Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: Figure 41.6 The nephron is the functional unit of the kidney. The glomerulus and convoluted tubules are located in the kidney cortex, while collecting ducts are located in the pyramids of the medulla. (credit: modification of work by NIDDK). Answer: kidneys
A:
The nephron is the functional unit of what pair of organs?