Affect Of Caffeine On Heart Rate Of Daphnia 4u493e

Affect of caffeine on heart rate of Daphnia Investigating the affect of caffeine on the heart rate of daphnia

This experiment will be carried out to investigate the affect on the heart rate of daphnia under different concentrations of caffeine.

Caffeine’s are produced as insecticides. Cocoa, coffee and tea in Asia have all been used for hundreds of years to produce ‘pick me up’ drinks containing caffeine. These days, caffeine is also used as a flavour enhancer in a wide range of cola and other soft drinks. In addition, it has medicinal uses in aspirin preparations and is found in weight-loss drugs and as a stimulant in students’ exam-time favourites like Red Bull. In humans, caffeine acts as a stimulant drug, causing increased amounts of stimulatory neurotransmitters to be released. Neurotransmitters are the nervous system\'s way of conveying messages between neurons, and also to muscle tissue. Some neurotransmitters that caffeine is known to increase the activity of are norepinephrine, dopamine, and serotonin. The increase in norepinphrine is what causes the heart rate to increase, Norepinephrine, is a powerfully stimulating neurotransmitter; it is associated with the \'fight or flight\' response, which includes an increased heart rate. At high levels of consumption caffeine has been linked to restlessness, insomnia and anxiety, causing raised stress and blood pressure. This can lead to heart and circulation problems. Daphnia’s are invertebrate; the division of the daphnia’s body into segments is nearly invisible. The most prominent features are the compound eyes, the antennae, and a pair of abdominal setae. In many species, the carapace, which is the exterior is translucent, as a result they make excellent subjects for the microscope as one can observe the beating heart. HypothesisCaffeine increases the amount of neurotransmitters to be released which in effect increases the heart rate. Therefore as the concentration of caffeine increases, the BPM will also increase.

Prediction: I predict that caffeine will increase the heart rate of the daphnia because caffeine is a stimulant which releases neurotransmitters. The heart rate of daphnia will increase when it is in caffeine solution compared to when it is in distilled water. Also, as the concentration of caffeine increases, the heart rate of daphnia will also increase.

Plan/procedure1) Place a few strands of cotton wool on a cavity slide; this will help restrict the movement of the water flea. Using a pipette, transfer one large water flea to a cavity slide. Remove the water from around the water flea using filter paper, then add one or two drops of distilled water or pond water. Use as much water as you can and do not use a cover slip. Together these precautions will help maintain sufficient oxygen supply to the flea. View the water flea under low power. Focus on its heart which can be seen through its translucent body.

2) Use a stopwatch to record the number of heartbeats per minute. This is made easier by working in a pair, with one person counting beats while the other person tells them the time period. Tap a pencil on a piece of paper and count up the pencil marks at the end of the time period. Record the heart rate at intervals of 2 minutes over a 10 minute period. It is a good idea to do a ‘blind’ study to avoid bias in the results. The person counting the heartbeats should be unaware as to whether the Daphnia is in water or water with added caffeine. 3) Repeat the procedure using other water fleas from the culture solution and fresh, clean slides. Replace the water with caffeine solution. Repeat the procedure using several different concentrations of caffeine. 4) Record your results in a suitable format and present them in an appropriate graph. 5) Compare the treatments and try to explain the effect of each treatment on the heart rate. 6) Comment on the validity of your study. For example, would it have been better or worse to use the same Daphnia throughout the study? 7) If time permits, look at the effect of other chemicals, e.g. ethanol, on the heart rate.

Equipment: o o o o o o o o o o o

Culture of daphnia Cavity slides Dropping pipettes Distilled water Caffeine tablets Cotton wool Beakers Measuring cylinders Stop clock Filter paper Microscope

The methodThe variables involved in this experiment areThe concentration of caffeine= independent variable. The BPM of daphnia= dependent variable. When experimenting with these variables, there are factors which can affect these variables, which should be taken into . The concentration of the caffeine will have to be checked whether it is safe for the daphnia to take in. care should also be taken, so that the concentrations are not altered which could affect the validity of the results. When measuring the BPM, it should be made sure the heart is correctly identified and that it is also measured properly. The variables

which we will be keeping the same are the volume of concentration, this is because by having different volumes of caffeine, the concentration level will be altered and this will not give us valid results. The size of the flie will have to be the same, as this can also be a factor affecting the heart rate, if we used different sized daphnia, we would not be directly measuring the affect of ‘caffeine’ on BPM as we would be taking others factors into . Plus, it would be sensible to have different persons for each trial measuring the BPM; this will give us an idea if the results are valid and reasonable. Furthermore the temperature conditions, the same equipment (microscope giving off heat), the same volume of distilled water and the same amount of time for measuring the heart beat of the daphnia. In order to keep the results reliable and valid, we will have to take the above factors into to help minimise the impact of the control variables. Furthermore the experiment will be repeated three times to get an average, giving us more valid and reliable results. The apparatus will also be analysed and altered so the most accurate results are given and that no systematic or random errors will be made using the equipment. I will also be doing a control experiment, to highlight that that the caffeine is having a direct affect on the daphnia, and to show that it cannot be any other factors affecting the BPM.

Ethical issues arising from the experimentEthical issues may arise from this experiment as we are testing living things for the use of science. This may be controversial. Using fleas, may be considered cruel and also against animal rights. Furthermore, there is a small risk of killing the fleas. If this experiment is created on a mass scale, then there is a danger disrupting the food chain. Therefore we will analyse aspects of the experiment, which may endanger the daphnia and produce other methods which will be safer and less harmful for the daphnia. To ensure the daphnia is not killedo o o o o o o

Distilled water placed on the cavity for the flea, so it does not suffocate and instead of tap water because the chlorine may toxicate. Strands of cotton wool will be added to restrict movement of the daphnia out of the slide. Large sized pipettes will be used so the flies aren’t squashed. Distilled water will be added on the slip, so the flea is not poisoned. A cover slip will not be used, which can squash the daphnia. Excess water on the sides of the cavity slip will be absorbed using filter, giving a sufficient supply of oxygen. Generally, at each stage of the experiment, the daphnia will be treated with extreme care to ensure the daphnia is not harmed; by doing so, this will prevent us from using too many daphnia, which is wasteful and unethical. Perhaps the most dangerous factor would be the high concentration of caffeine which could kill the daphnia; therefore the solutions will be diluted to a safe level. We will keep the microscope within the edge of the table so it does not fall and cause injury. Furthermore, using daphnia safely for this experiment can be justifiable, as the research can benefit the health of humans at large. Throughout the experiment we will be responsible for treating the daphnia with care.

The table below will look at the suitability, possible risks of the apparatus and changes made to improve accuracy and safety of the daphnia.

Risk assessmentapparatus Daphnia’s

Why it will be used/suitability Used to test the affect of caffeine on heart rate, it is suitable because it is translucent so you do not have to operate. To place the daphnia on under the microscope. Suitable to use when looking at things under a microscope. Used to select the daphnia and add distilled water

Possible risks There can be dangers to the daphnia’s i.e. poisoning, suffocation, killing. Smashing or cutting skin.

Precautions/changes Changes will be made in the methods and apparatus, to ensure safety. Handling with care

Squashing the daphnia.

Distilled water

To give to daphnia to prevent suffocation.

Spillage, causing slip.

Caffeine tablets

Used to measure the affect on BPM.

Poison daphnia.

Cotton wool Beakers

To restrict movement of daphnia. To keep the daphnia in.

Kill daphnia.

Measuring cylinders

To measure the caffeine.

Spillage.

Thicker width will be used by cutting the end of the pipette so it will be less dangerous for the daphnia. This will also make it easier to suck the daphnia when selecting it from the pond. Added in small, measured amounts. Distilled water will be used instead of tap water, because the chlorine can be toxic. Diluted to safe levels, the concentration up 50% will be used Applied with care in small amounts. Mixed with distilled water, to prevent suffocation. Handle with care + to increase accuracy, measuring cylinders with small intervals will be used. Handled with care, placed on clear, safe workplace. high magnification will be used to measure the BPM correctly thus increasing accuracy and validity, but the light will not shun for too long as it can harm the daphnia.

Cavity slides

pipettes

microscope To measure the BPM of daphnia

Kill daphnia

Fall, injure. Harm daphnia because of powerful light.

The results will be presented in a table and graph. The line graph will be suitable in order to illustrate the affect of different levels of caffeine on BPM and to analyse any possible correlations. The experiment will be suitable to test the hypothesis, because we can see if the heart rate increases by increasing the concentration of caffeine. The heart beat can be seen without operating. We know that by adding caffeine more neurotransmitters are released, therefore we can use this knowledge to see if it works in the experiment.

Results

Affect of different caffeine concentrations on BPM of daphniaAmount of Caffeine (%)

0.1 0.2 0.3 0.4 0.5 0.6 1

Volume of Distilled water (cm3) 5 10

Number of beats per minute Trial 1 Trial 2 Trial 3 49 94 78

57 84 77

65 92 79

110 97 139

118 103 127

104 101 142

Number of beats per minute Trial 1 Trial 2 Trial 3 56 55 55 55 56 55

Average

57 90 78 110 111 100 136

Average 55.3 55.3