*** Official AP Biology Thread 2012-2013 ***

Test Preparation AP Sciences
941

<p>@jadenio
No, you’re wrong; the color of the plant depends on the light that is reflected not the light absorbed; therefore, graph 2 is the cholorophyll a because green light was absorbed in the least amount, so it is reflected.</p>

942

<p>Wrong. If something is green, it REJECTS green, silly.</p>

<p>He’ll need a tissue soon…</p>

943

<p>i am just hoping that i get most of the mc and some of my guesses right</p>

944

<p>Anyone thing it will be as low as 55% to get a 5 this year? Probably not…</p>

945

<p>I used minute 1’s data as expected and minute 10’s data as observed on chi square. Then my null hypothesis was that there wasn’t a significant difference in distribution of flies between minute 1 and 10. I later rejected my null… That makes the most sense to me, why else would they give you minute 1 data?</p>

946

<p>Not to sound rude, but don’t say you know things for a fact unless you actually do. I know for a fact that you are wrong. Green plants are green because their pigments reflect green light (aka they don’t absorb it). Graph 1 showed the high absorbance of green and low absorbance (reflecting) of violet and red, therefore it was not chlorophyll a.</p>

947

<p>it doesnt reject it, it reflects it lol. And also, im reporting the chi sqaure question as vague bc we dnt know what the expected would be. They didn’t give us enough information.</p>

948

<p>@jsjung96 I did that too, we should be good!</p>

949

<p>I’m not really sure what you guys are saying for part c for the aquatic organism vs chlorophyll question. Absorbing the correct wavelengths of light? And the question doesn’t ask about terrestrial plants at all. It asked how the aquatic organisms with the bacteria thingamabobbs caused plants in the same ecosystem (plants in water) to have the light absorbencies they had. Basically I said that aqua organisms, that were in the ecosystem first, absorbed the specific frequencies shown on graph I. When plants came, instead of competing for the same resources they adapted and absorbed the frequencies that the aqua organisms did not. </p>

<p>@jadenio better look over your facts again then, chlorophyll is green because it reflects green light. Not because it absorbs it. You have it backwards.
EDIT: Wau, these responses are coming in so fast</p>

950

<p>I said for the null hypothesis that each chamber would have an equal amount of flies so 20/20/20, but I still ended up rejecting it. But it does make sense that that is why they would give you the minute 1 data, though they may have given it to show that the flies moved from a position of equilibrium or to trip people up into thinking it was the observed.</p>

951

<p>reject = reflect imo.</p>

952

<p>I really wish they could’ve waited a year to change the format. The old format actually tested if you learned bio, not if you could analyze biology information.
Overall, though, I thought the multiple choice wasn’t too hard, and the only frq I didn’t completely get was the chi square, which I completely bs’ed. Hopefully the curve is nice.</p>

953

<p>minute 1 data was exactly what it says. Minute one. They included that to show that they started it with flies on both sides equally distributed. That is NOT the expected value of where the flies will be after 10 minutes.</p>

954

<p>It was a very open ended question, I agree. However, I do think there are a range of correct answers. I pretty sure 20/20/20 as an expected is correct if you had a null hypothesis saying “there will be no significant difference in the distribution of fruit flies…” I think it is heavily based upon your null hypothesis. I am also very certain that the null hypothesis in almost every case is rejected. And the critical value is 5.99 (Degrees of freedom is n-1, there are 3 groups so n=3, so degrees of freedom = 2. In biology we used 0.05 prob., and so the crit. val. is 5.99). Anyone else have an opinion similar/different to mine?</p>

955

<p>@UrAverageAzn: the only thing about your part C is that I don’t get how the grandma can compete for sunlight.</p>

956

<p>@the84lthline I get what you meant, but I wouldn’t have used that word in ur essay if you did.</p>

<p>@study addict How was there three groups? I had 1 df because there were two groups…ripe and unripe(whichever went to which side) so 2-1=1 and when i compared 1 against .05 i saw 3.84 and my critical value for my X^2 was 3.75 bc i said they would all go to the ripe (60,0,0) and i accepted my hypothesis. And i think you’re right. They’ll probably base it if its right against your null hypothesis.</p>

957

<p>*organisms omg sorry autocorrect.</p>

958

<p>We technically shouldn’t be discussing the exam BUT to clear up any misconceptions, here’s a graphic <a href=“http://www.sd84.k12.id.us/shs/departments/science/yost/Biology/5%20-%20Energy%20&%20Metabolism/chlorophyll_absorption_graph.jpg[/url]”>http://www.sd84.k12.id.us/shs/departments/science/yost/Biology/5%20-%20Energy%20&%20Metabolism/chlorophyll_absorption_graph.jpg&lt;/a&gt;&lt;/p&gt;

959

<p>and for all you people fighting up there ^^^^: here’s the absorption spectrum for chlorophyll a
<a href=“http://www.bio.davidson.edu/courses/bio111/bio111labman/lab1fig3.gif[/url]”>http://www.bio.davidson.edu/courses/bio111/bio111labman/lab1fig3.gif&lt;/a&gt;&lt;/p&gt;

<p>look pretty similar to anything?</p>

960

<p>I agree with you StudyAddict, they will be probably take using minute 1 or 20/20/20 as acceptable expected values…But for 20/20/20 you had to state there will be no significant change in movement, and for using the minute 1 values you would have to specify there would be no change from the first minute.</p>