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Species of the fruit fly Drosophila generally have four pairs of homologous chromosomes - VCE - SSCE Biology - Question 4 - 2011 - Paper 1
Question 4
Species of the fruit fly Drosophila generally have four pairs of homologous chromosomes. a. What is meant by the term 'homologous chromosomes'? The number of chrom... show full transcript
Worked Solution & Example Answer:Species of the fruit fly Drosophila generally have four pairs of homologous chromosomes - VCE - SSCE Biology - Question 4 - 2011 - Paper 1
Step 1
What is meant by the term 'homologous chromosomes'?
Answer
Homologous chromosomes are pairs of chromosomes in a diploid organism that have the same structure and gene sequence, where one chromosome is inherited from each parent. They pair up during meiosis, allowing for genetic recombination, which contributes to genetic diversity.
Step 2
Describe an event that could have caused the chromosome differences between D. nasuta and D. nasuta subspecies albomicans.
Answer
An event such as a chromosomal mutation or differing environmental pressures leading to adaptive evolution may have caused the chromosome differences. This could involve changes such as duplications, deletions, or rearrangements in the chromosome structure, resulting in karyotypic variability.
Step 3
Step 4
Explain how chromosome differences between Drosophila nasuta and Drosophila nasuta subspecies albomicans could result in their reproductive isolation and speciation.
Answer
Chromosome differences can lead to reproductive isolation if the hybrid offspring produced between the two taxa are sterile or less fit compared to the parent species. If the chromosomes fail to pair properly during meiosis, this could result in the production of non-viable gametes. Over time, these genetic divergences can contribute to speciation as the populations adapt to different environmental conditions and accumulate further genetic differences.