Investigation. Cells are the basic unit of life. Observe the two petri dishes, and record information about their appearances. Day Petri dish (on left) containing nutrients. Petri dish (on right) containing agar without nutrients. What is the purpose of using agar without nutrients in the petri dish on the right?
1) To serve as a control group
2) To provide a source of nutrients for the cells
3) To observe the growth of cells
4) To prevent the growth of cells