Topic 1 Flashcards

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1
Q

Why are daphnia used to investigate heart rate?

A

They are transparent so their hearts can be seen and heart rate monitored

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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
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3
Q

What factors should be kept the same in the Daphnia experiment?

A
  • Temperature

- Volume of caffeine solution

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4
Q

What are the ethical disadvantages in using invertebrates? 2

A
  • Can’t give consent

- Extreme conditions could cause distress

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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
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6
Q

What dye is used to investigate concentration of vitamin C in food?

A

DCPIP

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7
Q

What colour change does DCPIP undergo when added to vitamin C?

A

Changes from blue to colourless

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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
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