Independent+Biology+Experiment

[| http://www.ableweb.org/volumes/vol-6/10-miller.pdf] Good idea for an experiment regarding enzymes.

Experiment on Living Matter Basic Plan--**What are you planning to do?**

|| Dependent Variable Name: What instrument will you use to make your measurements? What units will your measurements be in? What do you expect the uncertainty in these measurements to be? (+/- ?) || Independent Variable Name: What instrument will you use to make measurements of this variable? What units will your measeurements be in? What do you expect the uncertainty in these measurements to be? (+/- ?) || - heat-resistant glove - Benedict's solution - boiling wayer bath - cooked egg white - scalpel or single-edged razor blade - metric ruler - 6 large test tubes - 6 stoppers for test tubes - glass-marking pencil - test-tube rack - 10-mL graduated cylinder - 1% pepsin solution - 0.2% hydrochloric acid - cooked potato - 1% amylase solution - test-tube holder ||
 * "**Grand Idea**"--What is an important/interesting problem that relates to your investigation? ||
 * **Dependent variable** (this is what you will measure and //depends on// the value of the independent variable)
 * **Independent variable** (this is what you will change to see how it affects the dependent variable)
 * **Variables to Control** (what variables seem significant enough that you will be careful to keep them controlled? For each of these variables, explain briefly how you will be try to control them?) ||
 * **Materials and Setup** (Include both a list of materials that you will need and a labeled sketch to clarify the setup)
 * **Procedure**

Experiment 1: Investigating the Effects of Enzymes on Food Molecules

1) Predict weither pepsin can break down protein. 2) Put on an apron and safety goggles. Label three test tubes 1,2 and 3; and put them in a test-tube rack. Cut three 5-mm cubes of cooked egg white and add one to each test tube. 3) Put on plastic gloves. Use a graduated cylinder to add 6 mL of water to test tube 1, and 3 mL of water and 3 mL 0.2% hydrochloric acid to test tube 2. (CAUTION: Hydrochloric acid can damage skin and clothing. If hydrochloric acid spills, notify your teacher at once. Wash the affected area with large amounts of cool water for 10 to 15 minutes.) Carefully rinse the graduated cylinder. 4) To test tube 3, add 3 mL 1% pepsin solution and 3 mL 0.2% hydrochloric acid. Carefully rinse the graduated cylinder. 5) Put a stopper in each test tube, and gently turn the tubes upside down several times to mix the contents. Put the tubes back in the test-tubes rack. Set your test-tube rack where it will not be disturbed. Make a copy of the data table. 6) After 2 days, examine the contents of each test tube., Record your observations in your copy of the data table.

Experiment 2: Investigating the Effect of Temperature on Enzyme Activity

Part A: Observe the Catalase Reaction 1) Pot on your apron, gloves, and safety goggles. Use forceps to place a small piece of raw liver in an open petri dish. Use a dropper pipette to put a drop of hydrogen peroxide solution on the liver. (CAUTION: Hydrogen peroxide can be irritating to skin and eyes. If you spill any on yourself or your clothes, wash it off immediatley and tell your teacher.) Observe what happens. Liver contains the enzyme catalase, which breaks down hydrogen peroxide (H202) to water (H2O) and oxygen gas (O2). When hydrogen peroxide, which is formed in cells, is broken down by catalase, bubbles of oxygen gas are released. 2) With your teacher's guidance, select the proper equipment and technology to measure catalase activity - either a filter-paper disk or an oxygen probe. If using an oxygen probe, see your teacher for instructions. 3) To measure the activity of catalase, use a graduated cylinder to place 25 mL of hydrogen peroxide solution in a 50-mL beaker. 4) Use forceps to dip a filter-paper disk in liver puree. Place the filter-paper disk on a paper towel for 4 seconds to remove any excess liquid. 5) Use the forceps to place the filter-paper disk at the bottom of the beaker of hydrogen peroxide solution. Observe the filter-paper disk and record the number of seconds it takes to float to the top of the liquid. ||
 * **Background Understanding and Expectations** (What are you expecting and why?) ||
 * **Data Table** (make a data table with appropriate column headings; you can leave values for the dependent variable blank at first, but write down a few values of the independent variable that you plan to use) ||