Chymosin is an enzyme used to make cheese. Bacteria have been genetically modified to produce chymosin. Why are bacteria used as the host cells?
They contain no DNA of their own, so the new gene is never lost.
They have a nucleus, so the new gene is protected from damage.
They can produce chymosin without being given a gene to do so.
They reproduce quickly, so large amounts of chymosin can be made.
127 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.