<p>Real quick…for Question 1, isn’t glycerol a polar molecule (surrounded by -OH groups)? So wouldn’t that make it one of the hardest to pass through the phospholipid bilayer?</p>
<p>Also, some of my friends argued that the picture of frog eggs/RBCs/whatever was red blood cells, since the unit of measurement was in micrometers I believe.</p>
<p>I picked frog eggs…:/</p>
<p>it’s definitely left ventricle for whole animal fixing. i’ve done it myself in lab before. @momster: your son probably misunderstood what was being asked</p>
<p>[Redirect</a> Notice](<a href=“http://www.google.com/imgres?um=1&hl=en&safe=off&client=opera&sa=N&rls=en&channel=suggest&tbm=isch&tbnid=gX019AEsk8onbM:&imgrefurl=http://homepages.wmich.edu/~rudged/1700old.html&docid=97bwgHV5khXhWM&imgurl=http://homepages.wmich.edu/~rudged/frogblood.jpg&w=640&h=480&ei=w2lQT4_8BO_XiALzqPG0Bg&zoom=1&iact=hc&vpx=346&vpy=186&dur=1480&hovh=194&hovw=259&tx=90&ty=169&sig=107752768074392179802&page=1&tbnh=140&tbnw=173&start=0&ndsp=18&ved=1t:429,r:1,s:0&biw=1333&bih=685]Redirect”>http://www.google.com/imgres?um=1&hl=en&safe=off&client=opera&sa=N&rls=en&channel=suggest&tbm=isch&tbnid=gX019AEsk8onbM:&imgrefurl=http://homepages.wmich.edu/~rudged/1700old.html&docid=97bwgHV5khXhWM&imgurl=http://homepages.wmich.edu/~rudged/frogblood.jpg&w=640&h=480&ei=w2lQT4_8BO_XiALzqPG0Bg&zoom=1&iact=hc&vpx=346&vpy=186&dur=1480&hovh=194&hovw=259&tx=90&ty=169&sig=107752768074392179802&page=1&tbnh=140&tbnw=173&start=0&ndsp=18&ved=1t:429,r:1,s:0&biw=1333&bih=685)</p>
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<p>this is the image that was on the exam itself</p>
<p>Sucrose be all hydrophilic though =p</p>
<p>I hate how frog red blood cells have nuclei…</p>
<p>For some of these questions, MS treatment for example, seems like you guys weren’t paying enough attention to what was written in the test. Which is surprising given how you have more or less recreated the test here. </p>
<p>For sexual selection/ethology questions, it’s important to remember that no organism (aside from, very rarely, humans) makes choices based on concerns about genes.</p>
<p>@Cocytus: Glycerol is polar, but like water, it is small. Sucrose is large and chloride is charged so glycerol would diffuse faster.</p>
<p>@cadaeibfed: mind clarifying what you mean by your reference to the MS treatment question? Do you disagree with one/both of the answers proposed?</p>
<p>Those who answered “prevent leak” failed to notice a word in the question.
Assuming the wording was the same as on the test I saw.</p>
<p>… It is a well known fact in neuroscience that ms patients are treated with potassium channel blockers b/c the depletion of the myelin sheath results in the leakage of ions, thus resulting in impaired action potential propagation. Blocking potassium channels prevents the is leak from having such a pronounced effect on action potentials.</p>
<p>Mind enlightening us with your rationale/wording that invalidates this well known fact? This is confirmed also by my physio textbook and neurobio textbook.</p>
<p>“voltage-gated”</p>
<p>darksigma is absolutely right on the MS question. On a side note CEE has moved the semifinalist announcement to March 14 due to scheduling problems. Also is anybody in this thread participating in the USA Brain Bee, just curious.</p>
<p>Considering it</p>
<p>Considering it? It takes place March 4 and 5</p>
<p>announcement on March 14th? that’s the first day of the semi-final… how is that going to work?</p>
<p>Here’s a copy of the email sent to my USABO Sponsor.</p>
<p>Please note the following changes in the USABO calendar that will be available online ([CEE</a> | USABO 2012 Calendar](<a href=“http://www.usabo-trc.org/currentcalendar.php]CEE”>http://www.usabo-trc.org/currentcalendar.php)) at the close of business today Friday March 2. The date for announcing the Semifinalists has been moved which has caused a ripple effect in the schedule. If you have any questions or need to have an extension, please contact me.</p>
<p>Have a wonderful weekend!</p>
<p>Best,</p>
<p>Kathy</p>
<p>USABO Schedule Changes</p>
<p>March 14th: Semi-finalists posted to website (top 10% or 500 students)</p>
<p>March 21-30th: Semi-Final Examination Administered</p>
<p>March 31st: Last day for mailing Semi-Final Exams to CEE</p>
<p>How did you guys/gals remember the questions? It blows my mind. I have conveniently forgot everything!</p>
<p>Consider
You are a researcher studying squid giant axon. You discover a squid whose voltage-gated potassium channels are mutant, conducting only a small fraction of normal potassium flux. What impact would this have on action potentials in the giant axon? </p>
<p>This is the same question. The language about MS was entirely unrelated. However, it sent you thinking in the wrong direction. It could be said that you knew too much for your own good. You saw a few words in the question and assumed you knew what was being asked, basing your answer on “well-known facts” rather than what was on the paper in front of you. May well be that the question writer had this in mind when they wrote the question. </p>
<p>If you’re asked A, and you answer B, C, D and E perfectly correctly, you are still wrong. It’s important to always be sure you know just what the question is asking. Don’t assume you know. That’s a lesson I had to learn this same way. </p>
<p>I’m not trying to be contrary, I’m just trying to give some helpful advice. Take it as you may.</p>
<p>think what you may, but i’ve talked to other finalists, and almost all of them have the answer regarding potassium leak. If you think you can know too much for your own good for usabo, i think you really have quite the misunderstanding regarding the test’s scope. Pick up a copy of alberts and ravens and you’ll know exacly what i mean. Mind you, this isn’t your run of the mill ap biology class. though that rule may apply there, it sure doesn’t here.</p>
<p>know as much as you can, as the questions can be as unreasonable as the writers want. And btw, no those are not the same question. The difference is size. The size of the axon reduces leak b/c of the surface area to volume ratio. Again, open any intro neuro textbook and the answer will be right there for you.</p>
<p>Normally you don’t just dismiss info in a question as entirely unrelated. Ask yourself this: what is MS? the depletion of myelin. And what does myelin function for? Exactly. And now you have your answer.</p>
<p>This is just my two cents. Take it as you may.</p>
<p>@dude asking about brain bee, i was talking about participating next year lol. i prolly misunderstood your question</p>