Urea Has a Molecular Weight of 60

Question

Urea has a molecular weight of 60. You would expect
A) the sieving coefficient to be << 1.0
B) its rate of filtration to be = GFR x Uurea
C) its concentration in the ultrafiltrate to be the same as its concentration in plasma
D) its reflection coefficient to be 1.0
E) it to be secreted

Accepted Answer

Urea is a small molecule that is freely filtered across the glomerular membrane, so its concentration in the ultrafiltrate is the same as in plasma.