AP BIOLOGY

Detailed explanation-1: -Hence, the spongy mesophyll cells of the leaves will have the lowest water potential.

Detailed explanation-2: -The xylem channels of leaves have lowest water potential because they have very high solute concentration due to loss of water during transpiration.

Detailed explanation-3: -Evaporation from mesophyll cells in the leaves produces a negative water potential gradient that causes water and minerals to move upwards from the roots through the xylem. Gas bubbles in the xylem can interrupt the flow of water in the plant, so they must be reduced through small perforations between vessel elements.

Detailed explanation-4: -The spongy mesophyll cells below the palisade layer are less densely packed together, so the region is laced with air channels. This makes the spongy mesophyll highly adapted for gas movement and air exchange around the cells.

Detailed explanation-5: -Roots grow from their tips and initially produce thin and non-woody fine roots. Fine roots are the most permeable portion of a root system, and are thought to have the greatest ability to absorb water, particularly in herbaceous (i.e., non-woody) plants (McCully 1999).