AQA A-LEVEL BIOLOGY PAPER 3

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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 labora... tory-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. . 1 Suggest three possible limitations of this investigation. [3 marks] 1 2 3 Guppies with large brains are better at identifying predators. The scientists found that only female guppies with large brains were attracted to male guppies bright in colour. Do not write outside the box . Suggest and explain the advantage of this behaviour to the population of guppies. [3 marks] . Describe how the behaviour of female guppies could result in sympatric speciation. [3 marks] Turn over ► 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. Do not write outside the box . 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. . 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. Do not write outside the box [3 marks] 1 2 3 Turn over for the next question [Show More]

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