Physiology Lab Data - Anatomy and Physiology

1. Resting heart rate rises from 60 to 90 beats per minute during exercise. What is the percent increase?

   50 percent. The change is 30 beats per minute, and $\frac{30}{60} = 0.5$.

2. Students measure heart rate at five treadmill speeds. Which variable is the dependent variable?

   Heart rate. It is the measured response that depends on the speed the students set.

3. Plasma glucose rises from 90 to 150 mg/dL over 30 minutes. What is the average rate of change?

   2 mg/dL per minute. The rise of 60 mg/dL divided by 30 minutes equals 2.

4. Why does a strong correlation between two physiological variables not prove that one causes the other?

   A third variable or chance could produce the association. Causation requires a controlled experiment that manipulates one variable.

5. A data set has a standard deviation of 10 and a sample size of 25. What is the standard error of the mean?

   2. SEM is $\frac{10}{\sqrt{25}} = \frac{10}{5} = 2$.

6. Which type of graph best shows a continuous variable, such as blood pressure, changing over time?

   A line graph, with time on the x-axis and the measured variable on the y-axis to show trends.

7. What happens to the size of SEM error bars as sample size increases, if variability stays the same?

   They become smaller, because SEM is divided by the square root of n, so the mean is estimated more precisely.

8. What is the purpose of a control group in a physiology experiment?

   To provide a baseline that receives no treatment, so any difference in the experimental group can be attributed to the variable tested.

9. What can be concluded if the SEM error bars of two group means overlap substantially?

   The difference is unlikely to be statistically significant at p < 0.05. A formal statistical test is still needed to decide.

10. How is the standard error of the mean (SEM) calculated from the standard deviation?

    SEM equals SD divided by the square root of the sample size, $\frac{SD}{\sqrt{n}}$. It describes how precisely the mean is estimated.

11. On a standard graph of an experiment, which axis shows the independent variable?

    The x-axis. The independent variable is the one the experimenter sets or changes; the measured response goes on the y-axis.

12. What do error bars that show standard deviation (SD) represent?

    The spread of individual measurements around the mean. Wider bars mean more variability among subjects or trials.

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