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In the mid-1960s, DDT was widely used as an insecticide against mosquitoes - VCE - SSCE Biology - Question 23 - 2010 - Paper 1
Question 23
In the mid-1960s, DDT was widely used as an insecticide against mosquitoes. The sensitivity to insecticide in mosquitoes is determined by a single gene that has two ... show full transcript
Worked Solution & Example Answer:In the mid-1960s, DDT was widely used as an insecticide against mosquitoes - VCE - SSCE Biology - Question 23 - 2010 - Paper 1
Step 1
A. when spraying levels declined, heterozygous advantage occurred.
Answer
When DDT spraying was reduced, the graph indicates an increase in heterozygous mosquitoes, suggesting a heterozygous advantage. The heterozygous genotype is likely to have a fitness advantage in fluctuating environments, helping the population survive.
Step 2
Step 3
C. the number of alleles for resistance was equal to the number for sensitivity in 1966.
Answer
The graph reveals a significant presence of the resistant genotype in 1966. However, it does not specifically indicate that the number of alleles for resistance was equal to sensitivity; this cannot be conclusively stated from the provided data.
Step 4
D. the homozygous resistant genotype was unable to produce offspring at low spraying levels.
Answer
The data is insufficient to declare that the homozygous resistant genotype was unable to produce offspring at low spraying levels. However, the trends in the graph indicate that the homozygous resistant populations did seem to decline possibly due to environmental pressures.