BIOGRAPHY OF A RIVER

II.ActivityA. Have students write a hypothesis about what they think the results of the fecalcoliform testing will be and write a brief paragraph about why they made specificpredictions.(If using a coliform testing kit, follow the directions for procedure. Otherwise follow thedirections below.)B. Filter 100ml of each sample using a small filter. Clean all equipment before startingand between each sample.C. Use tweezers to remove the filter paper and place in a sterile petri dish.D. Break open an ampule of the m-ColiBlue 24 broth and pour over the filter paper.Label each dish.oE. Incubate at 44.5 C for 24 hours.F. Examine for growth at the end of 24 hours. Total coliform counts can be attainedby counting both the red colonies and the blue colonies. For E. Coli counts, countonly the blue colonies.G. Record data on Student Sheet.III. Follow-upA. Have students write a statement accepting or rejecting their hypotheses. Explainwhy the test turned out like it did.B. Have students list some possible sources of coliform contamination in the samplesthat were positive.C. Discuss how these contaminants affect the cost of purifying drinking water. Askstudents for ideas on how to prevent contamination.IV. Extensions3-70