Ijmb Model Questions Vol1 2017 Biology Question 10

Practice essay / theory question 10 from the 2017 Ijmb Model Questions Vol1 Biology examination. This question covers Genetics .

Ijmb Model Questions Vol1 2017 Biology Essay / Theory
Topic: Genetics
Question 10 IJMB_MODEL_QUESTIONS_VOL1 • 2017 • BIOLOGY • essay

A pedigree chart shows a family in which a rare autosomal recessive disorder (affected phenotype = albinism) appears in the following pattern: the proband (III‑2) is affected; both of his parents (II‑1 and II‑2) are phenotypically normal; his two siblings (III‑1 and III‑3) are also phenotypically normal. In the previous generation, the maternal grandparents (I‑1 and I‑2) are phenotypically normal, while the paternal grandparents (I‑3 and I‑4) are phenotypically normal as well. The disorder has a reported prevalence of 1 in 2 500 individuals in the population.

Question Parts

( a )
Determine the most likely genotype of each individual shown in the pedigree (use the symbols ++ for homozygous normal, +‑ for heterozygous carrier, and ‑‑ for affected).
( b )
Using the Hardy–Weinberg principle, calculate the expected carrier frequency (heterozygotes) for this disorder in the general population.
( c )
Discuss how a consanguineous marriage (e.g., first‑cousin union) in this family could affect the incidence of the disorder in their offspring, and state any two genetic counselling measures that should be offered.

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About This Question

This is Ijmb Model Questions Vol1 2017 Biology Question 10. It is one of the essay questions from the 2017 Ijmb Model Questions Vol1 Biology examination.

The question covers Genetics .

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