Photo AI
The inheritance of an allele for deafness is shown in the family tree below - Scottish Highers Human Biology - Question 14 - 2016
Question 14
The inheritance of an allele for deafness is shown in the family tree below. This condition is controlled by an allele which is A dominant and sex-linked B recessi... show full transcript
Worked Solution & Example Answer:The inheritance of an allele for deafness is shown in the family tree below - Scottish Highers Human Biology - Question 14 - 2016
Step 1
Identify the inheritance pattern from the family tree
Answer
In the given family tree, we observe that the affected individuals (indicated by filled circles/squares) appear in both sexes, suggesting that the trait is not restricted to one gender.
The males in the family tree show instances of deafness which could suggest a pattern of inheritance consistent with a recessive allele, particularly since an unaffected parent can produce affected offspring.
Step 2
Analyze the key to infer trait transmission
Answer
The presence of both affected males and females indicates that the trait cannot be sex-linked as it would typically show a pattern where mostly males would be affected if it were linked to the X chromosome. This makes the option of 'dominant and sex-linked' incorrect.
Since affected individuals arise from unaffected parents, we can rule out dominant inheritance as well.
Step 3