Water is a polar molecule and thus diffuses slowly into cells. What type of membrane protein would you expect to find many of in a cell that must be highly permeable to water?

Answer: yes

Aquaporins

Explanation:

Aquaporins are the transmembrane protein channels formed by integral proteins. Their function is to allow the rapid movement of water molecules across the cell membrane. Being a polar molecule, water can diffuse only slowly through the membranes. The presence of aquaporins allows the cells to quickly move the water across the membranes. For example, nephrons of kidneys, red blood cells have a higher concentration of this protein in their membranes.