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

The aim of this investigation is to investigate the affect of caffeine on the heart rate of Daphnia (Water Fleas).

Extracts from this document...


Activity 1.21 Does Caffeine Affect the Heart Rate? Aim: The aim of this investigation is to investigate the affect of caffeine on the heart rate of Daphnia (Water Fleas). Hypothesis: The heart rate of the Daphnia will increase when exposed to caffeine. Caffeine acts as a stimulant, which causes stimulatory neurotransmitters to be released in excess amounts. This makes the brain feel more alert and also increases mental activity. Therefore an increase in the heart rate is likely if more physical activity is taking place. Method: 1. Set up apparatus needed- 6 Daphnia, cavity slides, dropping pipettes, distilled water, caffeine tablets, cotton wool, glass beakers, test tubes, test tube rack, stop clock, filter paper, and microscope. 2. After equipment is set us, collect 6 Daphnia. Place 3 into pond water and 3 into caffeine solution. 3. ...read more.


8. After having repeated the experiment, change the cotton wool and repeat steps 4-7, this time using the Daphnia from the caffeine solution. Risk Assessment/ Safety: Wear gloves when working with biological specimen and ensure you wash hands after the practical as they may contain bacteria which could spread causing harm to others. Also make sure you wear lab coats in case of any spillage onto your clothes. Use goggles again to protect eyes, in case of spillage. Also wipe down surfaces and wash hands with anti- bacterial sprays/ soap to clean away any bacteria. Ethical Issues: Try to ensure that the Daphnia stay alive after use as they are living creatures too. To ensure the Daphnia stay alive, use pipettes when transferring the Daphnia from the solution, to the microscope and back into pond water. ...read more.


* Amount of caffeine solution used was not consistent so heart rate would vary slightly. * Size of Daphnia was not consistent therefore they may have reacted in different ways to the caffeine. * The time under the microscope varied slightly. * The cotton wool should have been changed for each experiment as it would have excessive solution, therefore making the Daphnia react differently. Conclusion: The results show that the heart rate decreased when the Daphnia were exposed to caffeine, which was the opposite of what should have happened. It proved the hypothesis wrong because the prediction made stated that as the concentration of caffeine increased, the heart rate of the Daphnia would also increase, but shown in the results, as the concentration increased, the Daphnia's heart rate decreased. Zoya Khan Biology Investigation- Marcia Johnson 30-10-2006 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Humans as Organisms 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 GCSE Humans as Organisms essays

  1. Marked by a teacher

    Does Caffeine Affect Heart Rate?

    4 star(s)

    A high dosage of caffeine results in an increased neurone firing in the brain. The pituitary glad sees all the activity and thinks some sort of emergency must be occurring, therefore releasing hormones that tell the adrenal glands to produce adrenaline.

  2. The effect of caffeine concentration on the heart rate of Daphnia.

    A way to improve my results would be to carry on doing replicates, as the more replicates undertaken the more reliable my results will be. Conclusion Due to the large variation in my results there is a large degree of error therefore trends are not very significant.

  1. The heart rate of a Daphnia (water flea)

    Conclusion When the temperature of the surrounding water of a Daphnia increases, the enzyme activity increases and metabolic rate increases until the temperature reaches the enzymes maximum thermal threshold. After this, the active site of the enzyme begins to disfigure and the Daphnia dies soon after as digestion stops without enzymes.

  2. Does caffeine affect heart rate

    The temperature played a key part because if it was hot then the daphnia would be more dehydrated than if it was cold, meaning that its heart rate would be higher as it is trying to cool itself down by taking in more solution.

  1. Effect of Ethanol on the Daphnia heart rate

    (from no ethanol at all, to 0.2%), from here onwards its heart rate changes at a relatively steady rate, probably because the Daphnia has already adapted to the fact that there is ethanol surrounding it, and therefore no more dramatic changes will occur.

  2. Potato and Osmosis Investigation

    For example if one of the potato tubes were to be one cm longer than the other tubes, the surface area of the tube would be larger so there would be more space for osmosis to occur. To obtain varied results it will be essential to vary the concentration of the sugar solution.

  1. Daphnia Investigation

    I could change the percentage of drug used in each experiment. * The amount of time we decide to time the heart rate for. Equipment: The equipment that I have decided to use is the following: * Stop Clock * Microscope * Glass * Daphnia's * Ethanol (0.2%, 0.4%, 0.6% and 0.8%)

  2. Investigating The Effect Of Drugs On the Heart Rate of a Daphnia.

    Receptors work by transferring energy into electrical energy. This is used to send an impulse along the nerve fibres to your brain or spinal cord. Other receptors are touch receptors in your hands are sensitive to movement, and smell receptors are sensitive to chemical energy.

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