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Figure 1 shows all the chromosomes present in one human cell during mitosis - AQA - A-Level Biology - Question 1 - 2018 - Paper 1
Question 1
Figure 1 shows all the chromosomes present in one human cell during mitosis. A scientist stained and photographed the chromosomes. In Figure 2, the scientist has arr... show full transcript
Worked Solution & Example Answer:Figure 1 shows all the chromosomes present in one human cell during mitosis - AQA - A-Level Biology - Question 1 - 2018 - Paper 1
Step 1
Give two pieces of evidence from Figure 1 that this cell was undergoing mitosis. Explain your answers.
Answer
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The chromosomes are clearly visible, indicating that they have condensed, which is a characteristic of mitosis.
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Each chromosome is composed of two chromatids, suggesting that DNA has replicated, a key feature observed during mitosis.
Step 2
Step 3
Step 4
Suggest one way the structure of the chromosome could differ along its length to result in the stain binding more in some areas.
Answer
The chromosome could have regions with different densities of chromatin, such as areas that are more compact or regions with varying histone modifications, which would lead to differential binding of the stain.
Step 5
Step 6
Give two ways in which the arrangement of prokaryotic DNA is different from the arrangement of the human DNA in Figure 1.
Answer
- Prokaryotic DNA is circular, while human DNA is linear.
- Prokaryotic DNA is not associated with histones, whereas human DNA is organized into structures called chromosomes with histone proteins.