Daphnia heart rate response to changes in surrounding medium

Question 1

Briefly outline how you measure daphnia heart rate

Answer 1

1) Set up equipment
2) Distilled water + crushed ice into beaker
3) Make it 5 degrees
4) Pipette volume into petri dish
5) Place daphnia in cavity slide
6) Place cavity slide into petri dish
7) Put petri dish under microscope
8) Time 15 seconds and count heart rate (x4)
9) Fill another petri dish and repeat with different temperatures
10) Transfer Daphnia back to the tub

Question 2

What temperatures could you use?

Answer 2

5, 10, 15, 20, 25

Question 3

How could you ensure this practical is ethical?

Answer 3

Use a wide pipette - don’t squish the Daphnia, less stress

Temp range 5-25. Doesn’t denature enzymes

Don’t leave in light for too long to avoid overheating

Question 4

What are control variables?

Answer 4

Same daphnia - different metabolic rates
Same light intensity of bulb
Same volume of water

Question 5

What would happen if the enzymes denatured?

Answer 5

No ESCs would form - no reactions take place - Daphnia would die