Question

WHAT WOULD BE MY CONTROL VARIABLES IN THE LAB BELOW.

1. Procedure

1. On stove top Heat up 250ML of water to 37°C. keep temp at 37°C to use in step 8.
2. Label the 4 clean test tubes A, B, C, D
3. Put 3ML of the egg white into each of the 4 labelled test tubes.
4. Tube A: Add 3ML OF Pepsin solution
5. Tube B: Add 3MLOF distilled water and 3ML OF Pepsin solution
6. Tube C: Add 3ML OF Lemon juice and 3ML OF Pepsin solution
7. Tube D: Add 3ML OF Baking soda solution and 3ML OF Pepsin solution
8. Pour the water from step 1into a 250ML beaker. make sure the water is still at 37°C.
9. Place all tubes into the 250ml beaker from step 8 make sure the water temp stays at 37°C let stand in warm bath for 30 minutes.
10. Take tubes out of warm bath
11. Examine and record the egg white appearance in each test tubes.

2. Substrate and Products

The substrate on this experiment is the egg albumen. The egg white suspension is heated and solidified to form a white opaque liquid. The pepsin is added to the substrate and the treated with one of the treatments varying in PH.

3. Experiment Controls

Tube A will serve as NEGTIVE control for the experiment

Control for the experiment:

Dependent Variable: Different PH Environment

      Independent Variable: Different PH environment (water, lemon juice and backing                    soda)

4. Hypothesis

Pepsin in the acidic environment of lemon juice will breakdown proteins from the egg white the best.

5. Graph Presentation

I will use a line graph to present my data.

Answer 1

A control variable is a constant element in a scientific experiment. Such as constant temperature, constant pressure, constant light, constant humidity, etc

in this case, The control variables are:

37^oC Temperature

250ml of water

3ml of egg white

4 test tubes

30 minutes time