Oxygen was added to Earth's atmosphere through the process of photosynthesis by early photosynthetic organisms like cyanobacteria. These organisms released oxygen as a byproduct, which accumulated over millions of years and eventually led to the oxygen-rich atmosphere we have today.
Oxygen makes up about 21% of Earth's lower atmosphere by volume.
The approximate percentage of oxygen in Earth's lower atmosphere is around 21% by volume.
The approximate percent of oxygen in Earth's lower atmosphere is around 20.95% by volume.
Earths atmosphere is rich in Oxygen, some 21% of the air is Oxygen. There is oxygen on other planets, but the percentage comes nowhere close to this. The percentage of Oxygen in earths atmosphere is thought to have been much higher in the past, before animals were about, but after the arrival of plants.
The approximate percentage by volume of oxygen in Earth's atmosphere at location 2 is around 21%.
The earths atmosphere is made up of 78% nitrogen and 21% oxygen
97%
no
The primary sources of oxygen in Earth's early atmosphere were likely photosynthetic organisms like cyanobacteria, which began producing oxygen as a byproduct of photosynthesis. Over time, this oxygen built up in the atmosphere, leading to the development of oxygen-rich conditions on Earth.
Free oxygen
Oxygen gas
Plants
oxygen
Nitrogen and oxygen,
no
mostly nitrogen with 21% oxygen
photosynthsis