Question

To determine the best method to disinfect toothbrushes, they were tested for bacteria before and then cleaned with several solutions. Some were cleaned with hot water, some with salt water, and others with hydrogen peroxide. The hot water decreased the amount of bacteria, but the hydrogen peroxide killed the most. The toothbrushes cleaned with salt water gained more bacteria. What is the dependent variable in this experiment?

1) Amount of bacteria on the toothbrushes
2) Type of solution used for cleaning
3) Temperature of the water used for cleaning
4) Time duration of the cleaning process

Answer 1

The dependent variable in the toothbrush disinfection experiment is the amount of bacteria on the toothbrushes, which varies depending on the cleaning solution used.

Step-by-step explanation:

The dependent variable in this experiment is the amount of bacteria on the toothbrushes. It is called 'dependent' because it is expected to change in response to the different cleaning solutions, which are the independent variables. The independent variables, in this case, are the type of solution used for cleaning toothbrushes (hot water, salt water, hydrogen peroxide), along with other controlled factors such as temperature and time duration for cleaning, all of which could affect the outcome measured by the dependent variable.

Understanding the relationship between the independent and dependent variables is critical when conducting scientific investigations. In this situation, distinguishing the effects of various disinfection methods on bacteria levels helps determine the most effective approach for sterilization. Hydrogen peroxide is recognized for its broad-spectrum efficacy against various microorganisms, including bacteria, which supports the experimental findings that it killed the most bacteria.