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Question 2
In this part of the experiment, you’ll prepare and test three milk solutions: milk and water, milk and lactase enzyme, and milk and heated lactase enzyme.

Prepare

Use masking tape to label the three beakers: “milk,” “lactase solution,” and “heated lactase solution.”
Measure 60 milliliters of milk in the graduated cylinder (or ¼ cup of in a measuring cup. Pour it into the beaker labeled “milk.”
In the beaker labeled “lactase solution,” add one lactase tablet and 100 milliliters (or 1/2 cup) of cool or room-temperature water. Use the stirrer to dissolve the lactase tablet in the water.
Add 100 milliliters (or 1/2 cup) of milk to the microwaveable container. Dissolve a lactase pill in the container. Put the solution in the microwave and heat it to boiling (about 2 minutes). Use oven mitts to remove the container. Pour the heated lactase solution into the beaker labeled “heated lactase solution” and let it cool.
Stay safe! Be careful while handling the boiled mixture to avoid spilling it on your hands.

Test

While you’re waiting for the lactase solution to cool, read the directions on the test strips. The test strips in the Edmentum lab kit will react to glucose within a few seconds. If you use different strips, the reaction time may vary. Now follow these steps to test the solutions. Record your data in the answer space.

Milk and water solution: Fill the first test tube one fourth full of milk. Fill the small graduated cylinder with water and gently add it to the milk in the test tube until the test tube is half full. Use the stirrer to thoroughly mix the solution. Then insert the test strip for 10 to 20 seconds. Look at the test strip, and record whether it changed color. Wash the stirrer.
Milk and lactase enzyme solution: Fill the second test tube one fourth with milk and one fourth with the lactase solution. Use the stirrer to thoroughly mix the solution. Insert the test strip for 10 to 20 seconds, and record whether it changed color. Wash the stirrer.
Milk and heated lactase enzyme solution: Fill the third test tube with one fourth milk and one fourth of the heated lactase solution. Use the stirrer to mix the solution. Insert the test strip for 10 to 20 seconds, and record whether it changed color.
Note: Keep the lactase and heated lactase solutions for the next part of the experiment.

Wash the “milk” beaker, the test tubes, and the stirrer. If you used paper cups as an alternative, throw them away.

Sagot :

Answer:

The bacterium should stop production of lactase.

Explanation:

This is because the E. coli bacteria can degrade lactose, but lactose is not preferred as source of fuel or energy to glucose. If glucose is present, E. coli would preferably employ it over lactose as Glucose needs little process and minimal energy to degrade when compared to lactose. Although, if lactose is the major sugar that is present, the E. coli will have no option than to employ it as it's source of fuel or energy. The formation of lactase enzyme utilizes energy, which cannot be utilised in the presence of high level glucose.

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