Unit 7 Contemporary Issues in Science - Question 3

A clear guide to tackling the ‘scientific article analysis’ question

If you’re preparing for the Unit 7: Contemporary Issues in Science external exam, you’ll know that Question 3 is one of the most difficult questions on the paper. It tests your ability to interpret, analyse, and evaluate scientific information.

🧠 What is Question 3 about?

Question 3 is worth 12 marks and is built around a scientific article presented in the exam paper.

You are expected to consider how the article has analysed the scientific information presented and whether this analysis supports the conclusions/judgements given in the article. This means:

• Show that you understand the science behind the issue

• Interpret the data, graphs or evidence given

• Discuss if judgements or decisions made are based on that evidence

• Commenting on the validity/reliability of the sources of the information

✔️ What Examiners Want to See

Step 1: Make clear, justified judgements

Examiners want to see that you understand the judgements on scientific issue in the article. Judgements are statements that the article has made about the scientific issue, for example "..users find the device easy to switch on" or "..the disease is more prevalent in tropical climates" To address this you could:

• Identify advantages and disadvantages

• Evaluate data on trends or patterns

• Identify where the writer has made a conclusion or statement about the issues discussed in the article

• Explain if something is beneficial or problematic

• Explain any scientific findings from experimental data or clinical trials

• Recognising trade-offs (e.g. cost vs performance, comfort vs effectiveness)

Your judgements should be logical and clearly linked to the article

Step 2: Comment on validity and reliability of the evidence

Show that you can evaluate the quality of the evidence, not just describe it. This includes:

• Is the data supported by research studies, trials, or data?

• Noting whether evidence is well-supported (large scale study) or limited (small scale study)

• Recognising that some studies may have small sample sizes or incomplete data

• Are conclusions based on the work of many research teams globally or one national team?

• Are the outcomes generalised even though the data only relates to small niche data sources

• Comment on any statistical treatment of the data

• Comment on whether the article is balanced, using evidence to determine both advantages and disadvantages

Show awareness that scientific conclusions depend on the strength of the evidence.

Step 3: Consider sources and references

Think about where the information comes from. You could:

• Refer to who carried out the research (e.g. scientists, clinicians, organisations)

• Comment on whether sources are reliable, recent, and relevant

• Recognise that articles may be edited or selective in what evidence they include

Example Question 3

Based on the Nature article: Ultra processed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial

Step 1: Judgements

The article describes a scientific study that compared two diets: one high in ultra-processed foods (UPFs) and one made mainly from minimally processed foods (MPFs). Both diets followed healthy eating guidelines. The results showed that both diets caused weight loss, but the minimally processed food diet led to greater weight loss overall.

The data shows that participants lost an average of 2.06% of their body weight on the minimally processed diet, compared to 1.05% on the ultra-processed diet. This suggests that eating foods that are less processed may be more effective for weight loss, even when the diets contain similar nutrients and calories.

However, the study also showed that some health markers improved on the ultra-processed diet, such as lower LDL (“bad”) cholesterol. This means ultra-processed foods are not always harmful if they are part of a balanced diet. Overall, a sensible judgement is that minimally processed foods appear to be better for weight management, but both diets can have health benefits.

Step 2: Validity and Reliability of the Evidence

The evidence in this study is strong because it was a randomised controlled trial, which is one of the most reliable types of scientific research. Each participant followed both diets at different times, meaning results were less affected by individual differences such as metabolism or lifestyle.

The study also used measured data, including body weight and body composition, which increases validity. The difference in weight loss between the two diets was found to be statistically significant, meaning it is unlikely to be due to chance.

However, there are some limitations. The study involved around 50 participants, which is not a very large sample size. The study also lasted only 8 weeks, so it does not show the long-term effects of these diets. Because meals were provided, people may have eaten differently than they would in everyday life, which could affect reliability.

Step 3: References and Sources

The article was published in Nature Medicine, which is a well-respected scientific journal. This increases confidence that the study was carried out carefully and reviewed by experts before publication.

The researchers followed recognised dietary guidelines and compared their results with previous research, which helps support their conclusions. However, because this is a single study, its results should be considered alongside other research before making strong public health recommendations.

Conclusion

In conclusion, the study provides good evidence that a diet made up of minimally processed foods leads to greater weight loss than a diet high in ultra-processed foods, even when both follow healthy guidelines. The evidence is reliable due to the study design, but the small sample size and short time period limit how widely the results can be applied. Overall, the findings support the idea that reducing ultra-processed food intake may improve health outcomes.

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