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Translocation
Translocation Transport of soluble food material from one plant to another via phloem or
xylem.
Phloem transports carbohydrates that are non-reducing sugars as reducing sugars like glucose are too chemically reactive to be transported.
Most common transported sugar is sucrose (table sugar) that is made up from glucose and fructose.
Translocation
Phloem transports sugars from a “source” to a “sink”
Source - Exporting Regions that produces sugar beyond their needs.
Sink – Any area that does not produce any or enough sugar.
Phloem transports sugars from a “source” to a “sink”
Phloem cells are connected by
Pierced structures that creates a direct connection between cytoplasm of connected phloem cells.
Translocation is accomplished by a
process called phloem
loading and unloading.
Phloem Loading Leads to buildup of sugars causing the
phloem cells to be hypertonic/ higher osmotic pressure (pressure that can be build in a space that is permeable to a solvent).
Causing water to enter sieve elements from xylem through osmosis.
Thus, phloem osmotic pressure increases.
In Sink Tissues Phloem unloading leads to lower
sugar concentration causing phloem cells to be hypertonic.
Water leaves phloem and enters sink sieve elements and xylem via osmosis.
Thus, phloem osmotic pressure decreases.
Phloem solution moves along a gradient of
pressure generated by a solute concentration
difference between source and sinks end pathways.
At source end of pathway
There is an active transportation of
sugars into sieve cells then water flows into sieve cells and thus
osmotic pressure increases.
At sink end of pathway
There is an unloading of sugars then water flows out of the sieve cells and thus osmotic pressure decreases.
The End :D
Done By: Jerry, Rafiqah, Hui Zhen, Benjamin