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Guppies are small fish - AQA - A-Level Biology - Question 1 - 2020 - Paper 3
Question 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 ... show full transcript
Worked Solution & Example Answer:Guppies are small fish - AQA - A-Level Biology - Question 1 - 2020 - Paper 3
Step 1
Suggest three possible limitations of this investigation.
Answer
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Laboratory-raised female guppies might not react/behave/choose in the same way as wild guppies.
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The transparent barrier might not allow for normal courtship behaviour/interaction.
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The duration of 10 minutes may not be long enough for females to make a final choice.
Step 2
Suggest and explain the advantage of this behaviour to the population of guppies.
Answer
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Females with large brains will mate with males bright in colour, ensuring that their offspring are more likely to inherit traits associated with brightness.
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Bright males may help produce larger-brained females, contributing to the population's fitness in avoiding predators.
Step 3
Describe how the behaviour of female guppies could result in sympatric speciation.
Answer
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If females prefer mates of a specific colour and that colour becomes more common, it could lead to reproductive isolation.
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This can lead to gene pools being kept separate as females increasingly choose specific traits.
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Changes in allele frequencies within the population may occur, which could eventually lead to the emergence of new species.