Flashcards in End Of Unit Questions Deck (18)
Why should we be careful not to waste the earths resources?
They're non renewable
Name three gases that scientists think were in the early atmosphere
Name 4 gases that are now in the atmosphere
•any other noble gas
How did the oceans form?
The earth cooled and the water vapour in the atmosphere condensed to become the oceans
What was the effect of algae and plants on the early atmosphere?
They absorbed all of the carbon dioxide released from volcanic eruptions and released oxygen
What are tectonic plates?
The earths crust and upper mantle that has been split into large slabs
Why do tectonic plates move?
The mantle below them is flowing due to convection currents from radioactive decay of the core which causes the crust to move
About how much do the tectonic plates move each year?
A few cm
What happens at plate boundaries?
Earthquakes, volcanoes and tsunamis
Why have the amounts of gases in the atmosphere been almost the same for the last 200 million years?
Various natural processes that move carbon into and out of the atmosphere have reached a balance
What has been the main cause of a change in the carbon balance in the atmosphere in recent years?
The large amounts of fossil fuels that we burn
Why were Wegener's ideas not accepted until the 1960's?
He couldn't explain why the tectonic plates moved to cause continental drift and it wasn't until the 60's when evidence could prove it
Why are there so many theories about how life began?
There is no evidence to prove any individual theory
Outline the Miller-Urey experiment
Used a mixture of:
And a high voltage to stimulate lightning. This produced amino acids that formed life
What is meant by primordial soup?
A mixture of organic molecules/amino acids needed for life, in water/oceans
Why is the fractional distillation of liquid air done commercially?
To separate air into individual gases, to produce liquid nitrogen and oxygen which have commercial uses
Explain how the fractional distillation of liquid air is done
•air is cooled until it becomes liquid
•put into a fractionating column
•nitrogen boils at the lowest temperature so is collected as a gas at the top of the column
•oxygen remains as a liquid with argon and is collected at the bottom of the column