There are different types of observers. Casual observers differ from scientific observer. Seeing and observing are two different things. Not that everybody seeing is actually observing the thing.
A casual observer just sits back and watch for something to happen while a scientific observer comes up with some hypothesis to work on it.
Answer:
There are two answers to this question. Gold or Aluminum.
Without oxygen, organisms can just split glucose into two molecules of pyruvate.With oxygen, organisms can break down glucose all the way to carbon dioxide. This releases enough energy to produce up to 38 ATP molecules. Thus, aerobic-respiration releases much more energy than anaerobic respiration.That's what Respiration to generate engery.