Q91 - Using SNPs, Autosomal STRs, Y-STRs, and mtDNA to Reconstruct a Family

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

Extranuclear & Non-Mendelian Inheritance

Polymorphic DNA sequences are widely used for molecular identification. Short tandem repeat (STR) is composed of multiple repeats of 2-8 nucleotides flanked by two conserved sequences. Each STR locus normally has more than two alleles. Single nucleotide polymorphism (SNP) is a variation at a single position in a DNA sequence among individuals. Each SNP usually has only two alleles. Seven individuals were genotyped for two autosomal and two mitochondrial (mtDNA) SNPs, two autosomal and two Y-linked (NRY) STRs (Table Q.91).

Table Q.91 lists, for each of seven individuals (Ind_1 through Ind_7), their genotypes at two autosomal SNPs, two autosomal STRs, two Y-linked (NRY) STRs, and two mtDNA SNPs.

Indicate in the answer sheet if each of the following statements is true or false.

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

A. If the same number of SNPs or STRs are used, SNPs are better than STRs for distinguishing individuals.

B. Ind_6 is more likely a child of Ind_2 and Ind_5 than Ind_3 is.

C. Ind_4 is possibly a brother of Ind_6.

D. It is possible that Ind_7 is a granddaughter of Ind_1 and Ind_6.

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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)