Science Flashcards

A passage describes an experiment where rats given high doses of artificial sweetener developed tumours. The author concludes the sweetener is dangerous for humans. What is the primary weakness of this conclusion?

Answer: High-dose animal results cannot automatically be extrapolated to typical human consumption levels or human physiology

Extrapolating from extreme doses in a different species to typical human intake ignores dose-response relationships and interspecies physiological differences.

Two scientists analyse the same climate dataset and reach opposite conclusions. Which of the following is the most scientifically sound response to this disagreement?

Answer: Commission additional independent analyses and examine methodological differences between the two studies

Scientific disagreement is resolved by further investigation and scrutiny of methodology, not by appealing to authority or convenience.

A headline reads: 'Scientists discover gene linked to intelligence.' A critical reader should first ask:

Answer: What 'linked to' means—association, predictive correlation, or causal mechanism—and how large the effect size is

Vague causal language like 'linked to' can mean anything from a weak statistical association to a strong causal mechanism; effect size and mechanism are essential to evaluate the claim.

A pharmaceutical trial is stopped early because initial results show the drug is highly effective. Critics warn this could overestimate the drug's benefit. Why?

Answer: Early stopping biases results upward because trials are more likely to be halted during chance positive fluctuations

Trials stopped at an unusually positive moment tend to capture a peak in natural statistical variation, causing the true effect to be overestimated relative to what a full trial would show.

A study finds that teenagers who play violent video games are more aggressive. The researchers controlled for prior aggression levels, age, and gender. A critic argues that more aggressive teenagers may simply prefer violent games. This is an example of:

Answer: Reverse causation as an alternative explanation for the observed correlation

Reverse causation suggests the effect (aggression) precedes and causes the exposure (game choice) rather than the other way around, which the study design cannot rule out.

A scientist proposes that meteor impacts caused mass extinctions. She points to a global iridium layer coinciding with the Cretaceous-Paleogene boundary as evidence. Iridium is rare on Earth but common in meteors. This evidence is best described as:

Answer: Consistent with the hypothesis and would be expected if a large meteor struck Earth, lending support without being definitive alone

The iridium layer is a predicted observable consequence of a meteor impact, making it consistent evidence that supports but does not alone confirm the hypothesis.

A government agency claims a new pesticide is safe because it has not been banned. A toxicologist responds that absence of a ban does not equal proven safety. Which principle does the toxicologist invoke?

Answer: The precautionary principle, distinguishing between lack of evidence of harm and evidence of lack of harm

The toxicologist correctly distinguishes between no evidence of harm (the regulatory status) and positive evidence of safety, which requires active testing.