Step 1: Analyze the diagram to understand the process and structures shown. The diagram illustrates homologous chromosomes paired up, with an exchange of genetic material between non-sister chromatids, which is known as crossing over.
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4.1 (a) The process shown in the diagram is crossing over (also known as genetic recombination).
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4.1 (b) Crossing over occurs during Prophase I of meiosis.
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4.2 (a) Point D indicates a specific segment on the chromosome where alleles (N/n) are located. This represents a gene.
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4.2 (b) Part B points to one of the two identical copies of a replicated chromosome, which is a chromatid.
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4.3 The part that joins together two sister chromatids is the centromere, labeled as C.
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4.4 Before crossing over, chromatid A has the genotype N, T, R. The homologous non-sister chromatid has n, t, r. The diagram shows that crossing over occurs between the T/t and R/r loci. After the exchange, the segment of chromatid A containing 'R' is replaced by 'r' from the homologous chromatid. Therefore, the resulting chromatid A will have the genotype NTr.
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4.5 (a) The diagram shows alleles for four different characteristics: N/n, T/t, R/r, and D/d. So, 4 characteristics are represented.
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4.5 (b) Each pair of alleles (N/n, T/t, R/r, D/d) represents a different gene. So, 4 different genes are represented.
Here are the answers:
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4.1 (a) The process shown in the diagram: Crossing over
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4.1 (b) Phase of meiosis represented above: Prophase I
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4.2 (a) Identify Point D: Gene
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4.2 (b) Identify Part B: Chromatid
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4.3 Write down the LETTER and NAME of the part that join together two chromatids: C, Centromere
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4.4 Write down the genotype of the resulting chromatid A after the process named in QUESTION 4.1 (a): NTr
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4.5 (a) State how many characteristics are represented in the diagram above: 4
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4.5 (b) State how many different genes are represented by the alleles in the diagram: 4
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