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The earth is about 4.5 billion years old, but life did not exist on this planet until about 3.6 billion years ago, when certain kinds of bacteria and algae began to appear.
The earliest evidence for life on Earth comes from fossilized mats of cyanobacteria called stromatolites in Australia that are about 3.4 billion years old. Ancient as their origins are,
these bacteria (which are still around today) are already biologically complex—they have cell walls protecting their protein-producing DNA, so scientists think life must have begun much earlier, perhaps as early as 3.6 billion years ago.
Land plants did not appear until about 450 million years ago; reptiles, 300 million years ago; and modern mammals, 75 million years ago. The first Primates appeared about 60 million years ago, and the first apelike men, about 10 million years ago. Man, himself, has been on earth for only about 200,000 years.
If the 4.5 billion year history of the earth were to be measured in proportion to one year, man would not appear until Dec. 31, at 10:30 in the evening!
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How much oxygen is used by the earth annually?
The oxygen isn't "used by the earth"; it is recycled by organisms. The total amount of oxygen on planet Earth remains more or less constant.
Oxygen is the most abundant element by volume in Earth's?
Oxygen is the most abundant element in Earth's crust.
What will happen when there will be no oxygen in earth?
the earth would die
Where is the forest that produces most of Earth's oxygen?
The bulk of oxygen production on Earth is from phytoplankton in the oceans.
Cyanobacteria changed the young Earth's atmosphere by producing?
oxygen
Was oxygen on Earth before or after life on Earth?
Elemental oxygen did not appear on Earth until some time after life did. In fact, the oxygen was produced by life carrying out photosynthesis. The first organisms on Earth were anaerobic, meaning their life processes did not involve oxygen. To most organisms like this, oxygen was highly toxic.
Effects of no oxygen on earth?
Oxygen is main gas of earth. If there is no oxygen in the earth all the life in the earth should die.
Where do you get your oxygen on earth?
we get oxygen from the trees
The constellations you see from earth appear to change as the?
Earth revolves around the sun. That is why the constellations we see from Earth appear to change.
Why can't earth's oxygen travel through space?
Earth's atmosphere, including the oxygen, is bound to Earth by gravity.
What is the diffenerce of earth and space?
There is oxygen and gravitational force on earth but there is no oxygen and gravitational force
How does oxygen make life sutable on earth?
Oxygen makes it human capable of breathing in earth that's why when there is oxygen, there is life.
Why does earth need oxygen?
The oxygen in the air of earth is the result of biological processes over the past 4000 million years. Trees give out oxygen as they photosynthesize ------------------------------------------------------------------------------------------- Initially Earth's atmosphere did not contain free Oxygen (we know this from the chemistry of sediments that were first formed). Life on earth then happened and by the process of photosynthesis slowly began releasing Oxygen into the environment. At first this Oxygen reacted chemically with stuff (eg Iron salts) in the environment but over time all this "stuff" was converted and free Oxygen began to appear in the environment. This speeded up the development of life and about 600 million years ago there was enough Oxygen for life to use it to build calcareous shells and eventually for life to move onto the land. Thus life has made the planet we have today, Earth has been "terraformed" and now has an Oxygen rich atmosphere.
What are molten substances that appear at the surface of earth?
The molten substances that appear at the surface of the earth is magma or lava
Did the primitive Earth have oxygen?
No. Oxygen is not believed to have been present in the early years of Earth's history.
What are the two geological features that appear to set Earth apart from all the other terrestrial worlds?
Earth supports life. It is the only planet with an oxygen-rich atmosphere and liquid water on its surface.
How much oxygen is used by the earth annually?
The oxygen isn't "used by the earth"; it is recycled by organisms. The total amount of oxygen on planet Earth remains more or less constant.
