Which combining form means kidney?

• A. ren/o
• B. gno/o
• C. lamin/o
• D. bi/o

Answer: (A)

The main idea here is recognizing the combining form that names a body part. ren/o means kidney, so it’s used to form terms related to the kidney, such as renal (pertaining to the kidney) or renography (imaging of the kidney). The other options come from different roots: gno/o relates to knowledge, lamin/o to a lamina or thin plate, and bi/o to life, none of which refer to the kidney.