Eye colour is controlled by genes - Edexcel - GCSE Biology - Question 1 - 2016 - Paper 1
Question 1
Eye colour is controlled by genes.
The allele for brown eyes, B, is dominant to the allele for blue eyes, b.
(a) A female with blue eyes and a male with brown eyes ... show full transcript
Worked Solution & Example Answer:Eye colour is controlled by genes - Edexcel - GCSE Biology - Question 1 - 2016 - Paper 1
Step 1
Complete the Punnett square to determine the phenotype of the child.
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Answer
The completed Punnett square for the alleles from a woman with genotype bb (blue eyes) and a man with genotype Bb (brown eyes) is shown below:
B
b
b
Bb
bb
b
Bb
bb
The possible phenotypes of the child are:
Brown eyes (Bb)
Blue eyes (bb)
Thus, the phenotype ratios are 2:1 in favour of brown eyes, therefore, the phenotype of the child will be brown eyes.
Step 2
Complete the tally chart, in Figure 2, for this data.
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Answer
Based on the results provided in Figure 1, the completed tally chart is as follows:
eye colour
tally
total
blue
brown
green
hazel
Total of all colours is 30.
Step 3
Give another appropriate method of displaying this information.
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Answer
The data could be displayed as a bar chart or pie chart.
Step 4
Which sequence is the complementary DNA strand?
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Answer
The complementary DNA strand for the given sequence ATGGCTAAGTA is option A: ATGGCTAAGTA, as DNA strands pair with their respective complement (A with T, G with C).
Step 5
Give a reason for filtering the mixture.
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Answer
Filtering the mixture is necessary to remove solid debris from the crushed fruit, ensuring a clear solution that contains only the DNA and liquid components.
Step 6
What is the role of the ethanol?
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Answer
The role of the ethanol is to precipitate the DNA out of the solution, allowing it to be collected and analyzed.
