11 Earth and Atmosphere
Q1. The Earth has a layered structure and is surrounded by an atmosphere.(a) Scientists believe that the Earth’s atmosphere was formed by volcanoes releasing gases.
This early atmosphere was about 95 % carbon dioxide.
The composition of the Earth’s atmosphere is always changing.
(i) The Earth’s atmosphere today contains about 0.035 % carbon dioxide.
What happened to most of the carbon dioxide that was in the Earth’s early atmosphere?
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(2)
(ii)About 60 million years ago a large meteorite hit the Earth.
This meteorite heated limestone in the Earth’s crust causing the release of large amounts of carbon dioxide.
Explain how carbon dioxide is released from limestone.
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(2)
(b) The graph shows the percentage of carbon dioxide in the Earth’s atmosphere over the last 50 years.
Explain, as fully as you can, why we should be concerned about the information displayed on this graph.
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(c) Scientists believe that all the continents of the Earth were once joined together.The huge ‘supercontinent’ was called Pangaea.
In 1915, Alfred Wegener had an idea that the change shown in the diagram was caused bycontinental drift.Most scientists could not accept his idea.
(i) Suggest why most scientists in 1915 could not accept Wegener’s idea ofcontinental drift.
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To help you with this question, the information and diagram from the beginning of the question are reproduced here.
The Earth has a layered structure and is surrounded by an atmosphere.
(ii)Use this information and your knowledge and understanding to explain how continents move.
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(Total 11 marks)
HT - 11 Earth and Atmos
Q2.In 1915, two different theories were suggested to explain the following observation:‘In South America and Africa many animal fossils are exactly the same.’
Theory 1
Wegener’s theory of continental drift.
•Continents were once joined together.
•The continents then split and slowly drifted apart. /
Theory 2
Other scientists’ land bridge theory.
•South America and Africa had once been joined by a land bridge.
•The continents were in fixed positions and could not move. /
(a) Describetwopieces of evidence that Wegener could use to support his theory
(Theory 1).
Use the diagrams to help you to answer this question.
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(2)
(b) Which piece of evidence could the other scientists use to support the land bridge theory (Theory 2)?
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(c) In 1912, Captain Scott led a scientific expedition to Antarctica.
The scientists collected many fossils in Antarctica.One fossil the scientists collected wasGlossopteris, a tree-like plant.Glossopterisfossils had already been found in Australia and Africa.
The work of the scientists on Scott’s expedition could have provided evidence for Wegener’s theory, rather than the theory proposed by the other scientists.
Explain why.
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(4)
(d) In 1962, scientists produced the theory of plate tectonics.The theory of plate tectonics supported Wegener’s theory that continents move.
Describe and explain what causes tectonic plates to move.
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(Total 10 marks)
M1.(a) (i)anytwofrom:
•used by plants
allow specific plants and algae
•used for photosynthesis
ignore oxygen released / respiration
•absorbed / dissolved in oceans
ignore oceans formed
•locked up in fossil fuels / limestone / sedimentary rocks 2
(ii)calcium carbonate / CaCO3 1
decomposed / thermal decomposition
donotallow reaction with oxygen
accept quicklime / calcium oxide produced
CaCO3→ CaO + CO2gains2marks 1
(b) increasing (CO2or global warming) 1
more rapidincrease recently 1
carbon dioxide causes global warming
accept greenhouse gasor climate change / sea level rising
orice caps melting donotaccept ozone layer or acid rain or global dimming
1
(c)(i) anyonefrom:
•Wegener had no evidence / proof
accept movement too slow to measure
•other scientists had different ideas / views
accept continents / plates fixed or land bridge
•did not respect Wegener as a scientist / geologist
1
(ii)anythreefrom:
•plates (move) ignore continents
•heat energy / radioactivity (causes)
•convection currents
•in mantle
3
[11]
M2.(a) the continents (of South America and Africa) fit together (like a jigsaw)
ignore seafloor spreading and references to tectonic plates
1
there are similar fossils (in South America and Africa)
allow same species
allow same rock (types)
1
(b) there are similar fossils (in South America and Africa)
allow same species
ignore same rock (types)
1
(c) (Glossopteris) fossil (also) found in Australia or Africa
ignore all references to South America
allow found in different continents / countries
1
(so) presence could have been explained by continents being joined
1
no land bridge proposed between
1
Antarctica and Australia / Africa
(so) can’t explain how fossils were in the three continents
1
(d)convection(currents)
ignore references to earthquakes / volcanoes
1
in the mantle
must relate to convection or magma rising
1
(are) caused by: heat
or
radioactive processes
or magma / molten rock rising
ignore lava [10]