University of Texas, Brownsville - CLSC 2429 Exercise 2:  Handling and Examining Cultures 1)How would you determine whether culture media given to you are sterile before you use them?   What are the signs of growth in a liquid medium? What is the purpose of wiping the laboratory bench top with disinfectant before you begin to handle cultures? Why can a single colony on a plate be used to start a pure culture? Why is it important not to contaminate a pure culture? What is meant by the term colonial morphology? Why should long hair be tied back when one is working in a microbiology laboratory? Can you think of an actual patient-care situation that would call for its control for the same reason?