The Heart Rate of the Daphnia

The Heart Rate of the Daphnia
My aim is to investigate the heart rate of the daphnia whilst the temperature of the surrounding environment is the variable to be changed. This variable will increase or decrease the heart rate. I will need to do some research and preliminary work before I choose my temperature and the way I carry out the process efficiently and effectively. Prediction I predict during the investigation the heart rate of the daphnia will increase as the surrounding temperature increases and vice-versa. But at a certain point the daphnia will stop responding if the temperature decrease or increases too much. Temperature (oC) Heart Rate (bpm) [image] I also predict that if the temperature doubles so should the heart rate of the daphnia. For example if at 10oC the heart rate is 50 then at 20oC the heart rate should be 100. Scientific Knowledge The daphnia adapts to its surroundings because it is a cold blooded animal and the daphnia doesn?t thermo regulate, meaning that there body temperature is the same as the water they are existing in.
The daphnia? internal body reactions increase as the temperature increases; this causes the heart to beat faster at higher temperatures. The heart rate increases because as the internal operations of a daphnia speed up the parts of the daphnia require oxygen. So, the heart beats quicker to provide oxygen to the cells as the metabolism increases. Also the heart beats slower when the temperature decreases because the chemical reactions have slowed down which decreases the amount of oxygen required. Heart rate, along with most metabolisms in a living organism, is controlled by the action of enzymes. The hearts pacemaker, (sino-atrial node (san), also controls the Daphnia?s heart rate. The pacemaker sends out an electrical signal across the heart that makes it contract. Hormones and transmitters control the rate set by the pacemaker. The hormones communicate with the pacemaker in the membrane. The transmitter substance and hormone fit onto a protein molecule of the cell membrane, this causes the pacemaker to react. The theory is very similar to that of enzymes, more heat produces more kinetic energy and thus the hormones move more rapidly, this increases the chance that it will collide with the protein molecule on the cell membrane. Temperature, pH, enzyme concentration, substrate concentration and inhibitors affect enzymes. For a non-enzymic controlled reaction, the general rule is the higher the temperature, the faster the reaction. The same rule is true for a reaction catalysed by an enzyme, but only up to about 35ËšC. the heart rate is at its fastest as this is when the enzymes are working at their fastest due to the large amount of kinetic energy the substrates have. Above 30ËšC, the enzyme molecules begin to vibrate so violently that the delicate bonds that maintain tertiary and quaternary structure are broken, irreversibly changing the shape of the molecule. When this happens, the active site shape has changed and therefore an enzyme-substrate complex is no longer possible. This means that the enzymes and other protein structures controlling heart rate can no longer work. We then say it is denatured. Although not all of the enzymes are denatured right after 30ËšC, enough will have been denatured to slow down to process sufficiently to stop almost all metabolisms. Variable The main variable of my investigation is temperature. I will have to make sure that I correctly measure and sustain temperature levels required to gain efficient and reliable results. Some other variables I will need to control and are stated below: - o The daphnia it self is quite delicate and could die easily. o The daphnia moves a lot on the microscope so it will be a task to control this movement. o The lab temperature could also effect the investigation. o The minimum and maximum temperatures that a daphnia can live in will have to be decided. o I might have to change the daphnia, which could affect the results because the new daphnia?s metabolism might work faster or slower than the original daphnia. Equipment o Daphnia o Microscope o Cover slip o Beaker o Water o Thermometer o Pipette o Counting instrument o Bunsen burner o Stop clock Preliminary Work We did a period when we did a trial with the daphnia. During this preliminary work I noticed the temperatures that the daphnia can survive and other factors, which will effect my actual investigation. I think that the heart rate of the daphnia will increase up until around 40ËšC at which point most of the daphnia?s enzymes will have denatured and rate of metabolism will have stopped or decreased sufficiently to have stopped the daphnia?s heart rate. The cover slip on the microscope killed the daphnia and also it was very hard to count the heartbeat because of how fast it beats. To tackle this problem I won?t use a cover slip and I will use a counting instrument to count the data. The problems encountered during the preliminary work have now been addressed and the following method has accounted for those problems accordingly. Method To determine if temperature does have an effect on the daphnia, I intend to carry out the following experiment. The experiment will involve measuring the cardiac activity of the daphnia at different temperatures, ranging from very cold (approx. 5 degrees Celsius) to quite warm (approx. 35 degrees Celsius); A selection of similar sized/age Daphnia will be taken. A variety of different temperatures of water will be set up, these temperatures will be kept constant whilst the daphnia are submersed in them. The temperatures will be set up by using ice to cool tap water down to lower temperatures and boiling water to heat it up. The temperature will be measured to within 0.1 0C on a mercury thermometer to ensure accuracy. The temperatures will range from 5 0C to approximately 35 0C and it will be done at 5 0C intervals.The daphnia will be submersed in the water and left to equilibrate, after few minutes one of the Daphnia will be removed and put onto a microscope slide, this will then be quickly put under the microscope. Under the microscope, the Daphnia will be observed for 20 seconds, this heart rate will be counted and recorded, this can the be multiplied by 3 to give a beats per minute. This way, the beats counted will be at as close temperature as possible, as they won?t have time to cool / warm significantly. The experiment will be repeated four times for each temperature. Measurements The measurements will be between 5oc ? 35oc going up in 5oc and I will do four trials for each temperature and do an average to increase reliability of the data. I am choosing these temperatures because I have learnt from my preliminary work that the temperatures at the extreme of the temperatures I?ve chosen are not suitable for the daphnia to survive. Results Temp oC Heartbeat after 20 (bpm) Heartbeat after 1 min Trial 1 5 55 165 Trial 2 5 45 135 Trial 3 5 49 147 Trial 4 5 53 159 Average Average 50.5 151.5 Trial 1 10 61 183 Trial 2 10 67 201 Trial 3 10 63 189 Trial 4 10 59 177 Average Average 62.5 187.5 Trial 1 15 69 207 Trial 2 15 78 234 Trial 3 15 72 216 Trial 4 15 75 225 Average Average 73.5 220.5 Trial 1 20 72 216 Trial 2 20 75 225 Trial 3 20 79 237 Trial 4 20 80 240 Average Average 76.5 229.5 Trial 1 25 81 243 Trial 2 25 94 282 Trial 3 25 93 279 Trial 4 25 89 267 Average Average 89.25 267.75 Trial 1 30 54 162 Trial 2 30 67 201 Trial 3 30 63 189 Trial 4 30 70 210 Average Average 63.5 190.5 Trial 1 35 45 135 Trial 2 35 50 150 Trial 3 35 53 159 Trial 4 35 61 183 Average Average 52.25 156.75 My results show that as the temperature increases, so does the heart rate of the daphnia. However after 25oc the heart rate of the daphnia decreases. [image] Trends and Patterns ======= The graph gradually increases as the temperature increases as I predicted controversially the temperature decreases at a certain point as I also mentioned in my prediction. The point at which the temperature decreases is at 25oc. All this is due to the increase in heat energy. The daphnia adapts to its surroundings because it is a cold blooded animal and the daphnia doesn?t thermo regulate, meaning that there body temperature is the same as the water they are existing in. The daphnia? internal body reactions increase as the temperature increases; this causes the heart to beat faster at higher temperatures. The heart rate increases because as the internal operations of a daphnia speed up the parts of the daphnia require oxygen. So, the heart beats quicker to provide oxygen to the cells as the metabolism increases. The temperature starts too decrease at 25oc because at 25 degrees Celsius, the enzymes start to break down, and the chemical reactions can no longer occur, so metabolism slows down causing the Daphnia? heartrate to decrease which will eventually terminate.

The Heart Rate of the Daphnia 7.5 of 10 on the basis of 2767 Review.