Question

Tubular secretion, the movement of solutes out of the blood into the tubular fluid, usually occurs by ______.

1) Active transport
2) Passive diffusion
3) Osmosis
4) Facilitated diffusion

Answer 1

Tubular secretion usually occurs by active transport, which is the movement of a substance across a cell membrane from an area of lower concentration to an area of higher concentration using cellular energy.

Step-by-step explanation:

Tubular secretion, the movement of solutes out of the blood into the tubular fluid, usually occurs by active transport. Active transport refers to the movement of a substance across a cell membrane going from an area of lower concentration to an area of higher concentration. In this type of transport, proteins within the cell membrane act as "pumps," using cellular energy (ATP) to move the substance.