Advertising objectives can be classified based on three primary purposes. what are the three purposes?

The three primary purposes that advertising objectives can be classified by area; To inform; this is in the case of a new product where the company needs to inform the customers and create awareness on the existence of a new product. Secondly; To persuade; once you are in a competitive environment there is need to persuade the customers to buy your product. Lastly, To remind; this is especially important for a mature brand. 

Spherical shaped cell might increase the surface area and decrease the volume.