Which of the following is NOT true about water transport across membranes?

The statement that water transport across membranes "requires energy in all cases" is not true. Water can move across membranes primarily through passive mechanisms, such as osmosis, which does not require input of energy. In osmosis, water molecules move from an area of lower solute concentration to an area of higher solute concentration until equilibrium is reached. This movement is driven by osmotic gradients and not by active transport, which would require energy.

Water transport is indeed essential for cellular function, as it maintains cell turgor, facilitates biochemical reactions, and aids in the transport of nutrients and waste products. The influence of osmotic gradients on water transport is fundamental to how water moves in response to solute concentrations, further affirming that energy is not a requirement in every situation.