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A student drew a diagram to model part of the process of meiosis - HSC - SSCE Biology - Question 28 - 2020 - Paper 1
Question 28
A student drew a diagram to model part of the process of meiosis. Homologous chromosomes paired Crossing over Recombinant chromatids KEY Maternal Paternal Expla... show full transcript
Worked Solution & Example Answer:A student drew a diagram to model part of the process of meiosis - HSC - SSCE Biology - Question 28 - 2020 - Paper 1
Step 1
Explain the misunderstanding of meiosis shown in this model.
Answer
The paired homologous chromosomes are incorrectly represented in the diagram. In a pair of chromosomes, one is paternal and the other is maternal. Prior to crossing over, each chromosome duplicates itself, resulting in two chromatids that should be identical. However, it is essential that these chromatids maintain their maternal and paternal identities, which is not correctly depicted in the model. The misconception arises from the idea that the chromatids can be represented as being interchangeably maternal or paternal, which is inaccurate.
Step 2
Explain the effect of meiosis on genetic variation.
Answer
Meiosis contributes to genetic variation through two key processes: independent assortment and crossing over. During Metaphase I, homologous chromosomes align randomly at the cell's equator, leading to different combinations of maternal and paternal chromosomes in gametes. Furthermore, during Prophase I, crossing over occurs, allowing homologous chromosomes to exchange segments of genetic material, which results in chromatids with new combinations of alleles. These processes ensure that the gametes produced contain unique combinations of genes, enhancing genetic diversity.