Chemistry C1 7.4 Life on Earth.

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There are many theories about how life began on Earth, which theory is correct?
All the theories about how life started on Earth are unproven and so we cannot be sure how life began.
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Where did the plants that produced the oxygen in the atmosphere come from?
They probably evolved from simple organisms like plankton and algae in the ancient oceans.
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How did the molecules of the simplest living things begin?
We do not know how these molecules were formed because despite scientist's suggested theories there is insufficient evidence.
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What was the Miller-Urey 1952 experiment based on what scientists at that time thought was in the early atmosphere?
A mixture of water, ammonia, methane and hydrogen and a high voltage spark to simulate lightning.
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What did the Miller-Urey experiment discover?
After a week they found that amino acids, the building blocks for proteins, had been produced.
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Since the 1950's theories about what was in the early atmosphere have changed, scientist have been able to produce amino acids using other mixtures of gases. What does one theory suggest?
That these organic molecules formed a 'primordial soup' and that the amino acids in this mixture combined to make proteins from which life began.
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Why are we not sure about how life began?
There is insufficient evidence/there are lots of theories but no proof.
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Amino acids are made from the elements carbon, hydrogen, oxygen and nitrogen. Suggest why Miller and Urey used a mixture of water, ammonia, methane and hydrogen in their experiment.
They contain all the elements needed to make amino acids, water contains hydrogen and oxygen, ammonia contains nitrogen and hydrogen, methane contains carbon and hydrogen and hydrogen is hydrogen.
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**LOOK UP MILLER-UREY EXPERIMENT**
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Card 2

Front

Where did the plants that produced the oxygen in the atmosphere come from?

Back

They probably evolved from simple organisms like plankton and algae in the ancient oceans.

Card 3

Front

How did the molecules of the simplest living things begin?

Back

Preview of the front of card 3

Card 4

Front

What was the Miller-Urey 1952 experiment based on what scientists at that time thought was in the early atmosphere?

Back

Preview of the front of card 4

Card 5

Front

What did the Miller-Urey experiment discover?

Back

Preview of the front of card 5
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