LIFE ON EARTH

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Mind Map by zoe98xoxo, updated more than 1 year ago
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yr 11 Biology Mind Map on LIFE ON EARTH, created by zoe98xoxo on 09/06/2013.
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LIFE ON EARTH
1 Analysis of the oldest sedimentary rocks provides evidence for the origin of life
1.1 The relationship between the conditions of Early Earth and the origin of organic molecules
1.1.1 Early earth contained no ozone layer so large amounts of UV radiation reached the earth, the reason for the absence of no ozone layer was their was little free oxygen. --> The volcanic emissions filled the atmosphere with methane, ammonia, hydrogen, carbon dioxide, carbon monoxide and small amounts of water vapour.The violent electrical storms and acidic rain formed the present warm and mineral - rich oceans.
1.1.2 There are only two possible ways organic molecules could have formed either on earth from simpler molecules, or by arriving from the cosmos
1.2 Discuss the implications of the existence of organic molecules in the cosmos for the origin of life on Earth
1.2.1 Organic molecules have been found in interstellar dust. When NASA scientists were investigating compounds that could be found in comets, moons and icy planets they exposed the chemicals to UV radiation which produced many complex organic compounds. This suggests that the conditions in interstellar ices could be the site of the production of the organic chemicals necessary for the origin of life.
2 THEORIES ABOUT HOW LIFE STARTED ON EARTH
2.1 SPONTANEOUS GENERATION
2.1.1 For many generations it was believed that life spontaneously arose out of different materials. E.g. garbage turned into rats, rotting meat turned into maggots.
2.1.2 SIGNIFICANCE
2.1.2.1 This theory is significant in understanding the origin of life, because it is untrue. We can further our understanding by learning from these errors. In 1862, Louis Pasteur carried out an experiment by using a flask containing boiled broth and showed that there was no spontaneous generation if contamination of the flask was prevented.
2.2 Chemicals for life formed on Earth (Abiotic synthesis in the Atmosphere and Oceans)
2.2.1 Haldane and Oparin suggested that Earth had all the necessary basic chemical components for life on Earth. They proposed that the early atmosphere on Earth contained little oxygen, and that the complex organic molecules could have been created from UV radiation, electrical discharges, and heat.
3 UREY MILLER EXPERIMENT
3.1 Urey and Miller set up a simulation of primitive earth. A mixture of hydrogen, ammonia, and methane in the form of steam was continuously electrically discharged for a week. The experiment resulted in a solution containing a number of amino acids and hydroxy acids which are vital components for living things. Urey and Miller’s experiment supported Oparin and Haldane’s theories on the origin of life, which showed that organic material, could be formed by raw materials.
3.2 REASONS FOR THIS
3.2.1 To test the hypothesis of Oparin and Haldane which stated that conditions on the primitive Earth favoured chemical reactions that synthesized organic compounds from inorganic compounds.
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