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The aim of this experiment is to investigate how temperature affects the rate of respiration in maggots. This will be measured by taking the rate at which 10 maggots respire at varying temperatures using the displacement of a coloured liquid in a capillary tube. This will be completely over the span of 2 minutes, as I predict the increase in temperature will cause an increase in rate of respiration.
All living cells carry out respiration, which the process in which cells take glucose and oxygen are combined to produce carbon dioxide and ATP.
As the temperature increases, particles move faster and faster, hitting each other more often than at lower temperatures. This relates back to kinetic energy. As respiration goes down to cellular level, this is dictated by enzymes. These are responsible for the reactions allowing cells to make energy. The more often the enzymes and substrates hit each other, the more often reactions take place. This acceleration in respiration will result in higher oxygen use at higher temperatures.
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I predict that, as the temperature increases, the rate at which the larvae will increase. This is because the enzymes and substrates move around at higher speeds at higher temperatures. Because of this, reactions the organism are carried out at a much faster rate. The increased particle movement speeds up the catabolic reactions happening in respiration.
Equipment List
Dependant
Variable
Independant
Variable
Controlled
Variables
Uncontrolled
Variables
This figure represents a prediction of what will happen in my experiment, although my temperatures will not increase to the point where the organism dies.
Fig.1
| Temperature (ºC) | ±0.5ºC | Initial Distance (cm) | ±0.05cm | Final Distance (cm) | ±0.05cm | Distance Travelled (cm) | ±0.05cm |
|---|---|---|---|---|---|---|---|
| 12.4 | 0.5 | 1 | 0.5 | 1 | 0.5 | 0 | 0 |
| 14 | 0.7 | 1.6 | 0.9 | 1.6 | 0.9 | 0 | 0 |
| 15.8 | 1.4 | 2.7 | 1.3 | 2.7 | 1.3 | 0 | 0 |
| 16.5 | 1.6 | 3.1 | 1.5 | 3.1 | 1.5 | 0 | 0 |
| 16.7 | 0.6 | 2 | 1.4 | 2 | 1.4 | 0 | 0 |
| 17.5 | 0.5 | 1.7 | 1.2 | 1.7 | 1.2 | 0 | 0 |
| 18 | 0.8 | 3.1 | 2.3 | 3.1 | 2.3 | 0 | 0 |
| 18.2 | 2.2 | 4 | 6.2 | 4 | 6.2 | 0 | 0 |
| 18.4 | 2.1 | 5.2 | 3.1 | 5.2 | 3.1 | 0 | 0 |
| 19.6 | 0.9 | 4.6 | 3.7 | 4.6 | 3.7 | 0 | 0 |
| 19.8 | 0.6 | 4.7 | 4.1 | 4.7 | 4.1 | 0 | 0 |
| 20.7 | 0.9 | 4.6 | 3.7 | 4.6 | 3.7 | 0 | 0 |
| 23.9 | 1.7 | 5.9 | 4.2 | 5.9 | 4.2 | 0 | 0 |
| 21.3 | 0.9 | 5.3 | 4.4 | 5.3 | 4.4 | 0 | 0 |
| 24.4 | 1.4 | 6.2 | 4.8 | 6.2 | 4.8 | 0 | 0 |
| 24.5 | 0.4 | 5.7 | 5.3 | 5.7 | 5.3 | 0 | 0 |
| 26.3 | 2.4 | 7.8 | 5.4 | 7.8 | 5.4 | 0 | 0 |
| 26.7 | 0.2 | 5.8 | 5.6 | 5.8 | 5.6 | 0 | 0 |
| 26.9 | 0.9 | 5.5 | 4.6 | 5.5 | 4.6 | 0 | 0 |
| 28.4 | 0.2 | 5.1 | 4.9 | 5.1 | 4.9 | 0 | 0 |
| 28.6 | 0.1 | 5 | 4.9 | 5 | 4.9 | 0 | 0 |
| 31.1 | 0.4 | 4.7 | 4.3 | 4.7 | 4.3 | 0 | 0 |
When measuring the distance travelled by the liquid drop, an uncertainty error of ±0.05cm has to be taken into consideration.
As the air was given time to increase or decrease in temperature respectively, an uncertainty of ±0.5ºC is added to the temperature.
The distance travelled in table 1 was calculated by subtracting the distance between the top of the liquid in the capillary tube after 2 min by the distance of the liquid at 0 min.
Distance travelled = measurement after - initial measurement
Controlled variables:
Volume of potassium hydroxide
This is kept constant at each test using 10ml using a measuring cylinder. This is because a difference in volume would cause a change in the quantity of carbon dioxide absorbed, and therefor change the speed at which the liquid moves up the tube.
Concentration of potassium hydroxide
Similar to the volume, the concentration of the potassium hydroxide would alter the rate at which the maggots respire. A higher concentration results in a higher rate of reactivity, meaning it was imperative that each test tube be able to absorb carbon dioxide at the same rate.
Time of exposure
This will be kept constant as to allow each set of maggots to take the same amount of time to respire. By using a stopwatch I was able to control the time the maggots were placed in the test tube, and their progression.
Ethics
When carrying out this experiment, it was important to consider ethical issues involved with this. This investigation was completely based on “observing and measuring aspects of natural animal behaviour”. Despite the low concentration of potassium hydroxide, I made sure to add the solution before adding the wire mesh. This was to make sure none of the corrosive substance got caught in the mesh and came in contact with the larvae. The maggots were handled with care in order to ensure full health both during and after the experiment. I made sure to not got further than 40ºC so as not to damage or harm the larvae. In addition, I made sure to remove the maggots from the test tube directly after the measurement. After the experiment was completed, all maggots were released into a local park and left inside pile of wood chips to ensure a lack of nutrition and therefor allowed to grow freely into flies.
Biological Uncertainties
Although I used maggots grown together as a batch, with all approximately the same size and weight, uncontrollable biological factors made it more challenging to collect precise data. Despite the fact that I chose maggots I had observed to be similar sizes, I could not accurately determine each individual maggots initial mass and it therefor varied. I chose maggots that were randomised out of a certain selection. This increased the probability of each test having a similar average maggot mass. Using this, I could determine anomalous results and remove them from the processing of my data. These could have been caused by biological uncertainties, such as damaged, weak , oxygen deprived maggots. The experiment was also conducted in two sessions, two weeks apart. The maggots were acquired from a fishing store the morning of each experiment, although I cannot accurately determine their respective stages in growth. This resulted in an uncertainty due to the fact could also not find a way to calculate the age to respiration ratio. These occasional anomalous results were drastically different from the set of data collected in Table 1, and would have drastically changed the result of the experiment.
Mass of maggots:
Mass of maggots was all determined using observation. In order to prevent this from happening, as well as to speed up the time of the experiment, I put 10 maggots. This reduced the risk of having drastically different average maggot sizes for each test.
Time of maggots in test tube:
I used a stopwatch accurate to the nearest 0.01min, although since the data was dependant on the time it took me to react and measure, I have attributed an addition uncertainty of ±0.05min. This resulted in the total uncertainty of ±0.1min.
Distance travelled by the coloured liquid:
Due to the fact I was pushing the bung into the test tube, making it airtight, excess air was being pushed out of the capillary tube. In order to make it work I pushed the bung further than necessary into the test tube, place the bottom of the capillary tube into the liquid, and loosened the bung to create suction. To receive the distance travelled by the coloured liquid, I put a ruler to the capillary tube and took the distance from the bottom at 0 minutes, and at 2. I took the measurement from the top of the convex meniscus. As removing the bung would have released the pressure keeping the liquid in the tube, I had to take the measurements with the maggot still inside the tests tube. As a result of this constantly moving meniscus, along with the uncertainty of a ruler measuring to the nearest 0.01cm, I considered an uncertainty of ±0.05cm.
Temperature the maggots were exposed to:
I used water and ice baths to affect the temperature the maggots were in. Due to the fact that there was a necessity for a bung to be placed above top of the test tube, it was impossible to remove ventilation of the tube when inserting the maggots. In addition, there was no way to accurately read the air temperature inside the test tube. In order to increase the accuracy of the results, I increased the time the maggots were to be put in the test tube from 1 minute to 2. This allowed the test tube to heat or cool to the appropriate temperature. As the air was given time to increase or decrease in temperature respectively, and uncertainty of ±0.5ºC is added to the temperature.
Overall the instrument uncertainties were of little significance to the results of the tests. While an uncertainty of ±0.1min is quite substantial over the span of 2 min, collecting a large number of data showed an undeniable trend line that would not have been significantly affected. In addition, the size of an individual maggot would not be enough to cause an observable variation in respiration carried out. When regarding the temperature the maggots were exposed to, it is clear that a more controlled room temperature would have been more appropriate, although this would have required a completely thermally controlled external environment. While all the figures collected cannot be considered as extremely accurate, Fig 2 demonstrates a clear trend line regardless.
When I first attempted to fill the capillary tube, I noticed that large drops would remain suspended underneath. This resulted in much more suction required from within the test tube. This made it so some tests went without any progression of liquid, as the 2 minutes went by and the maggots were still only sucking more liquid into the tube. In addition, I was unable to determine the volume of liquid suspended underneath, making each test unfair. I solved this issue by decreasing the volume I allowed the capillary tube to contain and removing excess liquid. In regard for possible improvements, I would add the liquid into the capillary tubes before hand and use a bung with a detachable connector tube to completely remove the issue of air flow affecting the liquids placement. When I first used the capillary tube, I found it difficult to accurately measure the displacement of the liquid.
It was very time sensitive and the meniscus was slowly increasing. I found that taking a marker and creating my own scale on the side of the tube greatly helped with the speed I could measure and therefor the accuracy. To improve this I would use to a capillary tube with a pre-marked scale to the nearest 0.01cm. As I used a test tube with a large volume, I found it took a while for the maggots to first exhaust the supply of air inside. This resulted in a large delay between their addition to the tube and displacement of the liquid. While this can be considered a weakness, I found that it was helpful because it also allowed time for temperature adjustment. To improve this investigation I should have reduced the size of the test tube.
Effect of Temperature on Respiration Rate in Brachycera Larvae. (2024, Feb 22). Retrieved from https://studymoose.com/document/effect-of-temperature-on-respiration-rate-in-brachycera-larvae
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