Science Fair Projects About Caffeine on Heart Rate Daphnia

Water Fleas Experiment

Water fleas can be a great test subject for medical experiments. They are easy to find and easy to examine. However, they are living creatures so make sure that you are humane in your experimentation methodologies.

PURPOSE

The purpose of this experiment was to determine how caffeine affected the heart rate of daphnia Pullex (Water Flea).

I became interested in this idea when I read two different sources that gave me conflicting information about caffeine affecting the heart rate so I wanted to test it.

The information gained from this experiment may be used by the medical world to show what caffeine does to the heart rate and to human health. This information may also be used by patients with serious heart problems, and also by heavy coffee drinkers.

 

View your specimens on TV with a Video Scope Eyepiece attachment to your student microscope!

HYPOTHESIS

My hypothesis was that as the caffeine increases, so would the daphnia heart beat.

I base my hypothesis on information collected from the Internet site "Healthcentral.com"that says "that caffeine taken in the faster the heart rate.

EXPERIMENT DESIGN

The constants in this study were:

-The same species of daphnia
-The same water temperature
-The same microscope
-The same kind of habitat
-The same amount of food

The manipulated variable was the amount of caffeine used in the water.

The responding variable was the rate of the heart beat. To determine the heart rate the beats were counted in pulses.

To measure the responding variable a microscope and video camera were used to record how many beats of the daphnia heart rate occurred in 10 seconds. These pulses were recorded with a video microscope and slowed down to accurately count the beats.

MATERIALS

PROCEDURES

1. Gather materials
2. Set up video camera to microscope
3. Mix 200mg of caffeine with 500mL of distilled water
4. Label plastic cup 200mg/L ? 500mL
5. Mix 80mg of caffeine with 500mL of distilled water
6. Label plastic cup 80mg/L ? 500mL
7. Mix 18mg of caffeine with 500mL of distilled water
8. Label plastic cup 18mg/L ? 500mL
9. On the first petri dish around the outside edge write the numbers 1-5 about 2inches apart.
10. On the second petri dish write the numbers 6-10
11. On the third petri dish write the numbers 11-15
12. On the fourth petri dish write the numbers 16-20
13. On the fifth petri dish write the numbers 21-25
14. On the sixth petri dish write the numbers 26-30
15. On the first petri dish in front of each number place one daphnia
16. Place petri dish under the microscope
17. Record daphnia on video camera for 12 seconds
18. After 12 seconds turn off microscope light and record for 3 seconds
19. After 3 seconds turn on light
20. Focus in on daphnia #2
21. Repeat steps 17-19 with daphnia 2-5
22. After recording daphnia 1-5 put one drop of 18mg caffeine on each daphnia
23. Wait 10 minutes
24. After 10 minutes repeat steps 17-19 with daphnia 1-5
25. Repeat steps 17-19 with daphnia 6-10
26. Repeat steps 22-24 with 80mg/L ? 500mL caffeine mix
27. Repeat steps 17-19 with daphnia 6-10
28. Repeat steps 17-19 with daphnia 11-15
29. Repeat steps 22-24 with daphnia 11-15 with 200mg/L ? 500mL
30. Wait 10 minutes
31. Repeat steps 17-19 with daphnia 11-15
32. Repeat all steps with daphnia 16-30

RESULTS

The original purpose of this experiment was to determine how caffeine affected the heart rate of daphnia (Water Flea). The results of the experiment were that in the first trial the more caffeine put into the water the higher the heart rate. In the first trial the lowest amount of heartbeats per minute was 360 beats per minute. The highest amount of heartbeats per minute was 486 times per minute. In the second trial the lowest amount of heartbeats in a minute was 366 times per minute. The highest amount of heartbeats in a minute was 444 times per minute.

CONCLUSION

My hypothesis was that as the caffeine increases, so would the daphnia heart beat.

The results indicate that this hypothesis should be accepted because the more caffeine placed into the water the higher the heart rate.
Because of the results of this experiment, I wonder if temperature make a difference in the caffeine- water mix placed on the daphnia to raise the heart rate. I also wonder if alcohol, a depressant, would lower their heart rate.

If I were to conduct this project again I would have a more accurate way to measure the heartbeats, a larger sample size, and more trials. I would also have a wider range of caffeine levels to test.