practical 1-heart rate

Question 1

what is the aim of the daphnia practical?

Answer 1

to investigate the effect of caffeine on the heart rate of daphnia.

Question 2

what is the independent variable in this practical?

Answer 2

Caffeine concentration

Question 3

what is the dependent variable in this practical?

Answer 3

Heart rate of daphnia

Question 4

Name some control variables of this practical

Answer 4

. temperature
. size of daphnia
. Time to acclimatise
. volume of solutions

Question 5

why do we use daphnia?

Answer 5

. They are very common and so there is no real threat to species.
. no threat to daphnis reproduction because they reproduce asexualy
. they are transparent so no need for dissection

Question 6

Describe the method for the daphnia practical

Answer 6

1. Make a range of caffeine solutions of different concentrations and a control solution that has no caffeine in it.
2. Transfer one daphnia into a cavity slide using a pipette.
3. get the average heart rate by measuring the BPM with no caffeine solution.
4. Using a tissue dab off the excess pond water and use a pipette to place a few drops of caffeine solution onto the daphnia.
5. Place the slide into the light microscope
6. count the number of beats in 60 seconds to