Question 25 BMAT 2019

Practice Question Solving
1

25- A student carried out tests to find out which molecules were present in a sample of urine from a human male. The student recorded the presence of large protein molecules in the urine, and suggested that this indicated that the kidney was not functioning correctly.
Which of the following could have resulted in a high concentration of protein in the urine sample?

1 damage to cell membranes between the blood vessels and the Bowman’s capsule

2 a reduced rate of active transport and selective re-absorption from the nephron

3 Cells in the collecting duct do not have receptors to bind to antidiuretic hormone
(ADH) and so are unable to respond to the hormone.

A none of them
B 1 only
C 2 only
D 3 only
E 1 and 2 only
F 1 and 3 only
G 2 and 3 only
H 1, 2 and 3

2

Hi!

here’s how i answered this:

  1. is correct, the membranes between the two are supposed to block most (and certainly most large) proteins. if they are damaged they could then let them through

  2. is incorrect, a reduced rate in the PCT (not the entire nephron) could cause this.
    Also if the entire nephron had a reduced active re-absorption rate, it would include reabsorption of Na⁺. We then wouldn’t have the medulla osmolarity gradient = more water in urine = more diluted = lower concentration

  3. is incorrect, if ADH can’t bind we won’t retain water = very diluted urine = lower concentration

The answer is B)

Hope this helps!

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