If you're like me, you have this recurring dream where someone hauls out the microscope and a slide and asks you to identify whether the cells you're looking at belong to a plant or an animal. Sounds like a nightmare, right? Well, luckily it turns out that the differences between plant and animal cells are easy to spot.

The best case scenario is that the cell you're looking at is green, the pigment that traps sunlight, which the plant then uses as part of photosynthesis. Still, you can't always count on this to be true. Flower cells may contain red, orange, and yellow pigments; root cells may contain no colorful pigments at all. In this case, you can recognize a plant cell by its rigid cell wall and by the fact that it contains a fluid-filled space known as a vacuole.

You see, unlike animals, plants aren't able to excrete excess water, which means that sometimes the fluid pressure inside their cells gets pretty high. This is where the cell wall comes in--it prevents the cell from bursting.

Another way the plant cell adapts to the fact that it can't excrete waste is in the function of its vacuole, which it uses to store and recycle metabolic products into substances used for plant growth. The vacuole also contains other organic materials, like the pigments that give flowers their color, and poisons to fend off predators.

So go ahead and turn that nightmare into a dream; impress your friends with your ability to identify cells. You might even consider investing in a microscope.