<p>the ochem question was what it was b/c sudan’s solution stains triglycerides and ninhydrin reacts with free amine groups (and thus reacts like crazy with amino acids, esp. basic amino acids). that was the only choice that fit.</p>
<p>PTH was an answer to the one regarding which hormone is produced in abnormal quantities. the neural/cardiac problems gave away the problem as being one of ion quantities and PTH regulates calcium levels</p>
<p>There was a question asking what would happen to an egg or something if a substance that I never heard of was added do it.</p>
<p>Choice A was something like “it would grow but produce no offspring”</p>
<p>I put that =p</p>
<ol>
<li>No, I am thinking of a different question. However, regarding extraembryonic membranes used for respiration, I agree that it was both allantois and chorion. Count that one as question 38.</li>
</ol>
<p>I thought it was only allantois, are you sure?</p>
<ol>
<li>There was a question like which of the following is not an advantage used to attract pollinators. The choices were sepals, petals, a foul odor, patterns visible only under UV light (or something). I put the UV floral patterns option, but I don’t think that’s right…</li>
</ol>
<p>I believe the answer was sepals. Some insects see infrared</p>
<ol>
<li>There was another question about the term that describes cations going from soil to roots. I put cation cotransport, but the answer should have been cation exchange.</li>
</ol>
<p>I put cation cotransport. Why do you say that it should be cation exchange?</p>
<p>Damn guys, how do you all still remember this many questions?</p>
<ol>
<li>Answer is the one about isoelectric point.</li>
<li>Only one of the choices had hydrophilic groups on both ends of the molecule; the answer was that one.</li>
<li>Least distance, greatest size</li>
<li>Phenylalanine</li>
<li>B3</li>
<li>Nyctinasty</li>
<li>Man, screw this question. This was my logic: it wouldn’t be gradient for sure, because gills extract oxygen from the water, which is way less concentrated in oxygen than air (which is what lungs extract oxygen from). As mentioned, both lungs and gills are rather expansive. I think there was a temperature choice? - temperature in lungs would usually be higher than temperature in gills. As for path lengths, water has to pass over the entire length of the gill, while in a lung the air only passes through a few millimeters of alveolus. So path length is the correct answer imo.</li>
<li>This question is pretty interesting. I had a good long debate with this over my friend (also a Finalist last year). We’re both pretty sure the answer is nondisjunction of the mom during meiosis I. Can anyone remind me what the question is? Normal father, carrier mother, child is XxY, am I right?</li>
<li>This is definitely Struthioniformes.</li>
<li>I remember the correct answer for this one having something to do with the adrenal glands.</li>
</ol>
<p>protein deficiency should be sulfur…</p>
<p>the fick’s law was maximize the gradient: you don’t have countercurrent exchange in mammalian lungs, while you do in gills</p>
<p>i thought it was nondisjunction in meiosis II, because that would guarantee you had two alleles of one type XXY. i have a couple of friends who agree with me</p>
<p>I see what you’re saying, but my logic is: no matter how hard you countercurrent-exchange, gills are going to move oxygen from water to blood, while lungs are moving oxygen from air to blood. Air is hundreds of times more oxygen-concentrated than water, so ultimately the oxygen gradient in a lung is going to be enormous compared to the gradient in a gill.</p>
<p>Granted, I still see your point. Out of curiosity, supposing you were correct, how would you justify that the answer is not path length?</p>
<p>Hi Rupnok - I noticed you seemed to know that some of the USABO questions were repeat ones from open and semi-final tests. How did you figure this out? (if rupnok doesn’t respond, does anyone else know how he or she figured this out? Also, if anyone has any old semi-finals they could share with me and/or a site where I might find some, Id greatly appreciate it. Please pm me a message. Thanks! :-))</p>
<ol>
<li>sure? my teachers says otherwise. and wikipedia agrees its sphenisciformes</li>
<li>agreed</li>
</ol>
<p>the question about Colchicine is dihaploid fertile. its used to artificially produce polyploidy in crop plants. its a spindle inhibitor</p>
<p>Darksigma (or whomever can help) – where you wrote “protein deficiency should be sulfur…” - is that the answer to the question that asked what you should check if all you ate was canned pasta? If so, how did you know it was sulfur? I looked through the entire Campbell’s book and couldn’t find a single reference to what minerals are lacking if one eats canned pasta. And I even checked the internet. Can you please elaborate on this answer? Thanks!</p>
<p>lack of protein -> lack of sulfur (CHONS),</p>
<p>Unfortunately, I can’t remember the details to this question, but when I work it out now, the answer does seem to be meiosis II. It could be that both me and that friend borked in figuring it out at the time. Are you certain the child’s genotype was homozygous for whatever condition?</p>
<p>Also, agreed on the colchicine.</p>
<p>And Struthioniformes just jumped out at me when I saw the question. I don’t know much about penguins and so I really can’t say.</p>
<p>There was another question about the term that describes cations going from soil to roots. </p>
<p>cation cotransport or cation exchange??</p>
<p>Cation exchange. I think it’s a rigorous term; you can’t call it anything else.</p>
<p>cation exchange, for sure</p>
<p>@oldguy: I’m pretty certain of my answer. If the child is to have the condition, it would have to have all recessive alleles (extrapolating from the info given in the text of the question).</p>
<p>btw, what was the vitamin deficiency question? the one that mentioned necklace lesions? Was it B3? (that’s what i guessed blindly)</p>
<p>Thanks darksigma!</p>