Q40 - Mendelian Randomisation Separates Correlation from Causation

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

Population Genetics & Hardy-Weinberg Equilibrium

Sir Richard Doll (1912-2005) invented statistical methods to prove smoking causes human disease. Mendelian randomisation was invented to investigate more subtle behaviours, such as the health impacts of alcohol (1) and high density lipoproteins (HDLs; ‘good’ cholesterol) (2). An underlying genotype, inferred to cause a behaviour, is identified, and its correlation with disease is assessed. White British people were recruited for this study.

Figure 1 for Q40: Mendelian Randomisation Separates Correlation from Causation

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

A. Compared to not drinking any alcohol, consuming small amounts of alcohol is beneficial to health.

B. Drugs which raise HDL are expected to reduce cardiovascular disease.

C. If people with the genotype aa, who happen to consume no alcohol for religious reasons, have a high risk of cardiovascular disease, it should be concluded alcohol contributes to disease directly.

D. If the allele a is found to be more common in Scotland, and A in Wales, the conclusions of a UK wide study will be strengthened.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions