Phloem Pressure Gradients Across Species
A scientist is studying sap flow in phloem vessels in three different tree, an American beech, a white oak, and an American chestnut of similar size and age. She found that the composition of the sap was identical among the trees as well as the diameter of their phloem vessels, but the rate of sap flow through the phloem vessels was different. The scientist measured the following pressures at the top (i.e., in the tree crown) and near the bottom (i.e., the base of the trunk) of each phloem vessel.
Which tree has the greatest flow rate (L/hour) of sap through the phloem vessel?
b) white oak
Explain why the tree you selected has the greatest flow rate (L/hour) of sap through the phloem vessel.
Topics:Bulk Flow, Flux, Biology, Plant physiology, Physiology
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