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.
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Answer
The individual chromosomes are visible because they have condensed during mitosis.
Each chromosome is made up of two chromatids, indicating that DNA has replicated.
Step 2
Tick (✓) one box that gives the name of the stage of mitosis shown in Figure 1.
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Answer
Prophase
Step 3
Suggest how this procedure moved the chromosomes apart.
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Answer
Water moves into the cells/cytoplasm by osmosis, leading to an increase in cell size and pushing the chromosomes further apart.
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.
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Answer
The differences could arise from variations in base sequences or differences in the histone interaction along the chromosome.
Step 5
What is a homologous pair of chromosomes?
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A homologous pair consists of two chromosomes that carry the same genes at the same loci, but may have different alleles.
Step 6
Give two ways in which the arrangement of prokaryotic DNA is different from the arrangement of the human DNA in Figure 1.
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Answer
Prokaryotic DNA is circular, unlike the linear DNA found in humans.
Prokaryotic DNA is not associated with proteins/histones as eukaryotic DNA is.
