a) Define the biological agents and the criteria used for their classification in four hazard groups. Indicate two routes of transmission of infection. [10 marks] b) Explain the difference between disinfection and sterilization. Name a sterilization procedure. [5 marks] c) A biopharmaceutical company has to decide if using Saccharomyces cerevisiae or Escherichia coli for producing a new drug. Indicate for which of the two the containment level is stricter and explain how you would achieve it. [10 marks]