I agree with @BasedBioGod Please DON’T discuss the open exam until Feb. 13.
Please don’t share anymore links on here, because anyone who hasn’t taken the test will be able to access it.
Even if you only let people who took the test, they could leak the document to those who did not take the exam. Someone who doesn’t take this exam seriously can do that anytime.
I agree. We should wait until the testing window closes to discuss.
how would you answer this (#4 on 2013 open exam):
Of the following amino acids, which is least likely to form strong interactions with other
amino acids that contribute to the tertiary structure of a given protein?
A. Histidine
B. Glutamate
C. Cysteine
D. Glycine
E. Serine
It’d be glycine. It only has a hydrogen as an R group, which really won’t do that much compared to any other amino acids.
Hi, I was wondering what the usual cutoff is for semis? What was the cutoff last year for instance
i think last year was something like 22.5 but last year was apparently REALLY hard so idk this year’s might be significantly higher. idk though, i havent taken it yet xD
hmm 22.5 seems really low too.
If you haven’t taken it, how do you know it was really hard? (I haven’t taken it either)
I asked around (in the same situation as you) and amongst people who took it, at least the people I asked, that seemed to be the general consensus
yeah i heard it was hard…expecting cutoff to be around 25-27
Could someone explain this problem? It’s number 8 on the 2013 open exam
- Below are the structures of five amino acids. Select the amino acid that would contribute most significantly to stability of tertiary structure of proteins.
I can’t post pics, but I picked D (cysteine), the only choice with sulfur because it would form a disulfide bridge. But the answer was A. Idk why that’s wrong.
I have the same question ^^. Also, would you say the 2013 exam was easy/average/ or hard?
Yeah i thought it was D too 
can someone explain?
Same question ^^^^^
If one were to follow the path of a human erythrocyte starting from an artery that leads to
the duodenum, the erythrocyte will most likely pass through ___ capillary beds before
reaching the right ventricle of the heart.
A. 1
B. 2
C. 3
D. 4
E. 5
Also, for this question, why is the answer D? I got A, because doesn’t it go out from aorta --> capillary bed --> vena cava --> right atrium --> ventricle?
In my opinion, 2013 was one of the easier exams.
As for the question, the statement is slightly vague and ambiguous.
The reasoning for A is that phenylalanine contributes a lot to the hydrophobic effect, which is one of the most important aspects of tertiary structures.
I’m taking it tomorrow and I’m gonna faaiil
For people who have taken the test, would you say that it was like, easier, or harder than the 2015 test? I have completed taking the test, but since this is my first year doing USABO I wanted to project where I would perform.