Question

1)Explain the most and least effective uses of a viable plate count.

2)Determine if complement is part of innate immunity or acquired immunity or both and defend your decision.

3)Explain how the results of a diagnostic test could be completely reversed if the test is given to the same patient several months/years apart.

Answer 1

1)A viable cell count allows one to identify the number of actively growing/dividing cells in a sample. The plate count method or spread plate relies on bacteria growing a colony on a nutrient medium. The colony becomes visible to the naked eye and the number of colonies on a plate can be counted.

• Determine viable cell for cell culture to calculate the dilution required
• it is vital when seeding plate for assays
• sensitivity
• adventage on counting living bacteria
• Any concentration of microorganisms can easily counted
• cheap and easily available
• water analysis
• by using selective medium possible to determine no:of bacteria of certain class even in mixed populations

it used for routine determination of cell number in food,medical,aquatic and research laboratories .

2)The complement system (also called the complement cascade) is a mechanism that complements other aspects of the immune response. Typically, the complement system acts as a part of the innate immune system, but it can work with the adaptive immune system if necessary.It act by defending against all the foreign pathogens through complement fragments that participate in opsonization, chemotaxis, and activation of leukocytes and through cytolysis by C5b-9 membrane attack complex.