Ransley Fernandes admin no. 40202
Unit 6 leaning aim C and D
Project Implementation and Review
Summary
In this investigation, I was able to investigate the effect of different caffeine concentrations
on the heart rate of daphnia. During this investigation, I was able to prove my hypothesis,
which states- when the caffeine concentration is increased, the heart rate of daphnia will
increase. In this report, I was able to evaluate the experiment, interpret the data using
statistical test like standard deviation, and was able to conclude with reliable results
gathered with this investigation. With secondary data and calculating standard deviation, I
was able to see the reliability of the results that I collected. With this reliability and accuracy
in results, it indicated that the method used in this investigation was effective and suitable
to perform. With this report, I can conclude by proving my hypothesis and collecting valid
and reliable data.
Hypothesis
My hypothesis states that, when I increase the concentration of caffeine, the heart rate of
daphnia will increase.
Method used during preliminary investigation.
Place few strands on cotton on the cavity slide to stop the movement of daphnia.
Use a pipette and remove 1 daphnia from the beaker and place it on the cavity slide.
Use a pipette to add four drops of caffeine concentration solution on the cavity
slide. You can begin with the lowest caffeine concentration.
Use a microscope to observe the heart rate of daphnia and count the heart beats for
60 seconds using a counter.
Copy down the number of heart beats got for 60 seconds in the table and repeat the
same steps with same concentration two more times to analyse the data
Repeat the experiment with different concentrations of caffeine solution to
investigate and prove the hypothesis, you can use the following caffeine
concentrations: 0.05M, 0.025M, 0.1M, 0.2M.
After getting all the results, plot a graph and calculate the mean.
Preliminary results
Caffeine concentration Heart rate of daphnia (beats per minute)
(M)
Trial 1 Trial 2 Trial 3
0.025 76 72 78
0.05 96 94 98
0.1 124 124 132
0.2 200 192 196
, Ransley Fernandes admin no. 40202
Unit 6 leaning aim C and D
Final method
Firstly, place few strands on cotton on the cavity slide in order to restrict the
movement of daphnia.
Using a dropping pipette, remove 1 daphnia from the beaker (containing daphnia in
water) and place it on the cavity slide.
Afterwards, use a tissue to remove the water around the daphnia, remember not to
dab on daphnia because it can die.
Using a dropping pipette, add 4 drops of caffeine concentration solution on the
cavity slide (I will start with 0.05)
For daphnia to adjust in the caffeine concentration keep the daphnia for 5 minutes.
Now using the microscope, observe the heart rate of daphnia and count the heart
beats for 30 seconds using a counter and then multiply by 2. (you can use a partner
if using a stopwatch or you can use a timer if you are performing the experiment
individually)
Copy down the number of heart beats you have got for 30 seconds and times by 2
to get heart rate in the table and repeat the same steps with same concentration 4
more times to calculate the mean, standard deviation and to plot the graph
Repeat the experiment with different concentrations of caffeine solution to
investigate and prove the hypothesis, you can use the following caffeine
concentrations: 0.025M, 0.05M, 0.1M, 0.2M.
Calculate the mean and plot a graph.
Caffeine Heart rate of daphnia (beats per minutes)
concentration
(M)
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Mean
0.025 64 60 68 66 66 64.8
0.05 88 86 84 82 90 86.0
0.1 116 108 114 106 110 110.8
0.2 212 208 210 218 206 210.8
The preliminary experiment provided with a few information and thoughts on improving my
experiment, which were causing errors and giving insufficient results. During the preliminary
experiment I was able to know some steps that I can possibly miss during the actual
investigative experiment. With this preliminary investigation, I had the ability to know the
errors that can likely occur during the experiment. In addition, missing some steps can
actually result in giving anomalous results as well as results which can lead to not supporting
my hypothesis. In the preliminary investigation, I did not use the tissue to eliminate the
water on the cavity slide before adding the concentration of caffeine, this could have caused
a difference in results as water can merge with caffeine and therefore can perhaps affect the
results.
The preliminary investigation however helped me to know that mistakes that can be caused
during the experiment. It is extremely important to adjust the microscope properly in terms
of stage using focus wheel, objective lenses required to see the daphnia effectively. This
