Question

multiple choice 10 points
to study the actions of the enzyme catalase on hydrogen peroxide, students performed the following experiment. catalase was extracted from potatoes by blending raw potatoes in a blender with cold distilled water. the filtrate was stored on ice. the following hydrogen peroxide solutions were made: 1 percent, 5 percent, 10 percent, and 15 percent. filter paper disks were soaked in the catalase filtrate and dropped into beakers containing the various solutions. the activity of the enzyme was measured by the amount of time it took for the disks to float to the surface of the solution on the bubbles produced by the reaction. the following data were obtained.

hydrogen peroxide solution	average time, in seconds, for disks to float
5%	25 sec
10%	20 sec
15%	10 sec

which of the following experimental designs should the students use as a control for the experiment?
poke the floating disks back down to the bottom of the beaker and retime the rise of the disks.
place a catalase - soaked disk in a beaker of water.
dip the disks in the 5% solution before putting them in any other solution.
shake the beakers during the time the disks are rising.
clear my selection

Explanation:

A control in an experiment with enzyme - catalyzed reactions involving hydrogen peroxide should lack the substrate (hydrogen peroxide) to show that the observed effects are due to the reaction with hydrogen peroxide. Placing a catalase - soaked disk in a beaker of water provides a scenario where there is no hydrogen peroxide, allowing comparison to the experimental groups with hydrogen peroxide solutions.

Answer:

B. Place a catalase - soaked disk in a beaker of water.