Objective 1 Assignment 2005
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This document contains two multiple choice questions related to scientific experiments. The first question asks which final step should be taken to prove that specific microbes cause a given disease based on Robert Koch's proposed procedure. The second question asks which graph best represents the freezing temperature data for cesium chloride solutions with varying amounts added to water, as shown in a table.
Objective 1 Assignment 2005
- 1. Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. Objective 1 Assignment 2005 Robert Koch In the nineteenth century Robert Koch scientifically investigated the transmission of diseases. He proposed a procedure that would enable a person to determine if a specific microorganism caused a given disease. The first four steps of this procedure are listed below: Microbes must be isolated from an infected host organism. The isolated microbes are then grown in a pure culture. The microbes from the pure culture are injected into a new host. If the new host contracts the disease, the microbes must be isolated from the new host and grown in a new culture. 1. What final step should be taken to prove that these specific microbes cause the given disease? a. Mix the microbes from the new and old cultures. b. Inject diseased organisms with the microbes from the new culture. c. Compare the original microbes with the microbes in the new culture. d. Inject an organism immune to the disease with microbes from the new culture. Freezing Solutions The freezing temperature of pure water is 0°C. A group of students performed an experiment to see if the solutions made by adding various types and amounts of solids to water had different freezing temperatures than pure water. The students dissolved various amounts of four different solids in 1,000 grams of water and then measured the freezing temperatures of the resultant solutions (see table below). Freezing Temperatures of Solutions Solid Added Grams of Cesium Sodium Calcium Sodium Solid added Chloride Chloride Chloride Hydroxide to 1,000 g Water 50 –1.0°C –2.9°C –2.2°C –4.4°C 100 –1.9°C –5.9°C –5.1°C –9.3°C 150 –2.7°C –9.0°C –8.7°C –15.0°C 200 –3.6°C –12.6°C –13.2°C — Note: a dash (−) indicates that the students did not perform this trial. 2. Which of the following graphs best represents the freezing temperature data for the cesium chloride solution shown in the table? a. c. b d . .