Preparation of Smears and Simple Staining Lab Report Answers

EXERCISE 5 — LABORATORY REPORTPreparation of Smears and Simple StainingPURPOSEEXPECTED RESULTS1. Sketch a coccus:2. Sketch a bacillus:3. Which species used in this exercise is a bacillus?

CONCLUSIONS1. Which bacterium is a bacillus?2. Which bacterium is larger?QUESTIONS1. Of what value is a simple stain?2. What is the purpose of heat-fixing the smear?3. Another method of fixing smears is to use methanol instead of heat. How does alcohol chemically fix the bacteria?4. In heat-fixing, what would happen if too much heat were applied?CRITICAL THINKING1. Methylene blue can be prepared as a basic stain or an acidic stain. How would the pH of the stain affect the staining of bacteria?2. Can dyes other than methylene blue be used for direct staining? Briefly explain.CLINICAL APPLICATIONS1. Bacteria can be seen without staining. Why, then, was Koch’s recommendation of fixing and staining important for the discovery of the bacterial causes of diseases?2. Quality control staff in a sterilization unit of a hospital used a simple stain to determine whether bacteria were present in sterilized materials. A simple stain of sterile saline used for respiratory therapy revealed the presence of bacteria. Is the saline contaminated?