This question is on meiosis: Variation occurs during meiosis, give the two ways this happens (include the phases where it occurs) (4 marks)
During prophase 1, homologous chromosomes will pair up to form a bivalent, this is where crossing over can occur. Chromatids will twist around each other and will break and reform, resulting in crossing over.During metaphase 1 the homologous chromosomes will align at the metaphase plate, this lining up will be completely random due to different alleles and crossing over, this is called independent assortment. This will also occur in metaphase 2.
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