What group of organisms must rely on cellular respiration for energy?

Oxygen is required and is used to break down nutrients , like glucose sugar they ( nutrients)  are later broken down to generate ATP (energy) carbon dioxide & water . organisms can use cellular respiration including bacteria , animals, plants and fungi.

Glucose, also called grape sugar, blood sugar or corn sugar, is among the simplest and one of the primary naturally occurring sugars. produced naturally by plants as the primary photosynthesis product, it is heavily used by living beings as a main energy source and is necessary for cellular respiration. chemically, it is a monosaccharide carbohydrate and serves as a building block for complex sugars like starch.