Solved UPSC CDS/OTA Question
A solved UPSC CDS/OTA PYQ - decoded step-by-step.
Solve it the standard way once - then learn the shortcut.
Q · Excretory Systemmedium · 45s
Which compound is used as a proxy for measuring renal plasma flow (RPF)?
TopicExcretory System
Question Typemultiple choice
Difficultymedium
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained - no skipped algebra.
PAH is filtered and secreted almost completely in one pass, so its clearance approximates renal plasma flow (RPF), whereas inulin clearance measures GFR.
Final Answer: Option C - PAH (para-aminohippuric acid)