Organisms can use a variety of carbon and energy sources, depending on their availability in the environment. Oxidation and reduction reactions play critical roles in metabolism, and the relative favorability of these reactions often dictates the type of metabolism an organism will employ in a given situation. For example, organisms that conduct aerobic respiration (like humans) use organic carbon compounds (like glucose) as both their carbon source and their energy source. A. What carrier molecules are reduced by the transfer of electrons from glucose? What are the oxidized and reduced forms of these molecules? Electrons are then passed down the electron transport chain, sequentially reducing proteins in the chain, in the process creating a proton gradient for ATP synthesis. B. What is the final electron acceptor for organisms performing aerobic respiration?

Microbes are microscopic living organisms that can only be detected with the help of specialized laboratory equipment called a microscope. These living organisms are so small that they are not visible to the naked eye.