Changes in the Earth and its Atmosphere

Question 0

What is the mantle?

Answer 0

Extends almost halfway to the centre

Has properties of a solid even though it flows very slowly

Question 1

Way are the four main layers if the earth?

Answer 1

Thin crust
Mantle
Inner core
Outer core

Question 2

What are the inner and outer cores made from?

Answer 2

Nickel

Iron

Question 3

What is the outer core?

Answer 3

Liquid

Question 4

What is the inner core?

Answer 4

Solid

Question 5

What is the rock cycle?

Answer 5

Rocks continually being broken up, reformed and changed

Question 6

What early theory was rejected?

Answer 6

The features on the earth’s surface were caused by shrinkage as the earth cooled

Question 7

What did scientists notice that was similar about the east coast of South America and the west coast of Africa?

Answer 7

Closely matching coastlines

Similar patterns of rocks which contain fossils of the same plants and animals

Question 8

What is tectonic theory?

Answer 8

At one point the land had been part of a few single land masses
The movement of the crust was responsible for the separation of the land (continental drift)

Question 9

What causes the tectonic plates to move apart slightly every year?

Answer 9

Radioactive decay deep in the earth releases heat

Causes molten rock to rise to the surface at the boundary between the plates

Question 10

How does convection work in the mantle?

Answer 10

Hot molten rock rises the the surface, creating a new crust
The older crust slowly sinks to where the convection current starts to fall
Causes land masses on these plates to slowly move across the globe

Question 11

What happens when the movement of the tectonic plates is not gradual?

Answer 11

Earthquakes and volcanic eruptions

Question 12

How long ago did the earth form?

Answer 12

4.6 billion years ago

Question 13

What was the main gas when the earth first formed?

Answer 13

Carbon dioxide

Question 14

What did intense volcanic activity release when the earth was first formed?

Answer 14

Water vapour which condenses to form the oceans
Mainly carbon dioxide with little or no oxygen
Small amounts of methane and ammonia

Question 15

What happened as green plants evolved?

Answer 15

Oxygen produced and carbon dioxide removed as plants photosynthesise
Microorganisms that cannot tolerate oxygen die
Most carbon from carbon dioxide in the air becomes locked up in sedimentary rocks
Some carbon dioxide dissolves in ocean
Ammonia breaks down to produce nitrogen
Other gases react with oxygen to release nitrogen

Question 16

What is the current atmosphere like?

Answer 16

Carbon dioxide has decreased significantly

Nitrogen and oxygen have increased

Question 17

What percentage is nitrogen in today’s atmosphere?

Answer 17

78%

Question 18

What percentage is oxygen in today’s atmosphere?

Answer 18

21%

Question 19

What percentage is carbon dioxide in today’s atmosphere?

Answer 19

0.03%

Question 20

How do we separate the gases in the air?

Answer 20

Fractional distillation

Gases can then be used as a source of raw materials in a variety of industrial processes

Question 21

Why are the levels of carbon dioxide increasing in the atmosphere today?

Answer 21

Volcanic activity

Burning fossil fuels

Question 22

What increases the reaction between carbon dioxide and sea water?

Answer 22

Increased carbon dioxide

Question 23

What is produced when carbon dioxide reacts with sea water?

Answer 23

Insoluble carbonates which are deposited as sediments

Soluble hydrogencarbonates

Question 24

What is the main effect of more carbon dioxide dissolving in the sea?

Answer 24

Lowers pH of seawater which impacts the marine environment

Question 25

What is the Primordial Soup Theory?

Answer 25

Life on earth began in an ocean or pond when a form of energy caused the combination of chemicals from the atmosphere to combine and make amino acids

Question 26

What was the form of energy in the Primordial Soup Theory?

Answer 26

Lightning

Question 27

What happened in 1950?

Answer 27

Two people carried out an experiment to test the Primordial Soup Theory by using electricity to represent lightning
They did generate amino acids
However a problem with this was that amino acids are not a living material