Answer: transport
Explanation: the cell membrane serves as a permeable barrier but allows active and passive transport across its surface. the membrane has different functions:
Mechanical Structure. Defines/encloses the Cell. ...
Selective Permeability. ...
Active Transport. ...
Bulk Transport: Exocytosis & Endocytosis. ...
Markers & Signalling. ...
Metabolic Activities.
the last 6 are functions of transport in some capacity.