Question

Got 4 correct in a row, Stage 0, described Every day at work, Clara poured a large cup of tea that she drank throughout the morning. She wondered how much bacteria might be growing in her cup of tea as the morning went on. To find out, Clara filled three identical cups with tea and placed them on her desk for three hours. After the first hour, she placed a drop of the tea from each cup on a separate microscope slide and counted the number of bacteria in the drop. Clara repeated this with each cup of tea after the second hour, and again after the third hour. Using a microscope to count bacteria on a slide. Which of the following was an independent variable in this experiment?

a. The number of bacteria in a drop of tea
b. The amount of time that the tea sat on the desk

Answer 1

In Clara's experiment regarding bacterial growth in tea over time, the independent variable is the 'amount of time that the tea sat on the desk', while the dependent variable is the 'number of bacteria in a drop of tea' which is measured.

Step-by-step explanation:

Independent Variable in Clara's Tea Experiment

In Clara's experiment to observe the growth of bacteria in a cup of tea over time, the independent variable is the factor that Clara manipulates to study its effect on the dependent variable. In this case, the independent variable is b. The amount of time that the tea sat on the desk. Clara changes the amount of time the tea is exposed before observing the resultant bacterial count, which is the dependent variable. The dependent variable, which is the outcome of interest, is the a. Number of bacteria in a drop of tea, which Clara measures after different time intervals.

The independent variable is crucial as it defines the different conditions in the experiment, allowing the experimenter to observe the impact on the outcome. By choosing time as the independent variable, Clara can study if bacteria populations increase, decrease, or remain the same over time. The experiment's goal is to establish a cause-and-effect relationship between the independent variable (time tea sits out) and the dependent variable (bacterial count).

Relating to other scientific investigations, the independent variable is the condition or component that is altered to test its effects on a dependent variable in various contexts such as bacterial growth on different surfaces, fungal activity on bacterial colonies, or the impact of doubling times on bacterial population sizes.