Biology

The correct answer is: D. They are involved in transporting molecules across the membrane.

Explanation:

Integral membrane proteins (also known as transmembrane proteins) span the lipid bilayer of the cell membrane and play a variety of roles, including:

Transporting molecules: Integral proteins act as channels, carriers, or pumps, facilitating the movement of ions, nutrients, and other molecules into and out of the cell. This makes them key players in processes like facilitated diffusion, active transport, and ion transport.

Why the other options are incorrect:

A. They are located only on the outside of the membrane: This is incorrect. Integral membrane...