testing the hypothesis that air contains bread mold spores?

 

Question: 35 of 44

INCORRECT

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Which of the following procedures is an appropriate negative control for testing the hypothesis that air contains bread mold spores?

Seal slices of bread in a container to minimize air contact.

A negative control verifies the testing environment. Here, the testing environment is the air. Therefore, excluding air from the bread in the container is the appropriate negative control.

Place slices of bread in a refrigerated environment.

The testing environment is the access to spores in the air, not the temperature of the bread. Therefore, this is an inappropriate negative control.

Add ingredients to the bread recipe that will slow mold growth.

A negative control verifies the testing environment. If mold growth is slowed in the container, it will not give a true measure of the number of spores in the container and will undercount the number of spores in the air.

Expose a different mold-supporting medium to air.

MY ANSWER

If a mold-supporting medium is exposed to air, it will work just as bread does. Therefore, it provides no added information, and is certainly not a negative control which verifies the testing environment.