Topic 2 Flashcards
1
Q
Describe the permeability of cell membrane experiment: stage 1, obtaining beetroot solution
A
- Use a scalpel to cut 5 equal sized pieces of beetroot on a cutting board
- Rinse pieces to remove pigment released in cutting
- Use a measuring cylinder to measure out 5cm3 of water
- In 5 different test tubes
- Place the test tubes into water baths at different temperatures
- Place 5 pieces of beetroot in 5 different test tubes for same length of time using stopwatch
- Remove beetroot from tubes leaving just coloured liquid
2
Q
Describe the permeability of cell membrane experiment: stage 2, using the calorimeter
A
- Switch calorimeter on and allow 5 minutes for it to stabilise
- Set up calorimeter using blue filter
- Use pure water to calibrate machine to zero
- Use pipette to transfer sample of liquid from first of beetroot test tubes to clean cuvette [3/4 full]
- Put cuvette in calorimeter and record absorbance of coloured solution
- Repeat for remaining test tubes
- Plot graph of temperature vs absorbance
3
Q
What is the relationship between light absorbance and permeability of the membrane? 4
A
- The higher the absorbance reading
- Less light passed through
- More pigment released
- Higher permeability of membrane
4
Q
Why is beetroot used to investigate cell membrane permeability?
A
It has a purple pigment that leaks out of the cell membrane according to its permeability
5
Q
Explain how to investigate the effect of enzyme/substrate concentration on enzyme controlled reactions
A
- Set up five concentrations of catalase/hydrogen peroxide depending on what’s tested
- Add a set volume and known concentration of hydrogen peroxide to a boiling tube
- Keep pH constant by adding buffer solution
- Set up apparatus with upside down measuring cylinder in trough of water connected to boiling tube with delivery tube
- Use pipette to add known concentration and volume of catalase
- Quickly attach bung and tube
- Measure volume of oxygen produced in measuring cylinder every 10 seconds for first minute of reaction
- Use stopwatch to measure time
- Plot data on graph of volume of oxygen produced vs time
- Draw tangent to determine initial rate of reaction