rp 4 variable effect on permeability of CSM

Question 1

method to investigate effect of named variable on permeability of CSM

Answer 1

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

Question 2

semi quantitative interpretation of results

Answer 2

use known conc of extract and distilled water to produce a dilution series
compare results with colour standard to estimate conc

Question 3

quantitative interpretation of results

Answer 3

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

Question 4

issues with comparing colour standard

Answer 4

subjective and colour obtained may not match any of the standards

Question 5

why wash beetroot

Answer 5

wash pigment of surface
release only due to named variable

Question 6

why regulary shake test tube containing cubes of plant tissue

Answer 6

ensure surfaces of cube remand in contact with liquid
to maintain a conc gradient for diffusion

Question 7

why control volume of water

Answer 7

too much water - dilutes pigment so solution appears lighter

Question 8

how to ensure temp kept same throughout experiment

Answer 8

take readings at intervals throughout experiment using digital themormeter
corrective measure if temp has fluctuated

Question 9

what does high absorbance suggest about cell membrane

Answer 9

more permeable
as more pigment leaks out making surrounding solution more concentrated

Question 10

temps affect on permeablity of cell surface membrane

Answer 10

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

Question 11

ph affect on permeability

Answer 11

high low ph increase permeability
transport protiens denature as h ionic bonds break changing tertiary structure

Question 12

lipid soluble solvent and permeability

Answer 12

conc increase permeability increases
ethanol my dissolve phospholipid bilayer so gaps form