beetroot/ membrane permeability prac

Question 1

blurt

Answer 1

testing permeability of beetroot membrane at dif alc concs
cut beetroot into uniform sizes using ruler
beetroot must be same age or membranes may be more permeable
measure conc of alc
dif beetroot pieces into dif concs
leave for measured amount of time
pour whats left into CUVETTE for colorimeter
calibrate colorimeter
see how pigmented
higher pigment the more has leaked from beets
so higher permeability
repeat at least 3 times for each conc

Question 2

whatre we measuring (DV)

Answer 2

the intensity of coloured pigment that leaves cells in a measured amount of time
absorbency

Question 3

what do colorimeters measure and how can this be used in this investigation?

Answer 3

intensity of colour
this can be used to make a statement about membrane permeability
provides a standard, quantitative figure for colour saturation
in % absorbance in AU

Question 4

how does alcohol affect permeability of cell membranes

Answer 4

non-polar which causes phospholipids to rearrange themselves diruptin membrane and making it more permeable

Question 5

how does temperature affect permeability of cell membranes

Answer 5

increases KE of cell membrane components, they move more creating more gaps
above 40 degrees C proteins in cell membrane will denature, creating more gaps

Question 6

control variables

Answer 6

age of beetroot, time left in alc solution, surface area of beetroot, beet samples taken from genetically identical plants
vol and temp of alc, volume of liquid in cuvettes, part of beet the sample was taken from, wavelength/filter used on colorimeter

Question 7

IV

Answer 7

alcohol conc, range of 5 minimum

Question 8

method

Answer 8

-cut beets into 1cm3 cubes
-leave overnight in distilled water
-put 5 cm3 of each alc conc in a test tube and add cube of beet
-leave for 45 mins
-take sample from test tube and put into cuvette
-measure absorbency using colorimeter
-repeat 3 X for each conc and calc avg absorbency for each

Question 9

hazards and risks

Answer 9

staining from betain (pigment in beets), wear coat to avoid staining, scalpal cutting- be careful

Question 10

what is a tonoplast

Answer 10

vacuolar membrane that separates vacuole from cell contents

Question 11

which variable should be on the x-axis

Answer 11

independent variable
(alc conc or temp)

Question 12

y-axis

Answer 12

dependent variable (absorbence)

Question 13

what should be plotted on graph

Answer 13

the mean absorbance for each concentration

Question 14

does glycogen have an osmotic effect on cells

Answer 14

no, insoluble.
wont increase osmosis into cell