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The effect of temperature on the Heart rate and
Respiration of Daphnia



Introduction
A lot of research has been conducted on the influence of temperature on physiological
processes in animal models, results typically show an increase in the process rate with
increasing temperature. The aim of this study is to…

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range expected from this experiment. The activation energy for heart rate and OCR will also
be produced by plotting an Arrhenius Plot of Ln(k) (rate process) against 1/T. The slope of
the line of best fit on this graph is equal to -Ea/R.


Hypothesis:
1) There will be a significant…

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to the jelly to ensure they remained static before the medium was added to the chamber,
which was illuminated with a bench lamp. A thermometer was then placed in the chamber
to monitor the temperature and the Daphnia were positioned so that the heart could be
viewed and the rate…

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C. During this time a different individual recorded
to obtain 5 results for heart rate at ~100
the concentration of oxygen displayed on the voltmeter every 60 seconds for 5 minutes.
C, ~200
This was then repeated to deduce heart rate and oxygen concentrations at ~150 C,
~250 C and…

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1/T was then calculated by converting the temperature in Degrees Celsius to Kelvin
C = 283K), then diving 1 by the temperature (eg.
by addition of 273. (eg. 100
1/283=353.4x10-5 ).

Ln(heart rate) was then calculated and plotted against 1/Temperature to produce an
Arrhenius Plot (see figure 3).

As the…

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Example: OCR at 100 C= 572, OCR at 200
C= 1150)
Q10 = 1150 / 572 = 2.01

As there was a variation between Q10 values at different temperatures, the mean
Q10 value was also calculated from these results (see table 2).


Activation Energy Calculations:
Ln(OCR) was then calculated and…

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Pearsons test performed on Prism produced a correlation coefficient value of r=0.987, and
p=0.0007).



The results show an increase in mean OCR with increasing temperature. Statistical analysis
tests showed a significant positive association between temperature and mean OCR of
Daphnia. The SEM for mean OCR also increases with temperature increase.…

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Mean: 1.78
(Table 1 shows the temperatures from which the mean Q10 Value for Heart Rate were
deduced. SD±0.036 and SEM±0.021).


The Q10 value for Oxygen Consumption Rate was found to increase from 2.01 to 3.25
between the temperature intervals of 10-200 C and 15-250 C. The mean Q10 value…

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(Figure 3 gives a visual representation of the association between the mean Ln heart rates
and 1/T. The Pearsons test performed on Prism produced a correlation coefficient value of
r=-0.999, and p=<0.0001. The gradient of the graph was found to be -5012 ± 127.9).


A significant linear associations was found…

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Discussion
For the one-tailed Pearsons test it was assumed that the data are parametric for both heart
rate and OCR. The results for mean heart rate against temperature and OCR against
temperature show a strong significantly positive relationship, supported by the Pearsons
statistical test (heart rate: r=0.987, p=0.0007) (for OCR:…

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