Answer:
The ATP acts as the energy currency of the cell requires for almost all the biological process. The glucose acts as the substrate for the production of ATP in the cells.
The ATP production depends on the number of cells as well as on the sugar concentration. The ATP production will be more if the number of the cells and sugar concentration will increase. In the given question, the ATP production will increase quickly as the number of cells are increasing but soon stops as the sugar concentration is constant. After the full consumption of the sugar, no ATP production will occur in the cell.