A materials science research group evaluated the effectiveness of a new organic additive, BioShield-Y, designed to reduce the degradation rate of biodegradable polylactic acid (PLA) bioplastic buried in compost. Sixty identical bioplastic sheets were manufactured: thirty sheets were treated with BioShield-Y, and thirty sheets were left untreated. All sixty sheets were buried in the same compost bin under controlled temperature and humidity conditions for 90 days. At the end of the 90-day period, the percentage mass loss for each sheet was measured. The results showed that the sheets treated with BioShield-Y had a significantly lower percentage mass loss compared to the untreated sheets.
Explain why the group of untreated bioplastic sheets was necessary for this study.
Practise AQA A Level Psychology Scientific processes with exam-style questions for A Level Psychology. 689 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
