Mediated transport of polar molecules and ions across the plasma membrane utilizes a(n) carrier that binds to the substance and causes a conformational change to allow its movement across the membrane.

The question is incomplete as it does not have the options which are:

Protein carrier

Lipid carrier

Porin carrier

All of the choices are correct

Protein carrier

Explanation:

The transport of molecules through diffusion can be passive or facilitated. The facilitated diffusion in which the molecules are facilitated to cross required tow type of protein channels which are the channel proteins and the carrier proteins.

The carrier proteins are the transmembrane proteins which are specific for ions and to transport the molecules change their shape of conformation. The change in the shape is responsible for the release of ions on the other side of the membrane.

Thus, Protein carrier  is correct.

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