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1Science Mock Examination Set 2

LEARNING Higher Order Skills and Thinking Processes in Science Primary 5/6 (Upper Block)© Singapore Asia Publishers Pte Ltd. All rights reserved.Reproducible for home/classroom use only.STRICTLY NOT FOR SALE.Look for other useful resources: www.sapgrp.com

Candidate's Name Index Number Class

SCIENCEEND-OF-YEAR

MOCK EXAMINATION Set 2

DURATION : 1 hour 45 minutes

MARKS :

INSTRUCTIONS TO CANDIDATES

1 Answer ALL questions in Booklet A and Booklet B.

2 Write your answers in the brackets provided in Booklet A.

3 Write your answers in the spaces provided in Booklet B.

4 The number of marks for each question is 2 in Booklet A.

5 The number of marks is given in brackets [ ] at the end of each question or part question in Booklet B.

© Singapore Asia Publishers Pte Ltd. ALL RIGHTS RESERVED.

100



BOOKLET APART I

For each question from 1 to 30, four options are given. One of them is the correct answer. Make your choice (1, 2, 3 or 4) and write your answers in the brackets provided.

(60 marks)

1 The diagram below shows a bird and a cactus.

bird

cactus

red flower

A cell from a part of one of the organisms above is shown below.

Where could the cell be taken from?

(1) The needle-like leaves of the cactus

(2) The stem of the cactus

(3) The red petals of the flower

(4) The body of the bird ( )



2 An experiment was carried out to find out the rate of photosynthesis of an aquatic plant at different light intensities.

bubbleslamp

water

pond weed

The graph below shows the results of the experiment.

Light intensity (lux)

Number of oxygen bubbles produced by pond weed

X

Which of the following is likely to increase the number of bubbles produced by the plant after point X on the graph?

(1) Increasing the light intensity

(2) Increasing the amount of carbon dioxide in water

(3) Increasing the amount of water

(4) Increasing the amount of oxygen in the water ( )



3 The diagrams below show the life cycles of the butterfly and cockroach.

nymph

cockroach

egg

egg

pupa

butterflycaterpillar

Based on the above life cycles, which one of the following statements is not true?

(1) At the pupal and nymph stage, both organisms do not feed on anything.

(2) The caterpillar does not look like its parent but the nymph looks like its parent.

(3) The cockroach has a 3-stage life cycle while the butterfly has a 4-stage life cycle.

(4) The young of both the butterfly and cockroach do not have wings. ( )



4 An experiment was carried out on a part of a plant. 2 rings of the stem were cut off at different depths. The plant was then placed in a beaker of red-coloured water as shown below. Figure 1 shows the cross-section of the stem with the water-carrying tubes and food carrying tubes before any cuts were made.

Leaf A (green)

region X

region Y

red-coloured water

Leaf B (green)

Leaf C (green)

water-carrying tubes

food-carrying tubes

Figure 1: Stem before the rings were cut

The diagrams below show regions X and Y of the stem. The shaded regions show the areas that were removed while the unshaded regions show the areas that were uncut.

portion that was removed

region Y region X

portion that was left uncut



Which of the following shows the colour of the leaves after the cuts were made and the stem was left in the beaker of water with red colouring for a few hours?

(1) (2)

red

green

green

red-coloured water

red

red

red

red-coloured water

(3) (4)

green

green

red

red-coloured water

green

red

red

red-coloured water

( )



5 The cells in our body require oxygen and food in order to produce energy to do work.

Which of the body systems below allow(s) our body cells to receive oxygen and food?

A B C D

(1) A only

(2) A and B only

(3) C and D only

(4) A, B and C only ( )



6 Mavis conducted an experiment on 2 similar seeds. The seed in set-up A was left to germinate in the presence of light while the seed in set-up B germinated without light. They were given the same amount of water every day.

seed

dish

lamp

Set-up A Set-up Bdish

seed

The graph below shows the changes in the mass of the 2 seeds when they started to germinate.

0 3 6

A

B

Time/days

Dry mass

Which of the following explains why the dry mass of the seed in set-up A increased after day 3?

(1) Seedling A absorbed a lot of water.

(2) Seedling A used up the stored food in the seed leaves.

(3) Seedling A started to respire.

(4) Seedling A started to photosynthesize. ( )



7 The diagram below shows a leaf insect.

Which of the following statements is true about the leaf insect?

(1) The leaf insect feeds on leaves by taking circular bites out of the edges.

(2) The leaf insect spends a few hours a day under the sun to make its own food.

(3) Chloroplasts can be found mainly in the leaf-shaped body of the leaf insect.

(4) The leaf insect has 2 body parts and 6 legs. ( )



8 The diagram below shows two plants, A and B, in a pond.

plant Aplant B

If plant A increased very rapidly, plant B may grow less well as it would compete with plant A for .

A light

B nutrients

C space

D carbon dioxide

(1) D only

(2) A and D only

(3) B and C only

(4) A, B, C and D ( )



9 Terrence was given a certain paper Y which changes colour from blue to pink when exposed to water. Paper Y was placed on both the upper surface of leaf A on a plant and on the underside surface of leaf B on the same plant.

paper Y(blue when dry;pink when wet)

leaf Apaper Y on the

upper side of leaf

leaf Bpaper Y on the

underside of leaf

Both papers were left on different sides of the leaves for 30 minutes. What would happen to the colour of paper Y?

(1) The paper on leaf A turned pink first.

(2) The paper on leaf B turned pink first.

(3) The paper on both leaf A and B turned pink at the same time.

(4) The paper did not turn pink on either leaf. ( )



10 The diagrams show three samples of fruit which are found in a park.

Fruit 1 Fruit 2 Fruit 3

The map of the park below shows where the parent plants and their seedlings are growing.

Plant Z

Plant Y

Plant X

Match the fruit to the correct plants in the map above.

Fruit 1 Fruit 2 Fruit 3

(1) Y X Z

(2) Y Z X

(3) Z Y X

(4) Z X Y ( )



11 The graph below shows the changes in the number of two populations of organisms A and B.

AB

Time

Number of organisms

What can be inferred from the graph?

A A could represent a plant while B could be a plant-eater.

B B could represent a plant while A could be a plant-eater.

C If both A and B are animals, A is the prey of B.

D If both A and B are animals, B is the prey of A.

(1) A and C only

(2) A and D only

(3) B and C only

(4) B and D only ( )



12 Selene wanted to make some homemade yoghurt using bacteria and milk. Before making the yoghurt, she conducted an experiment to find out if temperature would affect the growth of bacteria in milk. Which of the following set-ups would enable her to conduct a fair test?

Set-up A Set-up B

(1) 30 ml of cow’s milk at 30°C 40 ml of cow’s milk at 30°C

(2) 30 ml of cow’s milk at 40°C 30 ml of goat’s milk at 30°C

(3) 30 ml of cow’s milk at 30°C 30 ml of goat’s milk at 30°C

(4) 40 ml of goat’s milk at 40°C 40 ml of goat’s milk at 30°C ( )

13 A disease affecting only plants had destroyed all the plants in a habitat. Which of the following animals will not be affected by the event?

A grasshoppers

B praying mantis

C frogs

D snakes

(1) D only

(2) A and B only

(3) C and D only

(4) All would be affected ( )



14 Study the chart below carefully.

Breathing Methods

Group CGroup BGroup A

water spiderwater scorpiontadpole

In which group does the organism below belong to?

(1) Group A

(2) Group B

(3) Group C

(4) None of the groups ( )



15 The diagrams below show a butterfly fish, a clownfish and sea anemone.

butterfly fish sea anemone and clownfish

The 2 graphs below show a special relationship between the sea anemone, clownfish and butterfly fish in the same marine community.

Sea anemone

Clownfish

Clownfish

Butterfly fish

Based on the two graphs above, which one of the following statements is most likely correct?

(1) The number of butterfly fish does not affect the number of sea anemone.

(2) The number of butterfly fish will increase if the number of clownfish increases.

(3) The number of sea anemone will decrease if there are fewer butterfly fish.

(4) The number of sea anemone will increase if there are fewer butterfly fish. ( )



16 The diagrams below show two iron blocks. Both blocks are heated with different flames to 100°C.

Block A Block B

100°C100°C

Which of the following statements is/are definitely true?

A Block B has less heat energy than Block A.

B Block A is hotter than Block B.

C Both blocks have the same amount of heat energy.

D Different amount of time is required to heat both blocks to reach the same temperature.

(1) A only

(2) A and D only

(3) B and C only

(4) B, C and D only ( )



17 Four loads of different masses, A, B, C and D, were suspended at different heights above the ground as shown below.

8 kg

5 kg

8 kg

7 kg

tray of sand

A

B

C

D

Which of the loads will create the deepest depression when they are dropped in the sand?

(1) A

(2) B

(3) C

(4) D ( )



18 Joel heated a substance L for 30 minutes. Then he switched off the flame to allow it to cool down to room temperature. He recorded that substance L is a solid at S°C and a gas at T°C.

10°C30 °C

120 °C

Temperature

30 Time (min)

Which of the following shows the correct temperatures of S and T?

S T

(1) 0°C 100°C

(2) 5°C 125°C

(3) 10°C 100°C

(4) 30°C 120°C ( )



19 The diagram below shows part of the path travelled by a pebble when it is thrown from position A to position B, the highest point in its path, and to position C, a point before reaching the ground.

pebbleA

B

C

Which of the following rows identifies the energy the ball possesses at points A, B and C?

Position A(starting point)

Position B(highest point)

Position C (before reaching the ground)

(1) Potential energy and kinetic energy

Potential energy and kinetic energy

Potential energy and kinetic energy

(2) Potential energy Potential energy Potential energy and kinetic energy

(3) Potential energy Kinetic energy Kinetic energy

(4) Potential energy and kinetic energy Potential energy Kinetic energy

( )



20 The diagrams below show a glass with thin walls and another with thick walls.

glass with thin walls

glass with thick walls

What is likely to happen when boiling water is poured into them?

(1) The glass with thin walls will crack because the thin walls absorb water.

(2) The glass with thin walls will not crack because heat energy cannot pass through thin glass.

(3) The glass with thick walls will crack as the inner walls of the glass expand faster than the outer walls.

(4) The glass with thick walls will not crack as glass is a good conductor of heat. ( )



21 Shelia set up the following electrical circuits to find out if materials W, X, Y and Z were electrical conductors.

W A

X

Z

B

Y

E

D Z

X W

CY

She recorded her observations in the table below.

Bulb Did the bulb light up?

A Yes

B No

C Yes

D No

E Yes

From the observations, which materials are electrical conductors or electrical insulators?

Electrical conductors Electrical insulators

(1) X W, Y, Z

(2) W, X, Y Z

(3) W, Z X, Y

(4) W, X Y, Z

( )



22 The graph below shows the temperature of different states of water at different periods of time.

Temperature (°C)

100

0 A B

C D

E FTime (min)

Which of the following rows shows the correct descriptions of the different parts of the graph?

AB BC CD DE EF

(1)Neither

gaining or losing heat

Gaining heatNeither


Losing heatNeither


(2) Gaining heat Gaining heat Gaining heat Losing heat Losing heat

(3)Neither


Neither gaining or losing heat




(4) Gaining heat Gaining heatNeither


Losing heat Losing heat

( )



23 Mark set up an experiment as shown below.

Set-up A Set-up B

Which of the set-ups below could be carried out to enable bubbles to appear in the container of set-up A while causing water to rise up the tube in set-up B?

(1)

Set-up A Set-up B

cloth at 30°C cloth at 30°C (2)

Set-up A Set-up B

cloth at 10°C cloth at 90°C

(3)

Set-up A Set-up B

cloth at 90°C cloth at 10°C (4)

Set-up A Set-up B

water at 10°C

water at 90°C

( )



24 Megan placed a paperclip on a glass plane and then placed a magnet 3 cm from the paperclip. She observed that the paperclip moved towards the magnet.

She then repeated the experiment with the same magnet and paperclip on a plank of wood. However, the paperclip did not move.

Set-up A Set-up B

magnet

paperclip paperclipplank of wood

glass plane

Which of the following statements best explains the different results?

(1) Magnetic force is weaker on a plank of wood than a glass plane.

(2) The magnet in set-up B is weaker than in set-up A.

(3) Gravitational force is stronger on wooden surfaces.

(4) There is less frictional force acting on the paperclip in set-up A than in set-up B. ( )



25 The diagram below shows a wooden cork floating in a container of water.

jarair

cork

water

Which of the following diagrams shows what would happen when an empty jar is placed over the cork and pushed into the container of water?

(1) corkjarwaterair

(2) corkjarwater

(3) waterjarcorkair

(4) waterjarcorkair

( )



26 Felicia wanted to test if the total surface area at the bottom of a wooden block would affect the time taken for the block to reach the ground from a fixed height.

The diagrams below show the different wooden blocks.

5 cm7 cm

1 cm3 cm

7 cm12 cm

10 cm

7 cm5 cm

7 cm5 cm

3 cmA

B

C

D

1 m

ground

Which of the following should she choose to conduct a fair test?

(1) A and C

(2) B and C

(3) B and D

(4) C and D ( )



27 Ailene attached an iron block on a spring as shown below. The spring then stretched downwards.

spring

iron block

What is the force that causes the spring to stretch?

(1) frictional force

(2) elastic spring force

(3) magnetic force

(4) gravitational force ( )

28 Mike conducted an experiment to find out the effects of 5 chemicals P, Q, R, S and T on limestone. He mixed his chemicals in equal proportions and recorded his results in the table below.

Solution Mixture of Q and S

Mixture of P and R

Mixture of R and S

Mixture of P and T

Observation Corroded No change No change Corroded

Based on the observations, which are the chemicals that caused the limestone to corrode?

(1) P and T only

(2) Q and T only

(3) Q, R and S only

(4) P, Q, S and T only ( )



29 The diagram below shows a waterfall.

At which point does the water possess the most kinetic energy?

(1)

(2)

(3)

(4)( )

30 The graph below shows the average temperature around the world.

Temperature (°C)

Time (Years)

Which of the following are reasons for the results in the graph above?

A Deforestation

B Fumes released from vehicles and factories

C Using products containing CFCs

D Building of greenhouses to grow plants

(1) A and B only

(2) B and D only

(3) A, B and C only

(4) A, B, C and D ( )



BOOKLET BPART II

For questions 31 to 44, write your answers in the spaces provided.The number of marks available is shown in brackets [ ] at the end of each question or part question. (40 marks)

31 The diagram below shows a plant cell.

A

B C

D

E

List down 2 cell parts (A to E) in the plant cell above that can also be found in an animal cell and state their functions. [2]

(a) Cell part :

Name and function:

(b) Cell part :

Name and function:



32 Celine set up an experiment to find out if duckweeds can grow well in soapy water.

duckweeds

Set-up 1 Set-up 2 Set-up 3

?

She then counted the number of duckweeds at the end of 7 days. The results of the experiments are given in the table below.

Number of duckweeds Soap Pond water

Set-up 1 40 1 ml of soap 500 mlSet-up 2 40 2 ml of soap 500 mlSet-up 3

(a) What should Celine put in set-up 3 to conduct a fair test? Complete the table above. [1]

(b) Besides using the same type of soap, pond water and duckweed, what is another factor not stated above that should be kept constant in order for the experiment to be a fair test? [1]

(c) Describe how Celine can find out if fertilizers affect the growth of duckweeds

instead. [2]



33 The diagrams below show the male and female reproductive systems of a human and a flower.

A B

C D

E

PQ

R

TS

(a) Match the organs that produce the male and female cells from both systems in the table below. [2]

Human Flower

Male

Female

(b) Anne brought home some of her favourite fruit and cut them open.

flesh

seedFruit A

flesh

seedFruit B

What can she infer about the number of ovules of the flowers of the two fruit? [1]



34 The apparatus below illustrates the action of breathing.

rubber sheet rubber sheet pushed up

glasstubesbell jars

balloons

(a) What does each of the following structures represent? [1]

(i) Glass tube :

(ii) Balloon :

(b) From the diagram above, what happens to the balloons if the rubber sheet is pulled down? [1]

(c) What do you think will happen to the balloons if a piece of plasticine is stuck

in the glass tube while the rubber sheet is pulled down? [1]

(d) Why do you think our body responds by coughing violently when food goes into our windpipe accidentally? [1]



35 Mike conducted an experiment to compare the rate of photosynthesis between 2 plants, X and Y, when different light intensities were used.

Plant X Plant Y

The table below shows his results.

Light intensity (lux)Amount of starch produced (mg)

Plant X Plant Y

10 4 8

20 9 32

30 20 48

40 24 52

50 33 56

60 43 58

70 60 62

80 75 62

90 75 62

(a) State the relationship between light intensity and the rate of photosynthesis

of plant X from 10 lux to 80 lux. [1]



(b) Based on the results in the table, suggest which plant is more suitable to grow in an area with little light available. Give a reason to explain your answer. [1]

(c) What do you think would be the amount of starch produced by both plants when the light intensity was increased to 100 lux? [1]

Plant X: mg

Plant Y: mg



36 Janice found two feathers belonging to the same bird on the ground. She then conducted an experiment to find out which type of feathers help to keep the bird warm.

Feather A fluffy with many air spaces

Feather B tightly packed with little air spaces

First, she wrapped each beaker containing boiling water with the two types of feathers and recorded the time required for the temperature of the water to drop to 40°C.

Beaker A Beaker B

100°C 80°C 60°C 40°C Beaker A 0 min 10 min 14 min 21 minBeaker B 0 min 6 min 11 min 17 min

(a) What does the experiment show about the rate of heat loss of water using feathers A and B? [1]

(b) Feathers were used to fill the spaces between materials in some winter jackets to keep a person warm. Which type of feathers, A or B, would you suggest to be used as the fillings? [1]

(c) From the structure of the feathers in the diagram, suggest why the feather you have chosen in (b) is able to keep a person warm. [1]



37 Study the food web below carefully.

G

H

D B

A C

F E

(a) Organism B is affected by a disease and decreases in number. How does this event affect the population of F? [1]

(b) Explain your answer in (a). [1]

(c) Draw two arrows and write ‘X’ to indicate an organism in the food web above

such that when ‘X’ is introduced into the community, the population of ‘G’ will increase while ‘A’ and ‘D’ will decrease. [2]



38 Sammy designed a doorbell as shown below.

string

iron bell

fulcrum

steel rod

A

Bswitch

iron bar

State the main energy changes that take place in order for the bell to ring. [2]

Energy in steel rodEnergy in iron bell

Energy in wiresEnergy in battery



39 Kristine conducted an experiment to find out the amount of air spaces present in 3 types of soil. She put 200 g of soil into each of the three containers below.

soil A soil B soil C

She added 200 ml of water into each container. After 15 minutes, the results are shown below.

soil A

water

soil B

water

soil C

water

(a) What would Kristine observe when she first poured the water over the soil in the beakers? [1]

(b) What can she conclude about the three soil samples based on the results of the experiment? [1]



40 Jamie conducted an experiment in which she placed a similar iron ball on 3 similar ramps, A, B and C at the same height. Ramps B and C were painted with a different number of thick strips of paint. The balls were then rolled down the ramps.

Ramp A Ramp B Ramp C

iron ball thick strips of paint

The table below shows the results when the balls reached the bottom of the ramps.

Ramp A Ramp B Ramp CTime (s) 3 4 5

(a) What conclusion can Jamie make about the time taken by the iron ball to reach the bottom of the ramp and the number of strips on the ramp? [1]

(b) The diagram shows a car moving on a road with thick white strips. These strips are often found on curved roads.

What do you think is the purpose of the strips on the curved roads? [1]



41 David conducted an experiment using a string and a ball bearing to find out the factors that affect the time taken for the ball bearing to move from Point A to C and back to Point A again. The tables below show the results.

metal ballA

B

C

Using a 20-g metal ball

Length of string(cm)

Average number ofswings (per min)

5 70.8

10 65.3

15 60.7

20 55.2

Using a 15-cm string

Weight of metal ball (g)

Average number of swings (per min)

10 60.7

20 60.8

30 60.7

40 60.7

Table 1 Table 2

(a) What are the 2 conclusions that David can make about the experiment above? [2]

(b) If David decided to use a 30-g metal ball and a string of 15 cm, suggest what can be done to increase the number of swings to more than 65 swings per minute. [1]



42 Victoria poured 300 ml of hot water (90°C) into glass A. She then sealed it up with an airtight seal. She also poured 300 ml of cold water (5°C) into another similar glass, B.

airtight seal

water at 90°C

glass

water at 5°C

glass A glass B

(a) Draw where water droplets might form in the two glasses after 10 minutes in the diagrams above. [1]

(b) If the two glasses of water were left on the table for 5 hours, would the volume of water in the 2 glasses increase, decrease or remain the same? Give a reason for your answer. [2]

Glass A:

Glass B:



(c) Victoria notices that whenever she buys her favorite crispy fries to take home, the chef would always punch a few holes in the Styrofoam box.

holes

Styrofoam box

How does punching holes in the box help the fries stay crispy? [1]



43 Tricia conducted an experiment on two materials, A and B, to find out how fast each material increases and decreases in temperature over time.

Both materials were heated for 20 minutes. After 20 minutes, both materials were removed from the heat source and were allowed to cool for another 20 minutes.

Time (min)Material 0 5 10 15 20 25 30 35 40

A 30°C 48°C 63°C 85°C 110°C 79°C 58°C 41°C 30°C

B 30°C 42°C 58°C 76°C 90°C 86°C 82°C 77°C 72°C

(a) From the table above, compare the rate of temperature change between the 2 materials. [1]

(b) Tricia wanted to try a ‘cook-it-yourself’ meal in which a block of cooking

material is heated up and brought to the table. A piece of meat or vegetable is then placed on it to cook. The cooking material must remain hot long enough for the food to be cooked thoroughly for about 20 minutes.

a piece of meat

block of cooking material

Using the information from the table above, suggest which material A or B is more suitable to be used as the block of cooking material. Give a reason for your choice. [1]



44 Celine inverted 2 paper cups, A and B, vertically into a basin of water.

She observed that water entered cup A while none entered cup B.

water

cup A cup B air

basin

The diagram above shows what happens when the paper cups were inverted into the water at the same level.

(a) Suggest what could be different about the cups that caused the water levels in the two papers cups to be different. [1]

(b) Explain your answer in (a). [1]

A1Science Mock Examination Set 2


Answers to:SCIENCE

END-OF-YEARMOCK EXAMINATION SET 2

PART I1 (2) The cell in the diagram is a plant cell as it has

a cell wall and contains chloroplasts. The green stem of the cactus helps it to photosynthesize and so contains chloroplasts. Thus option (2) is correct. Options (1) and (3) are incorrect as the needle-like leaves and the red petals of the flowers do not contain chloroplasts. Option (4) is incorrect as animal cells do not contain cell wall or chloroplasts.

2 (2) The graph indicates that after point X, increasing

the light intensity would not increase the number of bubbles produced by the plant. Since the plant is already covered with water, it will not affect the rate of photosynthesis. Increasing the amount of oxygen will not increase the rate as well as it is not needed for photosynthesis.

3 (1) Option (1) is not true as the pupa does not feed

on anything whereas the nymph will continue to eat. The rest of the options are true.

4 (4) Leaf C is located below the regions before

any cut were made. It will turn red as the red-coloured water is transported to the leaf. Leaf B will also turn red as only the food-carrying tube is cut off while the water-carrying tube is still intact and can transport water to the leaf. Leaf A will remain green as the water-carrying tube is cut off and cannot transport any water to the leaf to turn it red.

5 (4) We need oxygen and food to produce energy

during respiration. Option (A), the digestive system, allows food we eat to be digested and absorbed into the bloodstream. Option (B), the circulatory system transports the digested food and oxygen to our body cells to produce energy. Option (C), the respiratory system allows oxygen to be absorbed into the bloodstream.

6 (4) The variable that was changed in the 2

experiments is the presence of light in set-up A. After germination, the seedling in set-up A is able to photosynthesize and it starts making

its own food, increasing in mass. The seedling in set-up B is unable to make its own food and thus does not increase in mass.

7 (1) By elimination, options (2) and (3) are incorrect

as the leaf insect is not a plant and does not have chloroplasts. Therefore, it cannot make its own food. Option (4) is incorrect as insects have 3 body parts and 6 legs.

8 (3) The leaves of plant B are higher than plant A

so it would not compete with it for light. Carbon dioxide is abundant in the air so they need not compete for it. Thus they compete only for space and nutrients.

9 (2) The paper on leaf B will turn pink first as the

underside of the leaf has more stomata and thus more water vapour would escape.

10 (3) Fruit 1 has stiff hairs to stick onto fur of animals

and is likely to disperse randomly around the park. Fruit 2 is dispersed by splitting action. Thus it will be dispersed a short distance around the parent plant only. Fruit 3 has a wing-like structure that enables it to be dispersed further in the direction of the wind away from the parent plant.

11 (1) One indication to determine if they are preys

or predators, plants or plant-eaters, is to look at the population size of A and B. A is more than B which shows A must be a plant or a prey. The other indication is that when A, a prey, increases or decreases in number, B, the predator, will also increase or decrease as well but at a later time after A.

12 (4) To find out if temperature affects the growth

of bacteria, only the temperature of the milk should change while all other variables including the type and volume of milk should be kept constant.

13 (4) If all the plants were destroyed, all other

organisms will be affected as plants provide energy directly or indirectly to all other organisms.



14 (3) The tadpole in group A uses gills to breathe;

the water scorpion in group B breathes using a breathing tube while the water spider in group C uses air bubbles to breathe. The water boatman should be in group C as it breathes using air bubbles.

15 (4) Option (1) is incorrect as can be seen from the

2 graphs; it shows the increase or decrease of butterfly fish will affect the clownfish population and the sea anemone as well. Option (2) is incorrect as if there were more clownfish, there would be less butterfly fish. Option (3) is incorrect because when there is less butterfly fish, there are more clownfish which means there would be more sea anemone.

16 (2) Since both blocks have the same temperature,

they have the same degree of hotness. Block A is larger in size than block B, so it would require more time to supply more energy to reach the same temperature as block B.

17 (1) Object A has the greatest mass and is hung

at the furthest distance from the tray of sand. Thus it has the most gravitational potential energy which is converted to kinetic energy to cause a deeper depression in the sand.

18 (2) Since the melting point of L is 10°C and the

boiling point is 120°C, it is a solid below 10°C and a gas above 120°C.

19 (2) At A, the starting point, and B, the highest point,

the pebble has potential energy. At C, before reaching the ground, the pebble has kinetic energy and potential energy.

20 (3) Option (1) is incorrect as glass cannot absorb

water. Option (2) is incorrect as glass can still conduct heat. Option (4) is incorrect as glass is a poor conductor of heat. Only option (3) is correct.

21 (2) Since bulbs A, C and E light up, W, X and Y

must allow electricity to pass through them so they are conductors of electricity. Z must be an insulator of electricity as bulbs B and D did not light up.

22 (2) AB represents melting where heat is gained by

the ice. BC shows the temperature increasing thus heat is gained by the water. CD represents boiling where heat is gained by the water to

become steam. DE shows the temperature decreasing thus heat is lost by the water. EF represents freezing where heat is lost by the water to become ice.

23 (3) For bubbles to appear in the water for set-up

A, the cloth on the flask must be hot to cause the air in it to expand and enter the water as air bubbles. For the water to be sucked up into the tube, the cloth in set-up B must be cold to cause the air in it to contract so that water can enter the tube to occupy the extra space.

24 (4) The only variable that is changed in the 2 set-

ups is the surface of the material. Wood has a rougher surface than glass. Since the paperclip on the glass moved towards the magnet, and not on the wooden surface, the factor that caused the difference is the frictional forces acting on the paperclip.

25 (3) When the jar is pushed into the water, the air

trapped in the jar prevents water from entering it. The cork will just float on top of the water and will not float in the air.

26 (3) To find out if the bottom surface area affects

the time taken for the block to reach the ground from a fixed height, she should keep the bottom surface area different but the thickness of the wooden block should be the same.

27 (4) The force that pulls the iron block downwards

and causes the spring to stretch is gravitational force.

28 (2) Chemicals P, R and S will not cause any

corrosion to limestone as no change was observed when the limestone was placed in the mixtures containing these chemicals. Thus corrosion to the limestone must be caused by chemicals Q and T only.

29 (3) Option (3) is the point just before reaching the

bottom of the water that has the most kinetic energy.

30 (1) Deforestation reduces the amount of carbon

dioxide being absorbed by plants while fumes from vehicles and factories increases the amount of greenhouse gases in the air. Greenhouse gases cause global warming. Building a greenhouse and using CFCs do not cause an increase in temperature.



PART II31 (a) Cell part: B The nucleus controls all the activities in the

cell. (b) Cell part: C The cytoplasm allows many activities to

take place there.32 (a)

Number of duckweeds Soap Pond

waterSet-up 3 40 0 ml of soap 500 ml

(b) It is the temperature of the water / the location of the experiment.

(c) She should have two set-ups, keeping the number of duckweeds, amount of pond water and the location of the set-ups the same. She should then put fertilizers in only one of the set-ups and observe any difference in the growth of the duckweeds.

33 (a)

Human FlowerMale A Q

Female C T (b) The flower of fruit A has many ovules while

the flower of fruit B has only one ovule.34 (a) (i) windpipe (ii) lung (b) The balloons become bigger / inflated. (c) The balloons will not be inflated. (d) When food gets into our windpipe, air

cannot enter our lungs. Thus we cough to try to force the food out of the windpipe.

35 (a) As the light intensity increased, the amount of starch produced also increased.

(b) It is plant Y. It produces a higher amount of starch as compared to plant X even when the light intensity is low.

(c) (i) 75 mg (ii) 62 mg36 (a) The rate of heat loss is slower using feather

A as compared to feather B. (b) I would suggest feather A. (c) The air spaces in feather A makes it a poor

conductor of heat and therefore, can keep a person warm better.

37 (a) F will increase in population. (b) When B decreases, the population of C will

increase. Thus F will also increase as there is more food for it.

(c)

A

F

CH

X

GD B

E

38

chemical electrical

sound kinetic

Energy in steel rodEnergy in iron bell

Energy in wiresEnergy in battery

39 (a) She would observe air bubbles coming out of the soil.

(b) Soil A has the most air space, followed by soil C and soil B.

40 (a) When there are more strips, the iron ball takes a longer time to reach the bottom of the ramp.

(b) The strips on the curved roads help to reduce the speed of the car so as to prevent accidents.

41 (a) The longer the string, the smaller the average number of swings.

The weight of the ball does not affect the average number of swings.

(b) He can shorten the length of the string to less than 10 cm.

42 (a)

(b) Glass A: The volume of water in glass A would remain the same as water vapour cannot escape through the sealed glass.

Glass B: The volume of water in glass B would decrease as water would evaporate.

(c) Punching holes in the box allows the water vapour to escape and not condense on the box to become water droplets which will drip down to the fries and make them soggy.

43 (a) Material A increases in temperature faster than material B and also decreases in temperature faster than material B

(b) It is material B. It allows heat to be retained for a longer time than material A.

44 (a) There could be a hole in cup A. (b) The hole in cup A allowed air to escape.

Therefore, water can enter to occupy the space.

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