1
1
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]
2
2
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]
3
3
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.
Scientists published the results of an investigation into the DNA of cats with and without polydactyly.
They compared the base sequence from a particular region of DNA that controls the development
of the limbs.
The table shows the base sequences.
cats without polydactyly
AGA CAC AGA AAT GAG
Hemingway’s cats with polydactyly
AGA CAC GGA AAT GAG
cats with polydactyly from Oregon and Missouri in the USA
AGA CAC GGA AAT GAG
cats with polydactyly from the UK
AGA CAC AGT AAT GAG
State the name of the process by which base sequences in DNA are changed.
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[1]
[Total: 1]
4
4
Xerophytes grow in habitats with low rainfall and soils that often have high concentrations of salts.
The photograph shows the xerophyte Yucca treculeana growing on salt flats.
Explain how xerophytes, such as Y. treculeana, are adapted to absorb sufficient water in the
conditions in which they live.
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[4]
[Total: 4]
5
5
Xerophytes grow in habitats with low rainfall and soils that often have high concentrations of salts.
The photograph shows the xerophyte Yucca treculeana growing on salt flats.
Explain how xerophytes are adapted to reduce water loss to the atmosphere.
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[3]
[Total: 3]
6
6
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.
Scientists published the results of an investigation into the DNA of cats with and without polydactyly.
They compared the base sequence from a particular region of DNA that controls the development
of the limbs.
The table shows the base sequences.
cats without polydactyly
AGA CAC AGA AAT GAG
Hemingway’s cats with polydactyly
AGA CAC GGA AAT GAG
cats with polydactyly from Oregon and Missouri in the USA
AGA CAC GGA AAT GAG
cats with polydactyly from the UK
AGA CAC AGT AAT GAG
The base sequences in the table provide evidence that indicates which country the male cat given
to Hemingway in the 1930s came from.
Suggest which country this cat came from and give a reason for your choice.
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[2]
[Total: 2]
7
7
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]
0
