Q1.          The vole is a small, mouse-like animal. Voles found on some cold islands to the north of Scotland are much larger than voles found in warmer areas such as southern France. Explain how natural selection may have caused the northern voles to be larger in size.
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(Total 5 marks)
 Q2.          The family trees below show the inheritance of hair colour in two families.

(a)     The allele for black hair is dominant over the allele for red hair.
Use the letter B as the allele for black hair.
Use the letter b as the allele for red hair.
Complete the diagram below to show the chances of Mary Jones inheriting red hair.
	(4)

(b)     John Smart and Mary Jones grew up, got married and had a child.
What would the chances be that the child had red hair?
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          Explain your answer.  Use a genetic diagram if it makes your answer clearer.
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(3)
(Total 8 marks)
 Q3.          (a)     Mice with black fur can have the genotype BB or Bb, whilst mice with brown fur have the genotype bb.
(i)      Use a genetic diagram to show what fur colours you would predict in the F1 offspring produced by two mice who are both Bb.

(3)

(ii)     Why might your prediction of fur colour in the F1 generation not be proved right?
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(b)     Using the example in part (a) to help:
(i)      describe the difference between dominant and recessive alleles;
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(ii)     describe the difference between alleles and genes;
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(2)

(iii)     describe the difference between homozygous and heterozygous chromosomes.
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(2)
(Total 10 marks)
 Q4.          Coat colour in rabbits is controlled by one pair of genes. The allele for black coat (N) is dominant to the allele for brown coat (n). The drawing shows the result of crossing a black-coated rabbit with a brown-coated rabbit.

Complete the genetic diagram to show how the young rabbits inherited their coat colour. Use the symbols N and n for the alleles. The alleles of the brown parent have been inserted for you.

(Total 3 marks)
 
Q5.          The map shows:
          the most densely populated industrial areas;
the frequency of pale and dark forms of the peppered moth;
the direction of the prevailing winds in the British Isles.

          Peppered moths usually rest on trees covered with lichen, and they are preyed upon by many birds. In areas of low air pollution the lichen on trees is usually pale in colour. In areas of high air pollution the lichen turns black.
          (a)     (i)      State a pattern of the distribution of the mutant dark form shown on the map.
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(1)
(ii)     Suggest a reason for your pattern.
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(1)
(b)     The dark form of peppered moth developed after a mutation in the pale form. What is a mutation?
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(1)
(c)     Using the idea of Natural Selection explain why the dark form of the moth is restricted to the areas shown.
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(4)
(Total 7 marks)
 Q6.          The drawings show two forms of the peppered moth.

          In an investigation, pale and dark moths were placed in different positions on trees in two woods. One wood was in an industrial area where the bark was blackened by pollution. The other wood was unpolluted, and the tree bark was covered in pale mosses and lichen. After three days, the surviving moths were counted. The results are shown in the table. 
WOOD	POSITION OF MOTH
ON TREE	PERCENTAGE OF MOTHS
EATEN BY BIRDS	
 	 	PALE	DARK	
Polluted	On main trunk	58	40	
 	Underside of branch	50	28	
Unpolluted	On main trunk	32	62	
 	Underside of branch	26	40	

(a)     What can you tell from these results about the survival of the two types of moth in polluted and unpolluted woods, and in different positions on the tree?
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(3)
(b)     Explain how the results provide evidence for one theory of evolution.
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(3)
(Total 6 marks)
Q7.          The fruit fly, Drosophila, has either long wings or vestigial wings, as shown in the diagram.
         Long-winged fly                     Vestigial-winged fly
         
 The size of the wings is determined by a pair of alleles: A and a.
Long-winged flies have one of two possible genotypes: AA or Aa. 
Vestigial-winged flies have only one genotype: aa.
(a)     (i)      What is the genotype of a heterozygous fly?
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(1)
(ii)     Why can vestigial-winged flies only have the genotype aa?
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(1)
(b)     A male and a female long-winged fly were crossed. They produced 96 offspring. 
72 of the offspring had long wings and 24 had vestigial wings. 
Use a genetic diagram to explain this.

 
(4)
(Total 6 marks)
 Q8.         The Blue-moon butterfly lives on a small island called Samoa, in the Pacific Ocean.

By Emoke Dénes [CC-BY-SA-2.5], via Wikimedia Commons
In 2006 Blue-moon butterflies almost became extinct.
Wolbachia bacteria killed males before they could hatch from eggs. Only females were resistant to the bacteria.
In 2006 the number of male Blue-moon butterflies had decreased to only 1 per cent of the population. Two years later, the number of males was equal to the number of females.
(a)     Scientists believe that a change in a gene suddenly occurred to make some males resistant to the bacteria.
What scientific term describes a change in a gene?
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(1)
(b)     The numbers of male Blue-moon butterflies in the population increased quickly after the new form of the gene had appeared.
Suggest why.
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(4)
(Total 5 marks)
 Q9.          (a)     What does the theory of evolution state?
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(2)
(b)     Daphnia are microscopic water fleas. Midge larvae prey on Daphnia. The midge larvae release a hormone into the water. Daphnia respond to these hormones by growing larger protective ‘helmet’-like structures
          Scientists were surprised to observe that the offspring of Daphnia females who had been exposed to these hormones always had larger helmets than offspring whose mothers had never been exposed to the hormones. The offspring with the large helmets went on to produce offspring with large helmets.
          Explain why the scientists’ observations seem to contradict the theory of natural selection.
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(2)
(Total 4 marks)

Q10.          (a)     Mr and Mrs Smith both have a history of cystic fibrosis in their families.
Neither of them has cystic fibrosis.
Mr and Mrs Smith are concerned that they may have a child with cystic fibrosis.
Use a genetic diagram to show how they could have a child with cystic fibrosis.
Use the symbol A for the dominant allele and the symbol a for the recessive allele.

                          
                                                   
(3)
(b)     Mr and Mrs Smith decided to visit a genetic counsellor who discusses embryo screening.
Read the information which they received from the counsellor.
 
•        Under an anaesthetic five eggs will be removed from Mrs Smith’s ovary.
•        The eggs will be fertilised in a dish using Mr Smith’s sperm cells.
•        The embryos will be grown in the dish until each embryo has about thirty cells.
•        One cell will be removed from each embryo and tested for cystic fibrosis.
•        A suitable embryo will be placed into Mrs. Smith’s uterus and she may become pregnant.
•        Any unsuitable embryos will be killed.

(i)     Suggest why it is helpful to take five eggs from the ovary, rather than just one.
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(1)

(ii)     Evaluate the use of embryo screening in this case.
Remember to give a conclusion as part of your evaluation.
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(Total 8 marks)
Q11.          The photograph shows a Crossbill.

A Crossbill feeds by using its bill (beak) to force apart the scales on conifer cones. It then uses its tongue to extract the seeds. If the bill is clipped it grows back again.
Scientists were interested in the evolution of the bill of the Crossbill.
In an investigation, they clipped the bills of several Crossbills so that their bills no longer crossed.
They observed that Crossbills with clipped bills took much longer to get seeds.
Use information from the investigation to suggest an explanation for the evolution of the bill in the Crossbill.
In your explanation, use the ideas of selection, competition and mutation.
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(Total 4 marks)
 Q12.          The diagram shows a family tree in which some individuals have an inherited disorder, which may cause serious long-term health problems.

(a)     What proportion of the children of A and B have the disorder?
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(1)

(b)     Explain the evidence from the diagram which shows that the allele for the disorder is dominant.
          Use the appropriate letters to identify individuals in your answer.
          You may use genetic diagrams in your explanation. There is space for you to draw a genetic diagram at the top of the facing page.
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(3)

(c)     (i)      What is meant by ‘embryo screening’?
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(1)

(ii)     A doctor suggests that couple C and D should have their embryos screened but that couple G and H do not need this procedure.
         Explain the reasons for the doctor’s suggestions.
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(3)
(Total 8 marks)
 Q13.          (a)     Explain, as fully as you can, how natural selection leads to evolution.
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(3)

(b)     Most penguins live in cold climates. The modern penguin best adapted for cold conditions is the emperor penguin.
          Scientists have found fossils of a ‘giant’ penguin which they have called Icadyptes.
          The diagram shows how the size of modern penguins compares with Icadyptes.

          The scientists were surprised to discover that Icadyptes lived in warm seas at a time when the Earth’s climate was much warmer than it is now.
          Explain why the scientists were surprised that Icadyptes lived in warm seas.
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(2)
(Total 5 marks)
 Q14.          The theory of evolution via natural selection was proposed by Darwin.
(a)     Explain how evolution occurs via natural selection.
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(4)

(b)     Darwin’s theory was only gradually accepted.
Give two reasons why.
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(2)
(Total 6 marks)
 Q15.          The theory of evolution via natural selection was proposed by Darwin.
(a)     Explain how evolution occurs via natural selection.
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(b)     Darwin’s theory was only gradually accepted.
Give two reasons why.
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(2)
(Total 6 marks)

M1.          any five from:
•        genetic variation exists in a population or
variation caused by mutation / change in gene / in DNA
•        larger voles have smaller 
or have more fat
‘they’ accept as larger voles
•        larger voles lose less heat / are better insulated or more energy stored
•        larger voles survive
•        larger voles breed
•        larger voles pass on (beneficial) gene / allele / mutation / DNA
ignore characteristic
[5]
 M2.          (a)     alleles in parents                       
alleles in sperms/eggs  (*)     B            b             B            b
alleles in children  (*)         
hair colour                         black         black         black         red
(*) NB ecf
Allow other letters if a clear key
each line correct for 1 mark each
4

(b)     evens/50:50/equal/half (e.c.f. from cross below) 
for 1 mark
parents        J Smart                      M Jones
             Bb                             bb
children       Bb  Bb                       bb   bb        *(ecf)
           black                           red
each line correct for 1 mark each
3

          J Smart must be BB or Bb
M Jones must be bb or from (a)
          Credit cross shown in a matrix:

for 2 marks

         Bb identified as black hair
bb identified as red hair
or
2 red : 2 black
for 1 mark
1
[8]
 M3.          (a)     (i)      gametes i.e. B b and B b
1
         correct combination of genotypes i.e. BB, Bb, Bb, bb
1
         correct analysis of phenotypes i.e. 3 black fur 1 with brown fur
1

(ii)     award one mark for the recognition
that it is down to chance (which two
gametes fuse) and not simply ‘because
it’s a prediction’
do not accept mutation
1

          (b)     (i)      B is dominant/ an allele is dominant if it is expressed in the heterozygous phenotype
candidates are likely to use a variety of ways of expressing their ideas
1

         b is recessive/ a recessive allele is not expressed in the presence of its
contrasting allele
do not accept powerful
do not accept stronger
1

(ii)     alleles are different forms of a gene controlling a characteristic and
occupying the same site on homologous chromosomes (e.g. B or b)
1

         genes are the units of DNA/sites on chromosomes carrying the information
that determines characteristics (e.g. bB)
1

(c)     homozygous: BB / bb / possessing a pair of identical alleles
for a character/true breeding
give credit to an explanation using a diagram
1

          heterozygous: Bb / carrying a pair of contrasting/different alleles for a characteristic
do not accept references to xx, xy
do not accept gene by itself
1
[10]
 M4.          genotype of parent A Nn
gametes N n n n
young genotypes and phenotypes all correct
for 1 mark each
[3]
  M5.          (a)     (i)      dark form lives in the industrialised/ densely populated areas
or
dark form lives to the East/downwind/North East of industrialised are
1

(ii)     more pollution/discolouration in those areas
or
pollution blown by prevailing winds
1

(b)     a change to the genetic material/DNA/chromosomes/genes in an organism
do not accept fault. error
1

(c)     survival in polluted areas:
one mark for each mark point to a maximum of 4
          (pollution) lichen/trees/buildings become(s) blackened
credit an answer given in terms of survival in polluted areas or non-survival in other areas
          (camouflage) black formed camouflaged / more difficult to see

          (predation) not preyed upon eaten by thrushes
(survival) survive to breed
or non survival
          (no pollution) lichen/trees/buildings remain(s)pale/non-blackened

          (no camouflage) black formed not camouflaged / easier to see
          (predation) preyed upon/eaten by thrushes
(survival) do not survive to breed
4
[7]
 M6.          (a)     greater proportion of dark moths survive in polluted woods
Greater proportion of pale moths survive in unpolluted woods
% survival on underside of branch is greater in both situations
each for 1 mark
3

(b)     ideas that (please indicate in body of answer by √1, √2, √3)
1. different sorts of moths / pale and dark moths
2. ideal of differential survival in different habitats
3. this is evidence for natural selection / survival of the fittest
     or idea that feature likely to be passed on
each for 1 mark
3
[6]
 M7.          (a)     (i)      Aa or aA
1
(ii)     allele / gene for vestigial wings / a is recessive
or vestigial is recessive or A is dominant or 
A would override the effect of a or A present gives long wings
1

(b)     parental genotypes correct – both Aa
NB can pick up chain of logic at any point correctly 
derived from candidate’s previous point
1
gametes correctly derived from P genotypes
1
offspring genotypes correctly derived from gametes
1
3:1 ratio recognised
wrong cross and not 3:1 ratio = max 2
1
[6]
 M8.          (a)     mutation
correct spelling only
ignore other adjectives eg random / spontaneous
1

(b)     ignore references to X / Y chromosomes
idea of mutant gene / new form / this allows hatching (of males)
1
(individual with advantage) (more) survive / (more) live / (more) don’t die
allow immunity rather than resistance throughout
1
(so survivors) breed / reproduce
1
mutation / gene passed (from survivors) to offspring / next generation
allow resistance / characteristic for gene
‘gene passed on’ is insufficient
1
[5]
 M9.          (a)     present day organisms have evolved from simpler organisms
ignore answers in terms of natural selection
1
          over long periods of time
or
millions / billions of years
1

(b)     (natural selection operates on successful)
characteristics produced by chance / (random) mutation
1
          in this experiment caused by hormones / environment
allow this example indicates
inheritance of acquired
characteristics for 2 marks
allow this is Lamarckism only for 1 mark
1
[4]
 M10.         (a)     both parents Aa
accept other upper and lower case letters without key or symbols with a key
allow shown as gametes in punnet square
1

aa in offspring correctly derived from parents / 
aa correctly derived from the parents given
ignore other offspring / gametes for this mark parents do not have to be correct
1

offspring aa identified as having cystic fibrosis
may be the only offspring shown or circled / highlighted / described
1
(b)     (i)     any one from:
accept converse if clear eg if you (only) took one it might have cystic fibrosis / might not be fertilised
•        sure / greater chance of healthy / non-cystic fibrosis egg / embryo /child
accept some may have the allele
reference to suitable embryo is insufficient
•        greater chance of fertilisation
1

(ii)             to gain 3 marks both advantages and disadvantages must be given
advantages
any two from
ignore references to abortion unless qualified by later screening
•        greater / certain chance of having child / embryo without cystic fibrosis / healthy
•        child with cystic fibrosis difficult / expensive to bring up
•        cystic fibrosis (gene / allele) not passed on through generations
disadvantages
any two from:
•        operation dangers eg infection
ignore risk unqualified
•        ethical or religious issues linked to killing embryos
accept wrong / cruel to kill embryos accept right to life
•        (high) cost
•        possible damage to embryo (during testing for cystic fibrosis / during operation)
3

plus
conclusion
a statement that implies a valued, qualified judgement
eg it is right because the risk of infection is small
or
eg it is wrong because embryos are killed
Note: the conclusion mark cannot be given unless a reasonable attempt to give both an advantage and a disadvantage has (already) been made
do not award the mark if the conclusion only states that advantages outweigh disadvantages
1
[8]
 M11.          any four from:
max two marks for a Lamarck explanation
•        mutation produced a bird whose bill was crossed
do not allow birds decide to mutate
•        birds compete for food / seeds
•        mutant crossbill able to obtain food faster / easier / more successfully
•        selected for or more likely to survive
•        reproduce / mate / breed / produce offspring
[4]

 

M12.          (a)     1 in 4 / 1/4 / 1: 3 / 25% / 0.25
do not accept 3:1 / 1:4 / 2:6
1
(b)     either from C and D
accept synonyms for dominant / recessive eg
Normal / faulty
accept genetic diagram if clearly referring to correct individuals or genotypes on family tree
allow ‘gene’ for ‘allele’
 
          any three from:
•        C and D have disorder
ignore ‘C & D are carriers’
•        I/J don’t have disorder
•        C and D have dominant and
recessive alleles
•        recessive alleles from C and D passed to I/J
or I/J have two recessive alleles
NB if allele was recessive then all offspring of C and D would have the disorder = 3 marks
or from A and B
assume response refers to A + B unless contradicted

•        A is homozygous recessive / rr, and B is heterozygous / Rr can be shown
in words or symbols
allow any symbol
•        offspring can be rr or Rr described
allow without key
3

(c)     (i)      (embryos) checked for inherited / genetic disorders / conditions
accept diseases for disorders
1
(ii)     any three from:
•        C/D have disorder / have dominant allele
accept disease / condition
accept ‘gene’ for ‘allele’
ignore reference to ‘carriers’
•        chance of embryo / foetus / child having disorder
or may pass on alleles for disorder to their offspring
•        C/D might want to decide on termination or prepare
for child with disorder
•        G and H don.t have disorder / both homozygous
recessive / have no dominant alleles (for this disorder)
•        so offspring (of G and H) cannot / don.t have disorder
3
[8]

 

M13.          (a)     variation / mutation
1
          individuals with characteristics most suited to environment
survive
allow survival of the fittest
1
          genes passed to next generation or these individuals reproduce
1

(b)     any two from:
•        similar in size to Emperor penguin or bigger than all
penguins
•        large size is adaptation to cold climate
•        since less heat loss per unit of body volume or smaller
surface area / volume ratio
2
[5]

 

M14.          (a)     organisms within species may show variation
1
because mutation(s) occur in individuals
1
this results in the individuals with characteristics most suited
to the environment being more likely to survive / to breed
1
as a consequence the genes that have enabled these
individuals to survive are passed on to the next generation
1

(b)     any two from
•        the theory undermined the idea that God made all the animals
and plants that live on earth
•        there was insufficient evidence at the time
•        the mechanism of inheritance / variation was not yet known
2
[6]

 

M15.          (a)     organisms within species may show variation
1
because mutation(s) occur in individuals
1
this results in the individuals with characteristics most suited
to the environment being more likely to survive / to breed
1
as a consequence the genes that have enabled these
individuals to survive are passed on to the next generation
1

(b)     any two from
•        the theory undermined the idea that God made all the animals
and plants that live on earth
•        there was insufficient evidence at the time
•        the mechanism of inheritance / variation was not yet known
2
[6]