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Patterns of inheritance

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Question 9

Phenylketonuria (PKU) is a metabolic disorder that displays an autosomal recessive inheritance pattern.

a.

Two healthy carriers of Phenylketonuria have twelve children.

Calculate how many of the twelve children you would expect to:

  • have Phenylketonuria
  • be carriers of Phenylketonuria.
[2]
b.

A daughter of these parents and a male who has Phenylketonuria have a child. Calculate the probability of the child having Phenylketonuria.

[3]
c.

DNA samples can be amplified using the polymerase chain reaction (PCR). In theory, how many fragments of DNA might be present after 18 cycles of PCR?

Assume one DNA fragment was present at the beginning of the PCR process. Represent your answer in the form 10x10^x10x, where x x\,x is a log⁡10\log_{10}log10​ value rounded to two decimal places.

[3]

Patterns of inheritance Questions

  1. A Level
  2. /Biology
  3. /Patterns of inheritance