Photo AI
Hereditary hypophosphatemic rickets (HHR) is a human disorder related to low levels of phosphate in the blood - VCE - SSCE Biology - Question 8 - 2014 - Paper 1
Question 8
Hereditary hypophosphatemic rickets (HHR) is a human disorder related to low levels of phosphate in the blood. HHR follows an X-linked dominant mode of inheritance. ... show full transcript
Worked Solution & Example Answer:Hereditary hypophosphatemic rickets (HHR) is a human disorder related to low levels of phosphate in the blood - VCE - SSCE Biology - Question 8 - 2014 - Paper 1
Step 1
Draw a pedigree to show the inheritance of HHR
Answer
The pedigree should represent the male with HHR as a filled square (●) and the unaffected mother as an empty circle (○). The children should be represented with the filled squares (for affected males) and filled circles (for affected females). Considering the information, the pedigree will have the male parent connected to the mother, with lines leading to the six children, showing three of them (the boys) shaded to indicate they have HHR.
Step 2
Determine the mode of inheritance of this different trait
Answer
The mode of inheritance is autosomal recessive. This is inferred because in the pedigree, unaffected parents (II-5 and II-6) have an affected child III-1, indicating that both parents are carriers of the recessive trait. Additionally, the mother of individuals I-2 does not pass the trait to all of her sons, which supports the notion of an autosomal trait.
Step 3
Step 4