Ap Bio Enzyme Lab

Test Preparation AP Test Preparation
1

<p>Working on a report for AP LAB #2, Enzyme Reactions. If anyone has done this lab, I would really appreciate some assistance. </p>

<p>The timed procedure asks the student to calculate the Amount H2O2 used by subtracting amount of KMnO4 from the baseline. My KMnO4 values are greater than that of the baseline, and so H2O2 will be a negative amount if I complete the calculations. This is definitely incorrect, because my lab group and I funneled in 10 mL of H2O2, so obviously there isnt a negative amount of the stuff (not to mention thats impossible!). Bio teacher says that it is probably an error of techique, and that she will give us lab credit if we explain what error may have caused this. </p>

<p>Has this happened to any previous Bio students? Or, does anyone have a more complete understanding of enzymes that could help me? </p>

<p>THANK YOU THANK YOU!</p>

2

<p>We did this exact same lab earlier this year. Are you sure you followed the procedure exactly? Did you transfer 10 mL of the reaction solution into a different cup before titrating? If you didn't, it would take way more KMnO4 to react completely with the H202 (which was what a few lab groups in my class did) and so you'd think you ended up with negative values, because you would have been titrating about 21 mL of reaction solution instead of 10 mL.</p>

3

<p>I have heard of a lot of people making the same mistake that ballauerna just described.</p>

<p>If that's not the case, then I would compare results with other lab groups and try to figure out what went wrong.</p>

4

<p>"Choose 2 factors that can affect rate of enzyme-catalyst reaction of catalase. Draw a predictive graph."</p>

<p>***????</p>

<p>"Name 2 organisms that could be used to determine reaction reate of an enzyme."</p>

<p>***????</p>

<p>I think it's plastids for second Q, but i'm completely dumbfounded on the first Q. help?</p>

5

<p>Nope...we did transfer 10 mL. However, my schools equipment is kind of faulty, and so the hydrogen peroxide was outdated and nonreactive when we first tried it. The original H2O2 was a 3% concentration, and the experiment called for a 1.5% concentration-so, we, at first, diluted the H2O2 by combining 100 mL if the peroxide with 100 mL of water. Since this didn't work, we re-did the experiment with non-diluted H2O2. At this point, we did have a reaction, with the beef liver and potato...but this titration problem occurred. Why would the undiluted cause such a strange reaction, though? The teacher won't hint to us at all! She says that this is how it will be in college--the professor will just leave the lab and come back expecting results. Hope she's exaggerating...</p>

6

<p>Oh, and the other groups weren't as far off as my group, but they still got negative values for some of tests.</p>

7

<p>radronOmega,</p>

<p>The answer to your first question is pH and temperature I believe...</p>

8

<p>want2BeIvy,</p>

<p>I think the fact that the H2O2 is old definitely may have to do something with it. Some of the H2O2 may have already decomposed into H2O and O2.</p>