Identify the correct statement regarding the excretion of acids by the human kidney :
1. The filtered bicarbonate is absorbed by anion transport
2. The intercalated cells of the distal tubule secrete hydrogen ions to reabsorb bicarbonate from the tubular fluid.
3. All of the filtered bicarbonate is normally reabsorbed in the first half of the distal tubule.
4. Urine pH is normally greater than that of plasma.