True regarding electrophoresis are all except
Electrophoresis depends on size as well as on shape
Electrophoresis is the process that uses an electric field to drive the movement of charged particles. Electrophoresis depends on the net charge of the particle, molecular weight, pH of the medium, the strength of the electric field and temperature.

About other options

Ampholyte is used in isoelectric focusing to create a pH gradient across the supporting media. Molecules stop migrating as soon as they reach their respective isoelectric point (pI).



Electrophoresis can adversely affect the structure and function of proteins.
Electrophoresis is the most common method for protein separation.
"Electrophoresis is the most common method of protein separation in the clinical laboratory". 
"PAGE and SDS-PAGE are extensively used for characterization and purification of tissue proteins, enzyme, receptors, and surface antigens".

Electrophoresis uses an electric field
Isoelectric focusing use ampholytes & pI
Adversely affect structure & function
Depends on size not on shape
Commonest method of purifying protein