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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 diagram incorrectly represents homologous chromosomes. In a pair of chromosomes, one is paternal and the other is maternal. Each chromosome duplicates itself, forming two chromatids. These chromatids should consist of a combination of maternal and paternal genes.
However, in the model shown, the chromatids appear to be depicted as entirely one type (either maternal or paternal) rather than a mix. This misrepresentation suggests that the chromatids do not exhibit genetic recombination during crossing over, which is a crucial part of meiosis that creates genetic diversity.
Step 2
Explain the effect of meiosis on genetic variation.
Answer
Meiosis results in genetic variation through several key processes. Firstly, during Metaphase I, homologous chromosomes are lined up randomly and independently, a process known as independent assortment. This leads to the formation of gametes with different combinations of maternal and paternal chromosomes.
Secondly, crossing over occurs during Prophase I, where segments of chromatids are exchanged between homologous chromosomes. This exchange results in new combinations of alleles on each chromatid, further increasing genetic diversity in the resulting gametes. Overall, these processes contribute significantly to the genetic variation observed in offspring.