# Single Mcat Forumla or Concept that saved your life!

Discussion in 'MCAT: Medical College Admissions Test' started by tmandudeguy, Jul 25, 2012.

1. ### tmandudeguy 5+ Year Member

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Trying to make a fun new sticky! Specifically for people who took the MCAT but it doesnt matter. Post a brief concept or formula and a short description about i and how it saved your life on a test or practice test. Give a way to easily remember it well.
Ill start

BIOLOGY- SARCOMERES

I made a pnemonic- Z.I.A.H.M. and they appear in this order!
Starting from the left the Z line is at the edge followed by the I reigon which is only th"I"n filaments followed by the A which is the legnth of the thick filament including the thin, followed by the H which is only t"H"ick followed by the M line. The only areas that get smaller are the reigons with only t"H"ick or th"I"n. So its the I and H reigons. Obviously the A doesnt because the length of thick filameny cant change.

2. ### Nandrolone

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The right hand rule. Use your right hand NOT your left hand.

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For all specific gravity/density problems.

Remember the definition of specific gravity and the densities of water, and you will be able to solve any problem with this formula.

4. OP

### tmandudeguy 5+ Year Member

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SOO TRUE^ I make that mistake for some reason when I'm in a hurry!!

Also an example of posting a formula on this thread would be:

PHYSICS- Conservation of Angular Momentum T = r Fsin (theta)

So in Physics class my professor lured someone who would show off by asking who has atheleticism and balance. A kid bounced up and stood on a rotating stool. My professor gave him light dumbbells and told him to stick his arms out. He spun the student and asked the studen to bring the dumbells close to his chest. The kid damn near FLEW OFF! I will never forget now that when: A spinning mass if brought closer to the center and "r" decreases, the angular momentum INCREASES to compensate for the force increase and conserve torque.

P.S. Please correct me if my concepts are flawed, its been a while

5. ### JoshuaGuit 2+ Year Member

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Thank you!!! This is the one type of physics problem I have never understood. You sir are a gentleman and a scholar!

If you decrease the distance of your arms, you must conserve angular momentum by traveling a greater distance. Pulling your arms in will result in a much greater angular velocity to conserve energy (KE = 1/2 (mv^2)). You have the same force acting on you, just a different velocity. Remember that linear momentum = m*v, the velocity component translates into the angular velocity. Correct me if I'm wrong though!

6. ### Jepstein30 2+ Year Member

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well that would have helped me get at least one more question right on my MCAT.. darn sarcomeres.

Figured it wasn't worth the time to memorize what each thing was so of course I get hit with a question that involves sarcomeres..

7. ### 05silvergt ASA Member 5+ Year Member

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I got this from TBR gen chem for determining pka of an acid from the ka.

-log ka = pka.

Ka = z x 10^(-Y) ---> pka = log [Z x 10^(-Y)] --> pka = Y - (log Z)

* If I made a mistake, it is because I'm doing this from memory and I haven't studied in a few weeks.

Edit: Thanks somefun for catching that. I've been drinking the mcat out of my memory recently.

#7
Last edited: Jul 25, 2012
8. ### somefun 2+ Year Member

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.

#8
Last edited: Jan 22, 2013
9. ### JoshuaGuit 2+ Year Member

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It's easier to remember the way that KhanAcademy teaches you, in my opinion.

Write the Ka equation of the buffer out:

HA <==> H+ + A-

Ka = [H+]*[A-]/[HA]

Rearrange to find the concentration of [H+] in order to determine the pH.

[H+] = Ka*[HA]/[A-]

To find pH, you take the -log of [H+]

-log[H+] = pH = -log(Ka*[HA]/[A-])
pH = -logKa - log([HA]/[A-])
pH = pKa - log([HA]/[A-])
pH = pKa + log([A-]/[HA])

Henderson equation!

10. ### bored 7+ Year Member

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Loe the Red Cat said Gre to An Ox

though its not really a concept and it didn't save my life.

#10
Last edited: Jul 25, 2012
11. ### imbackasd 2+ Year Member

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This is the same as Weight/Buoyancy = Density object/ Density of fluid right?

12. ### PanRoasted 5+ Year Member

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Has anyone actually gotten a question that directly asks you to identify parts of the sarcomere? I have never in my entire time of studying encountered something about sarcomeres that specific...

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13. ### Leonardo Noto

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I'm a physician who had a crummy high school education and got a 25 on the ACT, managed to improve to a 35 on the MCAT, and then rocked the USMLE's with 255/256 (only took COMLEX for step 3, but got 797/800). Let me teach you a little secret that you'll learn in medical school, but probably not until it's too late and definitely too late for the MCAT. The key to doing well on these tests is to find a good comprehensive review book (the big Kaplan book for the MCAT) and to work through it while you're learning the subject. That way you learn what the MCAT tests in, say, O-chem while you're doing your course work. Professors, especially in undergrad but also in med school, have this tendency to harp on whatever their particular research topic happens to be and to devise test questions however they particularly like to write/grade them, neither of which prepares you for a standardized test like the MCAT or the boards. If you use the review books to teach yourself what you actually need to be learning for your career goals (i.e., to become a physician, not an organic chemist) then come time for the MCAT you can spend a lot less time reviewing the basics and a lot more time hitting high-yield question banks. The next step is to do thousands of practice questions from Kaplan and friends and to READ the answers, even of the ones you got right (you may have gotten lucky and there is lots of good information along with the wrong answers too in these books).

Leonardo Noto
Physician-turned-Grumpy Old Writer

14. ### ascg 7+ Year Member

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do you work for kaplan?

15. ### mr chievous Removed

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Haha I was wondering the same thing

Never heard anyone recommend Kaplan...

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16. ### Leonardo Noto

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No. I'm an independent author who writes mostly fiction. I don't know about anyone not recommending Kaplan around here, but it got me a solid score on the MCAT and 99th percentiles on USMLE Step 1+2. For USMLE I also used a lot of other sources of questions, but if you only have time for one source, in my experience Kaplan is the way to go. I can't speak to the Kaplan review course b/c I couldn't afford it during undergrad and by the time I was in medical school I had developed a view that self-directed learning is best (Goljan's review course is very good for USMLE, however).

Leonardo Noto

17. ### chillaxbro 5+ Year Member

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Most important thing that helped me on physics was basically plugging in extreme numbers for each variable in the equation and seeing if it made sense or seeing what happens to the equation

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18. ### sciencebooks 7+ Year Member

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I remember that the "bands" are made of myosin as they're "think", lol. Oh, and the ones that disappear are "HI" because they say hi and then bye, .

19. ### sciencebooks 7+ Year Member

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Hope you did well and are happy with your final score! I was wondering where you disappeared to from the Q&A forum, .

20. ### argama 7+ Year Member

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not sure how useful this would be but someone told me this and now I know it well:

The layers of the adrenal cortex is like a date:

Outer Layer = Zona Glomerulosa where Mineralocorticoids (ie SALT) is secreted

Middle Layer = Zona Fasciculata where Glucocorticoids (ie SUGAR & SWEETS) are secreted

Inner Layer = Zona Reticularis where Androgens (ie SEX HORMONES) are secreted

Thanks TBR!!

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21. ### Jepstein30 2+ Year Member

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haha yea I figured I'd retire from that forum after taking my MCAT on 7/14..

hopefully I did well and won't have to make a surprise return!

will probably poke around there after my score is out, when I know I don't have to actually learn all that stuff again.

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