Medical researchers use tissue culture to grow genetically identical cells for testing four treatments. The nutrient medium, culture dishes and transfer equipment are sterilised before the cells are added.
Which action is most likely to introduce bacteria or fungi into a culture?
Sealing each dish lid with tape after adding the cells.
Keeping the sealed dishes at a warm, controlled temperature.
Lifting the dish lid only slightly while adding the cells.
Placing the dish lid inner side down on the workbench while adding the cells.
100 exam-style questions on Edexcel GCSE Biology 4.3 Selective breeding and genetic modification, covering 4.3.1 Selective breeding and its impact, 4.3.2 Tissue culture, 4.3.3 Genetic engineering overview, 4.3.4 Main stages of genetic engineering, 4.3.5 Advantages and disadvantages of GM organisms, 4.3.6 Agricultural solutions for a growing population, and 4.3.7 Evaluating genetic engineering and breeding. Each one has a worked solution and a mark scheme showing where the marks go.