• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Daphnia Investigation

Extracts from this document...

Introduction

Investigation: Does Caffeine Affect Heart Rate? Aim To investigate the effect of caffeine on the heart rate of Daphnia organisms (water fleas). Background Information Caffeine is a stimulant that targets the central nervous system and metabolic processes of organisms. Some plants produce caffeine naturally as an insecticide. Caffeine is used worldwide, both as a recreational and medical drug. Commercially, caffeine is used as a flavour enhancer and mild stimulant in a wide range of soft drinks, including Coke, Red Bull and Pro-plus. Daphnia are members of the invertabrate family. They are small crustaceans, between 0.2 and 5 mm in length and are commonly known as "water fleas". In many species, the Daphnia'a body is transluscant and can be observed clearly under a mircoscope. The heart of a Daphnia is located at the top of the back, just behind the head. Their average heart rate is approximately 180bpm under normal conditions. Ethical Issues There are many arguments against the use of animals in scientific experiments. The most controversial issues tend to be related to the unatural conditions in which they are kept and the somewhat risky tests that they are exposed to. ...read more.

Middle

Setting up a Microscope (Adapted from SNAB website, Practical Support article 8) * Check that the lens, eyepiece and stage are clean. If the lens needs cleaning, use a lens tissue. * Illuminate the stage. If present, use the built-in light; otherwise use the mirror and the light from a window or a bench lamp placed 15-20 cm away to reflect light up through the hole in the stage. When using a lamp, check that the light is not shining onto the stage from above. * Adjust the sub-stage condenser if present Place a slide on the stage and a pointed object such as a pencil on the light source. Adjust the condenser until both are in focus. * Adjust the light intensity using the iris diaphragm or light control knob. Check the field of view is evenly illuminated and then reduce the light as much as possible without getting a shadow around the edge of the image. * Place the slide in position. Do not tilt the stage, as there is liquid present in the slide. * Check that the low-power objective lens is in position. Bring the lens as close to the slide as possible. ...read more.

Conclusion

There are a few systematic errors that could have occurred due to faults in the method. For instance, the use of faulty or inaccurate measuring equipment when diluting the caffeine solution could have caused imprecise measurements of caffeine to be used. This could have lead to consistently inaccurate results. Another source of error could have been the actual counting of the Daphnia's heartbeats. Because the specimen had a rather unusual internal organ structure, it was difficult to distinguish the heat from the stomach at first glance. The lighting of the microscope was also inadequate and could have caused the recorder to initiate a "subconscious" counting rhythm, producing inaccurate results. To improve the investigation, these measures could be taken * A stroboscope could be used to record the Daphnia, and then play back the video at half speed. This would allow counting of the heartbeats to be calculated much more easily and accurately, increasing the validity of results. * The Daphnia used could be raised from larvae to ensure that they are the same age. Different aged Daphnia may, like humans, experience variation in their average heartbeat, therefore the results gathered from specimens of the same age would be more reliable. ?? ?? ?? ?? Frank Longford Page 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Energy, Respiration & the Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Energy, Respiration & the Environment essays

  1. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    between the two means in trend A is not by chance alone. So for this trend I will now have to reject the alternative hypotheses and accept the null hypotheses. For trend B the critical value for 5% significance is also 2.021, the value obtained by the t-test is 13.5, and this is significantly greater than the critical value.

  2. Marked by a teacher

    Biology coursework investigation: Comparing the length of ivy leaves (Hedera helix) in areas of ...

    4 star(s)

    The lower levels of light cause shade leaves to produce long internodes helping them to come into contact with any light that reaches the plant and make use of it thus enabling the plant to survive in areas of low light intensity.

  1. Marked by a teacher

    AS Edexcel Biology - Aim: To investigate the effect of caffeine on the heart ...

    3 star(s)

    Conclusion Having carried out this experiment fully, I am able to conclude that there is a correlation between the concentration of caffeine and the average beats per minute, the average beats per minute increases when the concentration of caffeine increases.

  2. Weed study. Dandelions - descrption and characteristics. Investigation to dandelion distribution.

    pH level is 5.5, and if I perspire it may affect the pH level. I will discuss my variables separately; these will be explained and justified with applied scientific knowledge. This is my aim for my experiment. Prediction It was predicted that there would be more dandelions present at the Lower lawn, than Templeton Lawn.

  1. In this experiment I aim to find out if caffeine has an effect on ...

    Prolong exposure of the Daphnia to the microscope light will overheat the Daphnia. To prevent the Daphnia from overheating, the microscope light should be turned off between observations and a heat sink should be used. * Heart beat of Daphnia can be very fast when caffeine solution was added.

  2. Investigate the effect of bile salt concentration on the digestion of milk by the ...

    Prediction: I believe that increasing the concentration of bile salts should allow the rate of digestion of milk by lipase to increase. Bile salts are the main constituent of bile, which in the body is secreted to emulsify fats (break them up into small droplets), thus increasing the surface area

  1. The aim of this experiment is to research on the effect caffeine has on ...

    it would be difficult to monitor their heart rate and it will also be unethical. Although animals were not available to experiment on due to ethics, when the highest dose of caffeine solution was administered on Daphnia, it caused their hearts to beat twice as fast and other groups of students carrying out the same practical noted the same pattern.

  2. Experiment. Hypotheses: The higher the concentration of caffeine the higher the heart rate of ...

    end so that it will be easier for the daphnia to be squeezed through with no harm. 2) Then place the daphnia on to a cavity slide and removing some of the pond water using filter paper. 3) Then pull out a few strands of cotton wool and place it on the daphnia.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work