LNAT Science 2 — Questions and Answers
Question 1: A scientific study reports that patients who took Drug X recovered 30% faster than those on a placebo. Which of the following would most weaken this conclusion?
- The study used a randomized double-blind design
- The patients who received Drug X also received more frequent nursing check-ins (Correct answer)
- Drug X has been approved by a regulatory authority
- The placebo group had a similar age distribution to the treatment group
Correct answer: The patients who received Drug X also received more frequent nursing check-ins
If patients on Drug X also received more nursing attention, the faster recovery could be attributed to that care rather than the drug itself.
Question 2: A passage states: 'All controlled experiments must have a control group.' A researcher conducts an experiment comparing three different fertilizers with no untreated group. Which best describes this experiment?
- It is invalid because it lacks statistical power
- It violates the stated principle by having no untreated baseline (Correct answer)
- It is valid because comparing groups to each other is sufficient
- It is invalid because fertilizers cannot be tested experimentally
Correct answer: It violates the stated principle by having no untreated baseline
The stated principle requires a control group, and the experiment has none, directly violating the condition.
Question 3: A scientist claims that a newly discovered chemical reduces air pollution by neutralizing nitrogen oxides. To best support this claim, the next step should be:
- Publishing the finding immediately in a press release
- Conducting peer-reviewed laboratory trials measuring nitrogen oxide levels before and after treatment (Correct answer)
- Surveying public opinion on air pollution solutions
- Comparing the chemical's cost to existing pollution controls
Correct answer: Conducting peer-reviewed laboratory trials measuring nitrogen oxide levels before and after treatment
Peer-reviewed laboratory trials with measurable before-and-after data provide the strongest empirical evidence for the chemical's claimed effect.
Question 4: A graph shows that ice cream sales and drowning incidents both rise in summer. A commentator concludes that ice cream causes drowning. This error is best described as:
- A selection bias
- Confusing correlation with causation due to a common cause (Correct answer)
- Overgeneralisation from a small sample
- A measurement error in the data collection
Correct answer: Confusing correlation with causation due to a common cause
Both variables are driven by hot weather (a confounding variable), so their correlation does not imply a causal relationship.
Question 5: In a clinical trial, 200 patients are split equally between a new antibiotic and a standard one. After 14 days, 85 patients in the new group recovered versus 80 in the standard group. Which statement is most accurate?
- The new antibiotic is definitively superior
- The difference is large enough to be clinically significant without further testing
- The result suggests a possible advantage but statistical significance must be determined (Correct answer)
- The trial is invalid because both groups should have received a placebo
Correct answer: The result suggests a possible advantage but statistical significance must be determined
A five-patient difference in a group of 100 may or may not be statistically significant, so further analysis is required before drawing strong conclusions.
Question 6: A passage argues that genetic modification of crops is inherently dangerous because it interferes with nature. This argument is an example of:
- An appeal to authority
- The naturalistic fallacy, assuming natural equals safe and unnatural equals dangerous (Correct answer)
- A valid empirical claim based on observed outcomes
- An ad hominem attack on biotechnology researchers
Correct answer: The naturalistic fallacy, assuming natural equals safe and unnatural equals dangerous
Equating 'natural' with 'safe' and 'artificial' with 'dangerous' commits the naturalistic fallacy, as many natural things are harmful and many artificial ones are beneficial.
Question 7: A researcher finds that a new material conducts electricity at room temperature with no resistance. She concludes it is a room-temperature superconductor. Her colleague insists the result be independently replicated before acceptance. The colleague's position reflects which scientific principle?
- Peer replication as a check against experimental error and fraud (Correct answer)
- The precautionary principle in environmental science
- Occam's razor preferring simpler explanations
- The principle of falsifiability as defined by Popper
Correct answer: Peer replication as a check against experimental error and fraud
Independent replication is a core scientific norm that guards against errors, equipment faults, and potential misconduct before a finding is widely accepted.
LNAT Science 2
A scientific study reports that patients who took Drug X recovered 30% faster than those on a placebo.
Which of the following would most weaken this conclusion?