Microbiology 208 Lab EXAM 1 questions for study

Microbiology 208 Lab EXAM 1 questions for study What is the significance of agar as an ingredient in the culture media? - Correct Answer Allows bacteria to grow in physically informative or useful ways What are the signs of growth in a liquid medium? - Correct Answer it can be estimated by the increase in turbidity which is caused by increase in number of microbial cell Why do we disinfect the bench-top before and after our laboratory period? - Correct Answer it helps prevent contamination What is a binomial name? - Correct Answer Taxonomic system of naming living things. First letter is capitalized, second part is the species (all in lower case) and both words are italicized. Why are culture tubes held somewhat horizontally when transferring cells rather than vertical? - Correct Answer This makes it the cultures easier to access especially when transferring from a broth, also this is more ergonomic/ allows for easier viewing of your transfer area. Why are test tube caps and petri dish lids never placed on the bench-top? - Correct Answer Risk of contamination How do you cool the inoculating loop after it has been sterilized and just prior to recovering live bacterial cells from a slant culture and from a plate culture? - Correct Answer Hold it still and allow it to cool, loop may be touched to an area of the agar that is colony free. What is a pure culture? - Correct Answer single species is isolated from other species in the population (opposite of mixed culture) What is colonial morphology? - Correct Answer shape, size, consistency, surface texture, elevation, color, density-can give us clues that can help us identify bacteria Why should long hair be controlled in a microbiology laboratory? How does this apply to a patient care situation? - Correct Answer So when you lean over the bench it does not catch on fire. In the OR if you lean over the patient something might fall into their incision. Why do you flame the neck of the culture tube when it is opened? - Correct Answer To keep from cross contaminating the culture of any bacteria on the outside of the tube and to keep from self-contamination of any bacteria remaining at the top inside of the tube from previous transfer. How old should a culture be when you describe the morphological characteristics of texture, size, shape and density? Explain and support your answer. - Correct Answer They will generally reach maturity within 24 hours and be ready for observation and identification. Define the acidic and basic dyes. What is the purpose of each? - Correct Answer Basic: Positively charged, stick to bacteria, purpose is to stain the bacteria so that you can see them. Acidic: Negatively charged, repelled by bacteria, purpose is the stain the background so that you can see surface features of the bacteria. What is heat fixation? Why do you heat fix a slide to be stained? - C