Philip Weiss

English

13 August, 18:43

Cells in the thyroid have much higher concentrations of iodide ions than the extracellular fluid that surrounds them, which is delivered by the

blood. Are iodide ions transported into the thyroid cells by active transport or passive transport?

O

A. active transport, because the cell must pump ions from regions of low concentration to high concentration

B.

active transport, because charged ions cannot diffuse through the lipid bilayer of the cell membrane

C. passive transport, because iodide ions diffuse into the cell from the surrounding fluids

D. passive transport, because charged ions are able to diffuse through the lipid bilayer of the cell membrane