<p>Just going from my prep-book…the chi-square is a way of analyzing the “error” from an experimental genetic cross by comparing it to a Punnett square. If the experimental cross results are the same as what the Punnet square predicts (i.e. in the experiment, 1/4 of the offspring of a Heterozygous and homozygous recessive were homozygous recessive) then the chi-square value is zero. The value rises as the difference between the Punnet square and reality grows. When it gets very high, there’s something other than chance working on the experiment, like crossing-over, mutations, nonrandom mating…</p>
<p>my stars, the chi-squared formula is complex by bio standards</p>
<p>to yizzle24
positive feedback</p>
<p>remember negative feedback maintains homeostasis
for example the release of insulin lowers blood glucose and when it is too low the pancreas releases glucagon to raise blood glucose levels
that would be negative feedback</p>
<p>positive feedback would be if the pancreas cranked out glucagon and have high levels of blood glucose and no insulin released to counter that</p>
<p>^ iirc positive feedback is when the body encourages an action already in place, not simply if there’s no negative feedback mechanism established?</p>
<p>ie. When a mother is lactating, the posterior pituitary produces more oxytocin to further stimulate lactation.</p>
<p>Ok, you’ll never forget this.</p>
<p>Positive Feedback = SEX!!! haha. once you start, you want to keep going. </p>
<p>you’ll remember it now haha. i did. :P</p>
<p>those are actually important words and i bet you’ll see at least a few on the test tomorrow, if this test is anything like the other tests that were released</p>
<p>What released test has “casparian cells made from suberin”? I know a majority of the words were on the released, but it’s stuff like this that confuses me.</p>
<p>what’s the difference between natural killer t cells and cytotoxic t cells?</p>
<p>Are the labs even really on the test??? Are they just easy qs about labs???</p>
<p>^^</p>
<p>Cytotoxic T cells kill the antigen, while helper T cells signal to other B cells to help produce antibodies:</p>
<ul>
<li>Memory cells (future protection)</li>
<li>Plasma cells (antibody making machine)</li>
</ul>
<p>^NKs use apoptosis to kill their targets, and are activated by a CD1D antigen presenter rather than a CD4 for killer T cells. Killer T cells also proliferate from helper T cells and make holes in the targets, causing them to lyse. </p>
<p>I don’t think there’s enough difference between the two for the AP to actually come up with an essay about (impossible question, maybe).</p>
<p>whats the difference between cyclic and noncyclic photophosphorylation?</p>
<p>Cyclic: Electrons go from PSII to PSI to PSII again.
Noncyclic: Electrons go from PSII to PSI.
That’s the basic concept of it.</p>
<p>Cyclic - electrons go back to PSI (P700) once through with electron transport chain.
ONLY PRODUCES ATP. NO ANDPH</p>
<p>Noncyclic - Produces NADPH when NADP combines with H+ and electrons from photolysis of water. ATP is produced as well. Uses photosystem II then photosystem I</p>
<p>PSII doesn’t have anything to do with cyclic.</p>
<p>Oh…I must have confused myself then 
sorry!</p>
<p>What happens if you score no points for one of the essay questions?</p>
<p>is anyone else staying up and studying, probably not the best idea but whatever, i underestimated the time i would need to study/review</p>
<p>if u get at least 50/100 and three points for each frq u pass
<a href=“http://appass.com/calculators/biology[/url]”>http://appass.com/calculators/biology</a></p>
<p>hey what do colleges except for credit (competitive like Tulane rice northwestern etc) i know 4 and 5, but realistically (especially cuz im a sophomore) and is there a break durring the exam??</p>