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

Effect of Caffeine on the Heart Rate of Daphnia

Extracts from this document...


1. Objective 1.1 Introduction Daphnia are fresh water animals, commonly called 'water fleas' because of the manner by which they swim - a sort of hopping or jigging in the water, a movement brought about by their swimming appendages. Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans. In most species, the body is covered by a carapace (dorsal section of the exoskeleton or shell) and has five or six pairs of legs. The most prominent features are the compound eyes and the second antennae. The heart is situated just behind the head, and the average heart rate is approximately 180 beats per minute under normal conditions. Most daphnia are filter feeders, ingesting mainly unicellular algae and various sorts of protists , bacteria and yeast. They live in various aquatic environments ranging from acidic swamps to freshwater lakes, ponds, streams and rivers. Daphnia reproduce parthenogenetically usually in the spring until the end of the summer. In harsh environmental conditions, production of new female generations stops and parthenogenic males are produced. Males are much smaller in size than the female. During mating, a male grasps a female from behind and prises open her carapace using a specialised abdominal appendage, and thus fertilises the eggs. Sexual reproduction allows greater offspring variation through genetic recombination. The lifespan of a Daphnia does not exceed one year and is largely dependent on temperature. For example, individual organisms can live up to 108 days at 3�C while some organisms live for only 29 days at 28�C. Also, Daphnia has been proven to be very sensitive to poor water conditions. ...read more.


3. The Daphnia is observed using low power magnification (40x). 4. The heart is identified and the heart beat is counted for 15 seconds. The values are multiplied by 4 to obtain the number of heart beats per minute. 5. Step 3 is repeated to obtain another reading. 6. The Daphnia is then removed and placed into a Petri dish filled with pond water. It is left to swim in the pond water for about one minute. 7. One drop of 0.1% caffeine solution is added into the cavity of the slide. The Daphnia is then placed onto the slide lined with muslin cloth. 8. The heart is identified and the heart beat is counted for 15 seconds. The values are multiplied by 4 to obtain the number of heart beats per minute. 9. The measurement is repeated to obtain another reading. 10. The experiment is repeated using 0.2%, 0.3%, 0.4% and 0.5% caffeine solution. 11. The results obtained are recorded. A graph of heart rate against concentration of caffeine solution is drawn to illustrate the relationship between the concentration of caffeine solution and heart rate of Daphnia. 7. Precautions: * The same volume of caffeine solution is used throughout the experiment. * Other factors affecting the heart rate such as the temperature of the solution is kept constant throughout the experiment. * The same Daphnia is used throughout the experiment to minimise errors. * The Daphnia is a very delicate creature. It should be handled with extra care. * Muslin cloth is used to ensure that the Daphnia remains in position in the cavity of the slide. * Excess water on the cavity slide is absorbed using paper towels. ...read more.


There are some organisations that oppose the use of animals in such experiments. This is based on a range of arguments; that it is cruel, poor scientific practice, cannot reliably predict effects in humans, poorly regulated, that the costs outweigh the benefits, or that animals have an intrinsic right not to be used for experimentation. Also, if every biology student uses the Daphnia for this experiment, the population of Daphnia in that particular area would decrease drastically and may cause a major disruption in the food chain of the aquatic habitat. This is only if all the Daphnia are euthanized after the experiment. Thus, the solution to this problem would be to avoid killing these animals and to return all the Daphnia to its original habitat. 10.5 Further investigations 1. This experiment can also be done using nicotine or adrenaline to replace caffeine and observing the effects on the heart rate of Daphnia. 2. Apart from stimulants, a depressant such as alcohol can also be used to replace caffeine in this experiment. Daphnia are prone to alcohol intoxication and make excellent subjects for studying the effects of the depressant on the nervous system. 3. The effect of temperature on heart rate in Daphnia can also be investigated. To carry out the experiment, identical culture solutions at temperatures of 5, 10, 15, 20, 25 and 30 degrees Celsius are used. The Daphnia is then placed into these cultures in turn, allowing 5 minutes to elapse before taking a new heart rate determination. Similarly, a graph of heart rate of Daphnia against temperature can be plotted. 11. Conclusion: - The higher the caffeine concentration, the higher the heart rate of Daphnia. Sources: Books 1. Title: Edexcel Biology for AS Author: C.J.Clegg Publisher: Hodder Education, 2008 Website 1. www.neiljohan.com/projects/biology/enzymes.htm 2. http://en.wikipedia.org/wiki/Caffeine 3. http://www.sciencebuddies.org/mentoring/project_ideas/Pharm_p009.shtml 4. http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/wimsmall/crust.html 5. http://en.wikipedia.org/wiki/Daphnia 6. http://en.wikipedia.org/wiki/Animaltesting ?? ?? ?? ?? ...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 Exchange, Transport & Reproduction 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 Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Biology coursework planning - the effect of lead chloride on the growth of cress ...

    5 star(s)

    They also fit well in the petri dish. The arrangement of the seeds on the cotton pad will be in a grid form where one seed will be placed on each corner of the squares making up the grid. This will provide enough distance between each cress seed so that

  2. Marked by a teacher

    Human Reproductive System

    4 star(s)

    It triggers the maturation of reproductive organs, helps in the development of sexual characteristics, assists in lactation, regulates bone density in a foetus, promotes blood flow within the uterus, protects the foetus form the effects of androngens in the female system and also maintains regulates and triggers the production of other hormones.

  1. Marked by a teacher

    Daphnia experiment - Does caffeine affect heart rate?

    3 star(s)

    Set up the microscope. 3. Fill a petri dish with water. This will be placed underneath the cavity slide, to absorb the heat from the lamp. If this is not done the daphnia will overheat, causing it to die. 4.

  2. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    Changing bacteria would make the results void as the structures vary in different types of bacteria. * The amount of bacteria on each agar plate- it is not known of how many bacteria are within the broth but the amount (ml)

  1. Peer reviewed

    "An investigation into the Respiration of Carbohydrate Substrates by Yeast."

    5 star(s)

    If the experiment was to be repeated, there are certain modifications that could be made to enhance the quality of the results. To keep the temperature constant throughout we could have used an electronic water bath to heat the yeast in and then left it in whilst collecting the gas.

  2. Peer reviewed

    Effect of Caffeine on the Heart Rate of Daphnia

    3 star(s)

    This has the overall effect of increasing the rate of glycolysis and increases the amount of ATP available for muscle contraction and relaxation. According to one study, caffeine in the form of coffee, significantly reduces the risk of heart disease in epidemiological studies.

  1. The Endocrine System

    subsequent to pituitary failure, it is called secondary hypothyroidism. Primary hypothyroidism can be clinical or subclinical. Clinical hypothyroidism is when there are definite symptoms with a raised TSH outside the reference range and low serum thyroxine level. Cretinism is defined by the Oxford Medical Dictionary as stunted body growth and mental development appearing in the first years of life

  2. The Skeletal and Muscular System

    The Ultra Structure of the Skeletal Muscle The skeletal muscles have thick and thin filaments. Thick filaments are made up of myosin and the thin filaments are made up of actin.

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