Q.52 Arrange the following in the increasing order in which they are excreted in a normal healthy individual
A. Urea
B. Glucose
C. Sodium
D. Water
Choose the correct answer from the options given below:
1. D, A, C, B
2. B, C, D,A
3. B, C, A, D
4. B, A, C, D
In a normal healthy individual, the kidneys filter blood and selectively excrete waste while reabsorbing essentials through glomerular filtration, tubular reabsorption, and secretion.
Correct Answer
The right sequence in increasing order of excretion is B, C, A, D (Glucose, Sodium, Urea, Water). This corresponds to option 3.
Glucose is completely (100%) reabsorbed in the proximal convoluted tubule (PCT), so none is excreted under normal conditions.
Sodium is over 99% reabsorbed across the nephron (PCT, loop of Henle, distal tubule), with minimal excretion to maintain electrolyte balance.
Urea, a nitrogenous waste from protein metabolism, has about 50% reabsorption, making it the primary excreted solute (25-30g/day).
Water forms ~95% of urine volume but is mostly reabsorbed obligatorily (~99%) via osmosis following solutes; excess is excreted based on hydration.
Options Explained
| Option | Sequence | Why Incorrect/Correct |
|---|---|---|
| 1. D, A, C, B | Water, Urea, Sodium, Glucose | Wrong: Water excretes more than glucose (none) or sodium (minimal); urea before sodium mismatches reabsorption rates |
| 2. B, C, D, A | Glucose, Sodium, Water, Urea | Wrong: Places water before urea, but urea (50% reabsorbed) excretes more than minimal sodium yet less volume than water |
| 3. B, C, A, D | Glucose, Sodium, Urea, Water | Correct: Matches near-100% reabsorption (glucose/sodium) > partial (urea) > bulk volume (water) |
| 4. B, A, C, D | Glucose, Urea, Sodium, Water | Wrong: Urea excretes more than sodium (99%+ reabsorbed sodium < 50% urea) |
This order reflects nephron efficiency: threshold substances like glucose fully reclaimed, ions like sodium tightly regulated, urea partially passive, water adjustable.
