Question

Match the following :

	List I (Part of nephron)		List II (Function)
A	Proximal convoluted tubule	I	Impermeable to sodium ions
B	Distal convoluted tubule	II	Impermeable to water
C	Dsecending limb of Henle's loop	III	Facultative reabsorption of water $N{a}^{+}$
D	Asecending limb of Henle's loop	IV	Reabsorption of nutrients and $N{a}^{+}$

• A. A- III, B- IV, C- II, D- I
• B. A- III, B- IV, C- I, D- II
• C. A- IV, B- III, C- I, D- II
• D. A- IV, B- II, C- I, D- III

Answer 1

Answer: (C)

A- IV, B- III, C- I, D- II

70-80% of the water, sodium and chloride ions are reabsorbed from the filtrate in the proximal convoluted tubule. Bicarbonate ions are reabsorbed with H${}^{+}$ ion secretion. As fluid flows along the DCT, reabsorption of Na+ and Cl${}^{-}$ continues due to Na${}^{+}$Cl${}^{-}$ symporters.The solutes are reabsorbed with little accompanying water. On the basolateral surface (blood) there is an ATP-dependent Na/K antiporter pump, a secondary active Na/Ca transporter, and an ATP-dependent Ca transporter. The basolateral ATP-dependent Na/K pump produces the gradient for Na to be absorbed from the apical surface via the Na/Cl symporter, and for Ca to be reclaimed into the blood by the Na/Ca basolateral antiporter. The thin descending limb has low permeability to ions and urea while being highly permeable to water. The thin ascending limb is impermeable to water, but it is permeable to ions.
Therefore, the correct answer is option C.