PMT EXAM QUESTIONS AND ANSWERS
The phospholipids form a bilayer because - Answers - The hydrophobic tails move away
from the aqeous environment
The protein, labelled in the diagram could be involved in - Answers - Facilitated diffusion
The fluidity of the membrane is determined by the proportion of - Answers - Cholesterol
b) A student carried out an experiment to investigate the effect of temperature on the
permeability of beetroot membranes. Beetroots are root vegetables that appear red
because the vacuoles in their cells contain a water-soluble red pigment. This pigment
cannot pass through membranes.
Six cubes of beetroot were cut. One piece of beetroot was placed into a tube containing
10 cm3 of water and left for 20 minutes at 5 oC. After the 20 minutes, each piece of
beetroot was removed from the tubes and the colour of the fluid recorded.
The procedure was repeated at five other temperatures. The results of this experiment
are shown in the table below.
Using the information in the table, describe the effect that temperature has on the
permeability of the membranes of the beetroot cells.
Remember that temperature in left hand column of table and colour of fluid in right
hand) - Answers - increase in temperature increases the permeability / eq ;
2. i a of change in {colour / permeability} related to {42 oC / 64 oC}
OR no change up to 42 oC ;
A second student carried out a very similar experiment, using three samples of beetroot
at each temperature. She used a colorimeter to determine the intensity of the colour of
the fluid produced.
The results of her experiment are shown in the table below.
State two variables that both of these students must keep the same if their results are
to be compared. - Answers - Any two from:
1. ference to pre-treatment e.g. rinsing method
;
2. {size / mass / surface area / volume / shape} of beetroot ;
3. b troot storage conditions / eq ;
4. {sa / type / species / eq} beetroot ;
5. {age of beetroot / storage time} ;
6. ( cubation) time / eq ;
7. {vol e / concentration / eq} of {water /
solution}(added to beetroot) ;
8. pH
The phospholipids form a bilayer because - Answers - The hydrophobic tails move away
from the aqeous environment
The protein, labelled in the diagram could be involved in - Answers - Facilitated diffusion
The fluidity of the membrane is determined by the proportion of - Answers - Cholesterol
b) A student carried out an experiment to investigate the effect of temperature on the
permeability of beetroot membranes. Beetroots are root vegetables that appear red
because the vacuoles in their cells contain a water-soluble red pigment. This pigment
cannot pass through membranes.
Six cubes of beetroot were cut. One piece of beetroot was placed into a tube containing
10 cm3 of water and left for 20 minutes at 5 oC. After the 20 minutes, each piece of
beetroot was removed from the tubes and the colour of the fluid recorded.
The procedure was repeated at five other temperatures. The results of this experiment
are shown in the table below.
Using the information in the table, describe the effect that temperature has on the
permeability of the membranes of the beetroot cells.
Remember that temperature in left hand column of table and colour of fluid in right
hand) - Answers - increase in temperature increases the permeability / eq ;
2. i a of change in {colour / permeability} related to {42 oC / 64 oC}
OR no change up to 42 oC ;
A second student carried out a very similar experiment, using three samples of beetroot
at each temperature. She used a colorimeter to determine the intensity of the colour of
the fluid produced.
The results of her experiment are shown in the table below.
State two variables that both of these students must keep the same if their results are
to be compared. - Answers - Any two from:
1. ference to pre-treatment e.g. rinsing method
;
2. {size / mass / surface area / volume / shape} of beetroot ;
3. b troot storage conditions / eq ;
4. {sa / type / species / eq} beetroot ;
5. {age of beetroot / storage time} ;
6. ( cubation) time / eq ;
7. {vol e / concentration / eq} of {water /
solution}(added to beetroot) ;
8. pH
