need help with 1,2, and 3 please APPLY THE CONCEPT Water and solutes are transpo

Question

need help with 1,2, and 3 please

APPLY THE CONCEPT Water and solutes are transported in the xylem by transpiration-cohesion-tension Suppose you measure water potential (y) in a 100-m-tall tree and its surroundings and obtain the results in the table. Note that gravity exerts a force of -0.01 MPa per meter of height above ground. 1. Is the water potential in the leaf sufficiently low to draw water to the top of the tree? 2. Would transpiration continue if soil water potential decreased to -1.0 MPa? 3. What would you expect to happen to the xylem water potential if all of the stomata closed? ? (MPa) -0.3 -0.6 REGION Soil water Xylem of root Xylem of trunk Inside of leaf Outside air -2.0 -58.5

Explanation / Answer

Water potential of pure water = Maximum = Zero

Water moves from high water potential to low water potential.

1. The water potential at the root cells is high so that it can be transported to leaf cells where the water potential is low.

Transpirational pull is the major driving factor of water movement through vascular tissues.

2. If water potential of soil water is decreased to -1.0, transpiration would not occur as it can not pass through the xylem cells of root where the water potential is -0.6.

3. If all the stomata are closed, water can not be transported via the vascular tissue. Transpirational pull along with capillary action and root pressure, maintains water column in the stem.

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