Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Example Input: A wall of rocks or concrete a called a groin.
Example Output: What is a wall of rocks or concrete called?

Example Input: Sodium-potassium pumps help nerve cells establish a voltage across their plasma membranes.
Example Output: Sodium-potassium pumps help nerve cells establish a voltage across their what?

Example Input: The golgi apparatus is often compared to a post office, moving proteins and lipids to where they need to go.
Example Output:
Which organelle is often compared to a post office, moving proteins and lipids to where they need to go?