instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
The active transport of ions across the membrane causes an electrical gradient to build up across the plasma membrane.
answer:
The active transport of ions across the membrane causes an electrical gradient to build up across the what?


question:
A student should use a balance to compare the masses of two small rocks.
answer:
Which tool should a student use to compare the masses of two small rocks?


question:
Goosebumps is the layman's term for mammals raising their hair with tiny muscles in the skin, something that is automatic in humans sensing cold.
answer:

What is the layman's term for mammals raising their hair with tiny muscles in the skin, something that is automatic in humans sensing cold?