affect of temperature on membrane permeability

Question 1

what is the independent variable

Answer 1

temperature

Question 2

how do you vary the independent variable

Answer 2

have different temperatures e.g 0,10, 20, 30 …
7 different temperatures

Question 3

what is the dependant variable

Answer 3

absorbance of betalains

Question 4

how do you measure the dependant variable

Answer 4

use a calorimeter
set at 490 nm
blue green filter

Question 5

what organism (beetroot) features should be controlled

Answer 5

use one beetroot
cut all samples from one beetroot

Question 6

what environmental features should be controlled

Answer 6

temperature of water baths
storage conditions of beetroot

Question 7

what procedural conditions should be controlled

Answer 7

amount of water in water baths
each beetroot piece cut to similar size
wavelength of light (490 nm)

Question 8

how many repeats should be carried out

Answer 8

3-5 repeats and calculate the mean

Question 9

how is the investigation made reliable

Answer 9

repeats
remove anomalies
make sure you can get same results if you were to do the experiment again

Question 10

how is this investigation made valid

Answer 10

control the variables
use more temperatures e.g higher temperatures or make them closer together

Question 11

two safety hazards and the precautions you could take

Answer 11

cutting beetroot could result in cutting yourself
water is hotter at higher temperatures - wear gloves

Question 12

what happens at higher temperatures to the beetroot membrane

Answer 12

fatty acid tails become less rigid
kinetic energy increases in cell membrane
fluidity increases
phospholipids do not pack as closely together
increasing membrane permeability

means more betalains are released from vacuole at higher temperatures (darker pink/ purple colour)