Maple syrup urine disease (MSUD) is a rare inherited human condition - AQA - GCSE Biology - Question 1 - 2022 - Paper 1
Question 1
Maple syrup urine disease (MSUD) is a rare inherited human condition.
The allele for MSUD is recessive.
1. What is a recessive allele?
Tick (✓) one box.
An allel... show full transcript
Worked Solution & Example Answer:Maple syrup urine disease (MSUD) is a rare inherited human condition - AQA - GCSE Biology - Question 1 - 2022 - Paper 1
Step 1
What is a recessive allele?
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Answer
A recessive allele is defined as an allele expressed only if a person has two copies of the allele. Therefore, this option should be ticked as the correct answer.
Step 2
What would this symbol represent?
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Answer
The symbol ♂ typically represents a male individual. In the context of MSUD, it signifies a male with the disease.
Step 3
Complete Figure 2 to show the possible genotypes of the children.
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Answer
Using the symbols provided: N for not having MSUD and n for having MSUD, the possible genotypes of the children can be outlined in a Punnett square:
N N
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n | Nn | Nn |
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n | Nn | Nn |
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This indicates all offspring would have the genotype Nn (heterozygous).
Step 4
Which scientific term describes the allele N?
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Answer
The allele N is described as dominant since it expresses the phenotype regardless of whether it is paired with another N allele or an n allele.
Step 5
What chemical substance are alleles made from?
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Answer
Alleles are made from DNA (deoxyribonucleic acid), which is the molecular structure that stores genetic information.
