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 a... 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 determine the phenotype of the child, we set up a Punnett square with the alleles from both the father and mother.
B B
------------
b | Bb | Bb |
------------
b | Bb | Bb |
From the Punnett square, all offspring (100%) will have the genotype 'Bb', resulting in a phenotype of brown eyes.
Step 2
Complete the tally chart, in Figure 2, for this data.
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Answer
Based on the data presented in Figure 1, we can compile the tallies as follows:
eye colour | tally | total
-----------------------------------------
blue | ||||||||||| | 9
brown | |||||||||||||||| | 14
green | ||| | 3
hazel | |||| | 4
The total counts for each eye color are:
Blue: 9
Brown: 14
Green: 3
Hazel: 4
Step 3
Give another appropriate method of displaying this information.
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Answer
The eye color data could also be displayed as a bar chart or a pie chart to visually represent the distribution of the eye colors within the sample population.
Step 4
Which sequence is the complementary DNA strand?
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Answer
The complementary DNA strand will pair with the given sequence ATGGCTAAGTA. The correct complementary strand is Answer D: GCATAGTCA.
Step 5
Give a reason for filtering the mixture.
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Answer
Filtering the mixture is necessary to remove solid debris, such as fruit pulp and cell wall fragments, leaving a clear solution that contains the DNA.
Step 6
What is the role of the ethanol?
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Answer
The role of ethanol is to precipitate the DNA, allowing it to be separated from the solution, as DNA is not soluble in alcohol.
