So phototrophs are those organisms that use light as their energy source to power the different processes inside that organism. While chemo tropes obtain their energy by basically breaking down or oxidizing either inorganic or organic matter. In the case of humans, we basically oxidize our organic matter. We oxidize our macromolecules such as sugars, lipids, and proteins. Now, the final way by which we can categorize organisms is by the source of electrons. So those organisms that basically obtain their electrons form organic materials such as sugars, proteins, or lipids.