| 1. | SER | 2. | Mitochondria |
| 3. | Chloroplasts | 4. | Vacuoles |
| a. | Mitochondria are easily visible under the microscope without any staining. |
| b. | The number of mitochondria per cell is always fixed irrespective of the physiological activity of the cells. |
| c. | Mitochondria are the sites of aerobic respiration. |
| d. | Mitochondria divide by fission. |