If you are looking at a single cell that is green in color. How do you know it is a plant cell?
The reason you know it's a plant cell is because the only thing that preform photosynthesis are plant cells. Chloroplasts are in plant cells and are required to carry out photosynthesis. Chloroplasts are found only in plant cells, and are a green color when looked under a microscope. Since they are only found in plant cells and make it green you will know that it is a plant cell. If there are green organelles then it is a plant cell. These will not be found in animal or any other types of organisms, except plants.
Hope this helps ;P
Thanks @emraldwonder. I did a bit of research and also chloroplasts contain a pigment known a chloropyll. And the chloropyll absorbs all light colors but green. So the green light is then reflected onto the plant showing parts like stems and leaves green.
Again thanks for your help, I really appreciate it!