A student filters crushed fruit mixed with detergent solution. The student discards the liquid and adds cold ethanol to the solid material left on the filter paper. Little DNA is collected.
Which change would best correct the method, and why?
Keep the filtrate, because released DNA passes through the filter.
Keep the residue, because released DNA stays inside the cell walls.
Keep the filtrate, because ethanol makes new DNA from dissolved sugar.
Keep the residue, because ethanol changes cell walls into DNA strands.
44 exam-style questions on Edexcel GCSE Biology 3.2 DNA and protein synthesis, covering 3.2.1 DNA structure as a polymer, 3.2.2 Genome and gene definitions, 3.2.3 Extracting DNA from fruit, 3.2.4 Base order determines protein shape, 3.2.5 Stages of protein synthesis, 3.2.6 Non-coding DNA variants affecting phenotype, and 3.2.7 Coding DNA variants affecting phenotype. Each one has a worked solution and a mark scheme showing where the marks go.