USABO 2010 - Discuss

<p>go one guys. wat is the 2nd question in the sequence? and third also</p>

<p>there was a question about flowering of long day plants. Theoretically, both 5/7/5/7 and 5.5/6.5/5.5/6.5 would work, but they didn’t ask for multiple answers, so I put 5/7/5/7. What did you folks do?</p>

<p>^What? I’m pretty sure you could pick multiple answers. I think put both C & D or something. So probably the ones you picked.</p>

<p>I put 5/7/5/7</p>

<p>Again, I’m confused about how many questions we could/were supposed to put multiple answers. If the question did not ask for “all possible answers”, I only chose one answer. I even asked my biology teacher if I should put more than one answer where there was more than one, but not asked for and he said “no”. I really may have bombed this, but it’s ok since I’m just a sophomore and haven’t taken AP Bio yet :slight_smile: (however I had qualifying scores when I took previoius open exams just for practice).</p>

<p>what’d you guys have for the flower genes one?</p>

<p>was it sepal petal petal sepal?</p>

<p>I think it was not stamen. I don’t remember what the options were, but it was options A, B, and C, not D (which I think was stamen).</p>

<p>So, any chance the cutoff will drop to like 17?</p>

<p>for the flower one, following the given model will yield sepal petal petal sepal. However, empirical evidence shows that while the first three whorls develop into sepals petals petals, the 4th whorl remains floral meristem. I put sepal petal petal.</p>

<p>I don’t remember sepal, petal, petal as being an answer choice. I think what I put was sepal, petal, carpel. Not stamen. Was there another similar question and I’m confused ?</p>

<p>no, you’re thinking of the right question. Sepal petal petal was definitely a choice.</p>

<p>I wonder how many students taking it this year. Hope for the cut off to be like 20</p>

<p>Messiah, can you explain how you got “sepal petal petal sepal” following the given model?</p>

<p>well, a and c mutually repress once another. If c is knocked out, then a will no longer be repressed in the 3rd and 4th whorls (counting from the bottom, normally sepals, up). The first two whorls will be normal, as c is not expressed in them. The 3rd whorl will have b as normal, but will express a instead of c and develop into more petals. The 4th whorl will have no expression of b or c, only a, so according to their model it should develop into sepals.</p>

<p>I swore it started with 2 mg… it said in the question and no didnt misread the question… Unless they just wanted us to calculate the half-life in general as in start with 1 mg… Was the protein bond one ELECTROSTATIC or HYDROGEN? What did you all get for the Carboniferous/insects one? Also what did you get for the mitochondrial toxin one (O2 consumption stops or higher pH difference)?</p>

<p>i think i put
hydrogen (what was the question? quaternary or tertiary?)
habitat (the right answer should be more oxygen in the air, though)
higher pH difference</p>

<p>Yes on the higher pH</p>

<p>What was the answer (and question) on the joint question. The xyz joint has what characteristics?</p>

<p>there was an xyz joint question… i dont recall that</p>

<p>^^Are you referring to a synovial joint? If so I think that was the 2006 test…</p>