Question

describe loading and unloading sieve tubes

Answer 1

Translocation of organic solutes such as sucrose takes place through sieve tube elements phloem.but before Translocation of sugars proceed,the soluble sugars must be transferred from mesophyll cells to sieve tube elements of respective leaves.
This transfer of sugars from mesophyll cells to sieve tube elements in the leaf is called as phloem loading and the transfer of sugars from sieve tube element to the receiver cell of consumption end is called as phloem unloading.
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