If you have a cycloalkane or cycloalkene with 2 substituents, so either way you number gives the same low numbers, how do you decide which gets the lowest number in the nomenclature? for example, what if a chlorine and methyl are 1 carbon apart?
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Assuming equal priority for all the substituents, you want the lowest number to be on the substituent that would come first alphabetically. Thus, a cyclohexane with a chlorine and methyl group one carbon apart would be 1-chloro-2-methylcyclohexane.
However, if there is a group with higher priority (say there was an alcohol on that same cyclohexane), that should ALWAYS be given the lowest possible number.
Tuesday, December 28, 2010
Tuesday, December 21, 2010
Bio III Questions
1) How does diffusion (e.g. through a cell membrane) compare to what occurs at the glomerulus (why can glucose easily pass through even though particle is charged)? Can urea passively pass through by diffusion for both a cell membrane and the glomerulus? Is filtration purely based on charge?
Diffusion will only allow the passage of small, nonpolar, uncharged molecules (besides water) through the cell membrane. Filtration in the kidney, however, allows through those particles PLUS some biomolecules (amino acids, glucose, vitamins being the noteworthy ones), a number of ions (Na+ and Cl- being the main ones), and some other waste products. This is because the glomerulus has much larger pores, which permit through these larger molecules. Urea requires a carrier protein, but no energy, to pass through a cell membrane as well as the collecting duct and ascending loop of Henle. It doesn't really show up significantly in the glomerulus. And filtration isn't based on charge at all; it's based on size.
Diffusion will only allow the passage of small, nonpolar, uncharged molecules (besides water) through the cell membrane. Filtration in the kidney, however, allows through those particles PLUS some biomolecules (amino acids, glucose, vitamins being the noteworthy ones), a number of ions (Na+ and Cl- being the main ones), and some other waste products. This is because the glomerulus has much larger pores, which permit through these larger molecules. Urea requires a carrier protein, but no energy, to pass through a cell membrane as well as the collecting duct and ascending loop of Henle. It doesn't really show up significantly in the glomerulus. And filtration isn't based on charge at all; it's based on size.
Let's think about this numerically. Let's say you're standing in air with 50 mmHg of oxygen (half the normal amount). Let's say that there's no shift. Well, looking at the curve, you'll have about 80% saturation. Then, in the muscles (around 20 mmHg), you'll have about 20% saturation. So, in the lungs, the blood is carrying 50 mmHg * 80% = 40 mmHg of oxygen. Then, in the muscles, the blood is carrying 20 mmHg * 20% = 4 mmHg. How much went into the muscles? Well, the difference: 40 mmHg - 4 mmHg = 36 mmHg.
With the shift, let's say we accomplish 100% saturation at the 50 mmHg of oxygen, and have 30% saturation in the muscles. We then have 50 mmHg * 100% = 50 mmHg in the lungs, and 20 mmHg * 30% = 6 mmHg on the blood in the muscles. Thus, we've given the difference of 50 mmHg - 6 mmHg = 44 mmHg to the muscles. This may not seem like a huge difference to the muscles, but it's still an improvement!
The "sense" strand is the strand of DNA NOT paired with mRNA during transcription (although, because of base-pairing, it will have the identical sequence of nucleotides to the mRNA but with T switched for U). The "antisense" strand is the one base-pairing with the mRNA.
4) For differentiating amides and steroids, we stated in class the need for a carrier protein to carry steroids through the blood stream given its lipophilic character. When the steroid passes approaches the cell membrane is it released from the carrier, and the after enter the cell does it once again pick up another carrier since the cytosol/cytoplasm is polar environment? How are T3/T4 able to wiggle past through the cell membrane when both are amides and why do they not require a carrier protein if they have the ability to pass through the lipid membrane? Finally, typically, when referring to thyroid hormone, is T4 the prevalent form in the blood stream?
I have to admit that I'm not sure about the carriers inside the cell for steroid hormones; my guess would be that they exist, but I'm not sure.T3 and T4 are usually grouped as amino-acid derived hormones, which is true; however, since they're derived from tyrosine and each features two benzene rings and are quite small, they can get through the cell membrane. On the other hand, they do have a polar amide on one end and a number of iodine atoms, which help them dissolve in the aqueous environment of the blood. The generic term "thyroid hormone" would refer to both T3 and T4 as a group, not just one of them.
Monday, December 20, 2010
PS Test 2 - 32 and 39
I had trouble understanding the explanations for 39 and 32 on the Physical Science Section Test 2, because it seemed like they contradict each other, but I don't know if that's because 32 regards a galvanic cell and 39 is about an electrolytic cell? Anyway, I understood the explanation for 32 to be saying that the EMF would increase since more electrons are flowing and the reaction rate is increasing. But then the explanation for 39 says that doubling the rate at which electrons are produced will not affect the potential difference.
Thanks!
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Ultimately, these two questions boil down to thinking about voltage. You can think of voltage as how intense the draw is on each electron, sort of like a force. Voltage itselfisn't a force, but it's an analogy that helps explain these two questions.
In the case of question 32, when we increase the concentrations of our reactants, that means that we'll have our reactions at our cathodes and anodes happening more often, or at a faster rate. Thus, at any given time, we start building up even more attractive force for the electrons at our cathode, and even more repulsive force from our anode. That is, our anode gets more negatively-charged and our cathode more positively-charged at any given time, since the reaction is going quicker. This means that we've increased the "force" or voltage on our electrons.
In 39, however, we haven't actually changed the effect on any given electron. Yes, we have more flowing, but each one experiences the same pull it did as when we have the original current. With the same "pull" as before, we have the same voltage.
Thanks!
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Ultimately, these two questions boil down to thinking about voltage. You can think of voltage as how intense the draw is on each electron, sort of like a force. Voltage itselfisn't a force, but it's an analogy that helps explain these two questions.
In the case of question 32, when we increase the concentrations of our reactants, that means that we'll have our reactions at our cathodes and anodes happening more often, or at a faster rate. Thus, at any given time, we start building up even more attractive force for the electrons at our cathode, and even more repulsive force from our anode. That is, our anode gets more negatively-charged and our cathode more positively-charged at any given time, since the reaction is going quicker. This means that we've increased the "force" or voltage on our electrons.
In 39, however, we haven't actually changed the effect on any given electron. Yes, we have more flowing, but each one experiences the same pull it did as when we have the original current. With the same "pull" as before, we have the same voltage.
Density/Specific Gravity Question from AAMC #4
Hi Alex,
Sorry to bother you again-but this question from AMCAS MCAT # 4 is driving me insane and I think it's because I'm overthinking it. So, here goes:
18) An object with 15 grams mass is immersed in benzene and suffers an apparent loss of mass of 5 grams. What is the approximate specific gravity of the object? (Data: Specific gravity of benzene = 0.7)
a) 1.4
b) 1.8
c) 2.1
d) 3.0
The answer is (c).
Solution given: The buoyant foce on an object immersed in a fluid is equal to the weight of the fluid displaced by the object (Archimedes' principle). There were 5 g of liquid displaced; thus, the ratio of object mass to fluid mass is 15/5 = 3. The specific gravity of the object (mass per unit volume compared to water) is three times the specific gravity of benzene (3 x 0.7= 2.1) because the volumes of object and displaced liquid are equal.
Solution given: The buoyant foce on an object immersed in a fluid is equal to the weight of the fluid displaced by the object (Archimedes' principle). There were 5 g of liquid displaced; thus, the ratio of object mass to fluid mass is 15/5 = 3. The specific gravity of the object (mass per unit volume compared to water) is three times the specific gravity of benzene (3 x 0.7= 2.1) because the volumes of object and displaced liquid are equal.
*I don't understand why the ratio of the mass of the object to the mass of the liquid is 3. Where are they getting these numbers? Please explainnn :(
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When we approach this question, the first thing that should hopefully stick out is that we're dealing a bit with buoyancy. We put the object in a fluid and the weight changes; what is responsible for that change? The buoyant force, of course.
So let's think about what forces are acting on the object before it's in the fluid. We have a force of gravity equal to the mass of the object times the acceleration due to gravity. That's really the only one we're concerned about in that case.
When we put the object into the fluid, the new net force is less. The "apparent loss of mass" here is due to the buoyant force, and must be equal to five grams times the acceleration due to gravity (why? Because if the apparent mass is now 10 grams, then the apparent weight would be 10 times the acceleration due to gravity. We've lost 5 grams times the acceleration due to gravity, which is completely attributable to the buoyant force).
Remember that, by definition, the buoyant force is equal to the weight of the fluid that's been displaced. It is also equal to the density of the fluid times the acceleration due to gravity times the submerged volume of the fluid (in this question, since they use the word "immersed," we know the full volume has been submerged). We care about the volume here, because we can use that to calculate the density of the submerged object. If we know the submerged object's volume (which must be equal to the volume of displaced fluid, logically), and its mass (provided in the question stem), we can figure out its density and thus figure out its specific gravity.
Our calculations would look like this:
(rho of fluid)(g)(V)=(mass of fluid)(g)
Taking out g on both sides, we have:
(rho of fluid)(V)=(mass of fluid).
Note that this is basically just a reiteration of the density equation.
From there, let's plug in:
(0.7)(V)=5 grams
and V thus equals 5/0.7.
Taking that one step further, we can say that if the volume of the cube must also be 5/0.7, and its mass is 15 grams, then its density is 15/(5/0.7) = 3*0.7 = 2.1. That gets us to answer choice C.
Saturday, December 18, 2010
FL 5, PS 26
The explanation doesn't make sense to me. I'm confused about how the negative sign was removed. By my calculation, the final answer will be e to the negative 1.
But im guessing the real answer may have to do with the nature of e and logs. Is there a way you can explain that pls?
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This question reads: “What is the ratio of the intensity of an X-ray beam after it passes through 1 cm of plasma to the intensity of the beam after it passes through 6 cm of plasma? (Note: Plasma has an absorption coefficient of approximately 0.2 cm-1.”
The first thing we notice is that the answer choices all include e… we’ll need natural logs or equations with e in them. Do we know any? Probably not. But they give us an equation in the passage: I = I0e-μx, where I is the intensity after passing through the medium, I0 is the original intensity, μ is the absorption coefficient, and x is the distance traveled.
The ratio asks for I1 cm/16 cm. We should already have an idea that the intensity at 1 cm is higher than 6 cm (since it gets less intense as it passes through the medium). We’re already down to (C) and (D) then. Let’s do the math.
I1 cm = I0e-μ(1 cm)
I6 cm = I0e-μ(6 cm)
Plugging in, I1 cm/16 cm = I0e-(0.2)(1 cm)/ I0e-(0.2)(6 cm)
Let’s get rid of the constant I0 to make this easier…
e-0.2/e-1.2 = e-0.2 – (-1.2) = e1 = e.
So the ratio is e/1, or answer choice (C).
If you kept getting e-1, make sure that you noticed the negative sign before μ in the equation; that might have been what messed you up.
Tuesday, December 14, 2010
Re-Cap of MSCT III
Hey everyone!
We covered a lot of information in MSCT III ranging from assumptions and inferences to inclined planes to the medical school application process, but the purpose of this monster “re-cap” will be to focus on how to use the rest of your time before Test Day to prepare for your upcoming MCAT whether it be in a week or three months.
Because this is such a lengthy packet, here’s a little outline of what you’ll find contained inside:
I. Kaplan’s Higher Score Guarantee
II. Computer and KapTest Syllabus Issues
III. Some Helpful Hints
IV. How to Use Your Resources
V. FAQs: Kaplan v. AAMC and Scoring Section Tests
VI. How to Approach MCAT Topics
VII. What to Do between Now and Test Day: Step 1 (Review)
VIII. What to Do between Now and Test Day: Step 2 (CBT Practice)
IX. Other Simulation Materials
X. Fun Stuff!
I. Kaplan’s Higher Score Guarantee
One of the best parts of Kaplan’s program is that we guarantee you a higher score on your MCAT or your money back. To bring you all back to the orientation from our Diagnostic (oh so long ago!), we ask for three things from you, and you get three things in return:
What You Need To Do
1. Your Required Homework: One last time, the required homework includes ALL (not just some or most) of the online workshops and quizzes, and the end-of-chapter review questions in the Review Notes. If any of these assignments remain uncompleted at this point, be sure to do them ASAP. All of them MUST be done by the time your enrollment expires. If you aren’t sure what your expiration date is, you can find it as soon as you sign in at www.kaptest.com. At the top of the page, it should say: “Access to this service will expire at 11:59 PM on [expiration date].” Also, if you are having issues with items getting checked off in your syllabus, please see Section II: Computer and KapTest Syllabus Issues. This is especially important if you end up claiming the Money-Back portion of the Higher Score Guarantee.
2. Kaplan Full-Length Tests #1-5: In addition to acting as great resources for computer-based practice, these Tests are designed to give you scores verisimilar to the ones you’ll see on Test Day. If you’ve had computer troubles with these Tests and would like them reset, please let me know by email. Also, make sure to see Section II: Computer and KapTest Syllabus Issues.
3. Come to Class: You must attend every session of the course, either with me or with another Kaplan teacher. If you still have outstanding attendance issues, you must find other classes to attend! The easiest way to do this is to sign in at www.kaptest.com, and click on the link that says “Missed a session? Find a make-up” just below the “GO” button for your online syllabus. You can look up classes within a given date and distance range. You may also opt to make-up two classes online using the Lessons-on-Demand. If you decide to go with this route, please let me know when you’ve watched the class so I can mark your attendance (in case it doesn’t automatically register). Please know that, because we updated MSCT II and MSCT III earlier this year, the Lessons-on-Demand will not quite line up with your Lesson Book (though you may still opt to use these Lessons-on-Demand, if you’d like).
What We Offer You
1. Readiness: If you get to Test Day and you don’t feel ready, just let us know and you can re-take the entire course for free. Please see my tips on pushing back your test date in Section III: Helpful Hints.
2. Satisfaction: If you take your MCAT and aren’t completely satisfied with your score, come back and re-take the entire course for free. It doesn’t matter how much you’ve gone up – even if you get a 44 and you really want a 45 (which is your goal anyways, isn’t it?), go for it!
3. Money-Back: If you take your MCAT and your score goes down, you can either choose to re-take the entire course for free, or get back your full tuition. If you have not taken the MCAT before, we’re talking about your score going down from your Diagnostic at the beginning of the class. If you have taken the MCAT before, we’re talking about your score going down from your previous official MCAT.
How to Claim Your Higher Score Guarantee
Assuming that you’ve completed the homework, your full-lengths, and have perfect attendance, you can claim your Higher Score Guarantee by coming to the Kaplan Center. You’ll need to have all of your books with you, and someone at the desk can process your Higher Score Guarantee. They’ll ask you to fill out a quick one-page form (for bookkeeping purposes). If you end up going with the Money-Back portion of the Higher Score Guarantee, it will have to be approved by the Center Director, also.
II. Computer and KapTest Syllabus Issues
Occasionally there are technical problems that my students run into, and I’ve listed some below. As with anything Kaplan- or MCAT-related, please don’t hesitate to contact me with any concerns you have.
My full-length test ran out of time prematurely/froze up!
If this happens on full-lengths 1-5, just shoot me an email at Alex.Macnow@Kaplan.com and I can get it reset for you. Other online resources have unlimited use, so you don’t need to have them reset. In general, make sure to empty the cache on your computer before completing any full-length test. This site explains how to empty your browser’s cache for Internet Explorer 7 and 8, Firefox 3.0 and Safari: http://kb.iu.edu/data/ahic.html.
My online syllabus isn’t checking everything off.
For any of the Online Quizzes, this is not a problem at all if you’ve seen a score. Even if the bar isn’t filled in on the right-hand side, you’re all set. If you’ve seen a scaled- or percent-style score, we will know you’ve taken the Quiz. For Online Workshops, this is not the case. If you are planning on using the Higher Score Guarantee, especially if it’s the Money-Back portion, please send me, by email, a list of the Online Workshops you’ve completed that aren’t checked off. This MUST be done before you claim the Higher Score Guarantee.
My attendance isn’t correct/isn’t entered.
I try to be accurate in recording of attendance, but occasionally – I’ll admit it – I do make mistakes. If this is the case with you, please let me know ASAP what session(s) are incorrectly recorded.
My online resources are going to run out before my Test Day.
If you see that your access will expire before your Test Day, please let me know this too so that I can get it fixed for you. You can extend your syllabus for other Test Dates in this cycle (January, March-June, July-September), but you cannot extend to later Test Dates. If you’re planning on pushing back the test to a date outside of the cycle, you’ll have to use the Readiness portion of the Higher Score Guarantee.
The make-up session finder isn’t working.
Because of the large number of students using the make-up session finder at any given time, it sometimes can’t handle the large influx of information. Try again in about fifteen minutes. If it still isn’t working, you can send me an email (Alex.Macnow@Kaplan.com) and I’ll look up classes for you. Please try to check with the make-up finder first, though.
III. Some Helpful Hints
Just because we are no longer meeting as a class doesn’t mean that you are on your own until Test Day. Please know that I will continue to support your efforts through email conversations and even face-to-face meetings at the Kaplan Center. My job is to help you pull yourself up towards that 45T! Don’t forget that I will continue to be here for you as a resource for as long as you are studying for the MCAT.
Continue to work through your online practice materials. Focus especially on the AAMC/Kaplan Practice Tests and the Kaplan section tests. But don’t take 15 full-lengths in 15 days! You’ve got to space them apart, giving yourself enough time not only to review the test and work through all the explanations but also to rest and recuperate. Do not allow yourself to burn out.
Continue to use the content flashcards that we’ve provided for you, the formula flashcards you’ve made for yourself, the Quicksheets and the High-Yield Problem Solving Guide for quick review and refreshment of point-raising concepts and problems (I have included a thorough review of them later in this email).
When tempted to delay your test to a later date, seriously – and I mean seriously – consider the consequences not just to yourself personally but also to your med school application. Don’t forget that even though the MCAT is now offered 28 times per year, the timelines and deadlines for med school applications haven’t changed at all. Most med schools still operate on a rolling admissions process – so it is to your considerable benefit to take your test as soon as reasonably possible, stick to that set test date and get your primary application (AMCAS/AACOMAS) and your MCAT scores to the med schools early in the application season. The #1 piece of advice I gave you in MSCT III for the medical school application process is be early. It is always to your advantage to have schools considering you as an applicant when they have a larger number of available seats.
As Test Day approaches, understand that your feelings of nervousness and anxiety are naturally going to increase. That, in and of itself, is NOT a sign that you aren’t ready to take your test. Keep in mind the evolutionary basis for stress and stress hormones (cortisol) and neurotransmitters (epinephrine and norepinephrine) – they evolved to allow us to run away from tigers so that we don’t get eaten. An MCAT is not a tiger coming for your butt. So, channel the nervous energy into positive action that moves you through the practice tests and keeps you focused on tackling your remaining weaknesses and turning them into strengths.
Finally, take to heart the notion that the MCAT is not just a hoop that you have to jump through, but is really one of the keys that opens the door to future opportunities. Think positive! Keep the big picture in mind: you struggle now, not just for the sake of Test Day, not just to get a higher score, but to preserve for yourself the greatest number of opportunities for choosing the medical school that is right for you. This, in turn, will help you be a better medical student, a better resident, and ultimately, will help you become the great doctor that you are meant to be!
IV. How to Use Your Resources
Now let’s review the resources you will continue to have at your disposal between now and Test Day as study aides and learning tools:
· Lesson Book (LB)
o During our sessions we reviewed content that was high-yield and/or particularly challenging, and we also reviewed a large number of MCAT-style questions in our passages and Critical Thinking Exercises. We recommend using the LB as an organizing principle in the first step (review phase) of preparing for the MCAT. This is more thoroughly outlined in Section VII: What to Do between Now and Test Day: Step 1 (Review). Make sure that it doesn’t just sit around on the floor now that you’ve finished the class.
· The Class Journal
o Did you totally forget about the fact that I made this resource for you? If so, take advantage of it now. The website to go to is www.blogspot.com, and here our sign-in information:
§ Username: mchv10702
§ Password: letsgo45T
· Review Notes (RN)
o Remember that you have access to the review material both in your Review Notes books and online. The online version of the Review Notes is in the “My ToolBox” tab of your online syllabus at www.kaptest.com. In the online version, you can choose to have it only show you certain topics/sections of the Review Notes. Don’t forget to have completed the practice problems in each chapter!
· Online Workshops/Quizzes (OWQ)
o These workshops and quizzes often present material usually not covered in the RN or in the LB, although it does double some of the material. They are required for the Higher Score Guarantee.
· Kaplan Subject Tests
o These are written with questions that are NOT in MCAT style, but are good for making sure you know the content.
· Kaplan QBank
o Design your own question bank! You can choose to cover certain topic areas so that you’re really directing your practice towards where you can get the most points.
· Topical Tests
o As we’ve noted earlier, these tend to be quite challenging, but they were not designed to be ignored: they exist as learning tools that are great for targeting very specific content areas. Take a quick glance through the names and you’ll see exactly what they’re testing.
· High-Yield Problem Solving Guide (HYPSG)
o This used to be its own standalone book, but now can be found in the back of each of the Review Notes with questions relevant to that particular science area. If you are consistently getting the same questions wrong, this is a good place to go. It will walk you through an example MCAT-style question, showing each and every step (and the logic behind why you’re doing that step). Topics include inclined planes and forces, equilibrium, nucleophilic substitution reactions, the oxyhemoglobin curve, and others.
· Flashcards
o You’ve got two types here, and both are great to have with you on Test Day. For the Kaplan flashcards, use them to double-check your memory on high-yield topics. Also, don’t forget to solidify the formulas! Not all questions are plug-and-chug, but knowing how the different variables/concepts are related can help you with the logic-style questions too. Once you’ve got the formulas down, start taking your formula flashcards and spreading them out on your floor, linking from one card to the next (ex: vf = vi + at à KE = ½mv2 à W = ΔKE à W = Fd à F = ma…).
· Laminated Quicksheets
o Newer than the flashcards, these do a nice job of condensing nearly all of the very high-yield (and some not so high-yield) MCAT concepts. I’ve added some addition comments on them below for your convenience:
o Physics Laminated Quicksheet
§ Work, Energy & Momentum
· You can derive this from the conservation of energy, but it’s a good idea to memorize vf = √(2gh).
§ Thermodynamics
· β from the Volume Expansion equation is equal to 3α (α comes from the Linear Expansion equation). You can think of β as just α in three dimensions.
§ Fluids & Solids
· Remember that Bernoulli’s Equation is merely stating that energy/volume is constant for an ideal fluid.
§ Optics
· Do NOT use ray diagrams on the MCAT; rather, solve optics-related questions mathematically.
§ Atomic and Nuclear Phenomena
· Don’t need to know Wien’s Displacement Law, but make sure you know the exponential decay equations. Also, make sure to understand the photoelectric effect qualitatively as well as quantitatively.
o General Chemistry Laminated Quicksheet
§ Atomic Structure
· Don’t solve electron configurations with the “diagonal line” method – on Test Day, under the stress, it’s just too easy to mess up. Rather, read the Periodic Table for what it is! Elements are in a given block for a reason.
§ Bonding and Chemical Interactions
· On the second page, they number three intermolecular forces but they’re not ordered in terms of increasing strength; also ion-dipole forces are left out.
§ Thermochemistry
· The van der Waals Equation of state is printed, but you definitely don’t need to have that memorized.
· On the other hand, you must know that 1 mole of an ideal gas at STP occupies 22.4 L.
· You don’t need to know the root-mean square speed formula.
§ Phases and Phase Changes
· Remember the van’t Hoff factor i for the freezing point depression and boiling point elevation formulas! It’s not printed in these equations.
§ Solutions
· Know these formulas cold. Be careful of units and when the words “solution,” “solvent and “solute” are used.
§ Redox Reactions & Electrochemistry
· Know what’s the same for all cells and what differs between Galvanic/Voltaic cells and Electrolytic Cells. The signs on the electrodes are only a convention and do not mean the same as positive and negative in electrostatics (Physics).
o Organic Chemistry
§ Alkanes
· Nucleophilicity, size, and polarity lists I- as more nucleophilic than F- because it is assuming protic conditions. Remember that if conditions are aprotic, then F- is more nucleophilic than I- because nucleophilicity parallels basicity in aprotic conditions.
§ Alkenes + Alkynes
· AAMC chose to remove electrophilic addition and these mechanisms from the test; nonetheless, some of their recent practice tests had passages that talked about these mechanisms so this material was kept on the sheet.
§ Alcohols
· You don’t need to memorize Wittig reaction. It’ll be given if you need it.
§ Spectroscopy
· You don’t need to know all of these values. The online workshop did a good job highlighting which numbers you need to know, and we reviewed them in class. In particular, you need to know O-H and C=O. Do NOT call O-H an “alcohol” peak; it show up for carboxylic acids and water, too. That said, remember that 13C-NMR could show up (although it’s rare).
o Biology
§ I looked through this carefully and couldn’t find anything low-yield. Know it all! In fact, there’s more useful information that is missing. For example, there’s a lot more you need to know about evolution than is in that box. As we’ve already discussed, there’s a lot to know for the biology section of the MCAT. Of the sciences, it makes up the largest percent of your score (75% of the Biological Sciences section!).
V. FAQs: Kaplan v. AAMC and Scoring Section Tests
In using these resources, students often ask about how realistic they are and how to score them. Here are some more common questions/concerns my students have.
Are the Kaplan tests designed to be harder/easier than the real thing?
NO! It would be of no service to you to artificially boost your confidence or make you feel like you’re “not getting it” by throwing the curve. Every test’s curve is different, and they all reflect years of research to be as accurate as possible. Can you really get seven wrong in Physical Sciences and get a 15 on the real test? Sometimes, yes. Can you get only five wrong in Verbal Reasoning and be down at a 10? Sometimes, yes. It all depends on the people taking the test and all that’s the same between the different administrations of the MCAT is the percentile score that matches with your scaled score. Do know, however, that Kaplan full-lengths #10 and #11 were designed to show you some darn hard passages and questions. The scaling is still accurate, but these are for people who are saying to themselves: “Show me what the worst-case scenario is for Test Day. What’s the worst they could give me?”
Are the AAMC practice tests old administrations of the MCAT?
Sort of. Each test is a cut-and-crop recreation of an MCAT from pieces of old MCATs. What this means is that you are NOT taking the August 2005 MCAT, but you may have a passage from it, together with one from 1997 and 2006. The scaling has been designed for this test as a practice test, so it does not reflect an actual MCAT’s scaling.
Which is more realistic – AAMC or Kaplan?
Based on my own experiences, as well as those of my students, the Kaplan tests are each, individually, more like the real deal than the AAMC tests. Kaplan tests are weighted (in terms of material) much like the actual MCAT – all different content and question types throughout the test. The AAMC tests each tend to be more weighted towards certain content areas or question types – and it’s different on each one! If you take them in bulk, you’ll find that your average Kaplan score will be right around your average AAMC score; however, you’ll see more fluctuation in your AAMC scores because of this weighting. Also, do NOT use the AAMC tests that use the old paper-and-pencil MCAT’s timing (3R, 4R, 5R, 6R, 7). Only use the ones labeled “CBT.”
How do I grade a Physical Sciences/Verbal Reasoning/Biological Sciences Section Test?
The best way to do this is to figure out how many questions you got right, and compare that to the scaling on the AAMC tests. Just go to “Take AAMC Tests” in the “My ToolBox” tab, and click on the link on the left-hand side that says “How is the MCAT Scored?” You’ll see a bunch of raw score to scaled score tables – you can get an idea of how you did. Again, do NOT use the AAMC tests that are out of 77 questions (Physical/Biological Sciences) or 60 questions (Verbal Reasoning). You can also check out the chart I made for you at the end of this packet.
VI. How to Approach MCAT Topics
I certainly hope that you feel that we’ve covered this pretty well in our classroom sessions, but here’s a little review of how to think about the sections and sciences that make up the MCAT.
Physics:
- Physics on the MCAT tends not to be plug-and-chug, but knowing all of the formulas is indispensible to your success here. Make sure to know them forwards, backwards, and upside-down, but also know what the variables mean! Just knowing C = κε0A/d doesn’t help if you don’t know what those letters mean.
- Work on linking the equations together conceptually (see flashcards in Section IV: How to Use Your Resources).
- Spend more time on the topics that are going to show up more. You can pretty much bet you’ll have a passage about kinematics, work and energy (like a roller coaster or ski jump) and a passage that involves a circuit diagram. Things like optics and physical thermodynamics are much less common, so prioritize!
General Chemistry:
- It’s all about linking the topics together here. Any “K” – that is, Keq, Ksp, Ka, Kb, Kw – is the same concept, just with a certain special circumstance. Treat them as such.
- Most Physical Sciences sections will have a persuasive argument passage, and it will usually be in general chemistry. This tends to boil down to periodic trends, all of which are dictated by how much elements “love on” electrons. The upper-right corner (He, F, O) definitely “love on” their electrons, and the lower-left corner (Cs, Fr, Ba) find it hard to commit.
- Don’t get trapped in math, especially for the “K”s listed above. Always try to approach a General Chemistry question conceptually before diving into math. One of my MCAT questions asked for the pH of a 0.5 M solution of arsenic acid (or something to that end), but only one of the answer choices was an acidic pH!
Verbal:
- Understand that the MCAT tends to like people who challenge the status quo. Thus, when someone is presenting a totally new idea, the author (and thus, AAMC) will tend to think positively of them. On the flip side, the author will tend to disagree with critics of that person with the new idea.
- I’ve said it a million times before, and I’ll say it once more: it’s all about the author’s opinion!
- If you’re struggling to finish, try one of these two Optimization Exercises:
- Force yourself to finish a passage and its questions in two or three minutes. Skim and answer. Then take as long as you want for a similar-length and -difficulty passage and take as long as you want to answer the questions. You’ll see that your number of correct questions tends to be basically the same. The reason is that it’s all about critical thinking and critical reading, NOT reading comprehension. Once you’ve proven this to yourself, you won’t be so worried to critically read.
- Start at the beginning of the passage and read only the first sentence. As yourself where the author’s going to go, and if you’ll need the next sentence. Confirm if you’re right or not. Keep going, sentence-by-sentence. This way, you again won’t be so worried to critically read.
Writing Sample:
- Look through the prompts on AAMC’s website and test yourself to see if you can come up with good ideas for databases (www.aamc.org/students/mcat/preparing/writingsampleitems.htm).
· Read through the directions – notice that the third task is always asking what YOU think determines when the prompt is true and when it is not true. Given that that is the ultimate goal, don’t try to be too gimmicky in your approach to the writing sample. You must come up with ideas that allow you to engage the reader in a thorough discussion of the prompt.
· Don’t forget that the most important thing to do during the Writing Sample is to accomplish all three tasks: explanation, counterexample, criteria. Not accomplishing them will drop you into the 1-3 (J-N) territory.
· Read the sample essays posted on the e-mcat website.
Organic Chemistry
- It’s all about trends. What makes a better nucleophile? A better electrophile? Redox reagent? Don’t memorize reactions!
- Be very familiar with isomerism. What exactly is the difference between a structural/constitutional isomer, a stereoisomer, a conformational isomer, a diastereomer, an enantiomer, a geometric isomer, an epimer, and anomer? Know these terms and know if the isomers have different chemical or physical properties, or both.
- Don’t forget about lab techniques. The focus in the spectroscopy and separation/purification chapters should be why someone would use each technique, and what the underlying principles are of those techniques.
Biology
- Most biology is anatomy and physiology, and it tends to be tested when something goes wrong. Certain diseases are particularly commonplace on the MCAT: multiple sclerosis, cystic fibrosis and congenital genetic diseases are particularly common.
- Keep in mind the yield of the topics here. Biology, in general, makes up 75% of the Biological Sciences section (making it the most heavily tested science). Molecular biology (transcription/translation/DNA synthesis), genetics (Punnet squares and Mendelian inheritance patterns) and endocrinology are the highest-yield within biology.
- For certain topics (hormones, digestive enzymes) MEMORIZE ‘em. Don’t be surprised if you have discrete that simply ask you if you know the information or not. For digestive enzymes, the focus is where it comes from, where it acts, what class of biomolecules it breaks down, and (if it starts as a zymogen – an inactive enzyme), what activates it. For hormones, focus on where it comes from, where it acts, what its function is, and what regulates it.
VII. What to Do between Now and Test Day: Step 1 (Review)
Let’s revisit the blueprint you were supposed to follow as we discussed way back in MSCT I:
· Before class: Complete all of the reading in the Review Notes plus the assigned OWQs.
· During class: Pay attention, participate, and take good notes.
· After class: Review what was discussed in class (paying special attention to topics that confused you), and supplement with Subject Tests/Topical Tests/Section Tests.
Regardless of how well you followed the blueprint above, go back and revisit each session. The degree to which you completed the preview and review assignments during the semester will dictate the length of time this review will take. If you completed all of the reading assignments, then your second reading of the RN will be quick. If you attended all the lessons, then reviewing your notes of each lesson will not take too long. If you completed all of the Topical Tests, then all we recommend is that you take a quick look at the passages and review questions that you recall gave you difficulty in the past.
The primary goal of this review process is to develop an understanding of the key science concepts you need to know for the MCAT.
· IF YOUR TEST IS IN LESS THAN TWO WEEKS FROM MSCT III: There is no time to waste! Get through as much material as possible and get yourself immediately to Step 2 (CBT Practice).
· IF YOUR TEST IS IN LESS THAN ONE MONTH FROM MSCT III: This extensive review process will probably take up one to two weeks, but the goal of the review process is to ready yourself to shift into the second phase of preparing for the MCAT.
· IF YOUR TEST IS IN MORE THAN ONE MONTH FROM MSCT III: It is generally not recommended use up all of your practice tests vastly before Test Day, but each student will need to adjust their test-taking/study schedule according to how busy they will be in next few months, and how many practice tests they want to take. The one simple generalization I can make is to make sure to complete Step 1. Whether you move on to Step 2, and/or to what degree you focus on the simulated tests and/or the practice material (read more below) is up to you – think about your schedule now and when you want to take each practice test. Please don’t hesitate to email me with any specific questions.
VIII: What to Do between Now and Test Day: Step 2 (CBT Practice)
The next phase in your preparation for the MCAT is to regularly take full-length practice tests, with more or less frequency depending on your specific test date. As best as you can, simulate the testing environment by taking the test in a quiet area, have no food or drinks at your side, and use scrap paper for your work. Turn off your computer’s spell check, grammar check, and auto-correct functionalities. Proceed through the test as you would on Test Day: knock off the discrete questions first, triage, time by sets of two passages (the key markers are 41, 25, and 9 minutes after the 1st, 2nd, and 3rd set of two passages in Physical/Biological Sciences and 43, 26, and 9 minutes in Verbal Reasoning), map and highlight strategically, make sure to answer the question asked, remain calm and cool when presented with questions that test you on material you don’t know, etc. For those who are extremely concerned with their timing, especially in VR, mark down the time remaining after every passage pair on your scrap paper and utilize the Optimization Exercises I’ve discussed in class (if you don’t remember them, refer back to Section VI: How to Think about MCAT Topics).
Obviously, after the test, you have to review it, but we discussed that this process can be quite time consuming. Let’s walk through it:
· First, to have a more informed sense of where you stand, take a look at the scaled score.
· Second, take a look at SmartReports and its assessment of your performance on the different types of questions asked, paying particular attention to your performance on the easy and intermediate questions. One caveat with this approach is that the computer’s categorization of what is easy and intermediate isn’t always perfect. Still, it gives us an idea.
· Those two steps are just warm-up steps when it comes to diagnosing your problems. The key step is that you review each passage of the exam: even those where you didn’t miss a question. In each case, scan through the passage one more time and ask yourself if there were any terms or concepts in the passage you didn’t quite understand. Make a note to study the issue in the future or open up your texts to study the issue now. Next, take a look at the explanations for each question because sometimes you can answer a question correctly for the wrong reason. It is human nature to focus on the questions we answered incorrectly, but sometimes there’s more to be learned from a question we answered correctly than one we answered incorrectly. So do your due diligence.
o As necessary, especially with VR review, reflect upon your timing through the passage and your timing through the questions. If all passages were created equal, the ideal is to spend about 3.5 minutes on the passage and 5 minutes on the questions. Of course, there’ll be variations off these numbers depending upon passage length and difficulty, as well as the number of questions and the difficulty of the questions. Nonetheless, if timing is a concern you’ll also want to identify what particular passage(s) or question(s) bogged you down.
· For Kaplan Full-Lengths #1, 2 and 3, don’t forget to use the Explanations-on-Demand to help solidify the mapping and Stop-Think-Predict-Match methods. Also, you get to hear more of my lovely voice when you watch them for any Physics question!
· Notice that during the exam review you will be referring back to your RN, LB, OWQ, and other resources. The main point is that in this phase you are using the exams to help direct your study. Of course, each individual practice exam fails to touch upon many science concepts, so, in between the exams, make sure to conduct a general review of all the science concepts as well (you can do this by looking at the laminated quick sheets, and/or the Kaplan flashcards or your own formula flashcards).
· In essence, this phase of getting ready for the MCAT boils down to the following: take practice test(s), review practice test(s), review notes. Lather, rinse, and repeat.
· The more practice tests you take, the more rounds of review you get in, and the more in-tune your mind becomes with how to study for the test. As we discussed in MSCT I and several other times, the most common mistake students make is to overemphasize Step 1 (studying content) and to fail to set enough time aside for Step 2 (CBT Practice). Moreover, the second step is not exactly distinct from the first step – review is built into the second step, but this review is more targeted and, because it is occurring in the greater context of a practice test experience, your mind will get better at learning how to study the RN, LB, OWQ. Thus, when you are completing Step 1, don’t overdo it: don’t try to have a perfect memory of everything before moving into the second phase.
· If you find that one section keeps lagging behind the others in terms of score, try a few of what I call “Mini-Diagnosis Cycles.” Rather than taking another full MCAT, take a few section tests in the area where you need the most work. You can scale your score using the method described in Section V: FAQs. Also, you’ll get a better idea of where your problems truly lie in that particular section. Is it a content problem? Do you keep getting stuck with certain types of passages? Either way, you’re directing your practice more specifically towards where you really need the points.
IX: Other Simulation Materials
We encourage you to practice on both AAMC and Kaplan-written tests before Test Day. The first five Kaplan Full-Lengths are required for the Higher Score Guarantee, but we recommend that once you’ve completed them that you trade off between taking Kaplan Full-Lengths and AAMC Practice Tests.
· AAMC Practice Tests 3-10 (again, do NOT use 3R, 4R, 5R, 6R, or 7! These ones are designed for the old paper-and-pencil test that was seven hours long).
· Kaplan Full-Lengths #6-11 (remember that Kaplan Full-Lengths #10 and #11 are designed to be extremely difficult; they are not for the faint-of-heart).
Other simulation resources may be shorter than the Full-Lengths, but are useful for “Mini-Diagnosis Cycles.”
· Kaplan Section Tests. In particular, I recommended these passages:
o PS Section Test 4, Passage 2: tough passage on azeotropes (worth doing because of hard-to-read diagram).
o PS Section Test 7, Passage 3: titration passage involving indicators.
o PS Section Test 7, Passage 6: tough Raoult’s Law passage.
o BS Section Test 7, Passage 1: good experimental passage.
X. Fun Stuff!
Okay, now for some fun stuff. Some of these I’ve mentioned before in the class, and many of them went viral (so you may already know them), but they’re all fun things to take a look at.
Physics
· Here’s an illuminating gallery from a “Festival of Lights” exhibition in Berlin and other cities. It may not really have much to do with light/optics, but it’s definitely pretty! (http://www.boston.com/bigpicture/2008/10/lighting_up_the_night.html)
· The Big Picture has also finished posting an amazing gallery from the Hubble Space Telescope that they’re calling their 2008 “Advent Calendar.” (http://www.boston.com/bigpicture/2008/12/hubble_space_telescope_advent.html)
· This was on a commercial a couple years ago, but this person’s house is actually pretty close to where I live at home. Lights are very cool. (http://www.youtube.com/watch?v=yIconc_rfqc&feature=related)
General Chemistry
- I would really enjoy attending this party. You definitely know these chemical principles already, but look out for sexy Carbon! (http://www.youtube.com/watch?v=a45dXztokZM)
- The MCAT definitely doesn’t require you to have the periodic table memorized, but there are fun quizzes to help you remember all the elements. (http://www.sporcle.com/games/elements.php)
- So, viscosity may not show up much on the MCAT, but what happens if it just goes away? Certain elements can exhibit “superfluid” properties where their viscosity decreases to zero, and they can then do some pretty interesting stuff. (http://www.youtube.com/watch?v=2Z6UJbwxBZI)
- This is a bit outdated, but another way to learn all the elements may be just to learn a little ditty for them. This doesn’t cover any discovered in the past 30 years or so, but the first 102 are there! (http://www.youtube.com/watch?v=SmwlzwGMMwc)
Organic Chemistry
- This may be more of a general chemistry topic, but Orgo needed some love. Ever wonder what exactly a triple point looks like? Here it is for tert-butyl alcohol (an organic compound!). (http://www.youtube.com/watch?v=BLRqpJN9zeA)
Biology
· Want something science-y and wacky? Well, apparently a group of Japanese scientists have figured out how to extract images directly from your brain. I’m not kidding! If I have time I may go to the trouble of reading the research report in Neuron. (http://www.pinktentacle.com/2008/12/scientists-extract-images-directly-from-brain/)
· Children sometimes say some darn cute stuff. Here’s a kid who can’t pronounce the word “blood” correctly. (http://www.youtube.com/watch?v=Q9yAkBSrMk0)
· Speaking of cute kids, ever wonder what effect anesthesia has on the very young? David after Denstist. (http://www.youtube.com/watch?v=txqiwrbYGrs)
· This is a beautiful representation of some of the inner workings of the cell created by Biovisions at Harvard University. (http://multimedia.mcb.harvard.edu/)
· Did you know that the longest accepted word in the English language is the proper name for titin (a protein found in the sarcomere)? Try pronouncing some of these horrifically long words. (http://www.youtube.com/watch?v=uUhQN-PGWDg)
· Some of the things the brain can do are just amazing. Daniel Tammet is “The Boy with the Incredible Brain,” who is not an idiot-savant, but does have some features of savantism. (http://video.google.com/videoplay?docid=4913196365903075662)
Other
· Last one must be motivational. It’s popular and well over a year old, but in case you haven’t seen it: Randy Pausch’s Last Lecture. (http://www.youtube.com/watch?v=ji5_MqicxSo)
Well, that’s it! Good luck on your MCAT, and please let me know how it goes. Feedback about the test, my teaching, and everything else is always welcome. Go get your 45T!
Best,
Alexander S. Macnow
Master Teacher – MCAT/DAT/OAT/PCAT
University City and Center City Kaplan Centers
cell: 610-291-4587
email: Alex.Macnow@Kaplan.com
Appendix
You can use this table as an approximation of your scaled score from a section test. In each column, the numbers represent percent correct (not number correct). Because there is variability from one MCAT to the next, this rubric provides a scaled score with ±1 accuracy. In other words, a 75% correct on Verbal Reasoning could be 9, 10, or 11 depending on the test administration.
| Scaled Score | Physical Sciences | Verbal Reasoning | Biological Sciences |
| 1 | 0 – 11 | 0 – 13 | 0 – 17 |
| 2 | 12 – 18 | 14 – 22 | 18 – 26 |
| 3 | 19 – 25 | 23 – 29 | 27 – 31 |
| 4 | 26 – 32 | 30 – 38 | 32 – 37 |
| 5 | 33 – 38 | 39 – 43 | 38 – 43 |
| 6 | 39 – 45 | 44 – 51 | 44 – 49 |
| 7 | 46 – 51 | 52 – 57 | 50 – 54 |
| 8 | 52 – 57 | 58 – 64 | 55 – 61 |
| 9 | 58 – 63 | 65 – 70 | 62 – 67 |
| 10 | 64 – 70 | 71 – 76 | 68 – 73 |
| 11 | 71 – 76 | 77 – 82 | 74 – 78 |
| 12 | 77 – 81 | 83 – 86 | 79 – 82 |
| 13 | 82 – 86 | 87 – 90 | 83 – 88 |
| 14 | 87 – 93 | 91 – 94 | 89 – 92 |
| 15 | 94 – 100 | 95 – 100 | 93 – 100 |
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