Required Practicals Flashcards
CP1: Daphnia
Why are daphnia suitable for investigating heart rate
they have transparent bodies so their internal organs can be observed using the light microscope
CP1: Daphnia
Give the method for this practical
- prepare 5 different concentrations of caffeine solution and a control solution of distilled water
- add a piece of cotton to the cavity slide, then using a wide spout pipette add your large daphnia
- Place the cavity slide onto the stage of the microscope and pipette 3 drops of your caffeine solution and observe the daphnias heart rate.
- Count and record the heart rate by creating an S shaped graph for 15 seconds
- Count the dots on your S shaped graph and express the heart rate as beats per minute (x4)
- Repeat steps 2-6 with other caffeine concentrations
CP1: Daphnia
What are some ethical considerations around using daphnia for the experiment
Cannot give consent
Cannot express pain
- may be more ethical to use them due to their simple nervous systems
CP1: Daphnia
What is some care that should be taken to minimise potential harm
- animals should be handled gently
- examination periods should be kept as short as possible
CP2 : Vitamin C content
what is the chemical name for Vitamin C and what is a property of it
Chemical name = ascorbic acid
good reducing agent and is easily oxidised
CP2 : Vitamin C content
method to find vitamin C concentration using a titration
- pipette 1cm3 of 1% blue DCPIP into a conical flask
- fill up the burette to the 0 mark with the first type of juice
- slowly add juice to the DCPIP using the burette, swirling with every drop
- as soon as the DCPIP loses its colour turn of the burette tap and record the results
- Repeat this 2 times per jucie
CP2 : Vitamin C content
whats the
IV
DV
CV
IV - type of jucie
DV - volume of juice that turned DCPIP colourless
CV - Conc of DCPIP
Volume of DCPIP
