C1 7 Our Changing Planet

Question 1

Label the structure of the Earth.

Answer 1

From inside to out:

• Inner core
• Outer core
• Mantle
• Crust
• Atmosphere

Question 2

What are the characteristics of the atmosphere?

Answer 2

• 80% of air lies within 10km of the surface
• Most of the rest is within 100km but not accurate

Question 3

What are the characteristics of the crust?

Answer 3

• Average thickness is 6km under oceans
• 35km under continental areas

Question 4

What are the characteristics of the mantle?

Answer 4

• Starts at crust
• Can go up to about 3000km below the surface
• Behaves like solid
• Can flow very slowly

Question 5

What are the characteristics of the core?

Answer 5

• Radius of about 3500km
• Inner core is made of iron and nickel, solid
• Outer core is liquid

Question 6

Where do all the minerals and other resources come from?

Answer 6

Crust

Question 7

How have scientists identified the Earth’s crust?

Answer 7

Through earthquakes, the directions the seismic waves travel due to refraction. The different densities differ the direction the waves travel.

Question 8

Why do continents move?

Answer 8

Due to the Earth’s crust and uppermost mantle being cracked into tectonic plates.

Question 9

What causes tectonic plates to move?

Answer 9

Radioactive decay in the core produce vast amounts of energy which heats up the molten rock in the mantle to become less dense and rise towards the surface. Cooler material snk to replace their place and create convection currents.

Question 10

What happens at plate boundaries?

Answer 10

Plates meet eachother can either collide to form mountains, slip past each other causing earthwuskes .etc

Question 11

Why aren’t earthquakes prevented?

Answer 11

They are hard to predict

Question 12

What did Alfred Wegener’s theory of the Continental Drift suggest?

Answer 12

All the continents were fixed together like a jigsaw and started moving further apart.

Question 13

Why didn’t scientists believe in his ideas?

Answer 13

He had no evidence to show how the continents moved further apart so people stayed to their theories such as the Land Bridge theory.

Question 14

What do scientists believe about the coming of carbon dioxide, nitrogen and water vapour?

Answer 14

These were released by volcanoes. The water vapour condensed into rain and water was collected in the hollows of the crust turning into oceans.

Question 15

What was the early atmosphere like?

Answer 15

It was mainly carbon dioxide and there could have been some water vapour with traces of methane and ammonia. There would have been very little or no oxygen. Some believe that nitrogen was also present.

Question 16

How did oxygen arrive to the Earth?

Answer 16

Simple organisms such as bacteria broke down other chemicals to provide themselves with energy. These evolved into other organisms such as algae which used the sun’s energy to make food through photosynthesis producing oxygen as a waste product. As more and more plants evolved the levels of oxygen rised and carbon dioxide dropped.

Question 17

What was done in the Milley-Urey experiment and what did it suggest about the molecules which made up the simple organisms?

Answer 17

Theory: Life started when chemicals in a “primordial soup” combined to created molecules such as DNA and other molecules in living things.

They put water, ammonia, methane and hydrogen to replicate the earth’s atmosphere and these were given a high voltage shock replicating lightning.

This provided evidence to support the theory that molecules (amino acids) can be made from a reaction of the gases in the early atmosphere.

Question 18

What was the Murchison Meterorite and what did it suggest about the molecules which made up the simple organisms?

Answer 18

Theory: Life started because meteorites picked up organic molecules from space and landed on earth.

Chemicals which make up the body (amino acids) were found in this meteorite showing that compounds may have come from outer space.

Question 19

What was the volcanic vents in the seabed experiment and what did it suggest about the molecules which made up the simple organisms?

Answer 19

Theory: Life started near volcanic vents where the chemicals produced helped sustain bacteria.

The water coming out from the hydrothermal vent is mineral-rich and therefore new animals are being discovered.

Question 20

What are the advantages and disadvantages of each theory?

Answer 20

Question 21

What are amino acids made of?

Answer 21

Oxygen, hydrogen, carbon, nitrogen and sometimes sulphur

Question 22

What happened to the carbon dioxide from the Earth’s early atmosphere? How did it get locked up in the Earth’s crust?

Answer 22

• It was taken up by plants during photosynthesis
• The carbon then ended up in plant material and got eaten by animals which transferred it to their tissues
• After they die, the fossils build up on the ocean’s sea bed creating sedimentary rock.
• Some were crushed and heated by the crust forming fossil fuels
• It also dissolved in ocean, it reacted and formed insoluble compounds turning into carbonate rocks.

Question 23

What happened to the ammonia and methane?

Answer 23

They reacted with oxygen and got rid of.

Question 24

What happened to the nitrogen?

Answer 24

It built up as it is unreactive

Question 25

How can gases in the atmosphere get separated by?

Answer 25

Fractional distillation

Question 26

How do the seas and oceans act as a buffer?

Answer 26

By absorbing CO₂but releasing it if necessary. The insoluble carbon dioxide such as calcium carbonate gets deposited as sediments on the seabed. Whereas soluble carbon dioxide such as calcium gets dissolved. Plants and sea creatures in the oceans release the carbon dioxide.

Question 27

What problem are the oceans currently coping with?

Answer 27

Additional carbon dioxide causing coral reefs to die due to acidic conditions.

Question 28

What is a solution for excess CO₂?

Answer 28

Carbon Capture and Storage

Question 29

Give a diagram of the carbon cycle.

Answer 29