Question

Aquaporin expression changes with water deficit.

Perhaps by using Darcy's Law: Darcy’s Law: J_j = -L_path ∆Ψ_w / ∆x

Where: L = hydraulic conductivity (how permeable is the pathway)

∆Ψ_w = water potential gradient

∆x = distance in the pathway

• Describe what aquaporins are and how the expression of aquaporins would alter the flow of water through tissues.

• As the soil dries out, how does ∆Ψ_w from the soil to the root change?

• What could the plant do to maintain ∆Ψ_w and the utility of the aquaporins (look at the equation and recognize that aquaporins increase L)?

(Be sure to include in the answer: Describes aquaporin structure, function, and places them in biological context that provides information on their influence on water flux, Establishes changes in ∆Ψ as soil dries, Describes cell level changes that maintain favorable water gradients)