thunkit said:
my question actually is that
1)are there living organisms that do not require oxygen,
2)why is this oxygen is important couldn't life have developed without oxygen
3)can there be living beings not made up of organic compounds
:D Thanks in advance for ur answers
(i m sorry if this question is stupid or posted in a wrong forum please delete it or move it to the appropriate one)
1) All known living things contain molecules with carbon, oxygen, hydrogen and nitrogen. So if you mean oxygen the element, then I would say no. However, most microbes get their oxygen from sources other than the atmosphere.
I conjecture that you are asking whether there are living things that can live without diatomic oxygen, which is the main component of oxygen in the atmosphere. There are many living things, mostly microscopic, that can live without atmospheric oxygen. In fact, the anaerobic bacteria outnumber the aerobic bacteria. Most of the biomass in on our world comes from bacteria, most of which are anaerobic.
There are also living things that have a choice. Yeast cells, for instance, can switch between aerobic and anaerobic respiration. In fact, alcohol is manufactured mostly by the anaerobic respiration of yeast. Note that yeast are not bacteria, although they are microscopic.
Many bacteria can not use atmospheric oxygen. In fact, some bacteria die on exposure to oxygen. Clostridium bacteria are an infamous genus of bacteria that die on contact with oxygen. Clostridium bacteria are opportunistic pathogens, so it is fortunate that they die when exposed to oxygen.
http://en.wikipedia.org/wiki/Anaerobic_organism
“An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present. There are three types:
obligate anaerobes, which cannot use oxygen for growth and are even harmed by it
aerotolerant organisms, which cannot use oxygen for growth, but tolerate the presence of it
facultative anaerobes, which can grow without oxygen but can utilize oxygen if it is present
Obligate anaerobes may use fermentation or anaerobic respiration.
Aerotolerant organisms are strictly fermentative.
In the presence of oxygen, facultative anaerobes use aerobic respiration; without oxygen, some of them ferment; some use anaerobic respiration.”
http://www.cehs.siu.edu/fix/medmicro/anaer.htm
“Anaerobic bacteria are widely distributed in nature. Many anaerobes are common soil bacteria while many others make up part of the normal flora. The sensitivity of anaerobes to oxygen may be due to several factors, including the genetic inability to make enzymes such as superoxide dismutase (SOD), catalase or various peroxidases.”
http://en.wikipedia.org/wiki/Yeast
“Yeast species either require oxygen for aerobic cellular respiration (obligate aerobes) or are anaerobic, but also have aerobic methods of energy production (facultative anaerobes). Unlike bacteria, there are no known yeast species that grow only anaerobically (obligate anaerobes). Yeasts grow best in a neutral or slightly acidic pH environment.
2) This isn't true. Life could have developed without oxygen in the atmosphere. Many scientists think that life on Earth developed before oxygen was present in the atmosphere. The currently accepted theory is that oxygen was introduced by living things to our atmosphere about 1 billion years ago.
There is a science fiction fantasy that hypothesized a planet where the living things used sulphur instead of oxygen in their bodies. However, the world was very hot, above the boiling point of sulfur. Therefore, the atmosphere had gaseous sulphur instead of oxygen.
The novel was "Ice World" by Clement. It isn't real, of course. However, the novel was more realistic than Star Trek. It is a little strange that in Star Trek is that practically every solar system contains a world with oxygen, and that these are the only worlds with life.
3) The phrase "organic compounds" is now used to specify molecules containing both carbon atoms and hydrogen atoms. There are no known living things that don't contain both carbon and hydrogen.
Some scientists are working on the theory that life is possible without organic compounds. There are theories that life on Earth started with inorganic compounds in clay or mineral deposits. Organic life evolved from these preorganic life forms, according to these theories. These theories are little more than speculations, right now.
However, it is possible that there are inorganic life forms on other planets.
One theme common in science fiction fantasies is the existence of silicon-life. In these fantasies, these organisms use silicon instead of carbon. There was one silicon-life form in the original Star Trek series, and another silicon-life form in the Star Trek-Next Generation series. Not including Data and other artificial life forms, of course.