A marine biologist wants to investigate whether the concentration of microplastic particles in the digestive tracts of bivalves is affected by their habitat depth.
The researcher needs a stratified sample of 50 bivalves from a coastal reef. The reef contains a population of 300 mussels (which inhabit the shallower intertidal zone) and 200 oysters (which inhabit the deeper subtidal zone).
The biologist plans to extract and count the number of synthetic microfibres found in each bivalve's digestive tract.
Explain one advantage of using a stratified sample of bivalves in this study.
689 exam-style questions on AQA A Level Psychology Scientific processes. Each one has a worked solution and a mark scheme showing where the marks go.