5: Effect of temperature on membrane permeability

Question 1

Independent variable

Answer 1

Temperature of water

Question 2

Dependent variable

Answer 2

% transmission of light through resulting solution

Question 3

Variables to control

Answer 3

Volume of water (10cm3)

S.a. of beetroot

Time beetroot spends in water

The colorimeter filter/wavelength

Part of the beetroot sample taken from (should be from core)

Age, variety and storage of the beetroot

Question 4

Beetroot cell vacuoles contain water soluble pigment called

Answer 4

betalain

Question 5

These pigment molecules are too _____ to pass through membranes

Answer 5

LARGE

Question 6

At low temperatures:

Plasmalamella and tonoplast are intact, so betalain cannot ______ __________

Answer 6

Pass through

Question 7

At high temperatures:

Proteins in membranes begin to lose tertiary structure, as a result

Answer 7

the membrane becomes more fluid and allows beta lain pigments to leak out.

Question 8

State the temperature range.

Answer 8

0 - 70 dC

Question 9

State which filter to use inside the colorimeter

Answer 9

Blue or green

Question 10

State 3 difficulties in the method

Answer 10

maintaining temperature

cutting beetroot to precise lengths

Duration of beetroot in water bath

Question 11

Why are test tubes placed in the water bath for 5 minutes BEFORE beetroot cylinders were added?

Answer 11

To equilibrate tubes to similar starting temperatures

Question 12

Why are beetroot cylinders washed with water before placing in test tube?

Answer 12

To remove excess pigments released from cut cells