<p>I don’t feel as though posting the 2013 open exam in a general forum follows CEE’s guidelines. I would advise that you remove it.</p>
<p>Is March 6 the score release date?</p>
<p>According to the USABO-TRC website, the score release date is still March 6 but the website says that the date is tentative.</p>
<p>Can someone explain the antelope problem? It was something about how the mother and child had a 25% of escaping and asked for the minimum chance the child needed to survive if the mother sacrificed herself. Also, what was the answer for multi-cell organism that repeatedly produced by fission with healthy offsprings.</p>
<p>You have a multicellular organism that reproduces asexually by fission. When you excise a 10,000 cell portion of its body, both the original organism and the excised portion grow into fully formed, healthy organisms. You take one of the offspring and and repeat the procedure for 123 generations. Each time, the resulting organism is healthy. What must be true of the nuclei of this species?</p>
<p>a) The cells contain plasmids
b) The cells have multiple forms of DNA polymerase
c) The cells have the majority of their genome stored in circular DNA
d) The cells contain active telomerase
e) The cells contain active fissonase</p>
<p>For this question, I put (d) that the cells contain active telomerase. Choice E is made up, there is nothing called fissonase. Most organisms already have multiple types of DNA polymerase and it doesn’t seem as if that has anything to do with the question. Choices A and C are probably true but again I personally don’t see how those answers relate to the question.</p>
<p>Here is a shortened version of the antelope question. Antelope and child stick together and there is a 75% chance of both being eaten and a 25% chance of both escaping. If mother sacrifices herself, what is the minimum chance that the baby can have to escape from the lions following such a sacrifice such that the mother’s action will be evolutionarily favored?</p>
<p>a) 25%
b) 33%
c) 50%
d) 66%
e) 75%</p>
<p>I answered this question using Hamilton’s Coefficient of Relatedness. In the first situation the total “value” is (0.25)(1) + (0.25)(0.50) = 0.375. This means that the “value” in the second situation must be at least that amount for the action to be evolutionarily favored. Therefore, 0.375 = (0.50)(x) and x = 75%, the answer.</p>
<p>What did all of you get for this question?</p>
<p>While conducting research on Euglena, a researcher observed that the contractile vacuole ceased functioning yet the rest of the organism seemed healthy and active. Which of the following is most likely responsible for the cessation of contractile vacuole action?</p>
<p>a) Moving the Euglena from a lighted to darkened environment.
b) Moving the Euglena from a freshwater environment to a seawater environment.
c) Moving the Euglena from a seawater to a freshwater environment.
d) Lowering the pH of the medium from 7.0 to 6.5.
e) Lowering the temperature of the medium from 20C to 15C.</p>
<p>I put Choice B. In the book it says that Paramecium and Euglena constantly use contractile vacuoles in their native environment, freshwater, since the water is hypotonic to the ICF of the Euglena. Therefore, if the Euglena is moved to a more hypertonic solution, it would no longer need to use its contractile vacuoles.</p>
<p>Which of the following oligonucleotides would have the highest melting point when paired with the proper complementary strand?</p>
<p>a) AAAAAAAA
b) ATGCATGC
c) CGCGCGCG
d) TTTTGGGG
e) TATATATA</p>
<p>I put Choice C since cytosine and guanine have triple hydrogen bonds between them and it would therefore take more energy to break those triple bonds than for any oligonucleotide which would have some double hydrogen bonds.</p>
<p>Like I said earlier: I HAVE CONTACTED THE USABO DIRECTOR AND SHE SAID IT IS NOT PERMITTED TO DISCUSS SPECIFIC EXAM PROBLEMS. YOU ARE IN VIOLATION OF CEE’S TERMS. STOP IMMEDIATELY!</p>
<p>Yeah its not really a good idea to discuss these sort of things in a public forum, where everyone can see stuff</p>
<p>trig1968 and MasterYaster - I don’t understand why we can not discuss the questions (now that the Open Exam date is closed for 2013). The whole idea here is to learn! Look at Chemistry, Physics and Math olympiads. Those questions are available to everyone. Biology Olympiad takers should have the opportunity to discuss the questions.</p>
<p>@diannaagron Holy Crap!!! I’m so sorry. I wasn’t anywhere close; I missed by a good 3 points so I wasn’t super disappointed. Dw, I have a good feeling about this test.</p>
<p>I did not have any past USABO semifinal exams.
Could someone send them to me?</p>
<p>Same here, where did you guys find semifinal exams?</p>
<p>They are found on the TRC webpage. It has semifinal exams starting from 2003 to last year’s.</p>
<p>The 2012 thread is littered with question discussions, and i don’t think CEE pursued any of the posters…</p>
<p>As far as I saw, the TRC has all of the OPEN exams, but only a sample of the 2006 Semifinal Exam. I found a copy of the full 2010 semifinal exam on scribd some time ago - it might still be available.</p>
<p>March 6th is only 2 days away. keeping my fingers crossed</p>
<p>I hope we can start discussing the questions like our seniors did last year.</p>
<p>I hope this doesn’t count as discussing anything on the exam because it’s not anything specific, but I remembered seeing a typo. Would that cause the question to be thrown out?</p>
<p>Probably not as long as it didn’t significantly alter the meaning of the question, though I don’t remember any typos.</p>