**Aquaporins** are:
- Water-tight membrane proteins
- Membrane channel proteins that facilitate rapid passive water transport across cell membranes
- Water-storing tissues in succulents
- Active ATP-driven water pumps
Show answer and solution
Correct answer: B. Membrane channel proteins that facilitate rapid passive water transport across cell membranes
Aquaporins (AQPs) are integral membrane channels that allow facilitated diffusion of water (and sometimes small solutes) through bilayers ~10×–100× faster than simple diffusion.
Important in roots (water uptake) and guard cells (stomatal movement).