The effect of caffiene
The effects of caffeine on the heart rates of Daphnia.
Introduction
In the water flea, Daphnia, the single, small heart is easily visible when viewed under a low power microscope. The heart rate can be monitored and measured in different conditions, such as change in water temperature, or in this case, the concentration of chemicals added to the water they habitat. A change in daphnia heart rate under the influence of a concentration of caffeine solution creates a procedure providing an interesting investigation into the effects of different chemical concentrations on a metabolic process and whether or not an increase of caffeine would increase the rate of metabolism in multi-celled organisms. These daphnia have been kept in a freshwater habitat at room temperature beforehand.
Hypothesis
It is predicted that a higher concentration of caffeine the daphnia are subjected to will increase the heart rate more than compared to a solution of a lower caffeine concentration. The change in metabolic rate will be reflected in the cardiac frequency.
Method
List of equipment needed:
Low power microscope
Glass slide for observation
Small piece of cotton wool
Pipette
Caffeine solution at different concentrations – 0.1%, 0.2%, 0.3%, 0.4%, 0.5%
Daphnia in freshwater beaker
Filter paper
Stopwatch
1. Take a small piece of cotton wool, tease it out and place it in the middle of the glass slide. Set up the microscope under a low power setting.
2. Select a large daphnia and use the pipette to gently transfer it from the freshwater beaker onto the cotton wool fibres. Immediately add water from the beaker using the pipette until the daphnia is just submerged enough by the water to keep it alive and immobilised.
3. Place the glass slide onto the stage of the microscope and observe the daphnia under the low light setting. Make sure you have correctly located the heart beating and not mistaking it for the movement of the gut or flapping of the legs.
4. For the first
Introduction
In the water flea, Daphnia, the single, small heart is easily visible when viewed under a low power microscope. The heart rate can be monitored and measured in different conditions, such as change in water temperature, or in this case, the concentration of chemicals added to the water they habitat. A change in daphnia heart rate under the influence of a concentration of caffeine solution creates a procedure providing an interesting investigation into the effects of different chemical concentrations on a metabolic process and whether or not an increase of caffeine would increase the rate of metabolism in multi-celled organisms. These daphnia have been kept in a freshwater habitat at room temperature beforehand.
Hypothesis
It is predicted that a higher concentration of caffeine the daphnia are subjected to will increase the heart rate more than compared to a solution of a lower caffeine concentration. The change in metabolic rate will be reflected in the cardiac frequency.
Method
List of equipment needed:
Low power microscope
Glass slide for observation
Small piece of cotton wool
Pipette
Caffeine solution at different concentrations – 0.1%, 0.2%, 0.3%, 0.4%, 0.5%
Daphnia in freshwater beaker
Filter paper
Stopwatch
1. Take a small piece of cotton wool, tease it out and place it in the middle of the glass slide. Set up the microscope under a low power setting.
2. Select a large daphnia and use the pipette to gently transfer it from the freshwater beaker onto the cotton wool fibres. Immediately add water from the beaker using the pipette until the daphnia is just submerged enough by the water to keep it alive and immobilised.
3. Place the glass slide onto the stage of the microscope and observe the daphnia under the low light setting. Make sure you have correctly located the heart beating and not mistaking it for the movement of the gut or flapping of the legs.
4. For the first