(Image from Purves, Life: The Science of Biology, 4th Edition, by Sinauer Associates).
First the crickets will be weighed and the weight recorded, then the equipment will be setup as below. After we will change the temperature of the water to see the effect of the temperature on the crickets’ respiration rate. We will measure the distance traveled by the ink up the scale. After a certain time we will reset the equipment and let the insects return to room temperature before setting up the next experiment. The variable for this experiment is the temperature and I think that if we raise the temperature the respiration rate (the amount of oxygen used) will increase.
I think that when I lower the temperature that the crickets are in, the amount of oxygen used up for aerobic respiration will decrease because when you lower the temperature you also lower the metabolic rate and making the cricket less active so the cricket can conserve energy to heat the vital organs that need to be kept at a certain temperature. For example when a human is in a heated environment they are comfortable (unless it is too hot) but if they are placed in a very cold area they try to make them selves as small as they can so the heat doesn’t have to travel as far and excrete the energy. This is why I think my prediction is correct.
We will take three different sets of results at the same temperature to get an average. We will take 5 different temperature readings. This is so we have a wide range of results to analyse.
Obtaining Evidence
Predicted averages are estimates.
In yellow are the actual results that our group made the rest are class results. (4.4, 6.8 in gray) were also ours.
In gray are the anomalous results.
In black is the worst result.
These experiments that we collected were made fair and accurate by using the same crickets, the same mass of crickets, let the crickets return to room temperature and reset the measuring device after each experiment.
Analysis
Mathematical analysis of graph
Variables
Slope 0.1858 ± 0.01038
Y-intercept -0.2375 ± 0.2171
X-intercept 1.278
1/slope 5.383
Best-fit values
SPAN -671.4
K 0.0002780
PLATEAU 671.1
Half Life 2494
Std. Error
SPAN 29292
K 0.01234
PLATEAU 29292
95% Confidence Intervals
SPAN -75980 to 74639
K -0.03144 to 0.03200
PLATEAU -74640 to 75982
Half Life 21.66 to infinity
Goodness of Fit
Degrees of Freedom 5
R² 0.9813
Absolute Sum of Squares 0.6892
Sy.x 0.3713
Data
Number of X values 8
Number of Y replicates 1
Total number of values 8
I found out that when I decreased the temperature that the crickets were in less oxygen was used up we get this because the ink traveled less at lower temperatures. The Scale had no meaning but the volume inside the tube would mean that less oxygen was used if the ink traveled less.
There is a positive linear trend in the results, so the relationship is when temperature is increased the distance of the ink traveled also increased.
Conclusion
To conclude when you increase the temperature the ink marker travels further up the scale and thus the crickets consume a greater amount of oxygen. This is because when you lower the temperature you also lower the metabolic rate and making the cricket less active so the cricket can conserve energy to heat the vital organs that need to be kept at a certain temperature.
My results support my prediction because I predicted that:
“I think that when I lower the temperature that the crickets are in, the amount of oxygen used up for aerobic respiration will decrease.” And my results show exactly that, but there is a catch after a certain temperature the respiration rate will decrease as the optimum temperature has been reached and adding a greater amount of temperature would cause the cricket to act differently and it’s cells to denature. So this proves that my prediction was correct.
Evaluation
The results that we used were not calculated results (apart from the one’s in yellow that were made by the group that I was in. So the results are not very good because they are not results they are numbers that were approximations of what should have happened.
The results are not very accurate because they are not proper results and the one’s that our group did were only a single set and so may not have been accurate.
The anomalous results have been marked on the table in gray and the worst result in black, these may have gone wrong because the results were not recorded accurately and the equipment may have not been reset properly; these were not proper results as they were copied from the board. The anomalous result that we made may have been because the crickets could have been distressed and cause a strange result, as the temperature was rather high. Again inaccurate reading or not following the fairness rules we set up could have caused it, the fairness rules were:
It will be a fair test and accurate because I will:
- Use the same crickets
- Same mass of crickets
- Let the crickets return to room temperature
- Reset the measuring device after each experiment
- Do each experiment 3 times to get an average.
The method was really quite difficult because the setup meant that if too much oxygen was consumed you could lose the ink marker and by some strange occurrence water got into the tube and drowned some crickets, this meant that the whole process had to be restarted. We changed the method twice because we found that the first way of doing it meant that the water got in too easily and the crickets drowned but the second method was better but still the water came in so, in the end we copied the results off the board.
If I did the experiment again I would not use different temperatures of water because of the drowning problem, I’d probably change the temperature of the air around and inside the tube. This would stop the drowning problem but may not be as easy to get the right temperatures.
I can reach a firm conclusion up to a point because after a certain temperature the cells of the cricket would start to denature, the optimum temperature. If we had gone over this point we would get a curved graph as the distance traveled by the ink would have decreased as the cells couldn’t respire properly. So my trend is correct up to that point but after that point the trend doesn’t work and a new trend is formed.
To improve the experiment I would:
- Not use different temperatures of water because of the drowning problem; I’d probably change the temperature of the air around and inside the tube. This would stop the drowning problem
- I could use a different insect to see how the rate of respiration varies between insect to insect
- I could use a different group of living thing to see how the groups vary. I would have to consider size, mass, amount of cells though.
- Warm-blooded and cold-blooded creature see how the temperature would affect their oxygen consumption
- Light intensities could cause a difference in respiration rates, as plants can’t photosynthesise with any light present.
- Change the oxygen and glucose levels
These improvements may also help me with my theories and give me a greater amount of evidence to suggest why what happens, happens. They would do this because they would test all aspects of respiration between creatures and so give me a greater amount of evidence.
I may find that light is a factor, that cold-blooded and warm-blooded creatures respire differently and so do different groups. By groups I mean:
- Mammals
- Fish
- Plants
- Insects
- Reptiles
- Amphibians
