rp 4 variable effect on permeability of CSM Flashcards
method to investigate effect of named variable on permeability of CSM
cut identical cubes of plant tissue - same age and type using scalpel
rinse to remove pigment or blot on paper towel
add same no of cubes to 5 Dif test tubes containing same vol of water but Dif temp 10 20 30
leave for same amount of time
remove beetroot measure intensity of colour of surrounding solution
semi quantitative interpretation of results
use known conc of extract and distilled water to produce a dilution series
compare results with colour standard to estimate conc
quantitative interpretation of results
measure absorbance of light of known conc using colorimeter
draw calibration curve - absorbance against conc of extract
draw line of best fit
absorbance value of sample read of calibration curve ti find associated extract conc
issues with comparing colour standard
subjective and colour obtained may not match any of the standards
why wash beetroot
wash pigment of surface
release only due to named variable
why regulary shake test tube containing cubes of plant tissue
ensure surfaces of cube remand in contact with liquid
to maintain a conc gradient for diffusion
why control volume of water
too much water - dilutes pigment so solution appears lighter
how to ensure temp kept same throughout experiment
take readings at intervals throughout experiment using digital themormeter
corrective measure if temp has fluctuated
what does high absorbance suggest about cell membrane
more permeable
as more pigment leaks out making surrounding solution more concentrated
temps affect on permeablity of cell surface membrane
temp incr
permeability increase
as phospholipids gain KE and fluditity increases
transport protiens denature at high temp as h bonds break changing tertiary strucutre
low temp increase permeability
ice crystals form pierce cell membrane and increase permeabilty
ph affect on permeability
high low ph increase permeability
transport protiens denature as h ionic bonds break changing tertiary structure
lipid soluble solvent and permeability
conc increase permeability increases
ethanol my dissolve phospholipid bilayer so gaps form