What does anaerobic mean?

Anaerobic refers to processes or organisms that occur in the absence of oxygen. In biology, anaerobic respiration is a form of energy production that does not require oxygen, allowing certain microorganisms and cells to generate energy under low-oxygen conditions. This is particularly relevant in environments such as deep soils, marshes, and the gastrointestinal tracts of animals, where oxygen is limited.

The other options do not accurately represent the meaning of anaerobic. For instance, processes "with air" (which implies the presence of oxygen) and "with water" may lead to aerobic processes. "With heat" might refer to temperature conditions but does not convey the critical aspect of oxygen availability. Thus, the definition of anaerobic distinctly highlights the absence of oxygen, making "without oxygen" the correct choice.