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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
The increase in the percentage of resistant rats during Year 2 can be explained by the principles of natural selection. Initially, there were some rats in the population that had genetic mutations conferring resistance to warfarin. When warfarin was introduced, non-resistant rats were more likely to die from poisoning, while the resistant rats survived and were able to reproduce.
This survival of the resistant individuals meant that they passed on their warfarin resistance traits to the next generation, leading to a greater proportion of resistant rats in the population over the year. This cycle of survival, reproduction, and inheritance caused the percentage of resistant rats to increase significantly during this period.
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
From the data presented in Figure 13, it can be concluded that warfarin-resistant rats have a selective advantage when warfarin is present in the environment. The graph indicates a decrease in the percentage of resistant rats when the use of warfarin was discontinued, suggesting that these resistant individuals are at a disadvantage in a non-warfarin environment. Hence, being resistant may not confer benefits when the selective pressure of warfarin is removed, indicating that resistance is advantageous primarily in an environment where warfarin is used.