2011-02-19

The Beginning Of Life

hi guys my geologic bost here i take it from (( the concise Dinosaur Encyclopedia)) book , i hope you like it




When the earth formed , about 4.6 billion years age , it's average temperature was a hot as the surface of the sun . but just 700 million years later , life was already underway
the earth is the only place where life definitly exists , although it's possible that elsewhere in the universe , other planets have living things of their own .As far as scientists can tell , life arosew on earth through a long series of chemical accidents that took place in watery surroundings .driven by solar & chemical energy , these created the complex substances that form the machinery of all living things .
?? What is life
over 99.99999% of our planet is made up by inanimate matter - matter that isn't alive. Unlike living things ,inanimate matter cannot grow or use energy , and it cannot respond to the world around it . most importantly , it cannot reproduce . so how did this unpromising starting-point generate things that were alive 4 billion years ago ? the answer , most scientists believe , is by a series of random chemical reactions , that took place between carbon-containing substances dissolved in the sea . Some of these reactions formed microscopic bubbles surrounded by oily membranes ,containing tiny drops of fluid shielded from the water outside . Others formed substances that could copy themselves , by attacting simpler chemicals from thier surroundings . Somehow the two came together & produced the first self-copying cells . When those cells started to use energy , life began










Powering Up
the first living things were bacteria . These got thier energy from dissolved chemicals, but as they multiplied , supplies of this chemical food dwindled , & a struggle for survival began .This struggle is a feature of life , because living things always outstrip resources .but there are hidden benefits ,as this struggle also makes living things evolve .
One early result of evolution was that some bacteria evolved a new way of life released oxygen as a waste product .The atmosphere's oxygen level began to creep up to 21 % today's level . Oxygen is a highly reactive substance for many primitive bacteria , a deadly poison - so they had to retreat into mud & sediment where oxygen could not be found . but as Oxygen became abundant , more complex forms of life evolved that turned Oxygen to their advantage .These organisms could use Oxygen to burn reserves of fuel stored inside their cells , which meant that they could release energy exactly when they needed it . life was beginning to speed up
The first of these aerobic organisms were single -celled aquatic microbes ,larger than bacteria & much more complex .Celled protists , they teem in freshwater & the sea today . But their place at the top was'nt destined to last because , over a million years ago , plants & animals began to evolve
Next time i will write about Earth's First Animals
hope you enjoy with this , espacially geologist ;)
see yaaa

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