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

Question

Where did the oxygen in Earth's atmosphere come from? How was the ozone play in the development of our current atmosphere?

2.Imagine that earth was not rotating and covered entirely with water rather then the current pattern of land and water. Assume that the sun is directly above the equator. What winds and pressure patters would occur?

3.What are the two ways that deforestation adds carbon dioxide to the atmosphere?

These are 3 question i need help on my homework if someone really smart can help me please because im almost finishing my studyguide and i have to study for that test tommorow(How can we study doing the study guide a day before the test and study with wrong answers?)

1 more question 4. Suppose Earth's atmosphere consisted of only of nitrogen and that Earth's surface was that of a desert. How would Earth's temperatures compare with existing temperatures?

Answer 1

(1) is interesting because there have been recent rock layers found (in Australia, I think) that show oxidation of iron content dated before the first signs of life. That would show that oxygen pre-dates living things and the old theory is then in question.
(3) two ways. A lot of forest clearing is done by "slash and burn" (Brazil) and that adds CO2 directly. But the forests are also a great recycler, absorbing CO2 as a nutrient and releasing O2 as the product of photosynthesis.

Answer 2

Oxygen is rather an extremely reactive gas, and it is likewise a poison too for many styles of existence, rather those that thrive in oxygen loose environments. except continuously replenished, it might react with each and every little thing until the ambience is depleted of loose molecular oxygen. Oxygen in our ecosystem is liberated and launched by using flora and a few microorganisms that use sunlight to transform water and carbon dioxide into sugars, which flora use for power. In turn, maximum animals and human beings consume flora for section or all of their sustenance. the approach, called photosynthesis, makes use of sunlight because of the fact the flexibility source and that's how green flora, blue-green algae and micro organism switched over the Earth's primitive carbon dioxide choked ecosystem into the oxygen-nitrogen ecosystem that sustains us right this moment. commencing some 3.5 billion years in the past, it became into not until the Cambrian era that oxygen ranges interior the air have been something like right this moment's.

Answer 3

The answer to 1) is somewhere in the course materials. The other 2 require you to think about what you have learned and apply it to the question. I recall one theory that said the plants had separated the O2 from the CO2 just as they do now. The CO2 was a by-product of some life form that lived on a sulphur enriched environment, much to its detriment. Nowhere near enough answer space to handle the other 2 questions.

Answer 4

God created the oxygen so that we could breathe.