Given a scientific passage and an answer, generate a question for the given answer.

Input: Consider Input: Passage: Bone marrow is a soft connective tissue that produces blood cells. It is found inside the pores of spongy bone. Answer: bone marrow

Output: What is found inside the pores of spongy bone?

Input: Consider Input: Passage: Cells are the tiny building blocks of living things. They couldn't be discovered until the microscope was invented. The discovery of cells led to the cell theory. This is one of the most important theories in life science. Answer: cells

Output: What are all living things made of?

Input: Consider Input: Passage: The sodium-potassium pump is an active transport pump that exchanges sodium ions for potassium ions. Answer: potassium ions
Output: The sodium-potassium pump is an active transport pump that exchanges sodium ions for what?