* Animals: All animals, from the smallest insects to the largest whales, require oxygen to survive.
* Plants: While plants produce oxygen through photosynthesis, they also require it for cellular respiration.
* Fungi: Most fungi are aerobic, although some can survive in low-oxygen environments.
* Many bacteria: While some bacteria are anaerobic (don't require oxygen), many bacteria are aerobic and use oxygen for energy production.
Essentially, any organism that uses cellular respiration to generate energy requires oxygen. Cellular respiration is the process by which organisms break down glucose to generate ATP, the energy currency of cells. This process requires oxygen as a final electron acceptor.
Exceptions:
There are some organisms that do not require oxygen and can even be harmed by it. These are called anaerobic organisms. They include:
* Certain bacteria: These bacteria can survive and thrive in environments with no oxygen. Examples include bacteria found in swamps, deep-sea vents, or the human gut.
* Some archaea: Archaea are single-celled organisms that can survive in extreme environments. Some archaea are anaerobic.
Overall, oxygen is essential for the survival and reproduction of most life on Earth.
