(Practical) Daphnia Flashcards
1
Q
What is the independent variable?
A
caffeine concentration
2
Q
What is the dependent variable?
A
heart rate of Daphnia
3
Q
What is a control measure?
A
Using regular water
4
Q
What are some control variables?
A
Similar size Daphnia, counting for the same amount of time, time for Daphnia acclimatisation, volume of solutions, temperature
5
Q
What is the method for this experiment?
A
- Remove Daphnia and place on the cavity slide
- Remove pond water and replace with distilled water
- Leave to acclimatise for 5 minutes and then count the heart rate under the microscope for 30 seconds. Counting can be done by dotting paper or using a slow motion camera which is more accurate
- Multiply by 2 for bpm
- Repeat this for 2 more Daphnia
- Repeat this process again but use the caffeine solutions ranging from 0.1 to 0.5, repeating each 3 times.
6
Q
What are some possible evaluation issues?
A
Ensuring Daphnia are the same size
If left under the microscope too long the temperature will increase along with the heart rate
A high caffeine conc. will kill the Daphnia
Counting the heart beat can be innaccurate
7
Q
Why are Daphnia used?
A
Transparent simple organisms
