Ijmb Model Questions Vol1 2025 Biology Question 10

Practice essay / theory question 10 from the 2025 Ijmb Model Questions Vol1 Biology examination. This question covers Mendelian Genetics, Pedigree Analysis, Population Genetics, Molecular Basis of Genetic Disorders .

Ijmb Model Questions Vol1 2025 Biology Essay / Theory
Topics: Mendelian Genetics Pedigree Analysis Population Genetics Molecular Basis of Genetic Disorders
Question 10 IJMB_MODEL_QUESTIONS_VOL1 • 2025 • BIOLOGY • essay

A pedigree of a Nigerian family shows a rare autosomal recessive disorder caused by a mutation in the gene encoding enzyme X. The proband (individual V‑3) is affected, while both parents (IV‑2 and IV‑3) are phenotypically normal. No other affected individuals appear in earlier generations.

Question Parts

( a )
State the most probable genotype of the proband and of each parent, providing a brief justification based on the mode of inheritance shown in the pedigree.
( b )
If the proband marries an individual from the same population who is phenotypically normal, calculate the probability that their first child will be affected, assuming Hardy‑Weinberg equilibrium with a carrier frequency of 1/50 for this disorder.
( c )
The disease results from a point mutation that creates a premature stop codon in the coding region of enzyme X. Discuss two molecular mechanisms by which a cell can mitigate the deleterious effect of such nonsense mutations.

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About This Question

This is Ijmb Model Questions Vol1 2025 Biology Question 10. It is one of the essay questions from the 2025 Ijmb Model Questions Vol1 Biology examination.

The question covers Mendelian Genetics, Pedigree Analysis, Population Genetics, Molecular Basis of Genetic Disorders .

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