Download 22. AQA C1 Miller-Urey Answers

Miller-Urey Experiment!
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Amino acids are important chemicals for life. They contain the elements carbon, hydrogen,
oxygen, nitrogen.
Two scientists did an experiment which showed that simple amino acids could have been
produced from the Earth’s early atmosphere.
The surface of the Earth was then at temperatures well above 100°C and the atmosphere
was mostly carbon dioxide with some ammonia, methane and water vapour.
! The experiment showed that simple amino acids could be produced by reactions
substances in the atmosphere.
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!! The diagram below shows a simple version of their experiment.
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1 (a) (i) Explain how the experiment suggests that reactions between the substances in the early
atmosphere could produce simple amino acids.
[4 marks]
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CH contains carbon or C and hydrogen or H. [1]
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NH (or ammonia) contains nitrogen or N. [1]
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H O contains the oxygen or O. [1]
Electric spark
CH4 H2
Water
H2O NH3
Condenser
Heat
Reservoir
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Amino acids contain carbon, hydrogen, nitrogen and oxygen or amino acids can be made
from (methane), hydrogen, and nitrogen and water. [1]
Lightning or high energy or heat needed for reaction. [1]
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Miller-Urey Experiment!
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!
Do not write
outside the
box
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Some people believe that this could be how life began on planet Earth.
! 1 (a) (i) This
experiment only provides weak evidence to support how life began on planet Earth.
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Suggest why.
[2 marks]
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Nobody knows what gases were in the Earth’s early atmosphere. [1]
There may not have been (continuous) lightning. [1]
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Miller and Urey selected the gases needed to make amino acids. [1]
There is more than one theory about how life was formed. Remember, there are
some questions that science cannot answer, maybe because there is not enough
repeatable, reproducible and valid evidence.
End
(Total 8 marks)
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