Question

1. a researcher conducts an experiment to test how temperature affects enzyme activity. state one way the researcher could improve the reliability of the results.

increase the sample size and

1. define the following terms:

a) control group: the group not being experimented on.
b) constant (in an experiment):

part c: data - based questions

1. a student conducted an experiment to determine the effect of caffeine on reaction time. the student measured the time it took for subjects to catch a dropped ruler before and after drinking a caffeinated beverage. the results are shown below.

subject reaction time before (ms) reaction time after (ms)
a 220 180
b 250 210
c 230 200
d 260 190
a) what is the dependent variable in this experiment?
b) calculate the average reaction time before and after caffeine.

• average before:
• average after:

c) based on the data, does caffeine appear to affect reaction time? support your answer with evidence.

Explanation:

Step1: Identify dependent variable

The variable that is measured and changes in response to the independent variable (caffeine in this case) is the reaction - time.

Step2: Calculate average before caffeine

The formula for the average of a set of numbers $x_1,x_2,x_3,x_4$ is $\bar{x}=\frac{x_1 + x_2+x_3+x_4}{4}$. For reaction - times before caffeine ($220,250,230,260$), $\bar{x}_{before}=\frac{220 + 250+230+260}{4}=\frac{960}{4}=240$ ms.

Step3: Calculate average after caffeine

For reaction - times after caffeine ($180,210,200,190$), $\bar{x}_{after}=\frac{180 + 210+200+190}{4}=\frac{780}{4}=195$ ms.

Step4: Analyze effect of caffeine

Since the average reaction time before caffeine ($240$ ms) is greater than the average reaction time after caffeine ($195$ ms), caffeine appears to affect reaction time by decreasing it.

Answer:

a) Reaction time
b) Average before: 240 ms
Average after: 195 ms
c) Yes, caffeine appears to affect reaction time. The average reaction time before drinking caffeinated beverage is 240 ms and after is 195 ms, indicating a decrease in reaction time after consuming caffeine.