*"Official" 2013 USABO*

<p>what about the pulmonary embolism question?</p>

<p>@ramboacid - No polar choice on Q1, I don’t think. I remember spending quite some time reading through it to find a polar or charged choice, but in the end I put proline. Also, I’m pretty sure collagen has both proline AND hydroxyproline. </p>

<p>@skater29 - The deadline to send in exams was yesterday. If anyone hasn’t taken the semifinal yet, it’s too late (as far as I was aware). Also, I don’t think anyone was DQed last year for answer discussion on CC prior to answer release (technically there wasn’t an official answers release, I thought). HOWEVER, I shall cease discussion on any questions that haven’t already been brought up just in case. </p>

<p>@ramboacid (again)</p>

<ul>
<li>The wood question was really weird. I put right, since xylem are usually wider than phloem and xylem were on the left. However, I was truly confused and out of time when I reviewed that question, so it’s quite probably that I missed it.</li>
<li>As far as the FRQ goes, Estrogen and Progesterone are only part of the problem. I felt that she’d be deficient in ALL anterior pituitary hormones, and would have all associated symptoms (TSH, ACTH, etc.). I figured that the symptoms provided implied a deficiency in GH, FSH, and LH, and that she should be treated w/ TSH, ACTH, FSH, LH, GH, and Prolactin (not sure if I put prolactin, though). </li>
<li>Horseshoe crabs was cheliceroformes. There’s a picture in Campbell and Reece. </li>
<li>I thought the fertilization question was fine, but I may be mistaken.</li>
<li>For the population growth question, did you just multiply population size by r? (because dN/dt = rN?). That’s what I did, and I got D</li>
<li>Seconded on the arthropods. Since there’s no negative deductions on part 3, I just put everything I could remember about arthropods on the table (in case something might turn out to be right). </li>
<li>Zone of maturation is right on root hairs. </li>
<li>I think you’re right on the nucleotide question. I don’t remember the choices too well, though. </li>
</ul>

<p>I have other questions w/ answers now, but will refrain from further discussion until we have a guarantee that discussing answers is fine.</p>

<p>the website says that deadline to submit tests is march 23. i think we are definitely okay to discuss.</p>

<p>@param123 - Taking your word for it </p>

<p>CONTINUING,

  • I wasn’t sure about the biome questions. For estuary, they gave examples of SOME autotrophs and heterotrophs that might live there, but didn’t really touch on the most important ones (mangroves, for example). As such, I wasn’t sure whether or not that was valid. Like - I’m sure estuaries have grass, algi, clams, worms, and crabs, but those aren’t really representative species of an estuary. I really didn’t like those questions.
  • For the apical dominance question, I put that auxins were no longer being produced in the apical meristem and that auxin kept the lateral buds from developing. I didn’t think that cytokinins were SYNTHESIZED in the lateral shoots. I was pretty sure that they came up from the roots
  • I didn’t realize the flower question had multiple answers, so I put Cactaceae
  • For the floral pattern question (missing B, but has A and C), I put that it would be missing stamens and petals.
  • I posted the answer to Klinefelter’s wrong. It’s actually MEIOSES I AND II of OOGENESIS and MEIOSIS II of SPERMATOGENESIS. Or at least - that’s what I got.
  • MORE TO COME.</p>

<p>wait every question worth 2 points in part A had multiple anwswers
? I only put Schwann cells for the multiple sclerosis question, I was considering oligodendrocytes as well darn it
</p>

<p>For the myoglobin structure question, I put that the oxygen atoms tunnel through alpha helices to reach the heme in the core, but I can’t confirm that on the web except that myoglobin is composed of 8 alpha helices.</p>

<p>@beandelphiki
I agree with the apical dominance question, cytokinins was almost correct except they’re synthesized in the roots and not lateral buds.
I also got D for the population growth question, it was only dN/dt = rN.
I put Cactaceae as well, but how did you know that question is supposed to have multiple answers? There weren’t directions indicating so, IIRC?</p>

<p>Cacti definitely evolved with insects, I put Rosacea but the right answer is Poacea since they are true grasses and don’t even have flowers.</p>

<ul>
<li>There were definitely multiple answers given for the Schwann + Oligo question.

<ul>
<li>I don’t remember what I put for myoglobin (maybe that?)</li>
<li>My bad - I think it only had one answer. Cactaceae was correct, as far as I"m aware</li>
</ul></li>
</ul>

<p>Were you a finalist last year ramboacid?</p>

<p>I know people who havent taken it because of exams in MA.</p>

<p>@beandelphiki
nah I wasn’t a finalist last year, this is my first and last year doing USABO as I’m sadly a senior. I got a 39 on the open exam this year so I was hoping to do well on semis, but I think I got duped by the test (why can’t CEE just say when there are multiple answers >.< lol) I got high honors in chem olympiad last year, so I’m gonna spend the next two weeks trying to make camp for that, though I’d much rather qualify for USABO since organic chemistry isn’t as fun as plants :D</p>

<p>@skater29
but the testing window is supposed to be over o.O
if people are still taking the test, how do we delete our posts?</p>

<p>If there was a delay it would be posted on the CEE web site like during the open exam. AFAIK there have been no weather emergencies in the northeast lately.</p>

<p>I beg to differ, organic chemistry is more enjoyable than basic chemistry.</p>

<p>For the Kleinfelter’s one, I’m pretty sure (but not positive) it was Oogenesis Meiosis I and II and Spermatogenesis Meiosis I</p>

<p>Also, for the GPCR question, doesn’t tryptophan (spelled that wrong) have slight polarity due to its nitrogen ring? That’s why I put tryptophan. Lol I guessed what ramboacid put for the myoglobin question.</p>

<p>@melkor I agree completely,
gen chem < organic chem < biochem and physiology ;)</p>

<p>@mg0305: you’re right re the meiosis klinefelter question.</p>

<p>@mg0305: Trp is effectively hydrophobic</p>

<p>[url=&lt;a href=“http://www.russelllab.org/aas/Trp.html]Tryptophan[/url”&gt;Tryptophan]Tryptophan[/url</a>]</p>

<p>“Role in structure: Being hydrophobic, Tryptophan prefers to be buried in protein hydrophobic cores. The aromatic side chain can also mean that Tryptophan is involved in stacking interactions with other aromatic side-chains.”</p>

<p>Also, Schwann cells are normally unaffected in MS (multiple sclerosis). In fact, because they aren’t targeted, Schwann cells are actively being researched as possible replacements for remyelinating axons in MS patients.</p>

<p>Myoglobin one was the answer choice that talked about rapidly flexing structure to form pockets by which O2 can access</p>

<p>@Darksigma - was the answer to the myoglobin question in Campbell or something outside of Campbell? Also, I thought the MS question was more of a generic “what cells are important in myelin synthesis” than a specific on MS. I’m quite probably mistaken, however. Did you put proline for the amino acid question?</p>

<p>@BeanDelphiki: Outside of campbell, I only knew it because I had a conversation about myoglobin/hemoglobin’s structural dynamics with a professor once.</p>

<p>MS question was definitely a question about MS
 otherwise they wouldn’t have mentioned the disease. Questions with multiple choices were clearly distinguished by the wording of the question - this was not the case for the MS question to my knowledge. But my original post about Schwann cells still stands.</p>

<p>Yes I put proline.</p>

<p>Here are some more questions to discuss.</p>

<p>A certain genetic defect is caused by a sex-linked dominant allele with 70% penetrance. If a man w/ this genetic defect marries a normal woman, what percentage of their children would have this defect?</p>

<p>a) 25% b) 35% c) 50% d) 70% e) 90%</p>

<p>in a chromosome w/ the genes E, F, G, and H, the crossing over frequencies are as follows: E & F: 11% / E & G: 9% / E & H: 3% / F & H: 8%</p>

<p>What of the following are possible crossing over frequencies of genes G and H?
a) 6% b) 8% c) 12% d) 17% e) 19%</p>

<p>For the second electrophoresis question (Part B), which amino acid will move the quickest towards the positive pole in this trial?
a) aspartic acid b) glutamic acid c) lysine d) glycine e) leucine</p>

<p>True or False
The sensation of cold doesn’t depend upon which section of the brain the cold receptors are wired to, but upon which receptors are stimulated.</p>

<p>Bone has interlocking stipules of calcium carbonate</p>

<p>The perception of sound is mediated by the movement of fluid in the semicircular canals against the cupulae</p>