AQA A LEVEL BIOLOGY PAPER 3 2020 QUESTON PAPER 

Section A box

Answer all questions in this section.

You are advised to spend no more than 1 hour and 15 minutes on this section.

0 1 Guppies are small fish. Female guppies are dull in colour. Male guppies can be

bright or dull in colour.

Scientists investigated the effect of female brain size on choosing a mate. They used

laboratory-bred female guppies with large brains and with small brains.

They set up a fish tank as shown in Figure 1.

Figure 1

They observed each female for 10 minutes and recorded which male they were

attracted towards. They repeated this with 45 large-brained females and

45 small-brained females.

0 1 . 1 Suggest three possible limitations of this investigation.

[3 marks]

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Guppies with large brains are better at identifying predators. box

The scientists found that only female guppies with large brains were attracted to

male guppies bright in colour.

0 1 . 2 Suggest and explain the advantage of this behaviour to the population of guppies.

[3 marks]

0 1 . 3 Describe how the behaviour of female guppies could result in sympatric speciation.

[3 marks]

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box 0 2 In northern India, there is a conflict of interests between farmers of livestock (eg cows)

and people trying to conserve ibex (a type of wild goat).

When livestock are given extra food, their populations can grow too large and

compete with ibex.

0 2 . 1 Name the type of competition between livestock and ibex.

[1 mark]

Livestock will outcompete ibex if they:

• are in the same habitat

• eat a similar diet.

Scientists investigated this conflict of interests.

Table 1 summarises some of the scientists’ findings.

Table 1

Type of

livestock

Difference between

livestock food and

ibex food*

Difference between

livestock habitat

and ibex habitat*

Cow 1.0 1.5

Horse 0.5 0.0

Yak 0.0 2.0

* A score of 0.0 indicates that the food or habitat is the same.

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box 0 2 . 2 There must be a balance between the need for conservation of the ibex and the need

for farmers to keep livestock.

Using all the information, suggest and explain three actions that the farmers could

take to achieve this balance.

[3 marks]

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2

3

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box 0 3 In Europe, viruses have infected a large number of frogs of different species.

The viruses are closely related and all belong to the Ranavirus group.

Previously, the viruses infected only one species of frog.

0 3 . 1 Suggest and explain how the viruses became able to infect other species of frog.

[2 marks]

0 3 . 2 Name two techniques the scientists may have used when analysing viral DNA to

determine that the viruses were closely related.

[1 mark]

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2

0 3 . 3 Determining the genome of the viruses could allow scientists to develop a vaccine.

Explain how.

[2 marks]

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box 0 3 . 4 Describe how the B lymphocytes of a frog would respond to vaccination against

Ranavirus.

You can assume that the B lymphocytes of a frog respond in the same way as

B lymphocytes of a human.

Do not include details of the cellular response in your answer.

[3 marks]

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