Download Q1. In 1912 Wegener suggested his theory of continental drift. In

Q1.
In 1912 Wegener suggested his theory of continental drift.
In 1912, many scientists did not accept Wegener’s theory because he could not
explain:
•
how Pangaea had split into continents
•
how the continents had moved apart.
(a)
Wegener used evidence to support his theory.
Give two pieces of evidence Wegener used.
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(2)
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(b)
Scientists have discovered that the Earth is made up of layers.
Complete the sentences by writing one word in each space.
Scientists now accept Wegener’s theory because they know that
the Earth’s ................................................ and upper part of the mantle are cracked into
tectonic plates.
The tectonic plates move at relative speeds of a few centimetres per year because of
convection currents in the Earth’s .................................................. .
These convection currents are driven by ................................................... released from
natural radioactivity.
A volcanic eruption or an .................................................. can happen at the boundaries
between tectonic plates.
(4)
(Total 6 marks)
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Q2.
There were many ideas about how the Earth was formed from a molten ball of rock and
minerals.
At one time scientists thought the features of the Earth were caused when the molten ball of
rock and minerals cooled and wrinkled.
(a)
Scientists now have evidence that the Earth has a layered structure.
Describe the layered structure of the Earth. You should indicate the relative sizes of the
layers.
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(3)
(b)
At one time scientists thought the Earth’s continents were formed in fixed positions
when the molten ball of rock and minerals cooled and wrinkled.
In 1912, the scientist Alfred Wegener suggested his idea about how Earth’s continents
formed.
Describe Wegener’s idea of how Earth’s continents formed.
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(2)
(Total 5 marks)
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Q3.
There are about 500 000 earthquakes every year. On 12 January 2010 there was an
earthquake near Port-au-Prince in Haiti. Many buildings were destroyed causing the deaths of
thousands of people. The earthquake did not come as a surprise to scientists who predicted the
earthquake a week earlier. The Government and people ignored the prediction.
By Photo Marco Dormino/ The United Nations United Nations Development Programme [CC-BY-2.0],
via Wikimedia Commons
The Richter scale is used to compare the size of earthquakes.
Richter scale value
Less than 2
(a)
Effect of earthquake
People do not feel the earthquake.
2–4
People feel the earthquake but the earthquake
rarely causes damage to buildings.
4–5
People feel the earthquake and the earthquake
causes minor damage to a few buildings.
5–6
Shaking of the ground and major damage to some
buildings.
6–8
Violent shaking of the ground and many buildings
destroyed.
8 – 10
Very violent shaking of the ground and most
buildings destroyed.
Use the information above to answer these questions.
(i)
Suggest the Richter scale value for the earthquake that happened near
Port-au-Prince in Haiti.
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(1)
(ii)
Governments and people often ignore scientists’ predictions of an earthquake.
Suggest three reasons why.
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1 ............................................................................................................
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2 ............................................................................................................
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3 ............................................................................................................
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(3)
(b)
During the twentieth century many scientists proposed ideas about the cause of
earthquakes and about the Earth’s crust.
In 1912 Alfred Wegener proposed his idea of ‘continental drift ’.
In 1930 Arthur Holmes suggested his idea of ‘mantle dynamics’.
(i)
What did Wegener mean by ‘continental drift’?
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(2)
(ii)
Holmes’ idea of ‘mantle dynamics’ provided an explanation for Wegener’s idea of
‘continental drift’.
Suggest what ‘mantle dynamics’ is and state what causes ‘mantle dynamics’.
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(2)
(Total 8 marks)
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Q4.
Earthquakes happen in some places on Earth.
The diagram shows some of these places that are between the continents of South America
and Africa.
(a)
(i)
Why do earthquakes happen in the places shown on the diagram?
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(1)
(ii)
Scientists cannot predict when earthquakes will happen.
Suggest why.
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(1)
(b)
In 1915, Alfred Wegener proposed the idea of continental drift.
He suggested that South America and Africa had once been joined.
Most scientists in 1915 did not accept his idea.
(i)
In 1915, Wegener’s idea was not accepted by most scientists.
Suggest one reason why.
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(1)
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(ii)
Use the information in the diagram to suggest two pieces of evidence that led to
Wegener’s idea being accepted by most scientists.
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(2)
(c)
Explain, in as much detail as you can, what is causing the continents of South America
and Africa to move further apart.
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(3)
(Total 8 marks)
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M1.
(a)
any two from:
•
similar fossils in Africa and South America
ignore same plants / animals
•
similar rocks in Africa and South America
•
‘jigsaw fit’
allow rocks / fossils match in Africa and South America
2
(b)
crust
1
mantle
1
heat / energy
1
earthquake
1
[6]
M2.
(a)
Earth consists of crust, mantle and core
1
relative positions (of crust, mantle and core) correctly given
1
crust is thinner than the mantle and core
accept correct information from a labelled diagram
1
(b)
continents were joined together
accept there was a supercontinent / Pangaea
1
the continents then drifted apart or moved apart
ignore attempts at explanations for movement
1
[5]
M3.
(a)
(i)
6-8
accept any value in the range 6-8
1
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(ii)
any three from:
• there are many earthquakes predicted by scientists each year
allow scientists / predictions have been wrong
• expense / inconvenience / panic caused by government / people taking action
• most / some earthquakes do little or no damage
• scientists do not know what is happening below the crust
ignore lack of evidence
• scientists cannot (accurately) predict where the earthquake will occur
• scientists cannot (accurately) predict when the earthquake will occur
allow earthquakes are random
• scientists cannot (accurately) predict the strength of the earthquake
If none of the last 3 points have been awarded then ‘scientists
cannot accurately predict earthquakes’ gains 1 mark
3
(b)
(i)
continents were once joined together
or continents breaking up / separating / fitted like a jigsaw
allow crust / plate for continent
accept there was a supercontinent / Pangaea
1
so the continents are moving
accept continents not in fixed positions
allow continents move apart for 2 marks
if no other mark awarded allow continents drift apart for 1 mark
1
(ii)
convection currents (in the mantle)
allow credit for both marking points if given in (b)(i)
accept movement / flow (in the mantle)
1
caused by heat
or
caused by radioactive processes
ignore chemical reactions
1
[8]
M4.
(a)
(i)
plate boundary
allow plates moving / colliding
allow fault line / sea floor spreading
allow plate tectonics
1
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(ii)
any one from:
•
do not know what happens below the Earth’s crust
allow it’s underground
•
no pattern
allow random
1
(b)
(i)
any one from:
•
he could not explain how continents could move
allow there was no evidence / no proof / did not know about plates
•
other ideas existed (that continents were in fixed positions or there
had been a land bridge)
allow it went against established ideas
1
(ii)
any two from:
accept in addition modern ideas such as sea floor spreading
ignore plants / animals
•
similar fossils
•
similar rocks
•
jigsaw fit
allow rocks match up
allow reference to super continent / pangea
2
(c)
(continents move) because there are convection currents
1
in the mantle
1
caused by radioactivity
if no other mark awarded
‘continents on different plates’ gains 1 mark
1
[8]
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E1.
(a) Most correct answers referred to the jigsaw fit of continents. Many students wrote
about fossil fuels instead of fossils or completely forgot to mention that they were the
same or similar. Also, a number of students wrote about the same animals or plants on
the continents, not fossils, so no credit was awarded. There were some strange answers
stating that Wegener knew that the equator does not move so the continents must have
moved. A misconception was that Wegener knew about plate tectonics. Several students
incorrectly thought that they had to explain how the continents had moved apart. A high
proportion of students did not attempt this question.
(b)
E2.
Crust and earthquake were the best known, with earthquake the most common correct
answer used to complete the sentences. Many students incorrectly thought that the
tectonic plates move because of winds or waves. The idea that heat/energy causes
convection currents was not well known. Some students incorrectly thought that they had
to use only words from the diagram to complete the sentences.
(a) A large proportion of students gained two marks for knowing the three main layers and
their order in the Earth. The relative thickness mark point was given less often. The inner
and outer cores were mentioned regularly, as was the atmosphere. A small number of
students correctly compared the structure of an egg (shell, white and yoke) to that of the
Earth to illustrate the relative thickness. Better students went into great detail giving the
relative thicknesses of the layers in kilometres. Very few students used diagrams to
answer the question.
(b)
E3.
A large proportion of students appreciated that the continents were once joined, with many
quoted the name Pangaea. Although some appreciated that the continents had split, they
did not necessarily go on to say that they had moved apart.
(a)
(b)
(i)
Most students could interpret the Richter scale value of the earthquake from the
information given in the question.
(ii)
The majority of students only got one or two marks, mainly because they repeated
the same idea twice. The most common correct answers were to do with predicting
exactly when or where an earthquake might happen, that scientists had often been
wrong before, that the government did not want to cause panic or unnecessary
expense and that the earthquake might be very minor or cause no damage to
buildings.
(i)
Many students carried over their thinking on earthquakes to this part of the question
and attempted to link their answer on continental drift to occurrence of earthquakes.
A number of students just re-stated the stem of the question but most were able to
gain marks by conveying the idea of continents moving. The idea of a supercontinent
was less well known. Most students could not explain clearly Wegener’s theory of
continental drift.
(ii)
Although students were given the implication that continental drift is caused by
mantle dynamics, few students scored one or two marks here. A small number of
students were aware of convection currents in the mantle and their affect on tectonic
plates. Fewer realised that they should go further and explain how the convection
currents are formed. There were some very clear answers given by students but
many answers indicated confusion between key terms such as ‘plates’/‘continents’
and ‘mantle’/ ‘core’/ ‘crust’.
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E4.
(a)
(b)
(c)
(i) Most students managed to get the mark for stating that the plates were moving or
it was a plate boundary.
(ii)
Surprisingly, few students could give a correct suggestion as to why scientists
cannot predict when earthquakes will happen. The main correct suggestions were
that scientists do not know what happens below the Earth’s crust or that there is no
pattern as to when earthquakes occur. The most common incorrect answers to the
inability of scientists to predict when an earthquake will happen simply repeated the
stem.
(i)
Wegener’s lack of evidence or that he could not explain how continents could move
was known by many students.
(ii)
Most students scored one or two marks. The majority of these students only got one
mark mainly because they repeated the same idea twice. This was the idea that the
coastlines had shapes that fit or that there were matching sedimentary rocks on both
continents. The similarity of the sedimentary rocks or the similarity of the fossils in
them was often not mentioned.
The explanation of what is causing the continents of South America and Africa to move
further apart was poorly answered. Most students made incorrect statements such as the
continents moved apart because of earthquakes, the oceans pushing them, sea levels
rising, tsunamis or global warming. Of those students who understood what actually
happens most gained marks for mentioning that convection currents happened in the
mantle. Only a very few students knew that these convection currents were caused by
radioactivity.
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