Excretory Products And Their Elimination Ques 35
35. Which one of the following statements in regard to the excretion by the human kidneys is correct?
[2010]
(a) Descending limb of Loop of Henle is impermeable to water
(b) Distal convoluted tubule is incapable of reabsorbing $HCO_3$
(c) Nearly 99 per cent of the glomerular filtrate is reabsorbed by the renal tubules
(d) Ascending limb of Loop of Henle is impermeable to electrolytes (a) Peritubular capillaries
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Answer : c
Hints & Solutions
(c) Urine formation involves three main process called, glomerular filtration, reabsorption and secretion. A comparison of the volume of the filtrate formed per day (which is 180 litres per day) with that of urine released (about 1.5 litres) suggest that nearly 99 percent of the glomerular filtrate is resorbed by the renal tubules. The descending limb of loop of Henle is permeable to water but impermeable to electrolytes. The ascending limb is impermeable to water but allows transport of electrolytes. Reabsorption of sodium ions and water takes place in distal convoluted tubule. Also, it is capable of reabsorption of $HCO_3$.
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