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← Theoretical 2

Q85 — The methuselah Mutation and Stress Resistance in Drosophila

Theoretical 2 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Comparative Thermoregulation

Researchers used random insertion transposon mutagenesis to disrupt genomic DNA in fruit flies (D. melanogaster). One of the isolated mutants, called mth, was examined for longevity and stress resistance, compared to the wild type (+) under the influence of paraquat (an inducer of intracellular superoxide anion production), starvation and high temperature. Results of the experiments comparing homozygous mth mutants and the wild type (+) are summarized below.

Three-panel bar chart comparing wild-type (+) and mth mutant survival, split by sex. Panel A: percent survival at 48 hours under paraquat, with mth flies of both sexes surviving far better than wild type. Panel B: average survival time at 25°C under starvation, mth surviving somewhat longer than wild type. Panel C: average survival time at 36°C (high temperature), mth and wild type showing more similar, modest survival times for both sexes. Survival of wild-type (+) and mth mutant Drosophila, males and females, under paraquat-induced oxidative stress, starvation, and high temperature.

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

A. For both wild type and mth populations, female fruit flies tend to be more resilient against all three kinds of stress than corresponding males.
B. The survival profile of mth mutants against oxidative stress is similar to what we would expect for superoxide-dismutase (enzyme protecting against oxidative stress)-deficient fruit flies.
C. mth mutants are expected to have a longer lifespan, compared to wild-type fruit flies.
D. High temperature is more detrimental to wild-type fruit flies than starvation.
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Question reproduced from IBO 2022, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)