Urea
A)is the waste product with the smallest molecular size in the glomerular filtrate
B)is in greater concentration at the end of the proximal tubule than in other body fluids
C)has a clearance rate greater than GFR
D)is both a and b
E)is all of the above

Question

Quizplus · Accepted Answer

Urea is in fact the waste product with the smallest molecular size in the glomerular filtrate, and its concentration increases as it passes through the proximal tubule, making option A and B both true. However, since it is actively reabsorbed by the renal tubules, its clearance rate is less than GFR, making option C false. Therefore, the best choice is D, which includes the true statements in A and B but not C.