Really short answer:
Chemistry.
Short answer:
Because life on our planet is based on water (H2O).
Long answer:
Oxygen is not a necessity for life; there are whole classes of microorganisms that are anaerobic.
Some of these organisms developed the ability to photosynthesize light and split water into oxygen and hydrogen (which combines with carbon into carbohydrates). In fact nearly all of the oxygen in the air we now breathe was produced by microorganisms more than 3.5 billion years ago who effectively polluted the environment for other organisms for which oxygen was poisonous.
However, some organisms not only survived the oxygen bloom, but subsequently developed the ability to chemically use this atmospheric oxygen. Some of these organisms evolved into multicellular organisms that eventually evolved into plants and animals dependent upon atmospheric oxygen.
Animals in particular are dependent on oxygen for a metabolic process called the Krebs Cycle, and I suspect this is what you mean.
Oxygen is essential for cells to perform their functions. Without oxygen, cells begin dying in a few minutes. Oxygen deprivation can cause human death in about four minutes.
oxygen fuels the brain.....
trace elements
Oxygen is essential for aerobic respiration, oxygen helps blood flow which helps with our circulation. Anaerobic respiration does not require oxygen.
16
Oxygen,gravity,tempeture,sleep,and shelter
oxygen fuels the brain.....
Oxygen is the gas we breathe. It is colorless, odorless, and tasteless. It is essential to humans' survival.
Although many would suggest oxygen, and this answer is true for all larger animals, a review of all living organisms suggests some that live in the absence of oxygen:anaerobes some of which substitute sulfur for oxygen in their life processesfacultative organisms
There are many things that are essential for survival. These include water, oxygen, food, warmth, etc.
Another critical gas is oxygen gas (O2). Much of life on this planet is aerobic, meaning oxygen is required for survival. Oxygen serves as a key constituent in the process that releases the energy stored in food.Oxygen is not essential to all life. In fact there are some organisms that die in the presence of oxygen. There was once a time when there was no oxygen in our atmosphere and only anaerobic organisms lived. Water is essential to all known life but not oxygen.
Because our red blood cells take in the oxygen we breathe in and distribute it to the other parts of our body. It also gives us a large part of our nutrition and energy.
It affects the oxygen level because it is essential for the survival and growth of organisms ata ll levels within its ecosystem.
Reproduction
No, killing the pig is not essential to the survival of the group. There are other ways to obtain food and resources for survival without harming animals.
yes
oxygen, carbon, water (H20), salt (Nacl)I'm pretty sure anything that there is a daily value for on a vitamin bottle is essential to human life, other animals are different.
However, volcanoes are essential to earths survival they act like a safety valve for the planet (it releases pressure)