Human kidneys can produce urine nearly

$A :$ In the descending limb of the loop of Henle,the urine is hypertonic,while in the ascending limb of the loop of Henle,the urine is hypotonic.
$R :$ The descending limb is impermeable to $Na^+$,while the ascending limb is impermeable to $H_2O$.

The concentration of sodium and chloride ions is lowest in which of the following regions?

If the kidneys fail to reabsorb water,what will be the effect on the tissues?

If Henle's loop were absent from mammalian nephron,which of the following is to be expected?

The concentration of urine depends upon which part of the nephron?