According to the pressure-flow hypothesis, what mechanism causes the movement of phloem sap from sources to sink tissues? see section 35.4 (page) .
a) transpirational pull from the leaves
b) solute potential differences between source and sink
c) root pressure
d) pressure potential differences between source and sink

D) Pressure potential differences between source and sink

Explanation:

high turgor pressure causes the movement of   phloem sap from source to sink, Sap moves through phloem via translocation, the transport of dissolved materials in a plant. Unlike the xylem, which can only carry water upward, phloem carries sap upward and downward, from sugar sources to sugar sinks.

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.

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