What Caused Oxygen to Appear on Earth?

In summary: This event took place about 2.3 billion years ago. About two-thirds of the earth's current atmosphere is made up of oxygen. The great oxygenation event occurred when photosynthesis by microorganisms released oxygen into the atmosphere. The rise of oxygen in the atmosphere caused the oceans to become more acidic and prevented the growth of anoxic organisms. Over time, the release of oxygen caused the oceans to become less acidic and allowed the growth of anoxic organisms. The great oxygenation event also led to the evolution of complex life.
  • #1
johncena
131
1
organic evolution took place in the absence of oxygen...if so, how oxygen came on earth??
 
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  • #2
With the evolution of organisms able to carry out photosynthesis they began converting carbon dioxide to oxygen and using the carbon. Further chemical and biological processes produce hydrocarbons taking hydrogen from water and yielding up net oxygen (usually again as CO2 which is again converted via photosynthesis). The oxygen was always there but in the form of CO2, H2O and mineral oxides.

You must distinguish the absence of free oxygen from the absence of oxygen in general.
 
  • #3
many micro-organisms produce poisonous substances to kill their competitors. (think of peroxide).
 
  • #4
I don't think oxygen was produced as a defense mechanism, but rather as a waste product.
 
  • #5
Careful about ascribing intent to the initial genetic advance. The microbes didn't choose to produce oxygen nor were they conscious of effect so the "why" of it shouldn't be debated at this level. The oxygen was a byproduct of an advantageous process and also a toxic substance so its production also made oxygen tolerance an advantageous trait. Both together also had the advantage of poisoning competitors more than selves. It is clear such a genetic innovation is a one way street and almost all organisms either adapted or died off... and so here we are.
 
  • #6
How was it possible for organisms such as plants or microbes to introduce oxygen to the Earth if their DNA template, from which all of their biological features come, contains oxygen? DNA consists of many nucleotides, which contain oxygen ,that are linked on the outer rim of the DNA through the use of phosphate groups, which also contain oxygen. So, if the number one important molecule needed for the survival and procreation of plants and microbes contains oxygen, I'm curious as to how microbes or plants introduced oxygen as a novel agent to the earth. :smile:
 
  • #7
You are confusing free oxygen, O2, with oxygen in general. There was plenty of oxygen in the early Earth's atmosphere in the form of CO2 and other compounds, plenty of of oxygen in the early Earth's oceans in the form of H2O, and plenty of oxygen in the early Earth's crust in the form of many oxygenated compounds.
 
  • #8
oxygen is oxygen whether it is incorporated into molecules within the atmosphere or water in the oceans...perhaps the original question was addressing diatomic oxygen as opposed to oxygen as a novel agent on earth. My apologies if so. As long as no one is under the assumption that microbes or plants introduced oxygen on an oxygen-less planet. =]
 
  • #9
That was answered in posts #2 and #4: There always was oxygen on earth, just not in the form of O2.
 
  • #10

1. How did oxygen first appear on Earth?

Oxygen first appeared on Earth approximately 2.4 billion years ago through a process called photosynthesis. Early photosynthetic organisms, such as cyanobacteria, used energy from the sun to convert carbon dioxide and water into oxygen and glucose.

2. Where did the oxygen in Earth's atmosphere come from?

The oxygen in Earth's atmosphere was primarily produced by photosynthetic organisms over billions of years. These organisms released oxygen as a byproduct of photosynthesis, gradually increasing the amount of oxygen in the atmosphere.

3. Did oxygen always exist on Earth?

No, oxygen did not always exist on Earth. The early Earth had a very different atmosphere, mainly composed of gases such as methane, ammonia, and carbon dioxide. Oxygen became a significant component of the atmosphere only after photosynthetic organisms evolved.

4. What role did oxygen play in the evolution of life on Earth?

Oxygen played a crucial role in the evolution of life on Earth. It allowed for the development of more complex and efficient organisms, as it is a vital component of cellular respiration. The increase of oxygen in the atmosphere also led to the formation of the ozone layer, protecting life on Earth from harmful UV radiation.

5. How do scientists know about the history of oxygen on Earth?

Scientists know about the history of oxygen on Earth through various sources of evidence, such as geological records, fossilized remains of ancient organisms, and chemical analysis of rocks. They can also study the composition of other planets and the processes of photosynthesis to understand how oxygen may have originated on Earth.

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