Unlike xylem, the movement of sap in phloem is:
1. essentially unidirectional
2. from a sink to a source
3. independent of movement of water
4. in any direction from source to a sink

During mass flow in phloem, active transport is required:
1. For uploading sap
2. For unloading sap
3. Both for uploading and unloading the sap
4. Active transport is not required