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Can we start an official aamc cbt11 thread. I took this test a few days ago and have some questions. Can I just start this thread? Or, is that sort of behavior for the more senior members.
I've also taken 3, 5, and 6. Its hard to say generally if this test is harder than the others. From a purely basic knowledge standpoint it compared evenly with the other tests. There weren't too many esoteric knowledge questions. And testing of concepts were pretty straight forward, I felt. They were basically looking for grasp of the general/popular concepts of a given topic. To that point however, I felt that the questions and passages were quite long and I had to read the question stems several times to clearly get what they were asking for. Also, there were more questions directly related to the passage.
My strategy is to go over the questions first than hit the passage. This way I can get simple questions out of the way and also, get a sense of where I should be focusing. This proved to be difficult, and I'm glad I got to see this. The question stems were long and time consuming. So the whole time I was stressing whether I'm spending too much time looking at the questions first. Also, as I said there were more passage related questions and so I didnt even get a chance to answer many of them.
The passages also took some more time analyzing. You definitely had to sit there and spend more time connecting the dots, if you know what I mean.
My feeling is, they are gravitating further away from just knowledge based questions to analytical and interactive (passage) questions.
Yeah, I found this exam to be quite difficult. Especially the Bio and the Verbal sections. I found a lot of the verbal answers required us to assume more than normal. When questions asked what does this imply?, i felt the answers were farfetched imo. And the Bio section was tough. They way they worded the question stems didnt help either.
For BS Item 34, I don't see why cytoseine tRNA would not be related to the cp450b, doesn't the passage say that the protein binds to cytoseine somewhere?
Is this question 124?
Posting in here cause this is the only CBT 11 thread I found.
For question 31, is |Wg| going to be greater than |Wa| until terminal velocity is reached? Will the abs values be equal once terminal velocity is reached?
I'm having trouble understanding this as well. They say during the first 600m, and at 600m terminal velocity is reached. At that point, I feel like the work of air resistance should be equal and opposite to the work of gravity since at that point there is no net force. AAMC does not seem to think so.
I was reviewing this test last night, and I feel like their explanation is a little confusing too. But here's what I got from it.
It's a setup where something that is released from rest, and reaches terminal velocity after falling 600m. The question asks about work by gravity and work by air resistance DURING that first 600m. My intuition was, velocity is down, so work by gravity is positive, and work by air resistance (going against velocity) is negative. That settles the first part.
Now what about the absolute values of work? That's the weird part, or at least it was for me. And the explanation doesn't even seem to address it, just says "here's how you calculate work by gravity, and oh, air resistance does negative work, therefore Wgrav > Wair."
I think the key is, the falling object started from REST, and accelerated down until terminal velocity was reached. At that moment, of distance traveled = 600m, he's falling at terminal velocity. So gravity must have done more work, since we started at rest, and now he still has kinetic energy pointing down.
Kind of like photoelectric effect, where a really high energy photon gives the electron it kicks off some extra energy to travel away with? Bad analogy? Probably.
I'd love if someone else has a better analysis. CoughCommissionerRaboCough.
I know there is a flaw in that argument. Is it because gravity acts at the full extent of its force the entire 600 feet, and air resistance starts at ~0 and increases to its value at 600 feet?
Another way to look at it is by using W = Fd. Since the object accelerates downward, the force due to gravity must be greater than the upward force due to air resistance. The gravitational force is constant, and the air resistance increases until it is equal and opposite to gravity, which is when terminal velocity is reached. But since Fa < mg for at least some time period, |Wa| < |Wg|.
I also agree that the photoelectric effect is just a bad analogy. You are right so many counts today!
I see how you are correct. But tell me why this thinking is wrong:
for 600 feet, there is a downward work = F*d = mg600.
Since air resistance also acts for the same distance, d is the same. Also, I thought force of air resistance is the same since at terminal velocity, F grav = -F air resistance.
I know there is a flaw in that argument. Is it because gravity acts at the full extent of its force the entire 600 feet, and air resistance starts at ~0 and increases to its value at 600 feet?
Hey guys,
I had a question on the PS (question#14) about the angular momentum quantum number for Mg2+ after losing its two electrons?
I selected 2 because it goes from 3s2 to a 2p6 when it forms a cation. But its apparently......spoiler alert......zero.
My friend just took AAMC test # 11 and his verbal score really plumetted. Did anyone else find this test's verbal section exceptionally difficult relative to the other AAMC CBT verbal sections?
For BS #129 (the Sn2 rxn problem), how could you tell what the 'D' is supposed to stand for? Without knowing that, how would you assign priorities?
What does each heading mean? 'CatB-/-', does that mean no CatB? So 'CatL+/+' means presence of CatL, 'CatL-/-' means abscence of CatL? So for 'CatB-/-,CatL+/+', when CatB is an "introduced" gene, the cell now has both CatL and CatB?
Then, on #132, the question states "If Experiment 2..." but I do not see where in the passage an "experiment 2" is mentioned. I ended up reading through the whole thing.
Am I missing something here? I lost precious time over these trivial points and thought at least this passage was very poorly designed. I hope I don't run into anything like this on the real thing.
My friend just took AAMC test # 11 and his verbal score really plumetted. Did anyone else find this test's verbal section exceptionally difficult relative to the other AAMC CBT verbal sections?
Hi, this is my first post on SDN. For PS 27, how do you get "P=Fv=-mgVt" from passage? Also, not really getting PS 28 either... Thanks in advance!
Which of the following statements best explains why air resistance is ignored when a compact object falls a very short distance?
A) The object's mechanical energy is constant.
B) The speed of the object remains small.
C) The area presented to the air negligible.
D) Gravity does negligible work in this situation.
The answer is B), but I personally thought C) was also justifiable since the object is "compact" so its "area presented to the air is negligible." And since the net force on the object as it falls is:
F = mg - b(v^2) = m(dv/dt)
where bv^2 is the term equal to air resistance, in which b is a constant that's negatively related to the "area presented by the object perpendicular to the motion through the air." So since both b and v are small, wouldn't BOTH contribute the fact that air resistance can be ignored. The only reason I could think of why B) is a better choice is that the air resitance is proportional to the square of speed while it's only proportional to b, so speed would have greater impact on air resistance. Kinda frustrates me since this is the only question I missed on PS for this exam.
Hey guys I have question on PS # 30. I the magnitude of the air resistance equals the weight of the parachutist, then how will the parachutist fall since the sum of all the forces in the vertical direction would be zero?
What is the magnitude of the air resistance force while the parachutist traveling at vT?
A 40 N
B 75 N
C 750 N
The air resistance on the parachutist at terminal velocity equals the weight of the parachutist which is given by F = m g = 75 kg × 10 m/s2 = 750 N. This is option C.
D 3000 N
Can someone explain to me what CatB -/- means, or CatL +/+ means? Or something like CatB +/-? I'm not understanding this notation.
I seriously think I had this exact same passage on my BS section last time I took the MCAT.
The "+" indicates an allele in the gene coding for the CatL protein that is ABLE to make the protein, so it is the functioning allele. The "-" is a mutant allele of the gene that is non-functional, and thus unable to properly code for the protein. Thus, the cells that were initially CatB -/- and CatL +/+ are able to synthesize the CatL protein but not the Cat B protein.
And since the presence of BOTH proteins AND the EGP viral glycoprotein are required for viral infection, the virus would not be able to infect mutant forms of the cell unless the necessary functioning versions of the gene(s) that were -/- were exegenously inserted.
Thanks. Passage seems a lot clearer with this explanation.
Still unclear as to why bother with the " / " and the dual +/+ or -/- from your explanation.
This "+/+" notation comes from scientific papers (research labs). For example, they would say a mouse is +/+ for long tail. That means that mouse is homozygous dominant for long tail trait. If they say +/- for long tail, that means that mouse is heterozygous for long tail. and if they say mouse is -/-, that means it is homozygous for short tail. It's just a type of notation they use. so just apply this same logic for CatL and CatB.
Hey guys I have a question on # 107 in the BS section. I was wondering if the concept being tested here is in relation to the inactivation of an X chromosome in a female somatic cell (Barr Body). Thanks.
Assume that a certain species with sex chromosomes R and S exists such that RR individuals develop as males and RS individuals develop as females. Which of the following mechanisms would most likely compensate for the potential imbalance of sex-chromosome gene products between males and females of this species?
A Inactivation of one R chromosome in males
The question asks the examinee to apply knowledge about sex chromosome inactivation to a system in which the male is homozygous for the sex chromosomes and the female is heterozygous. By analogy with the mammalian system in which the production of genetic products (mRNA and protein, for instance) from the two X chromosomes in the female is reduced by randomly inactivating one of the X chromosomes, the conclusion can be reached that if the male is homozygous (RR in the system described), inactivation of one R chromosome in males would achieve the appropriate reduction in output of genetic products. Thus, A is the best answer.
B Doubling transcription from the S chromosome in females
C Inactivation of the R chromosome in females
D Doubling transcription from the R chromosomes in males
Sup guys I have a question on # 121 of the BS section. My question is in response to the bolded statement below. Could someone please explain how decreased blood osmolality is indicative of high levels of hydration? Thanks a lot guys!
Which of the following physiological conditions would be LEAST likely to induce thirst?
A. Dry pharynx
B. Decreased blood volume
C. Decreased blood pressure
D. Decreased blood osmolality
This question asks the examinee to identify the physiological condition LEAST likely to induce thirst. Of the options listed, decreased blood osmolality is the option most indicative of high levels of hydration. Thus, D is the best answer.
remember osmotic pressure of of a solution = iMRT. So if blood osmolality is low, that means it is more dilute (smaller M) and contains less solutes (like albumin proteins and Na+), and since less solute for a given volume implies more solvent (in this case the blood plamsa itself), the high concentration of blood plasma indicates high levels of hydration.
Does anyone know what the significance is of the introduced bacterial gene in Figure 1 of Passage 7 in BS section? Is it just a control?
There is no figure 1, but I'm assuming you're talking about question 1.
There is no significance. It was a "discrete" question basically, with some relevance to the passage.
Just asking you what bacterial transformation is.
If you're referring to the passage as figure 1, it was just a piece of information. Didn't have anything to do with the questions.
Unless you didn't know what transformation was, in which you could conclude that to alter the expression of a protective capsule, you need to have a nucleic acid change.