Question

A group of biology students tests the growth of bacteria under different conditions. The students apply the same amount of bacteria to identical Petri dishes enriched with nutrients, then place each plate at a different temperature. The bacteria are allowed to grow for three days, after which the number of bacterial colonies on each plate is counted. What is the dependent variable in this experiment? A. the temperature at which the colonies grew B. the number of bacterial colonies after three days C. the nutrient type present in the Petri dishes D. the time of day that the experiment is performed

Answer 1

Answer: Option B

Explanation: Whenever any experiment is performed there are two types of variable in the experiment. One is the dependent variable and other one is the independent variable.

The independent variable can be defined as the variable which is not constant and can be changed in the experiment by the experimenter. Example: The temperature, pH, amount of nutrients.

The dependent variable is actually the result of the experiment which is to be obtained. In the given question the number of bacterial colonies grown after 3 days is the dependent variable.

Answer 2

Answer: B. The number of bacterial colonies that grew

Explanation: The number of bacterial colonies that grew depend on the temperature, nutrients, and time of day.