Suppose That a Scientist Is Experimenting in the Laboratory with Tissue

Suppose that a scientist is experimenting in the laboratory with tissue culture methods. Pith tissue that was isolated has grown an undifferentiated mass of cells (called a callus), and that tissue has been divided up and placed in the following culture media: (1) necessary nutrients plus indoleacetic acid; (2) necessary nutrients plus zeatin (a cytokinin); (3) necessary nutrients plus equivalent concentrations of indoleacetic acid and zeatin; (4) necessary nutrients plus an excess of zeatin and minimal indoleacetic acid. Explain what happens to the mass of tissue under each condition.