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Warfarin is a poison used to control rat populations - VCE - SSCE Biology - Question 7 - 2002 - Paper 1
Question 7
Warfarin is a poison used to control rat populations. Figure 13 shows changes in the proportion of rats resistant to warfarin in a particular population over a perio... show full transcript
Worked Solution & Example Answer:Warfarin is a poison used to control rat populations - VCE - SSCE Biology - Question 7 - 2002 - Paper 1
Step 1
Explain the process which led to the increase in the percentage of resistant rats during Year 2.
Answer
During Year 2, the use of warfarin resulted in the mortality of non-resistant rats, while resistant rats survived. This is an example of natural selection, where the resistant rats had a genetic advantage that allowed them to survive the poison.
Since resistant rats survived, they were able to reproduce and pass on their warfarin-resistant traits to the next generation. Consequently, the proportion of resistant individuals in the population increased over this year. The selective pressure of the poison favored those with hereditary resistance, leading to an overall rise in their percentage.
Step 2
Using the data in Figure 13, explain what can be concluded about the selective advantage to a rat of being warfarin-resistant compared to being nonresistant in an environment without warfarin.
Answer
The graph indicates that the percentage of resistant rats decreases when warfarin is removed, implying that non-resistant rats can thrive in the absence of the poison. Therefore, in an environment devoid of warfarin, being warfarin-resistant may not provide a significant advantage. Conversely, non-resistant rats are less likely to be at a disadvantage since they can breed effectively without the threat of the poison. This suggests that warfarin resistance serves as a selective advantage specifically in environments where the poison is present.