Which of the following is true about tubular reabsorption?

A) It always happens via the paracellular route.

B) It moves water and solute from the blood to the filtrate.

C) It always involves active transport.

D) It involves carrier-mediated transport.

Answer: D (It involves carrier-mediated transport).

Explanation:

Tubular reabsorption transports nutrients back into the blood. Tubular reabsorption of nutrients such as sodium, glucose, lactate amino acids, and other organic substances occurs via carrier membrane proteins to the proximal tubule.

Most of the substances that are reabsorbed via the proximal tubule require the use of carrier membrane proteins, for facilitated diffusion, active transport and secondary active transport.

Example of secondary active transport is the sodium-dependent glucose cotranspoter.