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MEMBRANE STRUCTURE &

TRANSPORT

ACTIVITY BOOK

Name: ______________________ Option Group: _____________

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1. In the space below draw a labelled diagram of the cell membrane as described by the

fluid mosaic model.

2. Cells can be stained with chemical that dissolve in water. After being stained the

membrane was observed using the electron microscope. The membrane had the

appearance shown below.

Explain why the membrane has this appearance.

7.5nm

MEMBRANE STRUCTURE QUESTIONS – SECTION 1

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3. Complete the following table by placing a tick to give the substance the correct

property.

Substance Hydrophobic Hydrophilic Amphiphilic Polar ionic

Phospholipid

Cholesterol

Glucose

Sodium chloride

Fatty acid

4. The image below is of a phospholipid bilayer. The phospholipids are forming a

“sheet”.

Explain why phospholipids never form this “sheet” structure in organisms.

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5. The fluidity of the cell membrane can be altered by various factors, including the

cholesterol content, the type of phospholipid in the membrane and its composition.

People suffering from the genetic disorder abetalipoproteinemia have altered

amounts of the two phospholipids sphingomyelin and phosphatidylcholine in their

cell membranes. The structures of these phospholipids are shown below.

Abetalipoproteinemia results from a reduction in cell membrane fluidity. Using simple

diagrams for the above phospholipids and the information in this question draw an

annotated bilayer(s) to explain the reduction in membrane fluidity.

Sphingomyelin Phosphatidylcholine

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6. In an experiment to investigate the structure of the cell membrane Larry Frye and

Michael Edidin, at Johns Hopkins University, labelled the plasma membrane proteins

of a mouse cell and a human cell with two different fluorescent markers and fused

the cells. Using a microscope, they observed the markers on the hybrid cell.

Use your knowledge of the structure of the cell membrane to explain the results seen after

one hour.

Mouse

cell

Human

cell

Hybrid

cell

Hybrid cell after

one hour

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7. Proteins are an essential component of the cell membrane. These membrane

proteins are located in various positions within the phospholipid bilayer to allow

them to perform a specific function. The images below are a representation of the

general shapes of some membrane proteins.

(a) Based on their shapes and sizes only which of the above images can:

i. Can form an intrinsic protein.

ii. Can form a transmembrane protein.

iii. Can form an extrinsic protein.

iv. Can form a glycoprotein.

v. Is a carrier protein.

vi. Is a channel protein.

A

B

C

D

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(b) Proteins are polymers of amino acids. The structure of a general amino acid is

shown below.

The letter R is a chemical group, called a side chain that gives the amino acid its specific

chemical property as shown in the table below.

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The image below is of a membrane protein. Amino acids are positioned at specific sites

within the protein polymer to allow it to do its function.

i. Using the table of amino acids on page 7, what type of amino acid R groups

would be found at positions 1 and 2 in the membrane protein above. Explain

your choices.

ii. Suggest, with an explanation, a function for this membrane protein

1 1

2

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iii. Which group(s) of amino acids from the table on page 7 will be needed to

produce an extrinsic protein, explain your answer?

8. An ionic molecule is one that has a true electrical charge, for example Na+ and Cl- that

is caused by either a gain or loss of electron(s). A polar molecule, however, has a

partial electrical charge caused by a difference in electronegativity of the atoms that

make up the molecule causing an even distribution of electron density. Non-polar

molecules have no partial charge so the atoms have equal electronegativity.

Glucose and water are polar, and non-polar molecules would be lipids, oxygen and

carbon dioxide. The image below is of a phospholipid bilayer showing what

substances can cross the bilayer and those that cannot cross the bilayer.

Non-Polar

Molecules O2 & CO2

Small polar

molecules H2O

Large

polar molecules Glucose

Ions

Na+ & K

+

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(ai) In relation to the structure and properties of the bilayer, explain the transport or

non-transport of the molecules shown in the image on page 9.

(aii) Explain what modification(s) to the bilayer structure would need to be made to allow

the transport of large polar molecules and ions.

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(b) Explain how phospholipids could arrange themselves as shown below.

9. The image below shows the entry of the HIV virus into a helper T cell.

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(a) Describe how HIV infects helper T cells.

(b) Explain how scientists could prevent entry of HIV into the helper T cell.

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10. Cell membrane proteins have carbohydrates attached to them in the ER and Golgi

body, then are transported in vesicles to the cell surface. On which side of the vesicle

membrane are the carbohydrates? Explain your answer with an annotated diagram.

11. An experiment was conducted to investigate the effect of temperature on the

permeability of the beetroot cell membranes. Beetroot disks were cut and added to

water and incubated at different temperatures and the colour of the water was

measured using a colorimeter with blue light. The results are shown in the table

below. The lower the percentage transmission reading the darker the red colour.

(ai) Plot the above data on the graph paper on page 14

Temperature (oC) 10 20 30 40 50 60 70

Percentage transmission

of blue light (%)

100 90 80 7 4 1 0

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(a ii) Describe the trend of the graph. Explain if you have confidence in the trend?

(a iii) State the controlled variable for this experiment.

(a iv) Can the reliability of this data be determined, explain your answer.

(a v) Discuss the precision and accuracy of the percentage transmission results.

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(bi) With reference to the structure of the cell membrane, explain the results.

(bii) Explain the difference in the results if the cell membrane was initially treated with

ethanol.

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QUESTIONS ON SECTION 2.0.1 TO 2.3.9 1

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2

0

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1. Consider the graph on page 23 and answer questions 1-4 that follow.

(a) For line A and B calculate the rate between 10 and 20 seconds and 30 and 40 seconds using

equation 3 (page 19). Show you calculation steps.

(b) Quote your answer to part 1a in minutes. Show your calculation steps.

(c) For both lines A and line B would you consider the rate to be constant between 20 and 40

seconds? Explain your answer.

(d) For line C, calculate the rate using equation 4 (page 20) if y is 300 AU.

2. Calculate the percentage change in the number of molecules transported across the membrane

between line A and B at 50 seconds. Show your calculation steps.

QUESTIONS ON SECTION 2.4.0 TO 2.4.5

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3a What is the percentage change in rate between 30-40 seconds and 90-120 seconds for line B?

Show all your calculation steps.

3b When considering your answer to part 3a what do you think is the relationship between rate and

the gradient of the line?

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4a. What are the possible biological explanations for the differences between the rate of line A, line B

and line C between 0 and 40 seconds?

4b. What are the possible biological explanations for the rate of line A between 70 and 130 seconds?

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Time (s)

Nu

mb

er

of

mo

lecu

les

tran

spo

rted

acr

oss

th

e ce

ll m

emb

ran

e A

U

B

A

C

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5. Based on its physical and chemical properties, investigators mathematically calculated a theoretical

rate of uptake for a new drug, called BBR3464 into a cancer cell. An experiment was undertaken to

confirm the theoretical calculations and to determine the exact membrane transport mechanism of

BBR3464 into the cancer cell. The results for both the theoretical and experimental results are

shown in graph below.

(a) Using the information in the graph and your own knowledge on membrane structure and

transport mechanisms suggest, with an explanation, the most likely transport mechanism for

BBR3464.

0

Extracellular Concentration of BBR3464 (mmol/l)

Rat

e o

f tr

ansp

ort

acr

oss

th

e m

emb

ran

e (A

U) 10

5

0 1 2

Key

Experimental Results

Theoretical Results

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Further experiments on the membrane transport mechanism of BBR3464 were undertaken. The results

are shown in the graph below.

(bi) Using both graphs suggest a reason for why further experiments were undertaken.

(bii) Suggest a control variable for the experimental method.

Extracellular Concentration of drug/mmol/l

Rat

e o

f u

pta

ke a

cro

ss t

he

me

mb

ran

e/A

U

0

5

10

0 10 20

Key

Experimental Results

Theoretical Results

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(biii) The structure of BBR3464 is shown below. In relation to the structure of the cell membrane

and the information shown in the image of BBR3464 explain the experimental results obtained

by the further experiments.

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QUESTIONS ON SECTION 2.4.6 TO 2.6.2 1

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2

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3

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4

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QUESTIONS ON SECTION 2.6.3 TO 2.6.7

1

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2

0

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3

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1. The image below shows three cells all in contact with each other and all having a cell membrane.

The number in the cells are the water potential values of the cytoplasm. Draw arrows on the

image to show any movement of water by osmosis.

-257 kPa

B -321 kPa

C

-212 kPa

A

QUESTIONS ON SECTION 3.0.1 TO 3.4.0

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2. The apparatus below was used to investigate osmosis. It consists of a capillary tube attached to a

visking tubing bag both containing solution A. Visking tubing is an artificial cell membrane. The

visking tubing is submerged into a beaker containing solution B. An air bubble is trapped in the

capillary tube. The composition of the solutions are as follows:

• Solution A: glucose 0.01mol dm-3, fructose 0.02 mol dm-3 and sucrose 0.3mol dm-3.

• Solution B: glucose 0.002 mol dm-3, fructose 0.06 mol dm-3 and maltose 0.005 mol dm-3.

The apparatus was left for 30 minutes after which the distance moved by the bubble was recorded

using the ruler.

The visking tubing is not permeable to disaccharides but is permeable to monosaccharides.

Capillary tube

Air bubble

Visking tubing

Solution B

Solution A

Ruler

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ai Suggest with an explanation appropriate solute potentials and water potentials for both

solution A and solution B.

aii Explain in which direction the bubble would move through the capillary tube.

b The starting position of the bubble in the capillary tube was 6.2 cm and at 30 minutes it had moved

to 14.8cm. The internal diameter of the capillary tube is 5.6mm.

bi Using the following equation calculate the volume of water that moved through the

capillary tube. Show your calculation steps and express your answer to 2 decimal places.

V = π x r2 x h π = 3.14

Answer______________________

bii Calculate the rate of water movement during the 30 minutes. Express your answer in

both minutes and hours.

Answers_____________________________________

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c. Name a solute that would:

i. Diffuse into solution A

ii. Diffuse out of solution A

3 A student sweetened some strawberries by sprinkling sugar on top of them one hour before

eating them. The student noticed that the sugar she sprinkled on them was no longer visible and

that there was juice at the bottom of the bowl.

The student thought that the juice was the sugar dissolved in water and that the water had come from the

fruit.

In order to test this hypothesis, she weighed some fresh strawberries and sprinkled them with sugar. One

hour later she rinsed off the juice and reweighed the strawberries. The mass of the strawberries before

adding the sugar was 77g. The mass after rinsing off the juice was 70g.

i. Calculate the percentage decrease in mass of the strawberries. Show your calculation steps.

Answer_____________________

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ii Suggest one possible source of error in the student’s procedure that could make this value for the

percentage decrease in the mass of the strawberries inaccurate. Explain how this source of error

would affect the value for the percentage decrease in the mass of the strawberries.

Source of error___________________________________________________________________________

Effect on value and explanation_____________________________________________________________

iii. Using your knowledge of cell transport mechanisms and the properties of water, explain how the

juice is formed from the water that came form the fruit.

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4. Isolation of mitochondria from liver cells was needed to investigate the effects of different

substrates on the rate of respiration. Images of the isolated mitochondria are shown below.

Explain the appearance of the three mitochondria.

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5

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6

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8. A plant cell has a solute potential of -1240KPa and a pressure potential of 350KPa. What is the

water potential of the cell?

Answer_____________________

9. A plasmolysed cell is found to have a solute potential of -960KPa. What is the water potential of

the cell? Explain your answer.

Answer_____________________

10. A plant cell, after being immersed in pure water for several hours, has a solute potential of -

800KPa. What is the water potential and the pressure potential of the cell? Explain your answer.

Answer_____________________

11. Two plant cells, A and B, are next to each other in a tissue. Their solute and pressure potentials

are: Cell A ΨS -630KPA AND ΨP 380 KPA, CELL B ΨS -650 KPA AND ΨP 320 KPA. IN WHICH DIRECTION

WILL WATER MOVE, FROM CELL A TO CELL B OR FROM CELL B TO CELL A?

Answer_____________________

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12. The diagram below shows two plant cells, X and Y. the figures show the solute and pressure

potential of for both cells and the water potential for cell Y.

i. Calculate the water potential for cell X. Show your calculation steps.

Answer_____________________

ii State the name of the condition shown by cell Y and explain how this condition could

have arisen.

iii Cell X has the higher pressure potential. Explain how this pressure potential is built up in

cell X.

iv Suggest the effect on a house plant if all their cells were in the condition as shown in cell

Y.

Cell X

ΨP = 1000KPA

ΨS = -1800KPA

Cell Y

Ψp = 0KPa

Ψs = -1000KPa

Ψ = -1000KPA

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1. The cytoplasm of three cells, A, B and C have a concentration of sucrose of: 0.2mol dm-3, 0.4mol

dm-3 and 0.65 moldm-3 respectively. Solute potential can be calculated using the equation:

Calculate the solute potential of cell A, B and C at a temperature of 15oC and 37oC. Show your calculation

steps and quote your answer to the nearest hundredth.

Answer for 15oC____________________

Answer for 37oC____________________

2. A cell is submerged in solution A which has a concentration of 250 mmol dm-3. In solution A the

cell has a volume of 1000µm3 and a concentration of 250 mmol dm-3. Water was added to

solution A to form solution B which had a concentration of 200 mmol dm-3. In solution B the cell

had a concentration of 200 mmol dm-3.

i. Using the equation V1C1=V2C2 calculate the volume of the cell in solution B. Show your

calculation steps.

V1 = volume of cell in solution A. C1 = concentration of the cell. V2 = volume of the cell in

solution B. C2 = Concentration of the cell.

Answer________________

APPLICATION & EXTENSION

ΨS = -ICRT Where: -i = -1 C = concentration in mol dm-3 R = Pressure constant = 8.31 T = temperature in oKelvin = 273 + the temperature of the cell in oC.

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3. Plant cell A has a solute concentration of 0.2 mol dm-3 and plant cell B has a solute concentration

of 0.4 mol dm-3. In terms of water potential, explain if these two cells can be in equilibrium with

each other.

4. For a protein to become functional it must be modified after its synthesis. One such modification

is called glycosylation and occurs when proteins have sugar chains added to key amino acids that

make up the primary structure. The drawings below represent red blood cells with a membrane

protein attached to which are different sugar chains. Red Blood cell 1 has been newly synthesised

in the bone marrow, while red blood cell 2 is three month old. The only difference between the

two cells is the glycosylation of the membrane protein with regard to the terminal sugar unit.

Image 1

Due to wear and tear of the red blood cell the terminal sialic acid sugar breaks off, this will target the cell

for destruction by the liver. A single liver cell is shown below.

Terminal sugar unit

sialic acid

RED BLOOD CELL 1

PROTEIN

GAL GAL

SIA SIA

RED BLOOD CELL 2

PROTEIN

3 1

2

GAL GAL

Terminal sugar unit

galactose

Cell membrane

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Image 2

During the life cycle of a red blood cell the haemoglobin inside the red blood cell becomes glycosylated by

glucose present in the blood. The concentration of glucose bound to haemoglobin forms the test for

diabetes called the HBA1c test.

Over a 12 month period a patient had her HBA1c measured and her results are shown below. Diabetes is

diagnosed with a HBA1c reading of >55 moldm-3 and pre-diabetes is diagnosed with a HBA1c reading of 30-

40 moldm-3.

Graph 1

The following questions require you use all the information in this questions as well as your own

knowledge.

LIVER CEll

Protein Receptor Protein

Binding site

Co

nce

ntr

atio

n o

f gl

uco

se b

ou

nd

to

hae

mo

glo

bin

/mo

ldm

-3

30

50

70

0

Time/Months

90

110

130

0

150

3 6 9 12 15

170

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(a) i. State the correct name given to the chain of sugars attached to membrane bound proteins as

shown with red blood cell 1 and 2.

ii. On red blood cell 2 the triangle and the circle represent hexose sugars. Suggest the name of

the bond between circles 1 and 2 and circle 1 and triangle 3.

iii. The terminal sugar in red blood cell 2 is galactose. Compare the structure of galactose with

β-glucose.

(b) Red blood cells are unusual in that they do not have any organelles inside them, just

haemoglobin. However, they do have a cell membrane which has the fluid mosaic structure.

i. State the names of the scientists who first describe the cell membrane as having a fluid

mosaic structure.

ii. State the name of the biological molecule that forms the bilayer of a cell membrane.

iii. Explain how the structure of the biological molecule you stated in your answer to bii gives it

the physical properties required to form a bilayer.

iv. The circular and diamond shaped proteins in image 1 and 2 above represent cell membrane

proteins. In relation to their positioning in the membrane of the red blood cell and the liver

cell, evaluate the physical properties required by these two proteins to explain how they have

come to be positioned the way they have in the two cell membranes.

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v. Using images 1 and 2, and your own knowledge, explain why the removal of sialic acid

causes the red blood cells to be targeted for destruction by liver cells.

vi. Describe how organelles in liver cells could lead to the destruction of red blood cells.

(c) Diabetes is described as a metabolic disorder. It’s a complex condition with several different

causes, for example, type II diabetes can be caused by insulin being less effective at lowering

blood glucose concentration. Whatever the cause of diabetes the result is the same – high

blood glucose concentrations. This can be very dangerous as glucose can cause damage to

nerves and small blood capillaries. To achieve an accurate measure of blood glucose

concentration scientists have exploited the life cycle of a red blood cell and the glycosylation of

the haemoglobin within it.

Using the graph 1, answer the following questions.

i. Suggest how long a red blood cell life cycle is.

ii. Over which time period was there the smallest drop in glucose bond to haemoglobin

(HBA1c)?

iii. When did the patient become pre-diabetic.

iv. Calculate the percentage decrease in glucose bound to haemoglobin between one and

three months. Show your calculation steps.

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v. Which time period showed the slowest rate of decrease of glucose. Explain your answer

mathematically. Show your calculation steps.

vi. Calculate the percentage decrease in glucose bound to haemoglobin between 1-3 months

and 6-9 months. Also express your answer as rate. Show all your calculation steps.

vii. The patient had further HBA1c tests at 18 and 21 months. The concentration of glucose

bound to haemoglobin remained at 30 moldm-3. The rate of glucose uptake to haemoglobin

from 12 to 18 months was calculated to be 0mol dm-3 month-1. Evaluate this answer.

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5. The mammalian kidney has many roles, these include regulating water levels in the body, excreting

waste products like urea into the urine and reabsorbing important substances like glucose, amino

acids and water that have been filtered out of the blood. As the kidney filters the blood under high

pressure a fluid called the filtrate enters the many kidney tubules through the small gapes in the

capillary. Once in the kidney tubules the filtrate composition is altered by reabsorption of

substances along the whole length of the tubule through the cells lining the tubule. The filtrate

now becomes urine which enters the bladder. These events are summarised in the diagram below.

a. i. On the above diagram place an “*” where filtration is occurring and a “#” where

reabsorption is occurring.

ii If the concentration of urea along the kidney tubule is plotted, the line would follow the

equation

Where: 𝑚 is the gradient and C is the value of y when 𝑥 is 0.

Blood from body to

kidney

Blood from kidney

back to body Urine to

the bladder

Start of kidney tubule

Blood capillary 1

Blood capillary 2

End of kidney tubule

Cells lining

the kidney

tubule

Filtrate

𝑦 = 𝑚𝑥 + 𝑐

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The concentration of urea in the filtrate at the start of the kidney tubule is 20 arbitrary units

(AU) and the value of m is 0.2 AU/%. Use these values provided to calculate the

concentration of urea at the end of the kidney tubule and draw a line on the graph below for

the concentration of urea along the length of the kidney tubule. The concentration at the

start of the kidney tubule has been plotted for you.

Distance along the kidney tubule (% of total distance)

Start of kidney tubule

End of kidney tubule

Ure

a co

nce

ntr

atio

n (

AU

)

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The diagram below is a simplified view of the cell membrane of the cells that line the kidney tubule. It

shows three membrane proteins along with the substances they are involved in transporting across the

membrane and into the tubule cell.

i. Using the information about the kidney tubule cell membrane and your own knowledge

explain your answer to aii.

An experiment was undertaken to investigate the membrane transport of glucose. The concentration of

glucose in capillary 1 was increased while the concentration of glucose in capillary 2 was measured. The

graph below shows the results of this investigation.

Glucose

Water

Amino acid

Concentration of glucose in capillary 2 and urine/mg cm-3

Co

nce

ntr

atio

n o

f gl

uco

se in

cap

illar

y 1

/mg

cm-3

12

10

8

6

0 2 4 6 8 10 12 0

2

4

Urine

Capillary 2

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iv State the concentration of glucose in capillary 1 above which glucose will be found in the

urine.

Answer________________

v Using all the information in this question and our own knowledge explain why glucose

concentrations above the answer you stated in part iv would result in glucose being

present in the urine.