Evaluating Procedures
(8 points)

PreAP Biology is required to come up with at least three "errors or weaknesses" - basically one from each bolded statement below. Another way of looking at this part is to determine what could be done to make the lab better. ALL labs we run will have limitations and areas which can be approved.

Include relevant comments on design and methods (process)
This section is not about you. It is not about human error. You will not earn points for putting down "we should have kept better watch of the time."

This section is about errors in the steps used to obtain the data. It is about the method chosen by which the data was collected.
Here's a couple of examples:

"The amount of time between trials was to short for the organism to adequately rest before the next trial."

"The combination of using 5 grams soil with 5mL water to create a muddy environment for the isopods caused the organism to curl up into a ball. This soil/water ratio created a very watery mix which may have caused the organism to seek "high dry ground" instead of seeking a less muddy environment."

"After running each trial, the reagent bottles used for the reaction may have had some residual unreacted hydrogen peroxide still in them when the next trial was run." Note: this last statement could be used under the "use of equipment" section below.

"The hydrogen peroxide used was left out in the light for several minutes before being poured into the reaction chamber. Since light can breakdown hydrogen peroxide, then when the experiment was run, we did not have the full 3% hydrogen peroxide at the beginning of each trial."
 

List weaknesses and how significant they are.
This section is NOT about you. It is NOT about
Sloppy technique or human error. You may not use sloppy technique or human error and earn credit. This section means you have listed more than one issue and assessed how the error effected the data obtained, the analysis of the data and/or the conclusion drawn from running the experiment.

 

Relevant weakness on precision and accuracy
This section include comments on relative weakness/limitations regarding precision and accuracy of measurements/data. Again, this section is NOT about you. You will not earn credit for statements such as "we could not read the graduated cylinder because one of use did not have their glasses when we ran the lab."

Here are some examples:

"The smallest unit of measure for the clock used to measure time was one minute. Accuracy to the minute is not good enough to obtain reliable data as the reaction stopped before each minute was up."

"Using a 50mL graduated cylinder was to large for the measurement of 5mL of water used during the experiment."

"The use of filter paper dots may have been a source of error. The amount of catalase absorbed by each "dot" may not have been the same, therefore one dot may have had more enzyme then another dot run in a different trial."

Include comments on use of equipment and management of time.
This section is NOT about you. Running out of class time cannot be used. This section is about the equipment and the time used to run the experiment. Use of equipment is the function of the equipment. It is not a function of how you were able to use the equipment. Here are some examples:

"Collection of the oxygen over the five minute intervals may have caused an error in the data."

"An error may have been introduced due to running the experiment over two days. The catalase used on the second day was 24 hours older than the catalase original used to obtain the "one dot" filter paper trials."

"Using a 50mL graduated cylinder was to large for the measurement of 5mL of water used during the experiment."