Question

testing an antibiotic description: bacteriologists are often called to test new kinds of antibiotics on specific types of bacteria to determine whether they will be effective. a common way of doing this is to follow the procedure outlined below. 1. nutrient broth (a food supply for bacteria) is prepared, put into two test tubes, a & b, and then sterilized. 2. a measured amount of the same bacteria is added to the nutrient broth and allowed to grow and multiply for the same amount of time. 3. to test tube a the antibiotic is added, to test tube b nothing is added. 4. both test tubes are incubated at 70 degrees f. for 24 hours. what is the independent variable (iv) in this experiment? the bacteria added to the nutrient broth the nutrient broth keeping the test tubes incubated at 70 degrees f for 24 hours the antibiotic added to test tube a adding nothing to test tube b

Explanation:

The independent variable is what the experimenter manipulates. In this case, the addition of the antibiotic to test - tube A (while nothing is added to test - tube B) is the manipulated factor. The other factors like the bacteria, nutrient broth, and incubation conditions are kept the same.

Answer:

The antibiotic added to test tube A