Persons 7 and 8 in Figure 4 are expecting a fourth child - AQA - GCSE Biology - Question 5 - 2022 - Paper 1
Question 5
Persons 7 and 8 in Figure 4 are expecting a fourth child. Determine the probability that the child will have MSUD. You should:
- draw a Punnett square diagram
- iden... show full transcript
Worked Solution & Example Answer:Persons 7 and 8 in Figure 4 are expecting a fourth child - AQA - GCSE Biology - Question 5 - 2022 - Paper 1
Step 1
Draw a Punnett Square Diagram
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Answer
To find the probability of the child having MSUD, we need to determine the genotypes of parents 7 and 8 from Figure 4.
Assuming:
Parent 7 (female) is a carrier for MSUD: Nn
Parent 8 (male) has MSUD: nn
The Punnett square looks like this:
N | n
-----------------
n | Nn | nn
-----------------
n | Nn | nn
From this, the possible genotypes of the offspring are:
Nn (not having MSUD)
nn (having MSUD)
Step 2
Identify the Phenotype of Each Offspring Genotype
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Answer
From the Punnett square, there are two potential phenotypes:
Nn (not having MSUD): 2 occurrences
nn (having MSUD): 2 occurrences
Hence, the probability that the child will have MSUD is:
extProbability(msud)=Total OffspringNumber of nn=42=0.5
