If a cell was observed under the microscope and found to have a rigid cell wall and be green in color that cell is most likely a animal cell plant cell bacterium cell algae cell

Dr. arenas is a scientist who has been trying to determine if increasing pressure will increase the sound that occurs when two chemicals explode. it measures the volume of the sound that occurs at the minimum pressure at which the explosion will occur. it then increases the pressure and measures the volume of the explosions that occur. what kind of investigation is the scientist conducting?