Scientists believe that during its early formation, Earth's atmosphere
contained little, if any, oxygen.
Fossil and rock records suggest
that by about two billion years
ago, Earth's atmosphere was
oxygen rich and that organisms
with complex cells existed. Many
scientists think that these organisms
released oxygen, changing the
composition of Earth's atmosphere.
Which process provides the most probable explanation of how the organisms released oxygen into the Earth's atmosphere?
А.
The cells produced sugar and oxygen during the process of photosynthesis.
The cells gave off oxygen during cell division as they rapidly reproduced.
B
The cells broke down carbon dioxide and oxygen to obtain energy in cellular respiration
The cells combined nitrogen and hydrogen to produce oxygen in the process of respiration