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.

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.

in 1972 the fluid—mosaic membrane model of membrane structure was proposed based on thermodynamic principals of organization of membrane lipids and proteins and available evidence of asymmetry and lateral mobility within the membrane matrix [s. j. singer and g. l. nicolson, science 175 (1972) 720–731].

after a the power stroke, adp is released, but the cross-bridge formed is still in place. atp then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.