Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Plasma membranes encloses and defines the borders of cells.

Answer: What encloses and defines the borders of cells?


Question: You call the hard case that surrounds the soft parts of some animals the exoskeleton.

Answer: What do you call the hard case that surrounds the soft parts of some animals?


Question: An experiment is a controlled scientific test that often takes place in a lab.

Answer:
What is a controlled scientific test that often takes place in a lab?