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
To complete the Punnett square for a female with blue eyes (bb) and a male with brown eyes (BB), we fill in the alleles:
B
B
b
Bb
Bb
b
Bb
Bb
All possible genotypes for the offspring are Bb, indicating that all children will have brown eyes.
Step 2
Complete the tally chart, in Figure 2, for this data.
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Answer
Based on the data collected from Figure 1, we tally the eye colours:
Blue: 9
Brown: 14
Green: 3
Hazel: 4
The completed tally chart is as follows:
Eye Colour
Tally
Total
blue
brown
green
hazel
Step 3
Give another appropriate method of displaying this information.
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Answer
Another appropriate method for displaying this information could be a bar chart or a pie chart. Both visual aids effectively represent the proportions of each eye colour within the sample size.
Step 4
Which sequence is the complementary DNA strand?
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Answer
The complementary DNA strand to the sequence ATGGCTAAGTA can be determined using base pairing rules, where Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G). Thus, the complementary strand is TACCGATTAC, which corresponds to option C.
Step 5
Give a reason for filtering the mixture.
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Filtering the mixture helps to remove solid particles from the liquid, allowing for a clear solution that contains the DNA in a purified form.
Step 6
What is the role of the ethanol?
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The role of ethanol in this process is to precipitate the DNA, making it visible and easier to collect and analyze.
