What's the difference between the outer and inner cores?
The outer core is liquid due to heat but the inner core is solid due to pressure
5 of 27
What are tectonic plates?
Areas of the Earth's crust + upper part of the mantle that move due to convection currents in the mantle
6 of 27
Why are there convection currents in the mantle layer?
Radioactive decay of atoms heats molten minerals and causes them to rise
7 of 27
What happens when tectonic plates suddenly slide past each other?
Earthquakes
8 of 27
How did the seas form?
Water vapour from the Earth's atmosphere condensed in hollows in the crust
9 of 27
What did the first organisms use for energy?
Breakdown of other chemicals
10 of 27
Where did the oxygen in the Earth's atmosphere come from?
Organisms who evolved to photosynthesise
11 of 27
What made it possible for animals to develop?
Increase of oxygen in the atmosphere
12 of 27
What are amino acids made from (mostly)?
Carbon, hydrogen, nitrogen and oxygen
13 of 27
What was the aim of the Miller-Urey experiment?
To see if amino acids could be created in the early atmosphere
14 of 27
Why did Miller and Urey use a high-voltage spark and what real-life event does it mimic?
For the energy needed to start a reaction - mimics lightning in storms
15 of 27
What did Miller and Urey find once their experiment had been running for a week?
A 'brown soup' mixture containing 11 amino acids
16 of 27
Why do some scientists think the Miller-Urey experiment is invalid?
It only works with the absence of oxygen, which would have been present in the early atmosphere
17 of 27
What are 2 other theories for why life began on Earth?
Extra-terrestrial seeding (molecules capable of starting life came from outer space e.g. in the Murchison meteorite) or that life developed deep under the oceans
18 of 27
What is a primordial soup?
A mixture of organic molecules
19 of 27
What's the biggest difference (in terms of gas composition) between the early atmosphere and ours today?
Today there is a much lower concentration of carbon dioxide (0.04%)
20 of 27
Where does carbon dioxide taken up during photosynthesis ultimately end up?
Comments
No comments have yet been made