Astudent cut a small piece of beef liver, placed it in a test tube, and added 2 ml of hyrdogen peroxide. the temperature of the peroxide was 37oc and the ph was 7.0. the reaction generated a gas that the student measured as the height of the foam in the test tube. in this case, the liver plus hydrogen peroxide generated 10 cm of foam (gas bubbles).

the student repeated the experiment but this time she boiled the liver for 2 minutes before adding the hydrogen peroxide. the boiled liver plus hydrogen peroxide did not generate any gas.

finally, the student placed a third piece of liver and the 2 ml of hydrogen peroxide in an ice bath for 2 minutes before combining the two in a new test tube. in this case, the liver plus hydrogen peroxide produced 4 cm of foam.

the enzyme in this experiment is catalase. it can be found in all living cells. it decomposes hydrogen peroxide, which is toxic to cells.

question:

1. what was the substrate in this experiment?

2. how does this experiment illustrate the specificity of the enzyme catalase? describe another situation to further confirm your answer.

3. hypothesize why the second experiment did not produce any reaction (gas bubbles).