Topic 1 Flashcards
1
Q
Why are daphnia used to investigate heart rate?
A
They are transparent so their hearts can be seen and heart rate monitored
2
Q
Explain how to measure the effect of caffeine on the heart rate of daphnia 9
A
- Make up a range of caffeine solutions of different concentrations using serial dilution
- Use a control solution with no caffeine
- Transfer one Daphina into a dimple on a cavity slide
- Use a pipette to place a few drops of caffeine solution onto Daphnia
- Wait for 5 minutes for all caffeine to be absorbed
- Place onto stage of light microscope and adjust focus to see Daphnia beating heart
- Count number of heartbeats in 20 seconds and x3 for bpm
- Repeat 10 times using same caffeine conc but different Daphnia
- Repeat using other concentrations and control
3
Q
What factors should be kept the same in the Daphnia experiment?
A
- Temperature
- Volume of caffeine solution
4
Q
What are the ethical disadvantages in using invertebrates? 2
A
- Can’t give consent
- Extreme conditions could cause distress
5
Q
What are the ethical advantages in using invertebrates? 3
A
- Less sophisticated nervous system than vertebrates
- Feel less pain
- More distantly related to humans
6
Q
What dye is used to investigate concentration of vitamin C in food?
A
DCPIP
7
Q
What colour change does DCPIP undergo when added to vitamin C?
A
Changes from blue to colourless
8
Q
Explain how to investigate concentration of Vitamin C 8
A
- Make up 6 vitamin C solutions of different known concentrations
- Use a measuring cylinder to measure out set volume of DCPIP at set concentration
- Add a Vitamin C solution to DCPIP drop by drop with pipette
- Gently shake for set amount of time using stopwatch
- When solution is colourless, record the volume of vitamin C solution added
- Repeat twice with same solution, and whole method with each concentration
- Draw a calibration curve of the result, by plotting graph of concentration of Vitamin C vs volume in drops
- With unknown solution compare volume to calibration curve to find concentration