Q1.
The diagram below shows changes in the foot bones of four ancestors of modern horses
over the past 50 million years.
(a) Describe two changes to the bones in the feet of horses that have taken place over
the past 50 million years.
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(2)
(b) Eohippus lived in swampy areas with soft mud.
Since this time the ground in the habitat has become drier and harder.
All of the horse ancestors were preyed upon by other animals.
(i) Explain one advantage to Eohippus of the arrangement of bones in its feet.
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(2)
(ii) The changes in the arrangement of the foot bones of horses support Darwin’s
theory of evolution by natural selection.
Explain how the arrangement of the foot bones of Eohippus could have
evolved into the arrangement of the foot bones of Equus.
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(4)
(Total 8 marks)
Q2.
(a) Evidence about extinct species of animals and plants comes from fossils.
Below is a photograph of a fossil of a bird-like animal called Archaeopteryx.
Archaeopteryx lived about 150 million years ago.
© Wlad74/iStock/Thinkstock
(i) Suggest how the fossil of Archaeopteryx was formed.
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(2)
(ii) Scientists have found other fossils of the ancestors of modern birds, but the
fossil record is very incomplete.
Suggest two reasons why there are gaps in the fossil record.
1. ____________________________________________________________
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2. ____________________________________________________________
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(2)
(b) There are many different species of bird on the Earth today.
Describe how these different species may have evolved from an ancestor such as
Archaeopteryx.
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(4)
(Total 8 marks)
Q3.
Figure 1 is a map showing a group of islands in the Pacific Ocean, near the coast of
California, USA.
Figure 1
A species of fox, called the Island Fox, lives on each of the six islands shown in Figure 1.
Figure 2 shows an Island Fox.
Figure 2
© GaryKavanagh/iStock
The foxes on each island are slightly different from those on the other islands.
The Island Foxes are similar to another species of fox, called the Grey Fox.
The Grey Fox lives in mainland California.
(a) Suggest how scientists could prove that the six types of Island Fox belong to the
same species.
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(2)
(b) Scientists believe that ancestors of the modern Island Fox first colonised what is
now Santa Cruz Island during the last Ice Age, approximately 16 000 years ago. At
that time, lowered sea levels made the three northernmost islands into a single
island and the distance between this island and the mainland was reduced to about
8 km.
(i) How could the Island Fox have developed into a completely different species
from the mainland Grey Fox?
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(5)
(ii) Suggest why the Island Foxes have developed into different varieties of the
same species instead of six different species.
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(1)
(Total 8 marks)
Q4.
The image below shows:
• Phiomia, an ancestor of elephants
• a modern African elephant.
Phiomia lived about 35 million years ago.
Phiomia African elephant
© Dorling Kindersley via Thinkstock
Both Phiomia and the African elephant reach up into trees to get leaves.
In the 1800s, Darwin and Lamarck had different theories about how the long nose of
Phiomia evolved into the trunk of the African elephant.
(a) (i) Use Darwin’s theory of natural selection to explain how the elephant’s trunk
evolved.
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(4)
(ii) Lamarck’s theory is different from Darwin’s theory.
Use Lamarck’s theory to explain how the elephant’s trunk evolved.
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(2)
(b) (i) In the 1800s, many scientists could not decide whether Lamarck’s theory or
Darwin’s theory was the right one.
Give two reasons why.
1. ____________________________________________________________
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2. ____________________________________________________________
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(2)
(ii) Before the 1800s, many people had a different idea to explain where all the
living things on Earth came from.
What idea was this?
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(1)
(Total 9 marks)
Mark schemes
Q1.
(a) any two from:
• larger / longer / thicker
allow examples eg fewer toes or bones fused
• fewer (bones in total)
allow smaller surface area touching the ground
• fewer bones touching the ground
2
(b) (i) large(r) surface / area in contact with the ground
or
low / less pressure on ground
1
(so) less likely to sink into mud / ground
or
(so) could run fast(er)
allow easy / easier to escape predators
1
(ii) variation (in size / number / arrangement of bones)
allow mutation(s) (in size / number / arrangement of bones)
1
(and) those with large(r) / few(er) bones more suited to running or run faster
(on harder / drier ground)
1
these survive and breed
allow ref to offspring for breed
1
(so) genes / DNA (for larger / fewer bones) passed on
allow alleles passed on
1
[8]
Q2.
(a) (i) any two from:
• (dead) animal buried in sediment
allow imprint in mud
• hard parts / bones do not decay or soft parts do decay
allow (one of) the conditions for decay is missing − accept
example, eg oxygen / water / correct temperature / bacteria
• mineralisation (of hard parts / bones)
allow replacement by other materials
2
(ii) any two from:
• conditions not right for fossilisation
ignore references to soft-bodied
• geological activity has destroyed fossils / has destroyed evidence
allow a named / described example − eg vulcanism / earth
movements / erosion
• fossils not yet found
allow description of why not yet found
2
(b) any four from:
• separation / isolation (of different populations)
• different environmental conditions (between locations)
• mutation(s) occur or genetic variation (within each population)
• better adapted survive or natural selection occurs
allow ‘survival of the fittest’
ignore animals adapt to their environment
ignore reference to stronger survive
• favourable alleles passed on (in each population)
allow genes for alleles
• eventually different populations unable to breed successfully with each
other
allow unable to produce fertile offspring
4
[8]
Q3.
(a) reference to interbreeding
1
successfully between Island types
allow ref. to production of fertile offspring
allow ref. to DNA analysis / comparison for 1 mark
ignore ref. to grey fox
1
(b) (i) (two ancestral populations) separated / isolated (by geographical barrier / sea)
1
and genetic variation (in each population) or different / new alleles or
mutations occur
1
under different environment / conditions
allow abiotic or biotic example
allow different selection pressures
1
natural selection occurs or better adapted survived to reproduce
1
so (favourable) alleles / genes / mutations passed on (in each population)
ignore they adapt to their environment
1
(ii) any one from:
• continued to mate with one another
• few beneficial mutations (between island varieties)
• similar conditions on each island so similar adaptations/features fit
1
[8]
Q4.
(a) (i) variation (in population) / mutation
1
longer nosed individuals get more food / leaves
allow longer nosed individuals more likely to survive
1
(these) survivors breed (more)
1
pass on genes / alleles / DNA (for long nose)
allow pass on mutation
1
(ii) Phiomia / ancestor stretched its nose (during its lifetime) to reach food /
leaves
1
passed on (stretched nose) to offspring
allow offspring inherit (stretched nose)
do not allow ref to genes
1
(b) (i) insufficient evidence / no proof
ignore other theories, eg religion
do not allow no evidence
1
mechanism of inheritance not known
allow genes / DNA not discovered
1
(ii) God made all living things / them
allow creationism
ignore religion
1
[9]
