What is the function of aquaporins in cells?

• A. They facilitate rapid water transport across membranes
• B. They transport ions across membranes
• C. They synthesize water molecules
• D. They break down glucose

Answer: (A)

Water movement across cell membranes is greatly enhanced by aquaporin channels, specialized membrane proteins that allow rapid, selective transport of water molecules. These channels form narrow, hydrophilic pores that let water rush through in single file, speeding up osmosis compared with diffusion through the lipid bilayer. This rapid water transport is crucial for processes like kidney water reabsorption and plant cell turgor, where quick adjustments to water balance are needed. Aquaporins are not ion channels, so they don’t move ions; they don’t synthesize water, and they don’t break down glucose. The function described here is rapid water transport across membranes.