Energy-Yielding and Processing Processes

Respiration, in which organic compounds undergo catabolism 

Fermentation, which differs from respiration in not having an electron transport chain 

Photosynthesis, in which light energy captured by plant and algal chloroplasts is used to synthesize sugars from carbon dioxide and water 

There are two major pathways in respiration. Oxic respiration (called aerobic respiration in the older literature) requires molecular oxygen, whereas anoxic respiration (anaerobic respiration) occurs in the absence of molecular oxygen. Oxic respiration uses the Krebs cycle to obtain energy from the reaction given above for cellular respiration  

FIGURE 2.9 Adenosine triphosphate, a molecule strongly involved with energy transfer in living organisms. 

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