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Joined: Sun Dec 29, 2019 5:47 pm


Post by lotus0618 » Wed Jul 29, 2020 11:04 am


Question 29 discrete

What's the difference b/t C and D? The question stem states that the tripeptides don't share common amino acids, so they all have different combinations. That's why I chose D (3^3 =27). Answer C would make sense to me if the tripeptides shared common amino acids.

Q 54 Passage 10:
I don't understand how we get mRNA: UAG as a stop codon from the cDNA: TAG. I got AUC as the mRNA so that's why I'm confused.


Q56 Passage 10:
So this is my thought process:
A. Too extreme "all." Also, electrons in the conductor are not bound to atoms. Idk about the external electric field...
C. There shouldn't be any free electrons in the conductor; otherwise, there would be no electrical field. Electrons should only be bound to the plates of the capacitor.
D. Too extreme "all."

1)Is my understanding correct?
2)can you please explain the external electric field to me? and what are the bound electrons here?
3)why do we want to ensure that the external electric field cancels out the internal electrical field?

Q55 Passage 10:
How do you know that you have to use the kinematics equation to find the acceleration here? is it cause of "average acceleration"? (I know how to do the rest of the calculations to figure out the force)
Posts: 39
Joined: Wed May 27, 2020 7:25 pm


Post by NS_Tutor_Nancy » Fri Jul 31, 2020 2:18 pm



Q29- So the popypeptide is 9 amino acids long and has been hydrolyzed to 3 tripeptides and no amino acids are repeated, that is the key here. To try to elaborate on the AAMC explanation, let's say our three tripeptides are ABC, DEF, and GHI. Because they are pieces from the original, we know that A B and C go in the order ABC, it can't be BCA or CAB, etc. So really now you are just concerned about what order these three segments go in, not the individual amino acids. There are 3 possibilities for which one goes first. After that there are 2 possibilities for which one goes second, and then you are left with 1 possibility for what goes last. 3x2x1 = 6.
Q54- The key to this question is knowing that an amber codon is a stop codon. If you substitute a stop codon into the coding region of cDNA that codes for the receptor, this is a nonsense mutation. When the cell machinery makes the mRNA transcript, it will be stop at the premature stop codon and when this is translated it will result in a truncated non-functional receptor. So no functional full length receptors will be synthesized.


Q55- The question stem does not directly give you the acceleration (which you need to find the force), so that is the first clue to you that you are going to need an equation to calculate acceleration. You are given an initial velocity, a final velocity, and time. It's impossible to know the exact acceleration at every second of the trip from this information, however you can use the equation (vf-vi)/t to find the average acceleration.
Q56- So here the internal electric field is within the conductor that form the defibrillator paddle, and the external electric field is in between the paddles. By definition, a conductor is a material that allows electrons to flow freely, so they shouldn't be bound to atoms and immovable. We want the internal and external electric fields to cancel out because the question stem says that the electric field is 0 and we need to explain why.

I hope this helps!
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