Q14 - Using Inulin Clearance to Measure Kidney Filtration
Inulins are inert polysaccharides which cannot cross cell membranes. Inulins were infused into a human vein at a constant rate of 0.2 moles per minute. After infusion is stopped, a total of 25 moles of inulins were collected in the urine.
This question mixes multiple-choice/numeric-estimate parts with True/False statements - answer each part using the information and data above.
A. Rate of inulin secretion is proportional to its concentration in blood.
B. A drug which freely passes through cell membranes will be lost in urine at a faster rate than inulins, when at the same concentration in blood.
C. Inulin is infused at 0.2 mol/min and plasma concentration plateaus at 1.6 mol/L. What is the glomerular filtration rate?
D. A total of 25 moles of inulin were collected in the urine, distributed at the plateau plasma concentration of 1.6 mol/L. What volume of plasma did this correspond to?
Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions