Weather patterns on Earth may be

The infrared (ir) and the ultraviolet(uv) represent the two extremities of the visible spectrum (400-700nm). while ir represents electromagnetic radiation with wavelengths longer than those of visible light, uv represents wavelengths shorter than visible light

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.