Ch3

Chapter 3Chapter 3 Movement of substances across Movement of substances across

cell membranecell membrane

Name:____________________________（　　　） Time and marks

Class: ____________________________

Date: ____________________________

Sections A & B: 35 min / 30 marks

Sections A to C: 40 min / 35 marks

Note:

1 Answer ALL questions.

2 Write your answers to Section A in the boxes next to the questions, and your answers to Sections B and C in the

spaces provided below the questions.

SECTION A MULTIPLE-CHOICE QUESTIONS (10 marks, 1 mark each)

Directions: Questions 1 and 2 refer to the diagram below which shows the fluid mosaic model of the cell

membrane.

1 What is/are the role(s) of structure A?

(1) For cell recognition.

(2) For carrying water-soluble substances across cell membrane.

(3) For supporting the cell.

A (1) only

B (2) only

© Oxford University Press 2009 - 3 -

New Senior Secondary Mastering Biology – Chapter test 3　Movement of substances across cell membrane

C (1) and (2) only

D (1) and (3) only



2 Which of the following correctly shows the path through which sugar and alcohol molecules pass

through the membrane?

Sugar Alcohol

A Path X Path X

B Path X Path Y

C Path Y Path X

D Path Y Path Y

3 According to the fluid mosaic model of cell membrane, which of the following statements is true

about membrane phospholipids?

A They have water-loving tails in the interior of the membrane.

B They occur in a bilayer, with membrane proteins restricted to the surface of the membrane.

C They are free to depart from the membrane and dissolve in the surrounding aqueous solution.

D They can move laterally along the plane of the membrane.

4 A cell that is hypertonic...

A will experience a net movement of water into the cell from the surrounding environment.

B has a lower concentration of solutes than the surrounding environment.

C will experience a net movement of water out of the cell into the surrounding environment.

D is in danger of plasmolysis.

5 The diagram shows an experiment on diffusion.

More sugar diffuses out of the tubing than that diffuses in. What is the concentration of sugar in

solution X?



A 10% B 20%

C 30% D 40%

6 Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small

intestine, however, rapidly move large amount of glucose from the intestinal lumen into their

cytoplasm which has a low glucose concentration. Using this information, which transport

mechanism is most probably functioning in the intestinal cells?

A phagocytosis

B active transport

C diffusion

D osmosis

Directions: Questions 7 and 8 refer to the diagram below shows how a unicellular organism obtains

food particles.

7 The food particle can enter the unicellular organism because

(1) the organism can move towards the food particle.

(2) the cell membrane of the organism is fluid in nature.

(3) the cell membrane of the organism is mosaic in nature.

A (1) and (2) only

B (1) and (3) only

C (2) and (3) only

D (1), (2) and (3)



8 Bacteria never obtain food in this way because

A bacterial cells do not have a true nucleus.

B bacterial cells are surrounded by a cell wall.

C bacteria are autotrophic organisms.

D bacteria cannot move around.

Directions: Questions 9 and 10 refer to two set-ups in an experiments shown in the diagram below.

Beetroot cells contain a red pigment in the vacuoles. Ten minutes later, a light-pink

colour appeared in the water in set-up 1 but the water in set-up 2 became bright red.

9 Which of the following may be the possible reason(s) for the results of the experiments?

(1) The differential permeability of the cell membrane is destroyed by high temperatures.

(2) The pigment molecules move faster under high temperature.

(3) The pigment becomes more intensify at high temperatures.

A (1) only

B (2) only

C (1) and (2) only

D (1), (2) and (3)



10 In what way(s) did the pigment molecules move out of the beetroot cells in set-ups 1 and 2?

Set-up 1 Set-up 2

A osmosis osmosis

B osmosis diffusion

C diffusion osmosis

D osmosis active transport

SECTION B CONVENTIONAL QUESTIONS (20 marks)

1 The figure below shows a mechanism for the uptake of sodium ions into an animal cell through a carrier

protein.



a Name the process by which sodium ions are being transported across cell membrane.

(1 mark)

b Explain why sodium ions cannot move through the phospholipid bilayer. (1 mark)

c Suggest two changes in the cell membrane that could result in an increase in the rate of sodium

ions uptake. (2 marks)

2 State three ways in which osmosis is different from diffusion. (2 marks)



3 Amoeba is a protozoan that lives in freshwater ponds. It constantly discharges excess water in the body

by a special vacuole. The graph below shows the changes in the frequency of discharge in an Amoeba as

the water potential of the surrounding medium decreases.

a On the graph, mark with the letter W the point at which the water potential of the surrounding

medium is equal to that of the Amoeba. Give a reason for your answer. (2 marks)

b Compare the water potential of the Amoeba and that of the surrounding medium when the

frequency of discharge is 30 per minute. (1 mark)



4 Pieces of potato strips were weighed, placed in sucrose solutions of different sucrose concentrations for

half an hour, and then re-weighed. The graph below shows the results of gain or loss in mass, expressed

as a percentage of the original mass, at each sucrose concentration.

a Which two terms can be used to describe the conditions of the potato cells at points A and B

respectively? (2 marks)

b Which sucrose concentration is equivalent to the concentration of the cell sap of the potato tissue?

(1

mark)



c A piece of potato strip is taken from the 0.35 M sucrose solution for 30 minutes, and then

transferred to the 0.15 M sucrose solution. Describe and explain what may occur to the potato

cells. (4

marks)

d Draw a diagram to show the state of the potato cell immersed in 0.375 M sucrose solution as seen

under a light microscope. Label the different parts of the cell and the solution(s) present.

(3 marks)



SECTION C HIGHER ORDER THINKING QUESTION (5 marks)

5 Read the following article and answer the questions.

The structure of cell membrane has been the research subject of many scientists in the past 200 years.

Until the 1970s, scientists believed that the cell membrane

was composed of a phospholipid bilayer sandwiched

between two layers of water-soluble proteins. This was the

‘sandwich model’ (Fig a).

However, further experiments showed that the membrane

proteins have a water-soluble part and a fat-soluble part. If

the membrane proteins are on both sides of the bilayer as

shown in Fig a, it would make the membrane unstable.

Fig a

Electron micrographs also showed that tiny dots are present between the two phospholipid layers.

These tiny dots were suggested to be proteins by Singer and Nicolson. These evidence led Singer and

Nicolson to propose the fluid mosaic model of the cell membrane in 1972.

a Explain why the membrane proteins having a water-soluble part and a fat-soluble part would make

the membrane in the ‘sandwich model’ unstable. (1 mark)

b What were the evidence that supported the hypothesis proposed by Singer and Nicolson?


protein coat

protein coat

phospholipid core


(2 marks)

c Suggest two features of scientific models from the information given in the article. (2 marks)

－ End of test －


New Senior Secondary Mastering Biology – Chapter test Answers

Chapter 3Chapter 3

AAnswersnswers

Section A Multiple-choice questions (10%, 1m each)

1 A 2 C 3 D 4 A 5 A 6 B 7 A 8C 9 A 10C

Section B Conventional questions (20%)

1 a Active transport 1m

b Sodium ions are charged/water-loving/insoluble in lipids. 1m

c Greater surface area of membrane

1m

More carrier proteins

1m

2 A differentially permeable membrane is always involved in osmosis while diffusion does not. 1m

Osmosis refers to the movement of water molecules only, while diffusion refers to the movement of any

molecules including water. 1m

During osmosis, there is a net movement of water molecules from a region of higher water potential (i.e.

lower solute concentration) to a region of lower water potential (i.e. higher solute concentration). During

diffusion, there is a net movement of molecules from a region of higher solute concentration to a region of

lower solute concentration. 1m

3 a Correct labelling of W at the left-most end of X-axis 1m

When the water potential of the surrounding medium is equal to that of the amoeba, no water is

discharged by the special vacuole. 1m

b The water potential of the medium is lower than that of the Amoeba. 1m

4 a A: turgid 1m

B: flaccid/plasmolysed

1m

b 0.25 M sucrose solution 1m

c Water moves into the cells due to osmosis. 1m

The cells gain water and increase in volume. 1m

The cell membrane pushes against the cell wall and the cells become turgid again. 1m

d Correct drawing and labelling of cell structures:

cell wall, cell membrane, cytoplasm, nucleus, vacuole 2m

Cell membrane clearly separates from the cell wall 1m

Label sucrose solution at the space between cell wall and cell membrane 1m

Section C Higher order thinking question (5%)

5 a The fat-soluble part of the membrane proteins will be repelled by both the aqueous medium and the

water-loving head of the phospholipids. 1m



b The membrane proteins have a water-soluble part and fat-soluble part. This implies that the membrane

proteins are not on both sides of the phospholipid bilayer. 1m

Electron micrographs show that tiny dots are present between the two phospholipid layers. These are

suggested to be proteins located across the phospholipid bilayer. 1m

c Scientific models are tentative and subject to change. 1m

Scientific models are built to visualize things that cannot be observed directly. 1m


Ch3

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