Atmospheric Oxygen (O2)

Definition

Atmospheric oxygen refers to the oxygen present in Earth's atmosphere. It makes up about 21% of our atmosphere and is essential for aerobic respiration in many organisms.

Analogy

Imagine atmospheric oxygen as one slice of a pie chart representing Earth's atmosphere. It's not the whole pie (since there are other gases like nitrogen and carbon dioxide), but it's an important piece that allows us - and most living things - to breathe and live!

Related terms

Photosynthesis: The process used by plants, algae, and some bacteria to convert sunlight into chemical energy (glucose) using carbon dioxide and releasing oxygen as a byproduct.

Aerobic Respiration: A metabolic process where cells use oxygen to produce energy from food, releasing carbon dioxide as waste.

Ozone Layer: A layer in Earth's stratosphere containing high concentrations of ozone (O3). It absorbs most of the Sun's harmful ultraviolet radiation.