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This is the official Q&A thread for AAMC CBT10.

Please post ONLY questions pertaining to AAMC CBT10.
Out of respect for people who may not have completed the other exams, do not post questions or material from any other AAMC exam.

Please see this thread for the rules of order before you post.

Good luck on your MCAT!
 

archange

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Can anyone help me understand question number 54 (2nd question of verbal passage 1) on CBT 10? It seems like answer choice A could be right and the explanation they give doesn't explain why it is wrong. Thanks!
 

shilgy

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hey, i also chose A for 54. i think the point is that A isn't necessarily wrong, but rather B is a better answer because it relates to the beginning of the paragraph. the question is why did dort mention sinkholes, well it probably relates to the point that he is trying to make. at least that is how i understood why B is a better answer but i may be wrong.
maybe you or someone else can help me on a question from the PS section? question #7 wouldn't a higher ksp make the solution more effective? what determines how effective this is?
thanks
 

BloodySurgeon

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hey, i also chose A for 54. i think the point is that A isn't necessarily wrong, but rather B is a better answer because it relates to the beginning of the paragraph. the question is why did dort mention sinkholes, well it probably relates to the point that he is trying to make. at least that is how i understood why B is a better answer but i may be wrong.
maybe you or someone else can help me on a question from the PS section? question #7 wouldn't a higher ksp make the solution more effective? what determines how effective this is?
thanks
Im going off by memory so stop me if im wrong, but the ksp should be as low as possible because you want to make a solid and the lower the ksp the less soluble it is. And I also got the wrong answer for the sinkhole question, I probably marked A as well.
 

chemnerd31

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Surgeon is correct on the Ksp part. The lower the Ksp the lower the concentration of ions before ppt will occur. Therefore since Cu has the lower Ksp it will ppt first and then Zn. As for 54 I picked A as well and dont see how B would even be a good answer.
 

TypeSH07

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#113 on BS? AAMC explanation is ridiculous....Was choosing between A and B but went with A...

I'm guessing you have to remember from the beginning that patients have pulmonary problems....which is a different virus from kidney?
 

TypeSH07

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Also for #143. Are amino acids protonated (COOH and NH3) when it is acidic and deprotonated (COO- and NH2) when it is basic? What if one was protonated and the other was deprotonated(pKa of 6.something?). Thanks!
 

justpremed

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i don't remember 113, but that's correct for 143 in terms of protonated when acidic and vice-versa...i'm not sure what you're talking about with the pka of 6.something
 

TypeSH07

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i don't remember 113, but that's correct for 143 in terms of protonated when acidic and vice-versa...i'm not sure what you're talking about with the pka of 6.something
Okay thanks. When it's a zwitterion can the + and - charges be on either one or does one specifically get a particular charge?
 

RySerr21

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Okay thanks. When it's a zwitterion can the + and - charges be on either one or does one specifically get a particular charge?
the + is always on the Nitrogen and the - is always on the Oxygen. think of electronegativity. oxygen never wants a positive charge.
 

RySerr21

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For #119 on bio would the answer still be oxygen if NADH was an option?
whats the question?? thats not my #119. seems like you are talking about electron transport chain...
 

RySerr21

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which participant in the ETC has the greatest attraction for electrons?
it will always be oxygen...no matter what. NADH is a carrier..if it had the greatest attraction then it would never release anything. the whole point of NADH is to travel to the ETC and release the electrons so they travel down teh chain and eventually to oxygen... if NADH never gave up its electrons you wouldnt make any ATP beyond that of glycolysis and the krebbs cycle.
 
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which participant in the ETC has the greatest attraction for electrons?
This question is testing your knowledge of WHY the electron transport is able to transport electrons sequentially from NADH to complex I to III to IV to Oxygen. The reason that the electrons are transported in this particular fashion is because the standard reduction potential becomes less negative as you move from the beginning of the ETC to the end of the ETC. The electrons have to be transported in a stepwise fashion with each reaction being spontaneous. Thus, each sequential carrier in the ETC must have a progressively higher an higher attraction to electrons.
Here's an image to help you understand:
http://www.web.virginia.edu/Heidi/chapter21/Images/21_03.jpg

Remember that the ETC is composed of a series of redox reactions that must be spontaneous so that the produced free energy can be used to transport H+ across the IMM to created the H+ gradient required for ATP synthesis.

As Ryser stated, O2 is the final electron acceptor, and thus, it must necessarily have the highest affinity for electron: it has the most positive reduction potential. A more positive reduction potential means that it is reduced, i.e. electrons are donated to it, with the most ease.

If this was not the case, then it would require energy to donate electrons to O2 which would defeat the whole purpose of the ETC to create chemical energy for use in the body. For the ETC to function properly, the final electron acceptor, O2, must be the most easily reduced species, and NADH is actually the hardest species to reduce in the ETC.
 

thierryhenry

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Did anyone else think that this was the most difficult verbal out of all the AAMC tests, with one of the least forgiving curves?

Man that verbal was bad, like a Kaplan VR.
 

Chemist0157

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I didn't feel that way. I got my typical score on VR from 10. Technically, the curve is steeper, but only by like 1 question when we compare 10's curve to the others.
 

sicboy188

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Did anyone else think that this was the most difficult verbal out of all the AAMC tests, with one of the least forgiving curves?

Man that verbal was bad, like a Kaplan VR.
yea that was my poorest performance on verbal. sucks that its my last test before the real thing. gotta chalk it up as a fluke.


can anyone tell me what going on with #14?
 

sicboy188

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also, isnt the explaination wrong for 24? isnt O from H2O2 oxidized from -1 to 0???
 

RySerr21

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also, isnt the explaination wrong for 24? isnt O from H2O2 oxidized from -1 to 0???
oxygen normally has on oxidation state of -2, unless h2O2 is one of those weird exceptions that i decided not to memorize.

EDIT: peroxided is one of the exeptions where oxygen has an oxidatin number of -1.
 

sicboy188

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ha, one more (sorry im loading them up)

for #42:
C seems like a better ans choice than B.

my reasoning: the accelerated neutron (accelerated via collision or radioactive decay ejection) would not be affected by the potential difference because it is not charged.

B seems to at least leave the possibility that the neutron can hold a charge.
 

sicboy188

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oxygen normally has on oxidation state of -2, unless h2O2 is one of those weird exceptions that i decided not to memorize.

EDIT: peroxided is one of the exeptions where oxygen has an oxidatin number of -1.
yea thats why i thought the explanation was wrong.
 

RySerr21

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ha, one more (sorry im loading them up)

for #42:
C seems like a better ans choice than B.

my reasoning: the accelerated neutron (accelerated via collision or radioactive decay ejection) would not be affected by the potential difference because it is not charged.

B seems to at least leave the possibility that the neutron can hold a charge.
are you on the paper version? my AAMC 10 question 42 is about bonding of solid nitrogen
 

sicboy188

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weird.. mines the CBT 10, but the question is from passage 7 (about the particle accelerators), first question.
 

RySerr21

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weird.. mines the CBT 10, but the question is from passage 7 (about the particle accelerators), first question.
ahhh. i think i figurd it out. i took my test on "random" instead of "Sequential" so the passage you described was actually mt first one. now back to the original question.

for #42:
C seems like a better ans choice than B.

my reasoning: the accelerated neutron (accelerated via collision or radioactive decay ejection) would not be affected by the potential difference because it is not charged.

B seems to at least leave the possibility that the neutron can hold a charge.
your reasoning seems to prove that answer C is incorrect rather than that it is a possibility. you mention that the neutron would not be affected by the potential difference. Answer choice C says that the neutron path will be affected. at the same time, your reasoning seems to be supported by answer choice B, that the neutron will not be effected because it is neutral.
 

sicboy188

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ahhh. i think i figurd it out. i took my test on "random" instead of "Sequential" so the passage you described was actually mt first one. now back to the original question.



your reasoning seems to prove that answer C is incorrect rather than that it is a possibility. you mention that the neutron would not be affected by the potential difference. Answer choice C says that the neutron path will be affected. at the same time, your reasoning seems to be supported by answer choice B, that the neutron will not be effected because it is neutral.
wow....i definitly was :sleep: when i read that. kinda sucks, considering i read it wrong AGAIN when i went over the test.

thanks for the correction.
 

sicboy188

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yea that was my poorest performance on verbal. sucks that its my last test before the real thing. gotta chalk it up as a fluke.


can anyone tell me what going on with #14?
can some help me with #14? Why does K violently react with cold water oppose to Mg, Zn...?
 

RySerr21

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can some help me with #14? Why does K violently react with cold water oppose to Mg, Zn...?
potassium is in the first column of elements, so you know it really really really really wants to get rid of an electron. therefore, it is going to be very reactive. Mg wants to get rid of two electrons so it is reactive but not as much as potassium. i'm not sure if that is the correct reasoning to solve that problem, but it happened to work. AAMC didn't give a very good explanation on that one.
 

BTC

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I got this one wrong too. From wikipedia:

Alkali metals are famous for their vigorous reactions with water, and these reactions become increasingly violent as one moves down the group. The reaction with water is as follows:
Alkali metal + water → Alkali metal hydroxide + hydrogen gas
With potassium as an example:
2K (s) + 2H2O (l) → 2KOH (aq) + H2 (g)
 

sicboy188

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I got this one wrong too. From wikipedia:

Alkali metals are famous for their vigorous reactions with water, and these reactions become increasingly violent as one moves down the group. The reaction with water is as follows:
Alkali metal + water → Alkali metal hydroxide + hydrogen gas
With potassium as an example:
2K (s) + 2H2O (l) → 2KOH (aq) + H2 (g)
wow.. thanks. maybe it has to do with the electron affinity trend (Alkali metals are furthest to the right, thus want to hold their electrons the least). that would explain it from ryserr21's perspective. just seems a little too arbitrary to be an obscure fact of alkali metals.
 

RySerr21

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wow.. thanks. maybe it has to do with the electron affinity trend (Alkali metals are furthest to the right, thus want to hold their electrons the least). that would explain it from ryserr21's perspective. just seems a little too arbitrary to be an obscure fact of alkali metals.
furthest to the left :) . i'm sure it was just a mind slip.
 

DrMattOglesby

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this is a stand alone question and does not depend on any passage:

I said the answer was A.
apparently i was wrong.

why does the acceleration not equal zero?
isnt acceleration defined as a change of velocity over a change in time? when the velocity is zero, then thatd make the acceleration zero as well?
 

BloodySurgeon

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The acceleration in the y-axis for free-falling body is always g. There is always a gravitational force on the object in the y-axis and this is the only force on the object neglecting air-resistance therefore if F=GMm/r^2 and F=ma then a = GMearth/r^2 = 9.8 m/s^2.
 

koopa_troopa

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Just because velocity is 0 at one point, does not mean it is not changing. You are correct in that acceleration is change in velocity over change in time. For example, if the velocity was originally 5 m/s, then the change in velocity (final - initial) is 0 m/s - 5 m/s = -5 m/s. There still is a change in velocity.
 

DrMattOglesby

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i just took the BS section of AAMC 10
and scored...
an 11!
thats good news.
maybe i wont void my scores afterall...
but i have a question concerning a question I missed; Isn't the liver SOMEWHAT responsible in regulating blood pressure? Isn't that where we have a bunch of angiotensinogen? Or am I getting confused with the lungs...?
 

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i just took the BS section of AAMC 10
and scored...
an 11!
thats good news.
maybe i wont void my scores afterall...
but i have a question concerning a question I missed; Isn't the liver SOMEWHAT responsible in regulating blood pressure? Isn't that where we have a bunch of angiotensinogen? Or am I getting confused with the lungs...?
Lungs is ACE, but I see why you may have chosen that. The thing is, it's definitely not the best answer. I remember the choices, and the others were far better (I'm sure you'd agree).

Plus, I think it was asking what would be MOST affected, right?

By the way, good job on the BS.
 

UrielSeptum

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I think ur right about that but that was more indirect than the other options, if I'm remembering correctly.

tweaked beat me to it =D
 

tweaked17

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I just went and looked at it. Here's the way I solved it: A & B are essentially the same thing. You have to eliminate both of them right off the bat. Now you're left with detoxification vs bp - which one is the liver associated with more often?
 

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hey guys

I just did this test and man, I got killed by verbal...just after getting an 11 on my last one and having stabilized in the upper 10 limits, I got a

12 PS

6 VR

13 BS

sorta concerned now since I got little over a week left...gahhh
 

greg1184

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Be wary that there is a mistake on #54 in the Verbal section. They highlighted the wrong answer as correct.

The question asks "Dort Mentions sink holes in order to:"
choice A's explanation says: "The elimination of an alternate hypothesis is the reason for the reference to sinkholes..." As a result this answer is obviously the correct one. Yet they highlight B as the answer when B's explanation is saying that B is not the answer.
 
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greg1184

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hey, i also chose A for 54. i think the point is that A isn't necessarily wrong, but rather B is a better answer because it relates to the beginning of the paragraph. the question is why did dort mention sinkholes, well it probably relates to the point that he is trying to make. at least that is how i understood why B is a better answer but i may be wrong.
maybe you or someone else can help me on a question from the PS section? question #7 wouldn't a higher ksp make the solution more effective? what determines how effective this is?
thanks
No. They made a mistake. The explanations are correct, but they highlighted the wrong choice blue.
 
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pluckyduck1105

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Hi guys. Can somebody explain to me how D is correct for #24 on PS?:

What are the oxidizing and reducing agents, respectively, in the reaction below?
2HCl + H2O2 + MnO2 ® O2 + MnCl2 + 2H2O
A
) H2O2; HCl B
) H2O2; MnO2 C
) MnO2; HCl D
) MnO2; H2O2
In the reaction pictured, Mn is reduced from +4 to +2; therefore, MnO2 is the oxidizing agent. O is oxidized from –2 in H2O2 to 0 in O2; therefore, H2O2 is the reducing agent. Thus, D is the best answer
What I don't understand is how you know that H2O2 is oxidized to O2, instead of H2O (this was what I presumed and therefore I got it wrong). To me, it seemed that H2O2 --> H2O + O-, and the highly unstable O- anions would come together to form O2. I don't know, does someone know what's going on here? Thanks!
 
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BloodySurgeon

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Hi guys. Can somebody explain to me how D is correct for #24 on PS?

What I don't understand is why the O in H2O has an oxidation state of 0. I read the Kaplan explanation for this test, and there is conflicting information. First, they make this list of the oxidation numbers of all the elements in each species within the reaction, and say that "O in H2O= -2." However, in their written explanation and the AAMC's explanation, it says that the O in H20 has an oxidation state of 0. Why would it have a 0 oxidation state of the oxygen is not in its elemental form? Shouldn't the H's be +1 each, and the O be -2? Thanks!

2HCl + H2O2 + MnO2 --> O2 + MnCl2 + 2H20

H2O2-->O2 : Reducing agent
H2O2: Oxygen = -2
O2: Oxygen = 0

MnO2-->MnCl2 : Oxidizing agent
MnO2: Mn = +4
MnCl2: Mn = +2
 

tweaked17

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2HCl + H2O2 + MnO2 --> O2 + MnCl2 + 2H20

H2O2-->O2 : Reducing agent
H2O2: Oxygen = -2
O2: Oxygen = 0

MnO2-->MnCl2 : Oxidizing agent
MnO2: Mn = +4
MnCl2: Mn = +2
right, except in the peroxide the oxygen's oxidation state is -1 because the hydrogen +1 rule takes preference (or because there's no way for the total charge to be zero if oxygen is -2.. either way).
 

Kaustikos

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So, no one had a problem with the last passage? I almost threw my laptop across the room when I read the passage.
 

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Can someone plz explain Oxidative phosphorylation? Is it the same as the electron transport chain? Or is it different? And How exactly does the H+ proton gradient make it work? I'm sorry but I looked it up and still don't FULLY understand it or what it is

thanks:)
 

Diksha

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Oxidative phosphorylation is the ETC. The ETC gradually takes the energy from the electron as it passes through; it uses this energy to pump H+ into the intermembrane space. The electrochemical gradient that is set up by this causes the H+ ions to enter back into the matrix through the ATP synthase protein; this protein has a spinning head phosphorylates ADP by harnessing the energy released by H+ moving down its gradient.