A-level Biology required practical Membrane permeably part 1

Question 1

What are we experimenting

Answer 1

The effect of alcohol concentration on the leakage of pigment from beetroot cells

You will investigate the effect of alcohol concentration on the amount of pigment leaking
through beetroot plasma membranes.

Question 2

Beetroot contains high concentrations of and where is it found

Answer 2

betalin.

This is a purple pigment found inside the
vacuoles of the cells.

Question 3

The pigment cannot move across

Answer 3

undamaged plasma membranes.

Question 4

What equipment do we need

Answer 4

five concentrations of alcohol labelled 100%, 80%, 60%, 40%, 20%
● 10 discs cut from a beetroot and rinsed thoroughly in water
● graduated pipettes or syringes
● test tubes
● bungs to fit some of the test tubes
● thermometer
● large beaker to use as a water bath
● stop watch
● test tube rack
● small beakers
● permanent marker pen
● water
● paper towels to blot discs.

Question 5

first step Set up a water …… at …….. o C (using a water bath or kettle and thermometer).

Answer 5

water bath at 30 degrees

Question 6

Second step Add ….cm of ………% alcohol to a test tube and put a bung in the tube.

Answer 6

10 cm cubed

100%

Question 7

third step Label the tubes with there ………

Answer 7

alcohol concentration

Question 8

Repeat the steps 5 and 6 with alcohol concentrations

Answer 8

80,60,40,20 percenatge

Question 9

step 5 :Put the boiling tubes of …….. in the water bath until temperature of the alcohol reaches
….. o C.

Answer 9

alcohol

30 degrees

Question 10

step 6 Blot …… discs of ……….. with a paper towel to remove excess ……

Answer 10

10

beetroot

water/ pigment as plasma membrane might already been damaged by u picking it up with a scalpel

Question 11

step 7 Gently put ….. discs of …… in each of the five tubes. Replace ……..

Answer 11

2

beetroot

the bungs as soon as
possible after doing so.