(N/A) $\Rightarrow$ Source: The part of the plant where food is synthesized,primarily the leaves.
$\Rightarrow$ Sink: The part of the plant where food is stored or utilized,such as roots,stems,fruits,or developing buds.
$\Rightarrow$ Food,primarily in the form of sucrose,is transported by the vascular tissue $Phloem$ from a source to a sink.
$\Rightarrow$ The source-sink relationship is not fixed; it can be reversed depending on the season or the plant's physiological needs.
$\Rightarrow$ For example,sugar stored in roots during winter may be mobilized to become a source in early spring to support the growth of new buds.
$\Rightarrow$ The direction of movement in $Phloem$ is bidirectional,meaning it can move upwards or downwards depending on the location of the source and the sink.
$\Rightarrow$ $Phloem$ sap consists mainly of water and sucrose,but it also transports other sugars,hormones,and amino acids to regions where they are required.