1
1
Diagram 1 and diagram 2 are maps showing some of the different regions in a country. Scientists
S
studied the distribution of the Hb allele in the country.
Diagram 1 shows the estimated frequency of the allele within the population.
Diagram 2 shows the estimated number of babies born with sickle cell anaemia in each region.
diagram 1
diagram 2
2
The scientists made a statement:
S
‘There is a relationship between the frequency of the Hb allele and the number of babies born
with sickle cell anaemia in regions A, B and C.’
Using the information in diagram 1 and diagram 2, discuss the evidence for and against this
statement for regions A, B and C only.
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[5]
[Total: 5]
3
2
Diagram A and diagram B are maps showing some of the different regions in a country. Scientists
S
studied the distribution of the Hb allele in the country.
Diagram A shows the estimated frequency of the allele within the population.
Diagram B shows the estimated number of babies born with sickle cell anaemia in each region.
diagram A
diagram B
S
Suggest how the scientists would identify the presence of the Hb allele in tissue samples.
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[1]
[Total: 1]
4
3
A scientist tested the resistance of one strain of bacteria to different antibiotics.
The scientist tested solutions of five different antibiotics, A to E.
She soaked a paper disc in each antibiotic solution.
The paper discs with antibiotics were placed in a Petri dish containing bacteria on agar jelly.
The diagram shows the appearance of the Petri dish after 48 hours. The shaded areas show where
bacteria grew. The clear areas show where bacteria did not grow.
area where
bacteria grew
A
E
B
clear area
where bacteria
did not grow
paper disc
with antibiotic
D
C
The results in the diagram show that this strain of bacteria is resistant to antibiotic A.
Five years ago, a similar investigation found that the clear area for antibiotic A was the same size
as antibiotic B is in the diagram.
Explain how bacteria become resistant to antibiotics.
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[4]
[Total: 4]
5
4
There are four blood groups in the ABO system in humans: A, B, AB and O.
A
B
o
The gene that determines blood group has three alleles: I , I and I .
The graph shows the percentages of the global population with the four different blood groups in
the ABO system.
45
40
35
30
percentage 25
of the global
population
20
15
10
5
0
A
B
AB
O
blood group
With reference to the graph, explain why the ABO blood group system is an example of discontinuous
variation.
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[2]
[Total: 2]
6
5
The American writer Ernest Hemingway lived on the island of Key West in Florida, USA in the
1930s. During this time he was given a male cat by a sea captain.
The cat had more toes than usual. This inherited condition is called polydactyly. The allele for
polydactyly is dominant.
Here is part of a pedigree diagram for Hemingway’s cats.
Explain why polydactyly is an example of discontinuous variation.
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[2]
[Total: 2]
7
6
Colour blindness is a characteristic that is inherited. Colour blindness is more common in males
than in females.
Here is a pedigree diagram showing the inheritance of colour blindness in a family.
There was no history of colour blindness in the parents and grandparents of individuals 1 and 2.
Suggest how colour blindness first occurred in the family in the pedigree diagram.
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[2]
[Total: 2]
8
7
The Galápagos Islands are a group of small islands in the Pacific Ocean.
In 1839 Charles Darwin published a book that described differences in a family of birds called
finches.
Each species of Galápagos finch had:
• a different diet
• a different beak shape, as shown in the diagram.
Galápagos finches share a common ancestor.
Suggest how Galápagos finches have evolved different shaped beaks.
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[5]
9
[Total: 5]
8
Black stem rust is a disease of wheat that is caused by a fungus.
Plant breeders used two varieties of wheat to produce a variety of wheat that is both rust-resistant
and has a high yield.
The diagram shows the breeding programme that was used.
Suggest why step 3 is repeated for many generations before the new rust-resistant variety is made
available for farmers to grow.
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[1]
[Total: 1]
10
9
The Hawaiian happy-face spider, Theridion grallator, is found on several of the Hawaiian islands.
Some of the spiders have a very distinctive pattern on their bodies as shown in the photograph.
Scientists think that the pattern on the bodies of the spiders is an adaptive feature.
Explain the term adaptive feature with reference to this pattern.
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[3]
[Total: 3]
11
10 Black stem rust is a disease of wheat that is caused by a fungus.
Plant breeders used two varieties of wheat to produce a variety of wheat that is both rust-resistant
and has a high yield.
The diagram shows the breeding programme that was used.
Suggest how plant breeders make sure that the plants that they use for step 3 are rust-resistant.
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[2]
[Total: 2]
12
11
Sickle-cell anaemia is an inherited disease.
The photomicrograph is of some blood cells from a person who has sickle-cell anaemia.
Explain how red blood cells become sickle-shaped.
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[3]
[Total: 3]
13
12 Merino sheep in South Africa have high quality wool with very thin hairs.
Breeders in New Zealand have used selective breeding programmes to improve the wool of their
sheep to match the quality of South African wool.
Describe the steps that breeders would take to breed sheep that have wool with very thin hairs.
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[5]
[Total: 5]
13 Explain how natural selection differs from selective breeding.
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[3]
[Total: 3]
14
14 Sickle-cell anaemia is most common in areas of the world where the infectious disease malaria is
found.
The distribution of sickle-cell anaemia is the result of natural selection.
Explain the distribution of the sickle-cell allele in human populations.
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[5]
[Total: 5]
15 A cause of variation is the formation of new alleles.
Describe how new alleles can be formed.
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[3]
[Total: 3]
15
16 An ecologist studied variation in a species of xerophyte.
The ecologist studied the features of the leaves in the species of xerophyte.
The graph shows the variation in the type of leaf spike.
Explain why the type of leaf spike shown in the graph is an example of discontinuous variation.
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[2]
[Total: 2]
16
17 Explain how bacteria become resistant to antibiotics and how humans can reduce the problem of
antibiotic resistance.
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[6]
[Total: 6]