<prompt> Secretory vesicles are transpoed ?Along concentration gradientAgainst concentration gradientMay be along or against concentration gradientHave no relation with concentration gradient  <response>: Ans. is d i.e., Have no relation with concentration gradientExocytosisExocytosis is a reverse of endocytosis. This process is involved when secretory granules are extruded from the cell. When secretory vesicle comes in contact with inside of cell membrane, the membrane of the vesicle fuses with cell membrane and then there is extrusion of the contents of vesicle from the cells as secretory granules. Similar to endocytosis exocytosis requires Ca and energy. Exocytosis is also called emiocytosis or reverse pinocytosis.Exocytosis secretion from the cell occurs two pathways : -Non-constitutive pathway :- Proteins from the Golgi apparatus initially enter secretory granules, where processing of prohormones to mature hormones occurs before exocytosis. This pathway is sometimes called regulated pathway. ii Constitutive pathway :- Involves the prompt transpo of proteins to the cell membrane in vesicles, with little or no processing or storage. 