the mcat is changing 1 learn about the mcat 2015 from the experts chris hinkle hannah whitehead

The MCAT is Changing

1

LEARN ABOUT THE MCAT2015 FROM THE EXPERTS

Chris HinkleHannah Whitehead

Today’s Agenda

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• The MCAT Today

• The MCAT2015

• Which test is right for you?

• Sample Questions

• The Princeton Review Program & Approach

• Questions & Answers

The MCAT

3

• MCAT Medical College Admission Test

• Developed by AAMC (Assoc. of American Medical Colleges)

• If you want to go to medical school in the U.S. or Canada … almost all schools require you to take the MCAT

AAMC

4

• Represents the United States medical schools and teaching hospitals

• Sets American agenda for medical education and research• Manages the creation and administration of the MCAT

worldwide

The MCAT According to AAMC:

44 Designed to assess problem solving, critical thinking, communication and writing skills

44 Designed to assess examinee's knowledge of science concepts and principles prerequisite to the study of medicine

MCAT 2013-2015

• 2013Elimination of the Writing Section and creation of a Trial Section.

• 2014Elimination of Trial Section in October

• 2015Last administration of the current MCAT in January

First administration of the new MCAT2015 in the Spring

Includes the addition of a new section;Psychological, Social, and Biological Foundations of Behavior.

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• Multiple-choice, 4 choices per question (A-D)

• Passage-based and freestanding questions

• Scores based on number of questions correct

• No guessing penalty (Never leave a blank)

MCAT Today Breakdown

6MCAT Today

SECTION SCORE RANGE

Physical Sciences 1-15

Verbal Reasoning 1-15

Biological Sciences 1-15

Optional Trial Section%

Correct

Composite 3-45

7

The MCAT Today

MCAT Today

FORMAT MCAT IS EXCLUSIVELY COMPUTER-BASED

Number of Questions 52 Physical Sciences; 40 Verbal Reasoning; 52 Biological Sciences; 32 Optional Trial Section

Total Content Time 4 hours, 5 minutes (includes Trial Section)

Total “Seated Time” 5 hours, 10 minutes

Breaks Optional breaksNo lunch hour

Frequency of Test 25 testing days – 28 total administrations (additional days added for 2014)

Registration Available up until the test week*

Results Delivery 30-35 days after your tests date and can be accessed through your AAMC account

Security Photo IDElectronic fingerprintElectronic signature verification

Testing Centers Smaller, climate-controlled computer testing rooms with standardized proctoring

* Note: many locations fill up much earlier

Your MCAT Today Testing Day

8MCAT Today

TEST SECTION QUESTIONS TIME

Tutorial (Optional) 10 minutes

Physical Sciences (7 Passages + 13 FSQ) 52 70 minutes

Break (Optional) 10 minutes

Verbal Reasoning (7 Passages) 40 60 minutes


Biological Sciences (7 Passages + 13 FSQ) 52 70 minutes

Trial Section (Optional) 32 45 minutes

Satisfaction Survey 12 10 minutes

Total Content Time 4 hours, 5 minutes


Total Appointment Time (includes check-in)

5 hours, 30 minutes

Why is the test changing?

• The MCAT is undergoing its biggest change since 1991.

• To adjust to these changes, AAMC has worked closely with medical schools to assess the MCAT, keep what works, remove what isn’t working and to enhance the test to include concepts the next generation of doctors will need.

• The MCAT has been a passage based test since 1991 precisely to encourage reasoning. MCAT2015 science sections are driven by changes in what med schools find most important and that the new psychology/sociology section is about recognizing additional factors in health and health outcomes.

9MCAT2015

What is changing?The test is longer

• 2 hours and 20 minutes more testing time• 1 additional section• 86 more questions• More time per question (1:35 per science Q; 1:40 per CARS Q)

• Possibly an indication of increased need for reading comprehension

The scores have changed• Each section will be scored on a 118-132 point scale centered on 125.• The composite score will range from 472-528 points centered on 500.• This is similar to a 1-15 point score on each section and a 4-60 point

composite score.

10MCAT2015

What is changing?4 Sections instead of 3 and focus has shifted

• Chemical and Physical Foundations of Biological Systems• This section will cover concepts in physics, general chemistry, organic

chemistry, and biochemistry. It will test your knowledge of the basic physical and chemical principles inherent in the functions of the human body. This section will also test your ability to apply your knowledge of these general principles to living systems.

• Critical Analysis and Reasoning Skills• This section will require you to analyze information from a wide variety of

humanities-based disciplines. No prior content knowledge is required, and all questions will be answerable from the provided material.

11MCAT2015

What is changing?4 Sections instead of 3 and focus has shifted

• Biological and Biochemical Foundations of Living Systems• This section will cover concepts in biology, biochemistry, and organic

chemistry. It will test your knowledge of the fundamental concepts governing the unique processes in living systems (growing, reproducing, responding, metabolizing, and adapting). At the same time, it will test your understanding of how cells, organs, and organ systems work together to accomplish these processes as well as your ability to reason about these processes.

• Psychological, Social, and Biological Foundations of Behavior• This section will test concepts in psychology, sociology, and biology as how

they apply to the socio-cultural and behavioral aspects of health and well-being. You will also be tested on research methods and statistics, and on your ability to apply your knowledge to understand how social and behavioral factors influence health.

12MCAT2015

• Multiple-choice, 4 choices per question (A-D)

• Passage-based and freestanding questions

• Scores based on number of questions correct

• No guessing penalty (Never leave a blank)

MCAT2015 Breakdown

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SECTION SCORE RANGE

Chemical and Physical Foundations of Biological Systems

118-132

Critical Analysis and Reasoning Skills 118-132

Biological and Biochemical Foundations of Living Systems

118-132

Psychological, Social, and Biological Foundations of Behavior

118-132

Composite 472-528

MCAT2015

14

The MCAT2015

FORMAT MCAT2015 IS EXCLUSIVELY COMPUTER-BASED

Number of Questions 59 Chemistry/Physics; 53 CARS; 59 Biology/Biochemistry; 59 Psychology/Sociology



Breaks Optional breaksProbable lunch break

Frequency of Test 14 testing days beginning 8 am (April-September 2015)

Registration Begins in February 2015Registration fee is $300 ($150 gift card for those registering for April 2015 test)Available up until the test week*

Results Delivery 30-35 days after your tests date and can be accessed through your AAMC account

Security Photo IDElectronic fingerprintElectronic signature verification

Testing Centers Smaller, climate-controlled computer testing rooms with standardized proctoring

* Note: many locations fill up much earlier

MCAT2015

Your MCAT2015 Testing Day

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TEST SECTION QUESTIONS TIMEExaminee Agreement 10 minutes

Tutorial (Optional) 5 minutes

Chemical and Physical Foundations of Biological Systems (9-10 Passages + 15 FSQ)

59 95 minutes


Critical Analysis and Reasoning Skills (9 Passages) 53 90 minutes

Mid-Exam Break (Optional) 30 minutes

Biological and Biochemical Foundations of Living Systems (9-10 Passages + 15 FSQ)

59 95 minutes


Psychological, Social, and Biological Foundations of Behavior (9-10 Passages + 15 FSQ)

59 95 minutes

Void Question 5 minutes

Satisfaction Survey (Optional) 5 minutes



Total Appointment Time (includes check-in)

7 hours, 45 minutes

MCAT2015

MCAT Today vs. MCAT2015

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TEST SECTION MCAT Today MCAT2015

Total Content Time 4 hours, 5 minutes 6 hours, 15 minutes

Total “Seated Time” 5 hours, 10 minutes 7 hours, 30 minutes

Sections • Physical Sciences

• Verbal Reasoning

• Biological Sciences

• Optional Trial Section (ends Oct 2014)

• Chemical and Physical Foundations of Biological Systems

• Critical Analysis and Reasoning Skills

• Biological and Biochemical Foundations of Living Systems

• Psychological, Social, and Biological Foundations of Behavior

Section Structure • Science Sections (70 minutes)7 Passages + 13 FSQ

• Verbal Section (60 minutes)7 Passages

• Trial Section (45 minutes)

• Science Sections (95 minutes)9-10 Passages + 15 FSQ

• CARS Section (90 minutes)9 Passages

Number of Questions 144 multiple choice(176 including optional Trial Section)

230 multiple choice

Scoring 1-15 Section Score x34-60 Composite Score% Correct on optional Trial Section

118-132 Section Score x4472-528 Composite Score

MCAT2015

Take the MCAT

Spring 2015

Apply toMedical School

Ideally June 2015 (as late as September 2015

Attend Medical School

Fall 2016

Final Chance for the MCAT

Summer 2015

17Which test is for you?

Learn about the Test Changes

Take a Psych & Soc course as

electives, if you have time

CLASS OF 2016

The Changes to the MCAT WILL Impact You

Some flex roomsince there area few current MCATofferings in Jan 2015

Take the MCAT

Spring 2016

Apply toMedical School

Ideally June 2016 (as late as September 2016

Attend Medical School

Fall 2017

Final Chance for the MCAT

Summer 2016

CLASS OF 2017

The Changes to the MCAT WILL Impact You

18Which test is for you?



electives



electives

Pulmonary respiration involves the transfer of gas across the

alveolar septum into the alveolar capillaries. The steps in

respiration include ventilation (moving gas into alveoli), diffusion of

gas through the alveolar septum, and transportation of the gas

within the blood. This process is used to maintain the partial

pressures of oxygen and carbon dioxide at values approximating

those in Table 1. The partial pressure of water in the alveoli is a

function of body temperature, and therefore it essentially remains

constant.

Ventilation of the alveoli results from the contraction of inspiration

muscles, including the diaphragm and intercostal muscles, which

increases the volume of the thoracic cage. The lungs expand due

to the negative pressure within the pleural cavity, the potential

space between the surface of the lung and thoracic wall. Once air

reaches the alveoli, it diffuses into the blood.

Chemical and Physical Foundations of Biological Systems The rate of diffusion (gas) depends on surface area (), partial

pressure gradient (∆), alveolar septum thickness (), gas solubility

in blood (), and gas molecular weight () according to Equation I.

Gases diffuse across the alveolar septum according to their partial

pressure gradient. A gas will continue to diffuse until the partial

pressure is equal in the alveoli and the capillary blood. The amount

of gas. such as oxygen, that is absorbed into the blood depends

on both ventilation of the alveoli and perfusion of the lungs.

Normally, oxygen diffuses fast enough that absorption is perfusion

limited In an abnormal lung, the diffusion of oxygen can be

significantly slower. During exercise, the amount of time red blood

cells spend in the capillary is significantly decreased, which can

affect blood oxygen saturation.

Sample Questions 19

Equation 1 Rate of diffusion of a gas across the alveolar septum

Chemical and Physical Foundations of Biological Systems Carbon monoxide is freely permeable across the

alveolar septum, and is used to measure the diffusion capacity of lungs (DL) since the partial pressure does

not significantly increase within the blood. The diffusion capacity takes into account the surface area and thickness of the alveoli as well as the solubility and molecular weight of the gas. A single breath of a mixture of gases with a known partial pressure of carbon monoxide is inspired and held for 10 seconds. The partial pressure of carbon monoxide is then measured in the expired air, and the difference in partial pressures is used to measure the diffusion capacity of the lungs according to Equation 2. At rest, the diffusion capacity is normally 25 mL/min mm Hg

𝐷𝐿=𝑣𝑐𝑜

∆𝑃Equation 2

20Sample Questions


1. Which of the following statements about carbon monoxide movement in the lungs is most accurate?

A. The movement of carbon monoxide across the alveolar septum is diffusion limited, and depends on the amount

of blood flow through the lungs.

B. The movement of carbon monoxide across the alveolar septum is diffusion limited, and is independent of the amount of blood flow through the lungs.

C. The movement of carbon monoxide across the alveolar septum is perfusion limited, and depends on the amount of blood flow though the lungs.

D. The movement of carbon monoxide across the alveolar septum is perfusion limited, and is independent of the blood flow through the lungs.

21Sample Questions


1. Which of the following statements about carbon monoxide movement in the lungs is most accurate?

A. The movement of carbon monoxide across the alveolar septum is diffusion limited, and depends on the amount

of blood flow through the lungs.

B. The movement of carbon monoxide across the alveolar septum is diffusion limited, and is independent of the amount of blood flow through the lungs.

C. The movement of carbon monoxide across the alveolar septum is perfusion limited, and depends on the amount of blood flow though the lungs.

D. The movement of carbon monoxide across the alveolar septum is perfusion limited, and is independent of the blood flow through the lungs.

B. A gas which is diffusion limited has an essentially constant partial pressure gradient despite changes in capillary blood flow. In this case, the transfer of gas into the blood depends only on how fast it crosses the alveolar septum. When a gas is perfusion limited, the partial pressure in the blood quickly rises to equal that within the alveoli, and the partial pressure gradient is lost. In that case, gas transfer depends only on how fast the blood moves through the capillary because it is essentially always saturated. These facts eliminate choices B and C. From Figure 1, the partial pressure of carbon monoxide does not rise significantly within the blood. The passage of CO into the blood depends strictly on how easily it diffuses across the septum and not by the amount of blood flowing through the pulmonary capillaries. Therefore, choice A is eliminated and choice B is correct.

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Sample Questions


2. Which of the following changes would increase the diffusion of a gas by the greatest amount?

A. Double the solubility, double the alveolar thickness, and quarter the molecular weight

B. Halve the solubility, double the surface area, and increase the molecular weight by a factor of four

C. Double the solubility, double the surface area, and double the molecular weight

D. Double the alveolar thickness, half the molecular weight, and half the solubility

23Sample Questions


2. Which of the following changes would increase the diffusion of a gas by the greatest amount?

A. Double the solubility, double the alveolar thickness, and quarter the molecular weight

B. Halve the solubility, double the surface area, and increase the molecular weight by a factor of four

C. Double the solubility, double the surface area, and double the molecular weight

D. Double the alveolar thickness, half the molecular weight, and half the solubility

C. This is a proportions question requiring equation 1.

For choice A: For Choice B:

For choice C:

For choice D:

Therefore, choices B and D will decrease the v and choice C will increase it the most.

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Sample Questions

Chemical and Physical Foundations of Biological Systems 3. The correct order of steps involved in pulmonary ventilation is:

A. contraction of inspiration muscles, decreased pressure in pleural space, increased lung volume, and ventilation of alveoli.

B. contraction of inspiration muscles, decreased pressure in the pleural space, ventilation of alveoli, and increased lung volume.

C. increased lung volume, contraction of inspiration muscles, decreased pressure in the pleural space, and ventilation of alveoli.

D. contraction of inspiration muscles, increased lung volume, decreased pressure in pleural space, and ventilation of alveoli.

25Sample Questions

Chemical and Physical Foundations of Biological Systems 3. The correct order of steps involved in pulmonary ventilation is:

A. contraction of inspiration muscles, decreased pressure in pleural space, increased lung volume, and ventilation of alveoli.

B. contraction of inspiration muscles, decreased pressure in the pleural space, ventilation of alveoli, and increased lung volume.

C. increased lung volume, contraction of inspiration muscles, decreased pressure in the pleural space, and ventilation of alveoli.

D. contraction of inspiration muscles, increased lung volume, decreased pressure in pleural space, and ventilation of alveoli.

A. The passage states that ventilation results from contraction of inspiration muscles, making contraction the likely first step and eliminating choice C. When the thoracic cage is expanded. it simultaneously increases the volume and decreases the pressure of the pleural potential space. This eliminates choice D. The negative pressure within the pleural space causes lung volume to increase. As lung volume increases, lung pressure decreases and air rushes into the lung. Therefore, choice B can be eliminated, and choice A is correct.

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Sample Questions


NOTE: THIS IS A FREESTANDING QUESTION

2. Perspiration is important in maintaining normal body temperature. Compared to water at its boiling point, which of the following is true about water at normal human body temperature?

A. More energy is required for gas expansion.

B. Average kinetic energy is greater.

C. Intermolecular forces are weaker.

D. The heat required to vaporize is higher.

27Sample Questions



2. Perspiration is important in maintaining normal body temperature. Compared to water at its boiling point, which of the following is true about water at normal human body temperature?

A. More energy is required for gas expansion.

B. Average kinetic energy is greater.

C. Intermolecular forces are weaker.

D. The heat required to vaporize is higher.

D. As water on the skin vaporizes it absorbs energy and cools the body. Temperature is a measure of average kinetic energy, so water has less average kinetic energy at 37°C compared to 100°C (eliminate B). Since it has less kinetic energy, the molecules interact with each other with stronger intermolecular forces (eliminate C). As temperature increases, water requires more and more energy to expand the volume of its gaseous phase (eliminate A). Although choice A might not be obvious to eliminate, choice D is a better answer. Water is much more likely to vaporize at its boiling point than at body temperature. It takes additional energy to go from the liquid to gas phase at lower temperatures. Therefore the heat required to vaporize is higher at lower temperatures.

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Sample Questions



1. The area of a human aorta (aorta) is 5 cm2, with flow speed equal to 20 cm/s. The flow speed of blood through a human capillary is 0.04 cm/s. with an area (cap) of 2.5 x 10-7

cm2. Assuming that the aorta and the capillaries are in direct continuity with each other, and the capillaries are parallel to each other, how many capillaries are there in the human body?

A. 0.1 billion

B. 1 billion

C. 10 billion

D. 100 billion

Sample Qs 29Sample Questions



1. The area of a human aorta (aorta) is 5 cm2, with flow speed equal to 20 cm/s. The flow speed of blood through a human capillary is 0.04 cm/s. with an area (cap) of 2.5 x 10-7

cm2. Assuming that the aorta and the capillaries are in direct continuity with each other, and the capillaries are parallel to each other, how many capillaries are there in the human body?

A. 0.1 billion

B. 1 billion

C. 10 billion

D. 100 billion

C. First we must calculate the flow rate through the aorta. To calculate flow rate, we use faorta = Aaorta × Vaorta = 5 × 20 =

100 cm3/s. Since the aorta and the capillaries are in continuity with each other (or in series), and the capillaries are in parallel to each other, then by the continuity equation, faorta = fcap = 100 cm3/s. Since the flow speed through the capillary is known, then the total area of the capillaries can be calculated. fcap = AcapTotal × Vcap, therefore 100 = AcapTotal × 0.04, thus AcapTotal = 2500 cm2. If we divide total area of the capillaries by the area of an individual capillary, we can get the number of capillaries in the human body. AcapTotal / Acap = 2500/(2.5 x 10-7) = 1010= 10 x 109= 10 billion.

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Sample Questions

Critical Analysis and Reasoning

Passage V (Questions 24-30)

The question is often asked how individuals, having no right to dispose of their own lives, can transfer to the Sovereign a right which they do not possess. The difficulty of answering this question seems to me to lie in its being wrongly stated. Every man has a right to risk his own life in order to preserve it. Has it ever been said that a man who throws himself out of the window to escape from a fire is guilty of suicide? Has such a crime ever been laid to the charge of him who perishes in a storm because, when he went on board, he knew of the danger?

The social treaty has for its end the preservation of the contracting parties. He who wills the end wills the means also, and the means must involve some risks, and even some losses. He who wishes to preserve his life at others' expense should also, when it is necessary, be ready to give it up for their sake. Furthermore, the citizen is no longer the judge of the dangers to which the law desires him to expose himself; and when the prince says to him: ‘It is expedient for the State that you should die; he ought to die, because it is only on that condition that he has been living in security up to the present, and because his life is no longer a mere bounty of nature, but a gift made conditionally by the State.

The death-penalty inflicted upon criminals may be looked on in much the same light: it is in order that we may not fall victims to an assassin that we consent to die if we ourselves turn assassins. In this treaty, so far from disposing of our own lives, we think only of securing them, and it is not to be assumed that any of the parties then expects to get hanged.

Again, every malefactor, by attacking social rights,

becomes on forfeit a rebel and a traitor to his country; by violating its laws he ceases to be a member of it: he even makes war upon it. In such a case the preservation of the State is inconsistent with his own, and one or the other must perish; in putting the guilty to death, we slay not so much the citizen as an enemy. The trial and the judgment are the proofs that he has broken the social treaty, and is in consequence no longer a member of the State. Since, then, he has recognized himself to be such by living there, he must he removed by exile as a violator of the compact, or by death as a public enemy; for such an enemy is not a moral person, but merely a man; and in such a case the right of war is to kill the vanquished....

31Sample Questions


Passage continued …

…We may add that frequent punishments are always a sign of weakness or remission on the part of the government. There is not a single ill-doer who could not be turned to some good. The State has no right to put to death, even for the sake of making an example, any one whom it can leave alive without danger.

The right of pardoning or exempting the guilty from a penalty imposed by the law and pronounced by the judge belongs only to the authority which is superior to both judge and law. i.e.. the Sovereign; even its right in this matter is far from clear, and the cases for exercising it are extremely rare. In a well-governed State there are few punishments, not because there are many pardons. but because criminals are rare: it is when a State is in decay that the multitude of crimes is a guarantee of impunity. Under the Roman Republic, neither the senate nor the consuls ever attempted to pardon; even the people never did so, though it sometimes revoked its own decision. Frequent pardons mean that crime will soon need them no longer, and no one can help seeing wither that leads.

But I feel my heart protesting and restraining my pen; let us leave these questions to the just man who has never offended, and has never himself stood in need of pardon.

Adapted from J.J. Rousseau, The Social Contract. ©1762

32Sample Questions


28. In the fourth paragraph, Rousseau employs the metaphor of war to achieve which of the following?

A. A comparison between putting a criminal offender to death and killing a vanquished enemy

B. A contrast between a rebel and a traitor to one's country

C. A contrast between the peaceful ideal of the State and the violent reality of the State

D. A contrast between putting a criminal offender to death and killing a vanquished enemy

NOTE: THIS IS A STRUCTURE QUESTION

33Sample Questions


28. In the fourth paragraph, Rousseau employs the metaphor of war to achieve which of the following?

A. A comparison between putting a criminal offender to death and killing a vanquished enemy

B. A contrast between a rebel and a traitor to one's country

C. A contrast between the peaceful ideal of the State and the violent reality of the State

D. A contrast between putting a criminal offender to death and killing a vanquished enemy

A. Yes. See fourth paragraph.

B. No. The contrast is not between a rebel and a traitor, but between someone loyal and a rebel or traitor.

C. No. Rousseau speaks of war in the fourth paragraph.

D. No. See fourth paragraph. These two things are similar; no contrast is drawn.

NOTE: THIS IS A STRUCTURE QUESTION

34

Sample Questions


29. As it is used in the passage, the term "Sovereign" refers to: A. the State.

B. a superior judge.

C. a higher being.

D. a King.

NOTE: THIS IS A VOCABULARY-IN-CONTEXT QUESTION

35Sample Questions


29. As it is used in the passage, the term "Sovereign" refers to: A. the State.

B. a superior judge.

C. a higher being.

D. a King.

A. Yes. In the sixth paragraph, the State is personified; this paragraph shows that "the Sovereign" is a thing rather than a person by the use of the pronoun "its."

B. No. See paragraph 6. The Sovereign is superior to the judge.

C: No. There is no indication that the State is run by a deity.

D: No. This is a trap based on the common use of the word; paragraph 6 clearly refers to “the Sovereign" as a nonhuman entity.

NOTE: THIS IS A VOCABULARY-IN-CONTEXT QUESTION

36

Sample Questions


30. Based on information in the passage, which one of the following opinions could most reasonably be ascribed to the author?

A. The rights of the individual are more important than the rights of the State.

B. All malefactors have a right to rehabilitation at the State's expense.

C. Rousseau does not feel he is qualified to judge the actions of others.

D. Individual rights are always protected by the State.

NOTE: THIS IS AN INFERENCE QUESTION

37Sample Questions


30. Based on information in the passage, which one of the following opinions could most reasonably be ascribed to the author?

A. The rights of the individual are more important than the rights of the State.

B. All malefactors have a right to rehabilitation at the State's expense.

C. Rousseau does not feel he is qualified to judge the actions of others.

D. Individual rights are always protected by the State.

C. A: No. This contradicts Rousseau's position.

B: No. This extreme position is not supported by the passage.

C: Yes. See seventh paragraph.

D: No. See fourth paragraph. "Social rights" are protected, not all individual rights.

NOTE: THIS IS AN INFERENCE QUESTION

38

Sample Questions

Secreted IL-1 increases the expression of adhesion factors on

endothelial cells, allowing white blood cells to move into potentially

infected tissues. IL-1 also induces fever by initiating signal

transduction in the hypothalamus. Researchers investigating the

role of NALP1 conducted experiments using Langerhans cells.

These cells were isolated from epidermal skin tissue taken from

vitiligo patients, as well as from patients with two wild type NALP1

alleles.

Experiment 1:

Langerhans cells from 10 vitiligo patients and 10 controls were lysed and

the cytoplasmic contents were collected. NALP1 cytoplasmic protein

levels were quantified and averaged among patient and control samples

(Table 1).

Experiment 2:

Mass spectrometry was performed on NALP1 isolated from vitiligo

patients and control individuals. Upon comparison of the two proteins, it

was found that both populations express an NALP1 protein that is the

same length.


Vitiligo is a chronic dermatologic disorder that results in irregular

depigmentation of the skin. especially on the face, hands, and

wrists. Vitiligo results from the death or dysfunction of the

melanocytes, derived from neural crest cells. While the precise

cause of vitiligo is unknown, the disease has been linked to

autoimmune, environmental, and genetic causes, especially

hyperthyroidism.

Studies among patients with vitiligo have linked the condition

with several mutations and variations in the NALP1 gene, which

codes for a cytosolic signaling protein. NALP1 has four splice

variants in humans and is expressed in several tissues, such as

the heart, thymus, spleen, kidney, liver, lungs, and peripheral blood

lymphocytes. NALP1 has several cellular functions. For example, it

is involved in the regulation of programmed cell death (apoptosis)

of T lymphocytes and Langerhans cells (macrophage-like white

blood cells found in skin tissue). More recently, mounting evidence

supports a crucial role of NALP1 in inflammation. In this context.

NALP1 increases the levels of active caspase I and caspase 5 in

response to pathogenic proteins. These three proteins (NALP1,

caspase 1, and caspase 5) form a large complex known as the

inflammasome.

The inflammasome can activate apoptotic pathways, and

cleaves pro-interleukin-I. Active interleukin-I (1L-1) is secreted

from the cell and functions as an inflammatory cytokine.

Biochemical analysis is still being performed on IL-1 to determine if

this protein undergoes any additional post-translational

modification; there is some evidence that it may be

phosphorylated. 39Sample Questions

Biological and Biochemical Foundations of Living Systems 3. According to the passage, how is the activity of interleukin-1 regulated? A. IL-1 is intracellularly phosphorylated by a phosphatase.

B. IL-1 is allosterically inhibited by caspase 1 and caspase 5.

C. IL-1 is translated on the RER and is secreted via vesicular transport.

D. IL-1 is synthesized as a zymogen.

40Sample Questions

Biological and Biochemical Foundations of Living Systems 3. According to the passage, how is the activity of interleukin-1 regulated? A. IL-1 is intracellularly phosphorylated by a phosphatase.

B. IL-1 is allosterically inhibited by caspase 1 and caspase 5.

C. IL-1 is translated on the RER and is secreted via vesicular transport.

D. IL-1 is synthesized as a zymogen.

D. According to the passage, pro-IL-1 is produced, and then cleaved and activated by the inflammasome. The initial inactive form of a protein is also known as a zymogen (choice D is correct). IL-1may be phosphorylated, but this would be done by a kinase or phosphorylase; phosphatase enzymes remove phosphate groups (choice A is wrong). Caspases 1 and 5 activate, rather than inhibit, interleukin-1, and there is no information in the passage to support the statement that caspases I and 5 interact allosterically with IL-1 (choice B is wrong). Finally, if NALP1 is cytosolic, it is likely that the inflammasome is also cytosolic, and must act intracellularly to activate pro-IL- 1. Active IL-1 is secreted from the cell via an uncharacterized mechanism after processing by the inflammasome. There is no information to support protein trafficking of IL-1 through the RER/Golgi/vesicle pathway (choice C is wrong).

41

Sample Questions

Biological and Biochemical Foundations of Living Systems 5. A scientist hypothesizes that the NALP1 mutation common in vitiligo may lead to death

of melanocytes. Which of the following is one mechanism by which this may occur? A. Overexpression of NALP1 leads to lower levels of IL-1, which increase movement of T lymphocytes into tissues,

leading to increased levels of T cell mediated melanocyte death.

B. Overexpression of NALP1 leads to higher levels of IL-1, which increase movement of T lymphocytes into tissues, leading to increased levels of T cell mediated melanocyte death.

C. Underexpression of NALP1 leads to higher levels of IL-1, which increase movement of T lymphocytes into tissues, leading to increased levels of T cell mediated melanocyte death.

D. Underexpression of NALP1 leads to lower levels of IL-1, which decrease movement of T lymphocytes into tissues, leading to decreased levels of T cell mediated melanocyte death.

42Sample Questions

Biological and Biochemical Foundations of Living Systems 5. A scientist hypothesizes that the NALP1 mutation common in vitiligo may lead to death

of melanocytes. Which of the following is one mechanism by which this may occur? A. Overexpression of NALP1 leads to lower levels of IL-1, which increase movement of T lymphocytes into tissues,

leading to increased levels of T cell mediated melanocyte death.

B. Overexpression of NALP1 leads to higher levels of IL-1, which increase movement of T lymphocytes into tissues, leading to increased levels of T cell mediated melanocyte death.

C. Underexpression of NALP1 leads to higher levels of IL-1, which increase movement of T lymphocytes into tissues, leading to increased levels of T cell mediated melanocyte death.

D. Underexpression of NALP1 leads to lower levels of IL-1, which decrease movement of T lymphocytes into tissues, leading to decreased levels of T cell mediated melanocyte death.

B. Table I and Experiment 2 indicate that the NALP1 mutation produces a protein of normal length, but in increased amounts (choices C and D can be eliminated). NALP1 overexpression could lead to increased melanocyte death via the NALP1-mediated pathway described in the passage; increased NALP1 would lead to increased active IL-1 (choice B is correct and choice A is wrong), which would enhance the movement of T lymphocytes into tissues. This could allow the T cells access to melanocytes, and T cells that recognize melanocyte-specific proteins could then kill these cells, leading to the symptoms of vitiligo (choice B is correct).

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Sample Questions


6. Additional experiments were conducted on the genomic DNA isolated from Langerhans cells from the 10 vitiligo patients in the passage. Researchers found that each patient had the same genomic mutation. Given the results in Table 1 and Experiment 2, which of the following could be true of this mutation?

I. The mutation is a nonsense mutation in the NALP1 gene. II. The mutation is in the promoter region of the NALP1 gene. Ill. The mutation resulting in the NALP1 phenotype could be in

the gene for another protein.

A. II only

B. III only

C. I and III

D. II and III

44Sample Questions


6. Additional experiments were conducted on the genomic DNA isolated from Langerhans cells from the 10 vitiligo patients in the passage. Researchers found that each patient had the same genomic mutation. Given the results in Table 1 and Experiment 2, which of the following could be true of this mutation?

I. The mutation is a nonsense mutation in the NALP1 gene. II. The mutation is in the promoter region of the NALP1 gene. Ill. The mutation resulting in the NALP1 phenotype could be in

the gene for another protein.

A. II only

B. III only

C. I and III

D. II and III

D. According to the results in Table 1 and Experiment 2, the vitiligo patients have an NALP1 protein that is the normal length, but in increased amounts. Thus, the NALP1 mutation likely affects the regulation of NALP1 expression, rather than the structure of the NALP1 protein itself. Item I is false: a nonsense mutation introduces a premature stop codon and would result in a shortened NALP1 protein (choice C can be eliminated). Item II is true: a mutation in the promoter region for the NALP1 gene could result in e gene expression. For example, the mutant promoter could attract RNA polymerase II with greater ease, leading to increased NALP1 expression (choice B can be eliminated). Item III is true: other proteins, such as transcription factors or repressors, can affect gene expression. A mutation in a protein that regulates NALP1 transcription could result in overexpression of the NALP1 protein (choice A can be eliminated and choice D is correct).

45

Sample Questions



48. Chloramphenicol is an antibiotic with an extremely lipid-soluble molecular structure. It binds to the large subunit of 70S ribosomes and prevents peptidyl transferase activity. Chloramphenicol is effective against almost all bacteria; however, it is considerably toxic to humans. This is most likely because chloramphenicol:

A. is able to diffuse into the mitochondria and affect mitochondrial protein synthesis.

B. is able to diffuse into the nucleus and block transcription of rRNA.

C. affects both human and bacterial ribosomes.

D. disrupts the cell membrane.

46Sample Questions



48. Chloramphenicol is an antibiotic with an extremely lipid-soluble molecular structure. It binds to the large subunit of 70S ribosomes and prevents peptidyl transferase activity. Chloramphenicol is effective against almost all bacteria; however, it is considerably toxic to humans. This is most likely because chloramphenicol:

A. is able to diffuse into the mitochondria and affect mitochondrial protein synthesis.

B. is able to diffuse into the nucleus and block transcription of rRNA.

C. affects both human and bacterial ribosomes.

D. disrupts the cell membrane.

A. Mitochondria have DNA and transcribe and translate a few proteins independently. The mitochondrial system is almost identical to that of the prokaryotes (this is where the theory that mitochondria are ancient bacterial parasites that live symbiotically within eukaryotes comes from). Chloramphenicol is able to diffuse into mitochondria in concentrations high enough to disrupt mitochondrial protein synthesis, ultimately causing the death of the eukaryotic cell. Human (eukaryotic) ribosomes are 80S ribosomes, so they would not be affected by a drug that inhibits 70S ribosomes (C is wrong), and there is no information given to suggest that they disrupt cell membranes or block transcription (B and D are wrong).

47

Sample Questions



15. Lysine exists as a zwitterion at pH 9.8. Which of the following moieties would most likely be found on its side chain at physiologic pH (approximately 7.4)?

A. An unprotonated amino group

B. A protonated amino group

C. A sulfur group

D. An ester group

48Sample Questions



15. Lysine exists as a zwitterion at pH 9.8. Which of the following moieties would most likely be found on its side chain at physiologic pH (approximately 7.4)?

A. An unprotonated amino group

B. A protonated amino group

C. A sulfur group

D. An ester group

B. The side chain on lysine is -CH2CH2CH2CH2NH2. Under acidic conditions, it would be protonated.

49

Sample Questions


Guided meditation and deep-breathing exercises have long been used as effective techniques for stress reduction. The mechanism of action for this non-pharmacologic intervention is not entirely known but scientists believe that the act of focusing ones thoughts and deep belly-breathing both serve to somehow inhibit the stress response activated by the hypothalamic-pituitary-adrenal axis. Practitioners of meditation are capable of reducing their heart and respiration rates seemingly on command.

Irritable Bowel Syndrome or IBS is a disorder that causes a range of abdominal discomfort and bowel irregularities, but unlike bowel diseases with similar symptoms, there are no physical abnormalities; rather, the disorder appears to be the physical manifestation of psychological triggers. For example, IBS is often comorbid with anxiety disorders or episodes of extreme stress. Acute anxiety and stress are known triggers for IBS symptoms, which usually include severe abdominal cramping, bloating, gassiness, constipation and/or diarrhea (sometimes sufferers experience one or the other more frequently, and a minority of sufferers experience both in an alternating pattern). IBS symptoms usually begin during late teen or early adult years, and a majority of sufferers are women.

The current standard non-pharmacologic treatment for IBS is cognitive behavior therapy (CBT). CBT treats IBS sufferers by treating the emotional and psychological triggers that cause physical symptoms. A trained therapist uses a structured, goal-oriented plan to identify thought patterns and behaviors that trigger IBS symptoms, and provides patients with very specific tools for recognizing these, and implementing techniques to replace these negative thoughts and behaviors with more positive ones.

In an attempt to determine if meditation is as beneficial as CBT for treating IBS, a recent six-month study was conducted on female IBS sufferers. Eligible participants had active IBS symptoms for at least three months during the past year. Participants with and without a diagnosed anxiety disorder were recruited to participate in this study. Subjects were randomly assigned to one of three groups: a CBT group, a guided-meditation group, and a no-treatment group. Approximately 65% of the participants had an anxiety disorder, and these subjects were roughly equally represented in each of the three groups. The results of this study, measured by percent reduction of IBS symptoms after treatment, are summarized in Figure 1.

50Sample Questions


1. Based on the results of this study, what can be most reasonably concluded about the efficacy of CBT for IBS sufferers who do not have an anxiety disorder?

A. CBT is more effective than no treatment and more effective than meditation.

B. CBT and meditation combined provide the most effective treatment possible.

C. CBT is not as effective as meditation.

D. CBT is equally effective for IBS sufferers with and without anxiety disorders.

51Sample Questions


1. Based on the results of this study, what can be most reasonably concluded about the efficacy of CBT for IBS sufferers who do not have an anxiety disorder?

A. CBT is more effective than no treatment and more effective than meditation.

B. CBT and meditation combined provide the most effective treatment possible.

C. CBT is not as effective as meditation.

D. CBT is equally effective for IBS sufferers with and without anxiety disorders.

C. According to Figure 1, CBT, appears to be far less effective than meditation at reducing IBS symptoms for participants without an anxiety disorder (choice C is correct and choice A is wrong). It is also far less effective for participants without an anxiety disorder than it is for participants with an anxiety disorder (choice D is wrong). CBT and meditation were not tested in combination (choice B can be eliminated).

52

Sample Questions


3. The average individual diagnosed with IBS is a 40-50 year old female who is white, educated, married, and middle to upper-middle class. Based on this information, what might you conclude about IBS?

A. IBS is underdiagnosed in less-affluent populations.

B. IBS rarely affects younger men and women

C. There is a causal relationship between education status and IBS.

D. Age, gender, race, and marital status should all be viewed as risk factors for developing IBS.

53Sample Questions


3. The average individual diagnosed with IBS is a 40-50 year old female who is white, educated, married, and middle to upper-middle class. Based on this information, what might you conclude about IBS?

A. IBS is underdiagnosed in less-affluent populations.

B. IBS rarely affects younger men and women

C. There is a causal relationship between education status and IBS.

D. Age, gender, race, and marital status should all be viewed as risk factors for developing IBS.

A. Since the passage states at the end of the second paragraph that "IBS symptoms usually begin during late teen or early adult years" choice B is wrong, and we might conclude that these individuals are not being diagnosed because they are less-affluent, and have perhaps less access to medical care (choice A is correct). In fact, many psychiatric illness and disorders are underdiagnosed in less affluent populations. Based solely on the information provided, you cannot conclude that there is a causal relationship between the listed factors and IBS (choice C is wrong), nor can you assume that any of these factors increase one's risk for developing IBS (choice D is wrong). Correlation does not imply or prove causation.

54

Sample Questions


4. Given the description of the study in this passage, which unknown factor might have the most influence on the validity of the results?

A. Sample size

B. Duration of IBS symptoms before entering the study

C. Participants' previous exposure to medication to treat IBS symptoms

D. Length of the treatment protocols

55Sample Questions


4. Given the description of the study in this passage, which unknown factor might have the most influence on the validity of the results?

A. Sample size

B. Duration of IBS symptoms before entering the study

C. Participants' previous exposure to medication to treat IBS symptoms

D. Length of the treatment protocols

A. In statistics, validity refers to the whether results of a given study are able to answer the question being posed by that study. In the case of this study, the question is whether meditation is as effective as the current standard therapy (CBT), at reducing IBS symptoms for participants with and without an anxiety disorder. Based on the description provided in the passage, we do not know all of the specifics about this study, though we do know that the study duration is six months (choice D is wrong). While we do not know the overall duration of IBS symptoms for participants, we do know that participants must have had active IBS for at least three months in the past year (choice B is wrong). Prior exposure to medication to treat IBS symptoms is of unknown importance, but the sample size of this study is definitely not known, and the results cannot prove that meditation is as effective as CBT without an appropriately large sample size (choice A is better than choice C).

56

Sample Questions

Psychological, Social, and Biological Foundations of Behavior 7. How might Sigmund Freud have treated an IBS sufferer?

A. By helping the patient discover the physical cause of their symptoms through various stress tests

B. With a psychoanalytic approach that would attempt to pinpoint the root of the disorder in a sufferer's unconscious

C. In a group therapy session with sufferers of other psychological disorders

D. Dr. Freud would be unlikely to treat an IBS sufferer, because he would not consider their disorder to have a psychological cause

57Sample Questions

Psychological, Social, and Biological Foundations of Behavior 7. How might Sigmund Freud have treated an IBS sufferer?

A. By helping the patient discover the physical cause of their symptoms through various stress tests

B. With a psychoanalytic approach that would attempt to pinpoint the root of the disorder in a sufferer's unconscious

C. In a group therapy session with sufferers of other psychological disorders

D. Dr. Freud would be unlikely to treat an IBS sufferer, because he would not consider their disorder to have a psychological cause

B. Sigmund Freud founded psychoanalysis, a major premise of which is that the unconscious is responsible for most (if not all) psychological disorders; additionally the passage states that the disorder is a physical manifestation of psychological triggers (choice B is correct). Freud believed that just about every ailment had some root in the psyche (choice D is wrong), and used a variety of treatment techniques, including free-association and hypnosis; however, Freud is not known for utilizing group therapy (choice C is wrong) or stress tests (choice A is wrong).

58

Sample Questions

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