AAMC CBT8 and 8R OFFICIAL Q&A

[Vihsadas]

This is the official Q&A thread for AAMC CBT8 and 8R.

Please post ONLY questions pertaining to AAMC CBT8 and 8R.
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!

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[gettheleadout]

This question really really baffles me, cause the first thing the passage does is "make a distinction between literature and literary art". But AAMC is telling me that they're one and the same? WTF? The author is always careful to say "literary study" or "literary scholarship", and never uses the word "literature" as a substitute for the study of the literature. The Kaplan explanation is also bad; it says "C" is wrong because the author never says anything about artistic pursuit. But in the second sentence he states "The two are distinct activates: [Literature] is creative, an art..."

So bothered by this.

This post is great and really highlights how inept the AAMC is at writing questions/answers.

 

[Synapsis]

But, as the passage is written, it's not metathesis, so you can POE the question to be anything, such as I did assuming they wanted it construed as "reverse decomposition."

Fair, so I guess I had the luck of not knowing what one of the answer choices meant. Wonder if that'll happen again lol.

 

[Gauss44]

#28
Which of the following statements best explains the tempurature change shown in figure 1?

Correct answer: B The work done by the gas in expanding decreases it's internal energy.



Me: In that case, wouldn't it be an exothermic reaction making the surroundings warmer? And D correct?

Please help!

 

[gettheleadout]

#28
Which of the following statements best explains the tempurature change shown in figure 1?

Correct answer: B The work done by the gas in expanding decreases it's internal energy.



Me: In that case, wouldn't it be an exothermic reaction making the surroundings warmer? And D correct?

Please help!

Ah I see where your confusion lies. There is no reaction, so nothing is exothermic. The ∆U of the gas in the balloon drops because it loses internal energy to work (done against the water) while expanding. Temperature is a measure of internal energy so as it expands the temp. of the gas drops. No heat flow is actually occurring. (First Law: ∆U = Q - W)

Thus, the process is not exo- or endo-thermic, but likely adiabatic, as we're not given any information about the thermal conductivity of the balloon.

In any case, D is incorrect because the graph actually shows temp. increasing with compression. (Depth increases to the right, and the balloon becomes compressed as it is submerged deeper by Boyle's Law.)

 

[onedirection]

The Double slit one

IN yOung's experiment, S produces spherical wave fronts,
The light entering S1 and S2 will most likely consist of plane waves if the distance between

I thought it was T1 and T2 is small because it would look likea flat line if things were close together

Why is it t1 and T2 is large

 

[monkeyvokes]

The Double slit one

IN yOung's experiment, S produces spherical wave fronts,
The light entering S1 and S2 will most likely consist of plane waves if the distance between

I thought it was T1 and T2 is small because it would look likea flat line if things were close together

Why is it t1 and T2 is large

the line would still be rather bent if the wave is new, closer to the slit. as it expands out it flattens out. Consider a very small circle and a very large circle, if you take a 1 inch segment of line from both then the large circle's segment will be much straighter.

 

[sunflower18]

This question was asked about once, I think, but I still didn't and don't understand.

BS 106:
"If restriction of blood flow to the kidneys (by placing clamps on renal arteries) resulted in an immediate but small increase in blood pressure, followed by the gradual development of severe hypertension, which hypothesis would best support these results?
A) Hypothesis A, because the clamps increased the vascular resistance to blood flow
B) Hypothesis A, because the clamps caused the kidneys to receive less blood
C) Hypothesis B, because the kidneys were responding to decreased glomerular blood pressure
D) Hypothesis B, because the volume of body fluids was probably decreasing"

So I put B, but the answer is C.

I understand why, in a normal and healthy person, the mechanism described by C makes sense -- if the kidneys are getting decreased amounts of fluid via the glomerulus, they will activate the renin-angiotensin system to conserve fluid to increase blood pressure. Because, by their perspective due to the clamps, the body is severely hypotensive. But actually it's not, so the activation of renin-angiotensin causes hypertension instead of the original goal of returning pressure to normal. I get that.

HOWEVER, Hypothesis B says that the failure of the kidneys to respond to changes in normal glomerular filtration rate causes hypertension. So I don't understand how Answer Choice C supports Hypothesis B, if the kidneys in Hypothesis B can't appropriately respond to hyper/hypotension, but Answer Choice C is all about appropriate renal response to perceived hypotension.

I guess I faintly see the connection between Answer Choice C and Hypothesis B, but I don't fully understand how tricking the kidneys into thinking that the body is hypotensive, which causes renin-angiotensin activation in attempts to normalize their perceived blood flow, is the same thing as a chronic inability of the kidneys to respond correctly to normal blood flow.

 

[caxoo]

AAMC 8R - Question 27

The Question: Reaction 1 is effective at decreasing acidic water hardness because:
a) increases pH and decreases CaCO3 solubility
b) decreases pH and decreases CaCO3 solubility
c) increases pH and converts HCO3 to water
d) decreases pH and removes Ca2+ from solution

The answer is A. I don't understand how it decreases CaCO3 solubility. From my understanding...

Equations involved:
1) CaCO3 + H+ (acidic solution) <-> Ca2+ + 2HCO3-
2) Ca2+ (from above) + X (what I'm labeling soap) <-> CaX(s)

3) (proposed removal step) Ca2+ + 2HCO3- <-> CaCO3(s) + H2O + CO2
(then you remove CaCO3)


So hardness is derived from presence of Ca2+ ions after dissociation from CaCO3 in (1). If you involve (3) you are removing the products from (1). In (3), removing CaCO3 causes more Ca + 2HCO3 to form CaCO3 from (3). As more Ca + 2HCO3 forms CaCO3, you see in (1) this means the product in (1) is decreasing, forcing more CaCO3 to dissociate from (1).

It doesn't seem to make sense that you're decreasing CaCO3 solubility; rather, you are in fact increasing solubility a la Chatlier since you're removing product from (1), allowing more of CaCO3 to dissolve to revert back to equilibrium.

It does make sense to me that you're overall removing Ca2+ from the solution, and D seems correct to me. But apparently not! I feel like it has something to do with the fact that CaCO3 is involved in both (1) and (3) but I can't figure it out. Also apparently reaction (1) decreases amount of CO2. So the answer must stem from the fact that D says it would decrease pH. I really don't understand how it decreases CO2 (it in fact seems to increase CO2 to me). Also it still doesn't make sense that the solubility of CaCO3 is decreased. Anybody figure this one out?

Thanks in advance

 

[greenseeking]

I said the same thing, but 270 degrees and 90 degrees are the same thing, so there can't be 2 answers. 45 degrees doesn't make sense so you're left with 180 degrees.

Still don't know how 180 degrees is justified other than the fact that none of the other answers were correct. It's like saying I know these are wrong, and don't know about this, but I'm picking it anyways.

This is the PS section Question 12.

I know this is an old post but has anyone figured this out yet? I got 90 degrees. because you're talking about B2 not B1. The above explanation of 270 and 90 being the same doesn't make sense to me.

 

[FeinMS]

Read the question carefully, the question asks something like "By how much angle does B2 rotate H nucleus?" Not "At what angle does B2 rotate with respect to H nucleus?" I got the question wrong thinking that the question was asking for the latter, and ended up debating whether the answer is 90 or 270 which are the same thing.
Since H nucleus was parallel to B1 and end up being anti parallel to B1, it must be turned by 180 degrees. And B2 does that turning.

 

[greenseeking]

Read the question carefully, the question asks something like "By how much angle does B2 rotate H nucleus?" Not "At what angle does B2 rotate with respect to H nucleus?" I got the question wrong thinking that the question was asking for the latter, and ended up debating whether the answer is 90 or 270 which are the same thing.
Since H nucleus was parallel to B1 and end up being anti parallel to B1, it must be turned by 180 degrees. And B2 does that turning.

Ok- also, how is 90 and 270 the same? isn't 270 actually -90 (90 in the other direction?)

 

[FeinMS]

Ok I guess it's more correct to say that 90 and 270 are anti parallel with each other. But if you interpret the question as "at what angle does B2 rotate with relative to B1?" you can't find an answer because the only thing you know is that B1 and B2 are perpendicular to each other. Let's assume B1 points north, then B2 can point either east or west. And depending on what you choose between east and west, the angle can be 90 (if west is chosen and angle is measured counter-clockwise bc it's the convention) or 270 (if east is chosen, and angle is measured ccw.) That's why I was debating between 90 and 270. The problem lied within misinterpreting the question.

 

[missdoc92120]

Is there a shortcut to this problem? I understand how to do the punnet square but that takes too long.

143.) In a particular species of plant, tall vine depends on a dominant gene(T) and a pink flower is the result of the heterozygous condition of the genes for red and white flowers(Rr). What fraction of the offspring from the cross of a tall pink plant (heterozygous for height) with a short, pink plant would be expected to be pink AND tall?
the answer is 1/4

Thanks!

 

[FeinMS]

No just do the punnet square. If you have trouble doing 2 traits, do one trait by one and multiply the probability

 

[sshah92]

I think PS #46 might be wrong.

Ba2+ is an ion that is very toxic to mammals when taken internally. Which of the following compounds, mixed in water, would be the safest if accidentally swallowed?

BaSO4, Ksp = 1.1E-10
BaCO3, Ksp = 8.1E-9
BaSO3, Ksp = 8.0E-7
BaF2, Ksp = 1.7E-6

Isn't is BaF2? For first three, Ksp = [M][M] so molar solubility is simply X^2. For the last one, Ksp = [Ba2+][2F-]^2 or 4M^2. Thus the molar solubility of BaF2 is the lowest and therefore BaF2 would be safest to ingest, right?

From my understanding, the relative Ksp values for a group of salts is NOT a good indicator of their relative solubilities. This is because the units of solubility product (Ksp) vary with the number of ions. Solubility is determined by the molar solubility of a salt, not the solubility product Ksp.

RIGHT?! @BerkReviewTeach, this is what I gathered from the TBR course material

EDIT: Have a few more questions! I'm thoroughly confused by Passage II (the semicarb/furaldehydge one). If anyone could go over the passage that would be awesome!

BS #100: Why does higher melting point indicate thermodynamic stability? From my understanding, thermodynamic products take longer to form because they have higher Ea's, but how does this translate to having higher melting points?

BS #102: In each experiment, the crystals are collected on a Hirsch funnel and washed with two portions of cold water in order to:

Isn't the answer A) recrystallize the product? I thought about removing soluble impurities but there's a layer of filter paper seperating the thin holes of the Hirsch funnel -- would these impurities go THROUGH the filter paper then?

 

[sshah92]

BS #113: Phagocytosis results from ACTIN polymerization, not microtubule formation. This isn't really basic MCAT material buuut anybody can look this up (and it's covered in cell bio textbooks). Both modulate the cytoskeleton, but to say that phagocytosis is tremendously affected by microtubule disassembly seems like a FAR faar stretch. How is B justified as the right answer?

From passage: "Another drug used to treat gout is colchicine, an inhibitor of microtubule reorganization."

"Colchicine most likely relieves gout symptoms through what mechanism?
B- Inhibition of leukocyte phagocytosis of uric acid crystals."

 

[sshah92]

BS #129: If Anolis lizards have XY chromosomal sex determination, the locus of a gene for the UV reflectance pigment:

D) could be on a sex chromosome or on an autosome

So I got this right solely off this assumption: Humans too have XY chromosomal sex determination; doesn't mean the locus of any gene has to be located on a sex or autosomal chromosome.

However, looking back at the passage, it does say that the dewlap is a structure found only in males. Now if the gene for the UV reflectance pigment is NOT located on females, can't we assume that it must be on a Y chromosome?

Is the MCAT wanting us to think that there is a very remote possibility that this gene could be on an autosomal chromosome and that it's expression is turned off in EVERY female?! Whether it's some form of imprinting or epigenetic regulation, this seems super unlikely... I'm confused.

BS #131: Which of the following conclusions about dewlap reflectance is supported by information in the passage?

A) Lizard habitat is determined by dewlap reflectance for each species.
B) High UV dewlap reflectance is most important in brightly lit habitats.

A and B sound extremely similar to me. The right answer is B but I chose A. As we see from Figure 1, the 3 species that live in unshaded fields possess dewlaps that are more capable of reflecting UV light than the other two species that live in shade. B just seems like a bad choice since what exactly would "important" entail, whereas A seems justified in this sentence from the passage: "The investigators concluded that there was a relationship between dewlap UV reflectance and habitat." What gives?

 

[sshah92]

BS #134: I just took Cell Bio last semester and from my understanding, myosin II walks toward the + end of actin filaments, which are embedded in the D disks. This causes contraction in smooth muscles. Myosin II does NOT walk toward the - end.

But the answer says otherwise: "The - ends of the microfilaments are capped by Z lines, and the + ends are capped by another protein." Isn't this just... wrong?

BS # 135: Treadmilling occurs over a RANGE of concentrations. According to Fig 1, CC+ is at 1 micromolar and CC- is at 4 micromomlar. If we're at 1.5 (or even 2.5, or 3.5 micromolar), the positive end is polymerizing (because the cell has sufficient free actin to support growth at the + end) while the negative end is depolymerizing. The CCo should be somewhere between these two points, around 2.5 micromolar, but even that number (which doesn't say much about treadmilling) isn't 1.5 micromolar.

Shouldn't the right answer be D (between 1 and 4 micromolar)? I see nothing on the graph or in this passage that supports 1.5 micromolar being the only concentration at which treadmilling occurs!?

 

[sazerac]

Treadmilling means the addition and subtraction rates are exactly equal and it neither grows nor shrinks.

At a concentration of 3.5, you'll be adding super fast and subtracting hardly at all, and you won't be treadmilling you'll be growing. At what X value on the graph are the addition and subtraction rates equal?

Remember, the BS section is also a VR section. It tests you on reading the passage as presented and not bringing in outside knowledge.

 

[sshah92]

Treadmilling means the addition and subtraction rates are exactly equal and it neither grows nor shrinks.

At a concentration of 3.5, you'll be adding super fast and subtracting hardly at all, and you won't be treadmilling you'll be growing. At what X value on the graph are the addition and subtraction rates equal?

Remember, the BS section is also a VR section. It tests you on reading the passage as presented and not bringing in outside knowledge.

Right, but 1.5 wouldn't be treadmilling either because we'd be adding relatively slowly at positive end but subtracting even more from the negative end. Doesn't seem like a likely answer either whereas D seems like the safer choice. I'd definitely agree that not bringing in outside knowledge is crucial for VR and to a certain extent PS but exposure to upper division material definitely helps on the BS.

 

[sazerac]

Right, but 1.5 wouldn't be treadmilling either because we'd be adding relatively slowly at positive end but subtracting even more from the negative end. Doesn't seem like a likely answer either whereas D seems like the safer choice. I'd definitely agree that not bringing in outside knowledge is crucial for VR and to a certain extent PS but exposure to upper division material definitely helps on the BS.

You aren't reading the graph correctly. Draw a vertical line at 1.5, and note that only at that value will the (+) be above the zero on the Y axis as much as the (-) is below the zero line. The slope of the (+) line is >>> the slope of the (-) line.

 

[sshah92]

Can anyone explain the answer to BS 134 again?

The answer: "The - ends of the microfilaments are capped by Z lines, and the + ends are capped by another protein." However, myosin walks toward the + (barbed) end on actin filaments during contraction, and the barbed end is capped by Z lines. The minus (pointed) end is capped by another protein. The answer was wrong, right?

 

[sakabato93]

I think PS #46 might be wrong.

Ba2+ is an ion that is very toxic to mammals when taken internally. Which of the following compounds, mixed in water, would be the safest if accidentally swallowed?

BaSO4, Ksp = 1.1E-10
BaCO3, Ksp = 8.1E-9
BaSO3, Ksp = 8.0E-7
BaF2, Ksp = 1.7E-6

Isn't is BaF2? For first three, Ksp = [M][M] so molar solubility is simply X^2. For the last one, Ksp = [Ba2+][2F-]^2 or 4M^2. Thus the molar solubility of BaF2 is the lowest and therefore BaF2 would be safest to ingest, right?

From my understanding, the relative Ksp values for a group of salts is NOT a good indicator of their relative solubilities. This is because the units of solubility product (Ksp) vary with the number of ions. Solubility is determined by the molar solubility of a salt, not the solubility product Ksp.

You had the right way of thinking; in order to determine which species would produce the most ions you have to solve for an at least approximate value for the molar solubility. You can compare the Ksp's of the first three compounds because they have similar expressions for the solubility constant (Ksp= S*S=S^2) because they form the same amount of ions when dissociated. You can conclude that of those three, the first species would produce the least amounts of Barium ions. Next you have to compare the molar solubilities of the first species and the last species. BaF2 has a different solubility constant expression than BaSO4 because BaF2 produces 2F- as opposed to 1SO4 from BaSO4. Thus you have to modify the expression as such: Ksp=S*(2s)^2=4S^3 (Remember to square the second term because you have to raise the term to the power of the amount of moles of ion produced).

After you approximate the values you should get ~10^-5 for BaSO4 and like 10^-2 or 10^-3 for BaF2, can't remember which. From this its obviously BaSO4.

Hope this helps!!!!!

 

[sakabato93]

BS #100: Why does higher melting point indicate thermodynamic stability? From my understanding, thermodynamic products take longer to form because they have higher Ea's, but how does this translate to having higher melting points?

Well, Ea is a characteristic of reaction profiles, so it has more to do with kinetic control of products. Products preferred by kinetic control are the ones that have lower Ea's, which facilitates faster formation of the product.

High melting point doesn't necessarily indicate higher melting point (it may, I'm not sure). The idea is that from the passage data, the tester should be able to come to the conclusion that the thermodynamic product is the species that has the higher melting point. You should be able to determine the species by comparing all of the products that were generated at the same temperature.

 

[sakabato93]

BS #129: If Anolis lizards have XY chromosomal sex determination, the locus of a gene for the UV reflectance pigment:

D) could be on a sex chromosome or on an autosome

So I got this right solely off this assumption: Humans too have XY chromosomal sex determination; doesn't mean the locus of any gene has to be located on a sex or autosomal chromosome.

However, looking back at the passage, it does say that the dewlap is a structure found only in males. Now if the gene for the UV reflectance pigment is NOT located on females, can't we assume that it must be on a Y chromosome?

Is the MCAT wanting us to think that there is a very remote possibility that this gene could be on an autosomal chromosome and that it's expression is turned off in EVERY female?! Whether it's some form of imprinting or epigenetic regulation, this seems super unlikely... I'm confused.

Well, the idea is that we don't have any information about whether or not the female lizards have the pigment. The passage says that UV pigment is located in the dewlap, but it doesn't identify any gene linkage that relates the two.

BS #129: If Anolis lizards have XY chromosomal sex determination, the locus of a gene for the UV reflectance pigment:
BS #131: Which of the following conclusions about dewlap reflectance is supported by information in the passage?

A) Lizard habitat is determined by dewlap reflectance for each species.
B) High UV dewlap reflectance is most important in brightly lit habitats.

A and B sound extremely similar to me. The right answer is B but I chose A. As we see from Figure 1, the 3 species that live in unshaded fields possess dewlaps that are more capable of reflecting UV light than the other two species that live in shade. B just seems like a bad choice since what exactly would "important" entail, whereas A seems justified in this sentence from the passage: "The investigators concluded that there was a relationship between dewlap UV reflectance and habitat." What gives?

Agreed. Absolutely agreed. Absolutely, absolutely agreed. I had qualms with the entire passage actually.

 

[sshah92]

Well, the idea is that we don't have any information about whether or not the female lizards have the pigment. The passage says that UV pigment is located in the dewlap, but it doesn't identify any gene linkage that relates the two.



Agreed. Absolutely agreed. Absolutely, absolutely agreed. I had qualms with the entire passage actually.

Thank you so much!

 

[Schenker]

BS #131: Which of the following conclusions about dewlap reflectance is supported by information in the passage?

A) Lizard habitat is determined by dewlap reflectance for each species.
B) High UV dewlap reflectance is most important in brightly lit habitats.

A and B sound extremely similar to me. The right answer is B but I chose A. As we see from Figure 1, the 3 species that live in unshaded fields possess dewlaps that are more capable of reflecting UV light than the other two species that live in shade. B just seems like a bad choice since what exactly would "important" entail, whereas A seems justified in this sentence from the passage: "The investigators concluded that there was a relationship between dewlap UV reflectance and habitat." What gives?

This is a classic passage-based question trick also encountered in the verbal section.

Which of the following conclusions is supported by information in the passage?

A) A specific conclusion that would be a logical hypothesis to make but that slightly, and subtly, oversteps the scope of evidence in the passage.
B) A vaguer conclusion similar to answer choice A.
C) A conclusion that is obviously bogus.
D) A conclusion that is also obviously bogus.

That is, answer choice A makes a causative claim on the relationship between reflectance and habitat where only a correlational relationship can be drawn from the data. An experiment that supports answer choice A would have to release lizards of different dewlap reflectances into the wild and observe their habitat preferences; I could be wrong since I don't have access to the passage, but I would guess that the passage stopped short of describing any such experiment. On the other hand, answer choice B simply states the existence of a correlational relationship between reflectance and habitat, namely, that the data suggest that high UV dewlap reflectance carries some sort of non-random significance in bright habitats.

This isn't to say that of two similar answer choice the more vague choice is always correct.

 

[Osteoth]

Man the PS on this test was hard!

 

[dudewheresmymd]

The kaplan explanation to C in this questions says "
Since speed is an indication of kinetic energy and temperature, its variation will affect temperature,

thus serving as another predictive component—we can eliminate choice (C) as well."

What the heck is it the speed of the balloon or the speed of the gas molecules inside the balloon? This is vague. Anyone care to comment?

 

[faith hopelove]

BS #102:

In each experiment the crystals are collected on a Hirsch funnel and washed with 2 portions of cold water in order to?

The answer is to remove soluble impurities. I thought the answer was to remove in soluble impurities because was were collecting the solids. What am I missing here?

 

[SKation]

Thanks guys!

Hey,

I'm still confused in the same aspect you were, is the 10 m incline plane talking about the height of the plane or the hypotenuse portion of the plane?

Thankss

 

[gettheleadout]

So, this is from AAMC 8 Passage 4 of the PS section:

Q: "When designing his experiment, Galileo could have allowed the spheres to drop from a height of 10 metres rather than using the 10 metre inclined plane. The main advantage of using the inclined plane is that on the inclined plane the (ignoring air resistance, friction, and rotation):

A) final velocity of a sphere is faster
B) final velocity of a sphere is slower
C) spheres take longer to reach the bottom
D) spheres take less time to reach the bottom

Answer: C

Apparently, the "path is longer for the incline plane than the free fall, and therefore, it takes the spheres longer to reach the botoom on the inclined plane"

Why is this??? If the height of the free fall is 10 m, and the length of the inclined plane is 10 m, then for both cases, the distance is 10 m, no?

I'm so confused

If the sphere is dropping straight down, then the acceleration = gravity and capped at 10m/s^2

But if you go down the incline plane, the acceleration is proportional to the angle of the incline. So if there is an incline (<90 degrees), then the acceleration will always be less than 10 m/s^2 and take longer to reach the bottom.

The equation for the incline is F=mgsin(theta), so that means a = gsin(theta). So if sin(theta) is anything less than 1, which it has to be if there was an incline, then a < g

The horizontal (along length of inclined plane) component of gravity is less than the vertical component of gravity in free fall, so the acceleration is reduced for the inclined plane, which is why the balls take longer.

Thanks guys!

Hey,

I'm still confused in the same aspect you were, is the 10 m incline plane talking about the height of the plane or the hypotenuse portion of the plane?

Thankss

Merging with Official AAMC 8 Thread.

 

[467167]

For question 40, how do I know what gas forms? I knew that it couldn't be A or B, and CO2 seemed the most logical. However, I'm trying to figure out why a gas forms in the first place and why NiCl2 and H2CO3 can't form. Any explanations? I've looked at the Kaplan and AAMC explanations, which make sense, but am still not sure why the two products I listed above wouldn't form.

 

[DrknoSDN]

Technically H2CO3 does form but H2CO3 spontaneously decomposes into H2O and CO2. Just one of the gas evolution reactions that needs to be memorized. Like all spontaneous reactions, it occurs because of free energy change being favorable for the forward reaction.

 

[WierdScience]

BS #102:

In each experiment the crystals are collected on a Hirsch funnel and washed with 2 portions of cold water in order to?

The answer is to remove soluble impurities. I thought the answer was to remove in soluble impurities because was were collecting the solids. What am I missing here?

Washing with water would not remove insoluble impurities because they would just stay on the Hirsch funnel paper with the rest of the solids. The water is only going to clean off the soluble impurities, which will end up in the solution below the funnel. And the reason for cold water is to not dissolve the desired chemical.

 

[Thisisthelife]

Verbal # 61 (#87 on the R version)

Could somebody who got this right please explain how they arrived at the correct answer and why D is a better answer than C?

 

[IslandStyle808]

Verbal # 61 (#87 on the R version)

Could somebody who got this right please explain how they arrived at the correct answer and why D is a better answer than C?

I also came to the same wrong answer (LOL). So in terms of picking the right choice in a certain timeframe, my answer may not help, but I will tell you what I know. The key to question lies in two aspects 1) the authors main message 2) the proof in the paragraph. The main message of the paragraph is that "literary scholarship has its own valid methods" (2nd to the last paragraph, last sentence). This is why C is wrong because you are taking an approach that is of scientific method, which the author says is okay, but does not help as much as a literary analysis. The second proof is in the 2nd paragraph "...assimilate it to a coherent scheme which must be rational if it is to be knowledge. " However, the AAMC does a junk job of giving a complete explanation as to the whole "isolating the story elements." This actually is told in the next sentence in a cryptic manner. "It may be true that the subject matter is irrational, or at least contains strongly unrational elements..." Here you need to infer that you need to look at the unrational elements to be able to analyze the literary work. This is most likely why D is the correct answer.

I also would like to hear from someone who got this answer correct because their method to getting to the right answer maybe much more beneficial.

 

[Thisisthelife]

I also came to the same wrong answer (LOL). So in terms of picking the right choice in a certain timeframe, my answer may not help, but I will tell you what I know. The key to question lies in two aspects 1) the authors main message 2) the proof in the paragraph. The main message of the paragraph is that "literary scholarship has its own valid methods" (2nd to the last paragraph, last sentence). This is why C is wrong because you are taking an approach that is of scientific method, which the author says is okay, but does not help as much as a literary analysis. The second proof is in the 2nd paragraph "...assimilate it to a coherent scheme which must be rational if it is to be knowledge. " However, the AAMC does a junk job of giving a complete explanation as to the whole "isolating the story elements." This actually is told in the next sentence in a cryptic manner. "It may be true that the subject matter is irrational, or at least contains strongly unrational elements..." Here you need to infer that you need to look at the unrational elements to be able to analyze the literary work. This is most likely why D is the correct answer.

I also would like to hear from someone who got this answer correct because their method to getting to the right answer maybe much more beneficial.

Actually, this was quite helpful. I think I get it now. C is really too much of a scientific approach. It is the kind of approach that a biologist would take. I think the key word is "structure" which is too analogous to "evolutionary structure." And as you said, the main message is "literary scholarship has its own valid methods." Awesome analysis. Thanks! But yes now the question is how to figure that out given the time we have....

 

[vanillabear55]

nvm, figured it out!

 

[orangetea]

bump! i am still confused about the lizard question and how it can be on both sex and autosome...

 

[straight2thapros]

Thanks for your reply. Your reasoning for the second question makes sense; the only part confusing me was the solubility of the CaCO3.

As for the first question, I'm still confused. If Ca2+ is being removed, wouldn't the equilibrium shift to the left, increasing the solubility of CaCO3. Shift to the left would also lead to a decrease in H+, since HCO3- are being produced. Thanks.

I think the way to think about this problem is slightly different than how others here are describing.

The passage, in my view, doesn't really explain what's going on but instead is relying on your knowledge of the bicarbonate buffering system:

CO2 + H2O<>H2CO3<>HCO3- + H+

The acidic solution caused CaCO3 to dissolve... It's not like we added CaCO3 to pure water because the solution would then be basic. If you thought of it in that way, (as I did when I took this exam), you may assume that making a right shift (in given equations) would decrease pH (because as mentioned before, HCO3- is being removed from what was thought to be an alkaline solution).

Let's look at the equations again:
Ca2+ + 2HCO3- --> CaCO3 (s) + H2O + CO2 (g).
Ca2+ + 2HCO3- +Ca(OH)2 - --> 2CaCO3 (s) + 2H2O

A better way of thinking of this problem is that these reactions are moving to the left of the bicarb equation. In the first reaction, it's easier to see, because we have Le Chatlier's principle at work: removing CO2 from boiling causes left shift (in bicarb eq.) and decrease in H+ and increase in pH. In the second, I would argue that removing CaCO3 is the equivalent of removing CO2 which also results in leftward shift. Alternatively it may be thought that HCO3- is being drawn away and thus needs to pull H+ with it.

I might be wrong but I think this is more satisfactory of an explanation to think of it in terms of the bicarb equation

 

[IslandStyle808]

I think the way to think about this problem is slightly different than how others here are describing.

The passage, in my view, doesn't really explain what's going on but instead is relying on your knowledge of the bicarbonate buffering system:

CO2 + H2O<>H2CO3<>HCO3- + H+

The acidic solution caused CaCO3 to dissolve... It's not like we added CaCO3 to pure water because the solution would then be basic. If you thought of it in that way, (as I did when I took this exam), you may assume that making a right shift (in given equations) would decrease pH (because as mentioned before, HCO3- is being removed from what was thought to be an alkaline solution).

Let's look at the equations again:
Ca2+ + 2HCO3- --> CaCO3 (s) + H2O + CO2 (g).
Ca2+ + 2HCO3- +Ca(OH)2 - --> 2CaCO3 (s) + 2H2O

A better way of thinking of this problem is that these reactions are moving to the left of the bicarb equation. In the first reaction, it's easier to see, because we have Le Chatlier's principle at work: removing CO2 from boiling causes left shift (in bicarb eq.) and decrease in H+ and increase in pH. In the second, I would argue that removing CaCO3 is the equivalent of removing CO2 which also results in leftward shift. Alternatively it may be thought that HCO3- is being drawn away and thus needs to pull H+ with it.

I might be wrong but I think this is more satisfactory of an explanation to think of it in terms of the bicarb equation

I feel bad for saying this, after all your hard work, but the person you are responding to asked that question 5 years ago.

 

[cafeverona]

EDIT: PS Question 24: "An astronaut on Earth notes that in her soft drink an ice cube floats w/ 9/10 of its volume submerged. If she were instead in a lunar module parked on the Moon where the gravitation force is 1/6 that of Earth, the ice in the same soft drink would float:"

Answer = with 9/10 submerged


I know this was asked before, but my question is on the wording of the passage. Since when does gravitational force refer to the gravitational constant, g? I thought the entire force on the moon that was due to gravity was 1/6 the force on the earth due to gravity (mg). So, 1/6(mearthgearth). Honestly, none of the answer choices made sense with this line of thinking, but I'm still confused...

 

[sxld_cu]

Gah, scored two points lower than normal because of verbal.

Anyone else get absolutely murdered by verbal?

EDIT: just figured out why... 4 questions wrong on that damn literature studies passage

GAH ME TOO - same passage too!

 

[sxld_cu]

Can someone explain #99 in BS - Which of the following rationales explains which compound is the product of kinetic control?
I was stuck between A) semicarbazone has a lower melting point and C) its reaction profile has lower activation energy
I chose A and C is the correct answer. Why would choice A not be correct? Thanks very much!

 

[sxld_cu]

Ah sorry to keep on posting... I have a question on #19 of PS that I hope someone can help me clarify
The question is on Passage IV about Aristotle and Galileo's theories on falling objects (natural motion, violent motion etc.)
Although I originally got this question right, I don't think I had the correct thought process.
When it says that a 10 m plank is being used, does this imply that the plank is being held vertically? That is what I assumed since the answer explanation says that "ignoring air resistance, rotation, friction, the final velocity of a sphere that drops is the same as the final velocity of a sphere that moves down the inclined plane". I'm presuming that this means that the sphere starts at the same height, have the same potential energy so will have the same kinetic energy at the bottom. However, that must mean that the displacement is the same (on the contrary, the answer explanation says that the path on the plane is longer) so under conditions of no friction, air resistance, time would be the same. I assumed that because it was on a nearly-frictionless plane, the sphere on the plane would encounter friction and air resistance, slowing it down and increasing the time needed to reach the bottom.

Also, second question on PS #27: Which of the following would not help in predicting the results shown in Figure 1? (Passage about balloons and depth in tank, and as depth increases, temperature increases)
Choices A and B are easily eliminated
For choice C (variation with depth in the speed of the balloon), the answer explanation makes it seem like it is the speed of the air molecules it is considering. In that case, variation with depth in the speed of the air molecules in the balloon, that makes sense. But does speed of the balloon itself necessarily correlate with the speed of the molecules?

Can anyone help? Thank you!!

 

[cafeverona]

Ah sorry to keep on posting... I have a question on #19 of PS that I hope someone can help me clarify
The question is on Passage IV about Aristotle and Galileo's theories on falling objects (natural motion, violent motion etc.)
Although I originally got this question right, I don't think I had the correct thought process.
When it says that a 10 m plank is being used, does this imply that the plank is being held vertically? That is what I assumed since the answer explanation says that "ignoring air resistance, rotation, friction, the final velocity of a sphere that drops is the same as the final velocity of a sphere that moves down the inclined plane". I'm presuming that this means that the sphere starts at the same height, have the same potential energy so will have the same kinetic energy at the bottom. However, that must mean that the displacement is the same (on the contrary, the answer explanation says that the path on the plane is longer) so under conditions of no friction, air resistance, time would be the same. I assumed that because it was on a nearly-frictionless plane, the sphere on the plane would encounter friction and air resistance, slowing it down and increasing the time needed to reach the bottom.

Also, second question on PS #27: Which of the following would not help in predicting the results shown in Figure 1? (Passage about balloons and depth in tank, and as depth increases, temperature increases)
Choices A and B are easily eliminated
For choice C (variation with depth in the speed of the balloon), the answer explanation makes it seem like it is the speed of the air molecules it is considering. In that case, variation with depth in the speed of the air molecules in the balloon, that makes sense. But does speed of the balloon itself necessarily correlate with the speed of the molecules?

Can anyone help? Thank you!!

For PS 19--I thought this question was worded poorly, but you are to assume that the height of the plank is 10 m. Since the hypotenuse is the longest side of a triangle, the displacement in the incline setup would be greater than in the free fall set up. The plank can't be held vertically, because that wouldn't make it an incline plane. The horizontal component of the gravity on an incline is always less than the gravity due to free fall (sintheta for any angle of an incline is going to be <1...again, if it's vertical, it's not an incline). Thus, your acceleration on the incline will be less than your acceleration due to free fall, so it will take more time to go down the incline than just to free fall. According to the constant acceleration equation: d = 1/2at^2; when you decrease acceleration, you’re increasing time.

 

[sxld_cu]

Thank you @cafeverona! That makes a lot of sense! I agree, that question was worded a bit poorly but now I understand!

 

[Lunasly]

This is from AAMC8 BS

Which of the following characteristics clearly marks fungi as eukaryotes?
A) they have cell walls
B) they contain ribosomes
C) they contain mitochondria
D) they exhibit sexual reproduction

Answer is C, but why not D??

Since when do prokaryotes reproduce sexually????????????

To the best of my knowledge, prokaryotes do not reproduce sexually. Transduction, conjugation, and transformation have nothing to do with reproduction. Instead, they are just ways in which one can introduce genetic variability in an organism. However, according to sendoymbiotic theory, mitochondria are though to be bacteria (prokaryotes) themselves. Therefore, you can't have a prokaryote inside a prokaryote.

Can anyone else confirm answer choice D?

 

[sxld_cu]

To the best of my knowledge, prokaryotes do not reproduce sexually. Transduction, conjugation, and transformation have nothing to do with reproduction. Instead, they are just ways in which one can introduce genetic variability in an organism. However, according to sendoymbiotic theory, mitochondria are though to be bacteria (prokaryotes) themselves. Therefore, you can't have a prokaryote inside a prokaryote.

Can anyone else confirm answer choice D?

I believe the point of the question is to address that the defining characteristic of eukaryotes is membrane-bound organelles, which would only apply to mitochondria. I think they are assuming that conjugation is a form of sexual reproduction for prokaryotes