AAMC CBT9 and 9R OFFICIAL Q&A

[Vihsadas]

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This is the official Q&A thread for AAMC CBT9 and 9R.

Please post ONLY questions pertaining to AAMC CBT9 and 9R.
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!

 

[sanguinee]

@Cawolf So in electrolytic - the direction of flow is changing, but the anode and cathode remain at the same place and undergo the same function?

 

[Cawolf]

I think you are confused. The anode and cathode aren't names that apply to certain electrodes. They are descriptors of the role that electrode is playing the cell.

 

[sanguinee]

How exactly is this being calculated? I figured there would be more of III than II

 

[medic86]

How exactly is this being calculated? I figured there would be more of III than II
View attachment 188429

Look at the retention time data. The species that has the larger peak area is the species that predominates. Also, note that the passage just above this states that product II is rapidly converted to product III (and that table 2 tells you the standard retention time of the respective species).

With the peak areas, calculate it as such: 5/15 = 33%, 10/15 = 66%, which is related to what percentage of the mixture each species is responsible for.

 

[cafeverona]

Question 52 BS: Radioactively labelled uracil is added to a culture of actively dividing mammalian cells. In which of the following cell structures will the uracil be incorporated?

Ok this question should be really easy, but it's the way that it's phrased that throws me off. The question asks about how uracil will be INCORPORATED. As in, where will they be added? DNA converts to mRNA in the nucleus, so U is incorporated during translation in the nucleus. Are we supposed to just guess and know that the uracil is already a part of RNA and is therefore on the ribosomes? Help!

 

[TheRhymenocerous]

Question 52 BS: Radioactively labelled uracil is added to a culture of actively dividing mammalian cells. In which of the following cell structures will the uracil be incorporated?

Ok this question should be really easy, but it's the way that it's phrased that throws me off. The question asks about how uracil will be INCORPORATED. As in, where will they be added? DNA converts to mRNA in the nucleus, so U is incorporated during translation in the nucleus. Are we supposed to just guess and know that the uracil is already a part of RNA and is therefore on the ribosomes? Help!

Ribosomes are made of RNA!

 

[cafeverona]

Ribosomes are made of RNA!

Ok I guess it's that easy then haha. Thanks

 

[TheRhymenocerous]

Was anyone annoyed with/confused by #80?

"Elegiac" means mournful. An elegy is a funeral poem – clearly about death and loss. How is that "serenely reflective" and not "profoundly grieving?" I don't think profound grief is a great way to phrase it, but it's closer to the actual meaning than serene reflection... All my poetry classes really screwed me over on this one haha

 

[Cawolf]

@TheRhymenocerous

I did not know the definition before reading the passage.

The only description of their behavior is being "absorbed in calm discussion and pensive contemplation" and "mellow meditation".

I took these words to be most closely aligned with serenity and reflection.

I could see how knowing the definition may be misleading.

 

[TheRhymenocerous]

@TheRhymenocerous

I did not know the definition before reading the passage.

The only description of their behavior is being "absorbed in calm discussion and pensive contemplation" and "mellow meditation".

I took these words to be most closely aligned with serenity and reflection.

I could see how knowing the definition may be misleading.

Haha yeah, I didn't even look back at the passage because I was like "hell yeah, I know all about elegies." Even in the answer choices they back it up by defining it as "serenely reflective mourning." You can't just ditch the mourning part! Alas. Lesson is: don't assume they expect you to use your prior knowledge of poetry to answer a question.

 

[Cawolf]

@TheRhymenocerous I encountered many situations in verbal where knowing too much outside information was detrimental!

 

[TheRhymenocerous]

Okay, another question. For #47, I realize I probably should have chosen A because it's more general, but nuclei also do a lot of absorbing and emitting and I'm not really sure what "atomic structure" means. I think their explanation has a typo because it seems to say B is correct. Any insight?

 

[Cawolf]

@TheRhymenocerous

I also found the answer choices vague. The reason I chose A was because I was looking for an answer that could describe the photon raising the energy level of electrons - followed by de-excitation and subsequent photon emission. I believe "atomic structure" refers to the electronic structure. As poorly worded and archaic as the answer choices sounds, I encountered questions on the real MCAT that had answer choices (correct ones hopefully) that involved old and outdated terms.

 

[TheRhymenocerous]

I guess I should brush up on my vague, outdated vocabulary. Thanks @Cawolf!

 

[Fortyfive]

Hello,

This is a question on AAMC CBT 9, BS passage 6

According to the passage, Peptide A (@ 25 ng/mL) binds to a receptor on cell membranes and promotes a constant secretion of osteoblatin. Peptide B is a competitive inhibitor of Peptide A.

131. When osteoblasts (OB) are incubated with a constant concentration of peptide A (25 ng/mL) and increasing concentrations of B, osteoblatin concentration:
a) increases exponentially
b) increases linearly
c) remains the same
d) decreases
The question asks the examinee to identify the relationship between the osteoblatin concentration and the increasing concentrations of peptide B when osteoblasting are incubated with a constant concentration of peptide A. Peptide A stimulates the production of the osteoblatin, but peptide B does not. Furthermore, Peptide B competitively inhibits Peptide A by binding to the same receptor sites on the cell membranes. As the concentration of the peptide B increases, more and more receptor sites are occupied by the peptide B rather than by Peptide A. This prevents peptide A from being able to activate expression of osteoblatin, therefore decreasing the osteoblatin concentration (D). A, B, C are incorrect becuase the osteoblatin concentration does not increase exponentially (A), increasing linearly (B), or remain constant (C). Thus, D is the best answer.

Why does the osteoblatin concentration decrease? Wouldn't the osteoblatin already made (before B was added) just stay the same? The passage says nothing about osteoblatin disappearing on its own and Peptide B doesnt affect osteoblatin directly in anyway

Can someone plz explain? 0.o

Thanks

 

[RSK25]

Can someone explain 119 from Verbal Section ? This is 9R