Q1.
The bean aphid is a type of black-fly which lives on broad bean plants in summer.
In the autumn, males and females mate and produce eggs.
 
(a)     Name the type of reproduction which produces the eggs. 
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(1)
(b)     In spring these eggs hatch. The young aphids are all female.
Explain why they are all similar but not identical to each other.
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(c)     These females are then able to produce offspring without needing any males.
(i)      Name the type of reproduction where females do not need males to produce offspring.
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(ii)     How will the offspring from one of these females: 
A  compare with each other
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B  compare with the offspring from other females?
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(2)
(d)     Some scientists investigated mutations in these aphids. They exposed the aphids to X-rays.
They plotted their results.
 
(i)      What was the connection between the dose of X-rays and the percentage of mutations?
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(ii)     Name one other possible cause of mutations.
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(Total 7 marks)
Q2.
Charles Darwin proposed the theory of natural selection.
Many people at the time did not accept his theory.
(a)     There was a different theory at the same time as Darwin’s theory.
The different theory said that changes in an organism during its life could be inherited.
Who proposed this theory?
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(b)     Studying fossils helps scientists understand how living things have evolved.
The diagram below shows a fossilised snake.
 
© Peter Menzel/Science Photo Library
Explain how the fossil in the diagram above may have formed.
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(3)
(c)     There are many types of rat snake in the world.
The table below shows two types of rat snake.

© Kazzpix/iStock/Thinkstock 	
© Talkir/iStock/Thinkstock 	
Type of snake	Japanese rat snake	Texas rat snake	
Colour of snake	Green	Pale brown	
Type of environment	Grass	Dry and dusty	
The different types of rat snake have evolved from similar ancestors.
The rat snakes have evolved to to suit their environments.
Explain how the Japanese rat snake evolved to be different from the Texas rat snake.
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(4)
(d)     Many species of snake have become extinct.
Give one reason why a species might become extinct.
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(1)
(Total 9 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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(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)
Q5.
Darwin suggested the theory of natural selection.
(a)     Explain how natural selection occurs.
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(3)
(b)     Latitude is a measure of distance from the Earth’s equator. 
Scientists investigated the effect of latitude on:
•        the time taken for new species to evolve
•        the number of living species.
The table shows the scientists’ results.
 
Latitude 
in   degrees North of equator	Time taken for new species to evolve in millions of years	Relative number of living species	
0 (at the equator)	3–4	100	
25	2	80	
50	1	30	
75 (in the Arctic)	0.5	20	
As latitude increases environmental conditions become more severe.
(i)      Describe the patterns shown by the data.
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(2)
(ii)     Suggest explanations for the patterns you have described in part (b)(i).
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(2)
(Total 7 marks)
Q6.
(a)     Fossils provide evidence for what early life forms were like. From the evidence, scientists think that life began on Earth more than 3 billion years ago.
Many early life forms were soft-bodied. 
Explain why this makes it difficult for scientists to be certain about what these early life forms were like.
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(2)
(b)     The illustration below shows two types of pistol shrimp.
The shrimps live in shallow, tropical seas on opposite sides of Panama.
    Panama
 
Not to scale                    
Scientists put one Type A shrimp and one Type B shrimp together in a tank of seawater. 
The two types of shrimp snapped their claws aggressively at each other. 
They did not mate.
The scientists said that this was evidence for the Type A and Type B shrimps being classified as two different species.
(i)      Give one reason why the scientists’ opinion may be correct.
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(1)
(ii)     Suggest two reasons why the scientists’ opinion may not be correct.
1. ____________________________________________________________
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2. ____________________________________________________________
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(2)
(c)     Panama is a narrow strip of land which today joins North America and South America. 
It was formed by land moving up from beneath the sea. Panama has separated the Pacific Ocean and the Caribbean Sea for the past 3 million years.
Explain how two different species of pistol shrimp could have developed from an ancestral species of shrimp.
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(6)
(Total 11 marks)

Mark schemes
Q1.
(a)     sexual / sex
for 1 mark
1
(b)     idea that
sexual reproduction brings about a mixture of genes 
or similar / different genes / parents / gametes / DNA / 
characteristics / chromosomes (not features)
for 1 mark
1
(c)     (i)      asexual / cloning  (allow vegetative)
for 1 mark
1
(ii)     (A)    idea that (they are exactly the same). Do not allow 
          similar or just one named feature.
for 1 mark
2
(B)     different (allow similar but do not allow same).
Allow any one named difference
for 1 mark
(d)     (i)      greater the X-ray dose, greater the % of mutations
or % of mutations increases steadily / in proportion to X-ray dose
for 1 mark
1
(ii)     ionising radiations / ultra-violet light / alpha particles / beta particles 
/ gamma rays / radio activity / chemicals / drugs / smoking / natural 
in meiosis / spontaneous / cell replication / toxic waste / pollution
1
         Accept radioactivity but not radiations alone.
for 1 mark
[7]
Q2.
(a)     (Jean Baptiste) Lamarck
allow phonetic spelling
1
(b)     (snake is) covered in sediment / mud
or
sinks into the mud
1
(then) the soft parts decay / are eaten
or
bones / hard parts do not decay
1
(so) minerals enter bones
or
bones are replaced by minerals
1
(c)     Level 3 (3–4 marks):
A detailed and coherent explanation is provided. Logical links between clearly identified, relevant points explain how the rat snake evolved through the process of natural
selection.
Level 2 (1–2 marks):
Simple statements made, but not precisely. The logic is unclear.
0 marks:
No relevant content.
Indicative content
statements:
•        there are lots of different colours of snakes
•        some shades of green are closer to the colour of the environment (in Japan) than others
•        survivors (in each generation) will breed and produce offspring
explanations:
•        different colours are controlled by different genes / alleles / are caused by mutations
•        being green means they are best suited to grassy / green environments
•        being green means they are camouflaged
•        those that are camouflaged best will be able to catch more food
•        those that are camouflaged best will be able to avoid being eaten
•        survivors’ offspring will inherit the genes / alleles / mutation for the shade of green colouration
additional examiner guidance:
•        allow converse points relating to the Texas rat snake if they clearly identify the
reasons why this snake was at an evolutionary disadvantage, ie more likely to be caught and eaten by a predator
•        a good level 2 answer will clearly link survival and breeding to the passing on of the advantageous genes / alleles / mutations and link the idea of colour (AO2) to a
correct explanation of its significance for survival
4
(d)     any one from:
•        changes to the environment
•        new predators
•        new diseases
•        new (more successful) competitors
•        catastrophic event / described event
1
[9]
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]
Q5.
(a)    variation (between organisms within species)
allow described example
allow mutation – but not if caused by change in conditions
1
those most suited / fittest survive
1
genes / alleles passed on (to offspring / next generation)
allow mutation passed on
1
(b)    (i)      any two from:
allow converse
•        increase in latitude reduces number of (living) species
ignore references to severity of conditions
•        increase in latitude reduces time for evolution (of new species)
•        the less the time to evolve the fewer the number of (living) species
2
(ii)     any two from:
do not accept intention or need to evolve
•        (increase in latitude reduces number of (living) species because) less food / habitats / more competition at high latitude
allow only extremophiles / well-adapted species can survive
•        (increase in latitude reduces time for evolution (of new species) because) severe conditions act more quickly / to a greater extent on the weakest
•        (the less the time to evolve the fewer the number of (living) species because) species that evolve slowly don’t survive
2
[7]
Q6.
(a)     lack of fossils / fossils destroyed
allow lack of evidence
1
(due to soft parts) decaying / geological activity
allow an example – eg vulcanism or earth movements or erosion
allow converse points re skeletons, shells, hard parts
1
(b)     (i)      A and B did not mate successfully
‘A and B did not mate’ insufficient
allow did not produce fertile offspring
1
(ii)     any two from:
•        may not be mating season
•        A and B may not find each other attractive
•        this is just a one-off attempt / an anomaly / need repeats
•        may be juvenile / immature
•        may be the same sex
allow other sensible suggestion eg were put in unfavourable environment or one / both could be infertile
2
(c)     1.      (two ancestral populations) separated (by geographical barrier / by land) / were isolated
1
2.      genetic variation (in each population) or different / new alleles or mutations occur
1
3.      different environment / conditions
allow abiotic or biotic example
1
4.      natural selection occurs or some phenotypes survived or some genotypes survived
1
5.      (favourable) alleles / genes / mutations passed on (in each population)
1
6.      eventually two types cannot interbreed successfully
allow eventually cannot produce fertile offspring
1
[11]