C1.7 Changes in the earth and it's atmosphere

Question 1

What does the earth consist of and what is it surrounded by? (4)

Answer 1

• Core, mantle, crust

- Surrounded by the atmosphere

Question 2

“The Earth’s CRUST, the ATMOSPHERE and the OCEANS are the ONLY source of minerals and other resources that humans need.” Is this true?

Answer 2

Yes

Question 3

What are the average sizes of the three main parts of the earth? The core’s radius, the mantle’s depth, and the depth of the crust (km)

Answer 3

• CORE= radius of about 3500km
• MANTLE= 3000km deep
• CRUST= 6km under oceans, 35km (but up to 70km) under continents

Question 4

What are tectonic plates?

Answer 4

Where the Earth’s CRUST and upper part of the MANTLE have CRACKED into a number of large pieces

Question 5

What causes tectonic plates to move a few centimetres per year?

Answer 5

Natural RADIOACTIVE processes which release HEAT drive CONVECTION currents within the Earth’s MANTLE

Question 6

What can be a result of sudden or disastrous tectonic plate movements?

Answer 6

Earthquakes +/ volcanic eruptions at the plate boundaries

Question 7

In fifths, what are the gases that make up the atmosphere? (3)

Answer 7

• About four-fifths (80%) nitrogen
• About one-fifth (20%) oxygen
• Others, including carbon dioxide, water vapour and noble gases

Question 8

During the first billion years, something released gases and water vapour. What was it that did this and what were the gases and water used for? (3)

Answer 8

• Intense volcanic activity released gases and water vapour
• Gases= early atmosphere
• Water= condensed to form the oceans

Question 9

Suggest a theory as to how the atmosphere was formed (3) (more: ‘What was the early atmosphere like?’)

Answer 9

• During 1st bn. years atmosphere=CO2, barely any oxygen gas
• Similar to Mars and Venus today
• Maybe water vapour and itsy bitsy bits of methane and ammonia

Question 10

Explain one theory as to how life was formed (1 point)

Which experiment is used to prove this?

Answer 10

• Interaction between hydrocarbons, ammonia and lightning

- Miller-Urey experiment

Question 11

What happens in the Miller-Urey experiment? (5)

Answer 11

• Water, ammonia, methane and hydrogen in sterile FLASK
• HEATED to evaporate water= water vapour
• Electric SPARKS passed through the mixture of water vapour and gases
• simulating LIGHTNING
• 1 week= AMINO ACIDS

Question 12

Which theory did the Miller-Urey experiment support? Briefly explain the theory

Answer 12

• The theory of primordial soup

- Idea that complex CHEMICALS needed for living things to develop could be produced NATURALLY on the early Earth

Question 13

What produced the oxygen that is now in the atmosphere and how?

Answer 13

• Plants and algae

- Through photosynthesis, which uses CO2 from atm

Question 14

What happened to most of the carbon from the carbon dioxide in the air?

Answer 14

• Gradually became locked up in sedimentary rocks

- As carbonates and fossil fuels

Question 15

What was limestone formed from?

Answer 15

The shells and skeletons of marine organisms

Question 16

What do fossil fuels contain?

Answer 16

Carbon and hydrocarbons that are the remains of plants and animals

Question 17

What happens in the oceans (in context) that has a negative impact on the marine environment? (2)

Answer 17

• Oceans act as a reservoir for CO2

- Too muchCO2 absorbed by ocean

Question 18

Air is a mixture of gases. From this, how can we obtain raw materials and what can they be used for?

Answer 18

• Gases have different boiling points, fractionally distilled for materials
• A variety of industrial processes

Question 19

What did scientists once think was the reason for the features of the Earth’s surface?

Answer 19

-The features were result of the CRUST SHRINKING as Earth COOLED following formation

Question 20

What was Wegener’s theory and why was it not generally accepted?

Answer 20

• Continental drift: Earth’s CONTINENTS were once JOINED, gradually MOVED, millions of years
• He couldn’t explain HOW the continents had moved

Question 21

Why can scientists not accurately predict when earthquakes and volcanic eruptions will occur?

Answer 21

It’s difficult to know when or where the plates will move

Question 22

Why do we not know how life was first formed?

Answer 22

• We don’t know what gases were present

- Or if there was lightning that caused the gases to react

Question 23

What did Wegener’s theory offer an explanation of?

Answer 23

The existence of similar fossils and rocks on continents that are far apart from each other