2.53 describe the role of phloem in transporting sucrose and amino acids between the leaves and other parts of the plant

Plants have 2 main transport systems: Xylem and Phloem.

Phloem:
-transport sugars (sucrose and amino acids) from where they're made in the leaves to other parts of the plant.
-this movement of food substances around plant is called translocation.
-contain cytoplasm that goes from one cell to the next.

Translocation:
-movement of food substances from leaves to parts of plant.
Examples of translocation:

-During spring: sucrose transported from sources in root to sinks in leaves
-During summer: sucrose transported from sources in leaves to sinks in root.




Phloem: performs translocation of food substances from leaves to parts of plant.

















How does Phloem differ from Xylem in both structure and function?
Structurally, Xylem have tough walls containing lignin. In Phloem, the transport cells are called sieve tubes with thin walls.
Xylem have end walls that break down completely, but in phloem, end walls are filled with many holes forming a structure called a sieve plate.  Each phloem sieve tube has a smaller cell called a companion cell alongside and both these two cells must be alive for translocation to take place.