A student extracted DNA from frozen peas.
She mashed the peas with a solution of washing-up liquid and salt, then added a protease enzyme. She filtered the mixture and added ice-cold ethanol.
Explain why washing-up liquid is needed to release DNA from the nucleus.
Suggest why the student added a protease enzyme.
The student extracted more DNA from frozen peas than from fresh peas.
Suggest why.
The student said that the white strands she collected were pure DNA.
Give one reason why this may not be correct.
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.