Growth rate is measured by increased growth per unit time. Growth in an organism or ots part can occur in many different ways. When a cell divides and forms two cells. Of that only one participates in the next division cycle comes under the arithmetic growth pattern. Root elongation at constant rate is a classic example of arithmetic growth.
In the geometric growth pattern, both the progenies of the divided cell participate in the next division cycle. Exponential growth phase is observed in this pattern. The graph in geometric growth is a typical sigmoid curve whereas in arithmetic growth the graph is a straight line.
