The effect of temperature on cell membranes

Question 1

Independant variable

Answer 1

temperature of water

Question 2

Dependant variable

Answer 2

% transmission of light through resulting solution

Question 3

Other variables to be controlled (3)

Answer 3

• Volume of distilled water
• Time left in water
• Size of beetroot piece

Question 4

Equipment required (14)

Answer 4

• Raw beetroot
• cork borer
• white tile
• knife
• ruler
• beaker
• forceps
• water baths
• boiling tubes
• thermometer
• colorimeter & cuvettes
• stop clock
• distilled water
• syringe

Question 5

Outline the method

Answer 5

using cork borer and knife, cut pieces of beetroot into 1 cm length cylinders. Place in distilled water overnight to remove any dye released on preparation. Wash and blot dry. Place 8 boiling tubes of distilled water into 8 water baths of different temperature. Once at temperature, add a piece of beetroot to each and leave for 30 mins. Remove beetroot and shake tubes to disperse dye. Set colorimeter to % absorbance on blue/green filter. Calibrate using distilled water in a cuvette first then add 2cm3 of beetroot solution from the first temp to a new cuvette. Place into colorimeter to read % absorbance. Repeat for all other pieces.

Question 6

Possible evaluation issues (6)

Answer 6

• Some beetroot may have skin on affecting surface area.
• Difficulty in maintaining temperature
• Accurate reading of the colorimeter
• Accurate size of beetroot
• From the different parts of the root
• Ensuring same amount of time at the different temperatures