimulates osteoclasts. Osteotonin is not a real hormone. The correct answer is A.
Question: Neurons contain a high concentration of potassium ions relative to the fluids surrounding them. How could a neuron acquire even more potassium?

Options:
A. active transport
B. osmosis
C. endocytosis
D. diffusion
Answer: This question is asking how to move a potassium ion (which is small) from an area that has a low concentration to an area with a relatively higher concentration. In this case we are moving against the concentration gradient. The transport type that could do this is active transport, using energy to move the ions against their concentration gradient. The correct answer is A.