Q90 - Reading Mode of Inheritance from Four Pedigrees

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Pedigrees 1-4 show the inheritance of four different rare disorders. It is known that the disease in pedigree 4 is X-linked recessive.

Figure Q.90

Studying the pedigrees and indicate in the answer sheet if each of the following statements is true or false.

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. The disorder in pedigree 1 is most likely caused by a recessive allele.

B. Person III2 and III7 in pedigree 2 have the same genotype.

C. Pedigree 3 shows the inheritance of the disorder can be caused by a recessive allele on X-chromosome.

D. If the affected man and his unaffected wife in pedigree 4 have a son then the probability of this son be affected is 0.125.

Question reproduced from IBO 2016, Theoretical Paper B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)