Describe the structure of the Earth.
The Earth is built in layers. An atmosphere of gases surrounds the Earth. The Earth itself consists of a crust, mantle, inner and outer core.
How thick is the Earth's crust?
From 5km to 70 km
How thick is the mantle?
What can be found inside the Earth's core?
Where do humans find resources and minerals?
There is a limited supply of resources in the crust, oceans and atmosphere.
What are tectonic plates?
The Earth's crust and upper mantle is cracked into massive plates.
Why do tectonic plates move?
Convection currents occur in the mantle due to radioactive decay.
What evidence is there that tectonic plates have moved over many years?
Fossils and rock structures are very similar in South America and Africa.
Why is it difficult for scientists to predict earthquakes?
It is difficult to know when plates may slip past one another.
What was the Earth's early atmosphere like?
The atmosphere consisted mainly of CO2 with water vapour, ammonia and methane.
How were the gases in the Earth's early atmosphere produced?
Through volcanic activity.
How was oxygen produced?
As plants spread across Earth, they released oxygen increasing the overall level.
Why are there so many theories for how life started on Earth?
None of the theories are proven.
Explain the Miller-Urey theory.
They used various gases to recreate the early atmosphere then used a high voltage to produce a spark which provided the energy needed to start a reaction between the gases. The experiment formed amino acids which are needed for life to exist.
Give three theories about how life started on Earth.
-Miller-Urey theory -A meteorite -God
Give three places where carbon went
-Organic material -Sedimentary rocks -Fossil fuel (ie. crude oil)
How can the gases in air be separated?
Explain how the gases in air are separated.
The pressure is increased 150x, whilst being cooled with water. The pressure is released causing the liquids to cool and condense. CO2 and water are solids so are removed. The liquid then warms and boils in the fractionating column.
Describe the carbon cycle.
Why has the carbon cycle changed?
Humans burn fossil fuels, increasing the CO2 level in the atmosphere.
How does the increase in CO2 affect the sea environment?
Excess CO2 is dissolved in the sea which increase the acidity killing coral and fish.
What are the main gases in the atmosphere now?
Nitrogen and oxygen.
What are proportions of gases in the atmosphere?
78% nitrogen 21% oxygen 0.04% carbon dioxide
Where did the carbon dioxide from the early atmosphere go?
CO2 is taken in by plants meaning it can be used to produce new plant material. Most CO2 is organic material and materials formed by organisms.