Question

Which of the following is not true about tubular reabsorption?

• A. Nearly 99 per cent of the filtrate has to be reabsorbed by the renal tubules.
• B. The tubular epithelial cells in different segments of nephron perform reabsorption either by active or passive mechanisms.
• C. The nitrogenous wastes are absorbed by passive transport.
• D. Reabsorption of water also occurs actively in the initial segments of the nephron

Answer 1

The correct option is D Reabsorption of water also occurs actively in the initial segments of the nephron

Reabsorption of water occurs by osmosis in the initial segments of the nephron. Therefore water reabsorption is a passive process not an active process.

The filtrate formed is 180 litres per day however the urine formed is 1.5 litres. This is because nearly 99 per cent of the filtrate is reabsorbed by the renal tubules.

The tubular epithelial cells in different segments of nephron perform reabsorption either by active or passive mechanisms.

Active: Glucose, amino acids, $N{a}^{+}$, etc
Passive: Nitrogenous wastes, water