Question

Exercise 7 Experimental Variables EXERCISE 7: EXPERIMENTAL VARIABLES Determine the variables tested in the each of the following experiments. If applicable, determine and identify any positive or negative controls 1. A study is being done to test the effects of habitat space on the size of fish populations. Different sized aquariums are set up with six goldfish in each one. Over a period of six months, the fish are fed the same type and amount of food. The aquariums are equally maintained and cleaned throughout the experiment. The temperature of the water is kept constant. At the end of the experiment the number of surviving fish are surveyed. a Independent Variable: size of aquarium Chabitat space) 6. Dependent Variable: size of population c Controls: amount of food, cleanliness, temperature of aquarium 2. To determine if the type of agar affects bacterial growth, a scientist cultures E. coli on four different types of agar. Five petri dishes are set up to collect results: . One with nutrient agar and E.coli One with mannitol-salt agar and E. coli One with MacConkey agar and E.coli One with LB agar and E.coli >. One with nutrient agar but NO E. coli a. Independent variable: Types of agar b. bependent variable: Bacterial growth c. Controls: The nutrient ager without E.coli . . 3. All of the petri dishes received the same volume of agar, and were the same shape and size. During the experiment, the temperature at which the petri dishes were stored, and at the air quality remained the same. After one week the amount of bacterial growth was measured. a. Independent Variable: b. Dependent Variable: c. Controls:

Answer 1