<p>To Godfather:</p>
<p>Well, that's exactly my point--if it's so difficult for an insect to reach the island, it's highly unlikely that another fly (besides the founder) was able to colonize it. Thus, the initial Drosophila fly was able to start the entire population without gene flow from outside sources.</p>
<p>How does weather contribute to a founder effect? In the context of this problem, that doesn't make any sense.</p>
<p>Its nucleotide for sure</p>
<p>The dialysis lab was confusing.</p>
<p>It provided a 24hr period but how do we know that all the osmosis/diffusion had stopped and the solution was at Equilibrium at that point?</p>
<p>I did not like that lab for that reason, other than that the questions were easy that is like first lab of apbio.</p>
<p>what's the answer to the one about the tall straight tree and making it bushier?
it was on the eco section</p>
<p>i put something about cutting off the terminal caps? i'm forgetting the whole question...</p>
<p>can we get a compilation of the bio e and m questions?</p>
<p>Whats a good score to get into the UCs?</p>
<p>I took M, and I wanted to address some of the discussion so far.</p>
<ol>
<li>Hawaii question = hot spot.
It has to be hot spot. Those who didn't choose hot spot for the most part put rain as the answer. The differing climates would create a form of isolation between populations of the same Drosophila species. First, the mountain range itself, secondly, differing climates would produce different evolutionary pressures upon populations of the same species (but on different sides of the mountains). Thus, divergent evolution would occur and you would see the creation of a nice variety of species.</li>
</ol>
<p>The hot spot has nothing to do at all with the speciation that occurred. I can see why some would believe it has to do with isolation of some sort...but the presence of Hawaii as an island is already established, its not like we don't know where Hawaii is and the only way we know its an island is the fact it sits on a "hot spot"...just look at a map. Yes, Hawaii was formed from volcanoes and stuff, but then why would the original Drosophila colonizing species change? All other answer choices provide reasons as to why that original species diverged into multiple ones, due to isolating mechanisms/different niches.</p>
<ol>
<li>Dialysis lab
The balloon contained I believe, sugar/starch/protein/lipids. The only thing that diffused out was sugar.<br></li>
</ol>
<p>a. The hypothesis that the lab supports is "size of the molecule determines ability to pass through membrane." The other choices didn't work, like "only organic molecules pass" (proteins didnt...), "starch is less soluble than sugar" (has nothing to do with diffusion...it was in solution), "active transport is needed to move sugar" (dialysis membrane has no ATP or anything...) etc.</p>
<p>b. The I, II, III question involved which conclusions could be made. I put "water moves into balloon". I think we can all agree that this is true. However, I put "I only" as my answer for this question. II and III (I forgot which is which) stated "sugar stopped moving after exp finished" and "solutions are isotonic". Solutions are definitely not isotonic...when you have 4 different solutes in a bag and only one can move out...a whole lot of sugar wouldve had to move out to balance. It's possible, but theres no info to conclude. Also, we can't conclude that sugar stopped moving. No information in the paragraph said that all diffusion stopped after 24 hours, and the table never said that sugar was in equilibrium --- it just said it was "present" in the solution in the beaker. For all we know, balloon solution may have been hypertonic still to the beaker one and sugar may have still been moving after 24 hrs.</p>
<p>i said that Diffusion occurred for that bag one -- because osmosis is the movement of water, and clearly sugar moved (diffused) across the membrane.</p>
<p>Wikipedia says this : A cell in an isotonic environment is in a state of equilibrium with its surroundings. When the amount of impermeable solute is the same on the inside and outside of the cell, osmotic pressure becomes equal; the force of water trying to exit and enter the cell balances out. This pressure is what drives hypertonic or hypotonic cells to become isotonic. For example, in medicine, a 0.9% w/v solution of water and NaCl is considered isotonic in relation to red blood cells and their semi-permeable membranes.</p>
<p>I agree with what Wiki says, though I don't know what you were trying to prove? If you were trying to say that it was isotonic...the amount of impermeable solute is not known to be same on inside and outside at the end of the experiment.</p>
<p>I think I am going to have to agree with Echelon32 now. I see what he is saying...being a hotspot doesn't directly relate to speciation...</p>
<p>"what's the answer to the one about the tall straight tree and making it bushier?
it was on the eco section</p>
<p>i put something about cutting off the terminal caps? i'm forgetting the whole question..."</p>
<p>yep, that's correct!</p>
<p>water goes into the bag, so ultimately the solutions can be isotonic based on osmotic pressure. Also, even if what you are saying is true about the mystery amount, if there are a lot of solutes then wouldn't the bag just lyse?</p>
<p>Hmm...then I guess the discrepancy here comes down to what you define as the "end of the experiment." I decided that the "end" was at the 24 hr mark. And depending on the amount of sugar in the bag initially, there may not even be enough to equalize the solute concentrations (as in if there are 1000 g solute initially, one of which being sugar, even if all 1 g of sugar moves out, the bag would probably suck up all the water in the beaker and still be hypertonic, idk lol. </p>
<p>Oh and the bag is completely different from something like a cell's plasma membrane, in that since its constructed by humans, who knows what kind of material it is...it could be a supermaterial that can withstand enormous amounts of pressure from inside :P</p>
<p>I'd like to see what the other opinions are. This question was really tricky.</p>
<p>for the insects and insecticides one, i said that predators who eat the insects will die b/c of the insecticides or something along those lines. is that correct? what were the answer choices for that ques?</p>
<p>yeah springflower you're correct the predators die cause of biomagnification</p>
<p>and thanks for the confirmation on the bushy tree one</p>
<p>For the bag NaCl, can some1 recall what the question stated, and what the answer choices were.</p>
<p>I think the question said bag is placed into a solution with 0.9% concentration NaCl. So there had to be 99.1% water concentration. This would mean the cell would shrivel as through osmosis water would diffuse out (high to low).</p>
<p>the one with the vegetation cannot be lichens. They said the land was stripped of ALL vegetation, leaving ONLY the soil. Lichens erode ROCKS to soil, so there is no point of lichens living there is there is already soil. Lichens are pioneer organisms because they create an enviroment for which other producers can begin to grow. =ecological succession. Therefore, it must either be annual herbs or shrubs, because trees come last. However, in the Kaplan book, they have it as lichens->annual grass->shrubs->trees. So my answer of shrubs was most likely wrong. The answer is probably annual herbs.</p>
<p>asc3nd - I'm pretty sure it was a solution of distilled water in the beaker. I recall the paragraph stating that the bag was filled with solution X and after it was tied off, it was washed off with distilled water (this presumably done to prevent random solutes getting into the beaker water in the beginning).</p>
<p>so what was the answer?</p>