Stress

Early bacteria and mitochondria in eukaryotes use dioxygen (O2) and carry out aerobic ______

The first living organisms were ______

Dioxygen, O2, is toxic to all forms of ______

Life coexists with 21% O2 because of: antioxidant defense systems repair or replacement of the components damaged by ______

Animals, plants, and aerobic bacteria require O2 for efficient production of ______