Basics of Biology

Molecules and Energy

Why would most organisms die without oxygen?

Most living organisms are aerobic—specifically, they require oxygen to complete the total breakdown of glucose. In particular, as many as thirty-six ATP are produced through aerobic metabolism of one glucose molecule. Without oxygen, cells do not synthesize enough ATP to maintain a multicellular organism.

Most people think that we need oxygen to breathe. Although this is true, we also need oxygen to recycle the spent electrons and hydrogen ions (H ) produced as by-products of aerobic respiration. With these by-products, oxygen combines and forms what is often referred to as “metabolic” water.


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