Index

No.
I
MINISTRY OFEOUCATJON, SINGAPORE
PRIMARY SCHOOL LEAVING EXAMINATIONI
0009/2 (A) PSLE
2023

SCIENCE
(BOOKLET A)

Additionol Matetjal$; OpllcalAnswer Sheet(OAS) TotalTomeforBooklel& Aand B: 1 h 45min

INSTRUCTIONS to CANPIQATiiS

1. W te your Index No. in theboxes at ihe topright handcomer.

2. Oonot tum over thispage unOI you are told to do
so. 3-. F-Ollow all.lnstiuctionscareluUy.
4. Answer a.II questions.
5. Use a 2Bpencil to shade your answers on the Optical Answer Sheet (OAS).

,-.. Thisbooklet consists of18printed pages.

\:@ Singapore Examinations andAs-sment Boan!

 2

For each question from 1 to 28, four options are given. One of them is the correct answer.
Make your choice (1. 2,3 or4)and shade your answi,r on the Optical Answer Sheet.
(56marks)

1 What Is one effect of deforestation?

(1J more type<, of plants and animals

(2) increase i)l carb.on dioxide

(3) Increase in oxygen

(4) lower temperature

2 Which group of organisms hasa three-stage life cycle?

(1) beetle, chicken and frog

(2) chlci<en, frog andgrasshopper

(3) butterfly, frog andgrasshopper

(4) beetle, chicken andoockroach

3• Study the lollowlng structures.

Structures RandShelp the seeds to

(1) obtain sunlight

(2) obtain water

(3) germinate

(4) disperse
 3
4 The diagram:shows lhe human digestive
syst&m.

. A Js==,:-.

8--,.G.-/!

--0
.H---E

Which graph correctly shows the amount of undigested food leaving each organ A, B, C, D
and E after a heavy meal?

(1) (2)
Amount of Amount of
undigested undigested
food food
(units) (units)

ABCOEorgan

(3) (4)
Amount of Amount of
undigested undigested
food food
(units) (units)

OCBAEorgan EDCBAOrgan

00091Q2(1')
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Pa\
 4

5 Thetabl-eshows how animals canbe group-ed.

Gives birth Lays eggs

Can.swim A B
Cannot swim C D

The diagrain show&-anlmal X.

w-abbed feet

Which group does animal Xbeloog to?

(1) A

(2) B

(3) C.

(4) D

6 Thegraph shows the number of bacteria P and Q atdifferent temperatures.

Number
of
bacteria
,, '
' '' '
bacteria P , ,
' ,
''
'
'
0 10 20 30 40 Temperature 1•c

Which temperature is themost suitable for bothbacteria P andQ to

grow?

(1) 20 •c

(2) 2s •c

(3) 30·c

(4) 38 ·c
 3
4 The diagram:shows lhe human OOOM>2(A)
digestive
syst&m.

00091Q2(1')
(Go on to thenext
Pa\
 5
7 George-wrapped and tied ablack plasticbagaround part of a green plant as
shown.

leaves exposed to light

Food produced by the expo.sed leaves.ls transported .

(1) upwards only"by thewater carrying tubes

(2) downwards only by the foodcarrying tubes
(3) upwards anddownwards by lhe foodcarrying tubes
(4) upwards and downwards by both the water and foodcarryingtubes

8 The diagram shows the female part of a flower. There are tt,ree sections, P, Q andR
p

Which statement(s) ls/are correct?

A Pis where pollen grains.land.

B Q is where fertilisation occurs.

C R is where a seeddeyelops.

(1) A only
(2) A and Conly
(3) B and Conly
(4) A, BandC

00091'02(A)
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page)
 6
9 Devi wanted to know if substance S could keep ants away. She conducted ari experiment
using lwo Identical .glass containers P and Q. In P, she put in some ants, food and
substanoe S as shown.

cover

an1s on wail
of glass oa-a::J--substance S
container

glass container P food

.
Which diagram shows corr&ctly what must Deviput into glass container Q for a fair test?

(1) (2) -- --.- "'-.-- --

glass container Q glass container a

(3)
. (4)

tt I
11 I
II I

glass container Q glass containe<Q

000!.\'0'2.;A)
 7
10 The graph showshow the amount of light affects the rate of photosynthesis.

Rate of photosynthesis (units)

/
/
/
/
Amount of light
0 / 500 1000 1500 2000

(units) Sherwin and Michael ma<le the following statements.

Statement

Therate of photosynthesis increases "'(hen the amount of light

Sherwin
IAbove 1500untts, incneasing the amount of light has no effect on
'
incneases fromOto 1500 units.

Michael the rate of photosynthesis.

Who ls/are correct?

(1} Sherwin only

(2) Michael only

(3) BothSherwin and Michael

(4) Neither Sherwin nor Michael

-
11 Which termIs given to all the grasshoppers shown in a garden?

-,-.-. . .....
Mr
,\I( ----
grasshopper

d...

(1) population

(2) predator

(3) habitat

(4) communJty

0009i'02(A) (Go on to thenext page)

 8
12 Jeanie used four similar le.aves, A, B, C and D, of the;same mass to conduct ao
e,i;penm'lflt These leaves have more stomata (tiny openings) on their bottom surfaoes
thanoo theirlop surfaces. Leaves losewa.ter through their stomata.

She ooated some surfaces of the leaves with oil as shown in the table.

Loaf Treatment
A nooil .
B oil on bottom surface
C oil on lOp surface
D oil on top and bottom surfaces

Alter the leaves were leftIn an open area for anhour, she removed the oiland measured
the mass of each leaf. Which shows themass of the leaves In increasing order7 ••

(1) A,B,C,D

(2) A,c,s,o·

(3) D, B,C, A

(4) D, C, B, A

13 Fatimah investigated lhe·effect of light on the germination andgrowth·of-plant M. She

placed three seedsin each of twoidentical oontainers, RandS. and wat-them dally.
R wasplaced Ina well-lit room, while S wasplace.d in a dark room. Both rooms were kept
at the sametemperature.

She observed the following on Day 5.

R (well-lttroom) S (dark room)

What can she conclude from theinvestigation?

A The seeds need warmth for germination.

B The seeds donot needlight for germination.
C The seedlings grow fasler In the dark.

(1) Aonly

(2) B only

(3) Band Conly

(4) A,BandC

""°""'(A)
 9
14 J.iamin placedfivefruit fliesina jar containingfoodand water.The diagramshowsthe numb<!r
of fruit flies over 25 days.

netting
with
holes

dead flies
fruit fly

food.and water - :=::::'7

• •
Day1 Day10 Day17 Day25

Whichrow gives the correct conclusion, and reason for death of t e flies?

Conduslon based on observation Possible reason for death of flies

fr.om Day 1 to Day 17 from Day17 to Day25
(1) Living things respond Not enough air for the flies
(2) Living things reproduce Not enough air for the flies

(3) Llvlng things respond Disease

(4) Living thingsreproduce Disease

15 A crab is covered in a shell made of matefial w. The shell supports the body and
protects theinternal ol'l!ans of the crab. •

Whichproperty of materlal Wallows the shell to perform these functions?

(1) ability to float on water

(2) flexibillty

(3) strength

(4) watelJ)roof

OOQ9!02(A) (Go on to the next page)

 10
1 The.diagram shows a water·cycle.

river
'

Whichprocess(es) represent(s) condensation?

(1) A only

(2) B only

(3) Conly

(4) B andConly

17 Zhiming held magnet A on a slope. When he placed magnet B at the top of lhe
slope, magnet B moved down1he slope before coming to a stop as shown.

Which force(s) acted on magnetB when tt stopped?

Friction Gravitational force Magnetic force

(1) • • Key
(2) • • x . ,
• Y86
no
(3) •
(4)

000Qt'02(A}
 11
18 Some workers unrolled a netting to kee.p poople out of a work area.

netting
endof netting
fixed to wooden
rod

rolled

'""'41-l-+-+-f- l-f-4-11-4<-----.i;t"----

Based on the properties shown, whichmaterial is most suitable for making the netting?

Property
Material Key allows light to
strong flexible Dassthrouoh
yes
X
(1) A no
(2) B X

(3) C X

(4) 0 X X

19 A v.'Orker wants to fit a metal rim onto a metal wheel as shown. The wheel is too big for the
rim.
metalrim

How could the worker fitthe rim on the wheel?

(1) heat the rimandplace it over the wheel

(2) heat the wheel and placeIt in the rim

(3) ·cool the rim and place It over the wheel

0009I02(A} (Go on to the next

page)
(4) _ cool lhe wheel andrim to12
the same temperature and push them together

000Qt'02(A}
 13

20 Al Choo lighfed a candle inside a papeclantem·as,shown. After a While,p _)( of-the.paper

lantem becam&brown aod started to !,um.

metal wire

paper
fl me

Whfch statement bestexplains why part X started to bum?

' '
(1) Air is a·bad,x,nductor of heal

(2) Metal is.a go.od conductor of

heat.
' '' .
(3) Paperis a poor con-ductor of
heat.

(4) The cardboard base is a poor oonductor of heal

21 A bulb was conn_e,;ted in a cir.cult as shown.

When the switch was closed, ihe bulb-blew.

What would have prevented the bulb from,blowing?

(1) adding a bahe,y In series

(2) adding anotheriwltchin series ,

(3) closing the.switch more slowty

(4) using fewer batteries

''
OOOP/02(A) (Go on to1h11next
page)
 12
Hassan b_as·a,1oy. IN.henpart S of th&toyis pushed down, the ball moved as shown.

ball
.....0. ----......
,' ,," Q ......
path of/ ''
ball / net
'
'
'
''
I
''

Whichs.tatement on forcesis not correci?

(1} A foroe pushed theball up at P.

(2) A force is pulling theballdownwards at P.
(3) Theball slowed down from P to Q because of its weight.
(4) The ballstarted to fall at a as thepushing force Is usedup.

23 Which components can beplaced at A and B of the circuit.without changing the

brightness of bulbL?

A
L

.
A B

(1) ---l -®.-

(2) f- ---0--
(3) ---0-- _/_

(4) _/_
---0--

Oei09i'02(A)
 15

Diagram 1
Leela next placed object P aoove object.X as shown in Diagram 2. She repeated the
experiment with object Q·as shown in Diagram 3.

Diagram 2 Diagram 3

Which conclusion about objects P, Q and X is

correct?

p Q X
(1) nota magnet magnet non magnetlcinaterial

(2) magnetic material magnet magnetic material

(3) not a magnet magnetic material magnet

(4) non-magnetic material magnet magnet

25 Which of the following is .not

matter? t1) a beam of light

(2) a cloudin the sky

(3) a stream of water

(4) melting ice.cream

001»102(A) (Go on to thenext page)

 14
24 26 Twodifferent
Leela measured the springs
massXofand Y have
object the same
X a-sshown in length.
D.iagram
1. When two l!:lentical blocksare plac!l(! c:>n the $!)rings, the resultsare as shOwn.

4cm y

table top _,,=

Which graph·correctly shows the relationship between the elastic spring force and the
compression of the springs X andY'J

(1) (2)
cornpr$ssion compression

X y

y
X
0
0
force force

(3) compression
(4) compression

y X

0009/02(A)
 15

object spring balance

wJl.,rJv/ -1/;£/#,v;; able

Hisresultsare as shown.

Mass of
-
Surface areaIn fo,ce needed
Experiment
object contact (units)
(g) with table (cm')
A 20 4 4.0
B 20 8 4.1
C 4-0 4 8.0
D
- 40 8 7.9

Whiph two experiments support the hypothesis: "The force needed to move an object is not
affected by the surface area of Illeobject in contact with the table."?

(1) A and B
(2) AandC
(3) Band C
(4) BandD

28 Th.e length of Eva's shadow near a lamp post over some time is as
shown. length of Eva's shadow

What was Eva doing during that time?

(1) walking towards the lamp post

{2) walking away fromIlle lamp post
(3.) jumping up and downnear the lamp post
(4) standing still near the lamp post
(Go on to Boo le\ B)

0009/2B
 16
27 Gopalu,;ed the set-up shown to investigate the fo,ce needed to move an object.

PASTE YOUR
BARCODE
LABEL HERE

MINISTRY OF EDUCATION, SINGAPORE

PRIMARY SCHOOL LEAVING EXAMINATION

0009/2 (B) PSLE

2023

SCIENCE
(BOOKLETS)

Total Time for Booklets A and B : 1 hour 45minutes

INSTRUCTIONS TO CANDIDATES
1. Please check thatyourname, school and index number areprinted CORRECTLY
a
onthebarCQde. labelbefore pastingwithin thebox provided.
2. Donot turnover this page until youare told to do so.
a. Followall instructions carefully.
4. . Answer allquesdons.
5. Use a darl<blue or !?lack ballpointpen towrite your answers and use a pencil
tordrawings, diagrams or graphs.
6. Do not use correction fluld/tape.
7. Donot usehighlighter Qnany part of your answers.
8. If you use an Additional Booklet to write your answers, paste another o.f yourbarcode
labels onthe cover page of theAdditional Booklet. At the endof the examination,
youmust:

D
a. Insert theAdditiooal Booklet(s) between thepages of the mainAnswer Booklet

b. Write the number ofAdditional Booklet(s) that youhaveused in this box

,r-,. Thisbooklet consistsor12printedpages.

- Singapore.ExaminationsandAssessment Board

0009,'(}2(Aj
©MOE

0009/2B
 2

Fotquestions 29lo 40, Wlite your answers in )hisbooklet. Thenumber ofmal1<s available is shown
in brackets( ] al the end of·eachquesUon or part question. (44 marks)

29 (a) Use a pencillo tlrawlhe life cycle of•amosquito using only words andarrows. [1]

(b} State one characteristic of the aduHmosquito thatclassifies it as anInsect [1]

Johnstudied the effect of temperature on thelifecycle ofmosquito'es., His findings are as

shown.
Number of.deys
to complete
one life cycle

Temperature I •c

(c) Explainhow global warming willaffect thelife cycle of mosquito_esand)henumber of

adult mosquitoes. • • [2]

0009128
 3

30 The table shows tile amount of blood transported per minute to some parts of tile
body when a person Is resting andjogging. •

Amount of blood transported perminute (units)

Part of body
Resting Jogging
Leg muscles 900 4700
Digestive system 1200 720

(a) Explainwhy there is an increasein theamount of blood transported to the leg

muscles when jogging. [2]

(b) Using the information given, explain hpw the absorption of-digested food is
affected during jogging. [2]

(Go on to·the next page)

0009/2B
 4

31 A special disc can be.used to findouthow !)diluted water is.Polluted water has dirt
in it. The discis tied to a rope and loweredinto water ijntilit can no longer be
seen.

disc

Yunxi used the same disc tomeasure the depth at whichacanno longer be seen In
three different lakes. Theresults are as shown.

Depth at which disc can no longer be seen (cm)

LaRe
1 •measurement 2/'IC measurement 3-;i measvreme·nt

R 345 355 355 .

s 750 745 755
T 580 575 585

(a) State one variable that was change(/. (11

(b) Expfai.n why theresults werereliable. r11

(c) Based on Yunxi'sresults, identify the lake that wasleast polluted. Explain why. [21

0009/2B
 5

32 A scientist made the following obse,vations of organisms B, C, E, F and G:

• B and C live in the water, and feed on F.

E liveson bothland and water, and eats both B and C.
• G lives on land and feeds on E.

(a) Draw a food web to show the relationships among all the organisms above. (21

(b) Organism E builds a nest in water for shelter as shown.

, £- r.
...- ';,I= ) :
'.
,._.r
·
·s, ..
'
entrance to •
the nest

Using the food web in (a) and theiolorrnation above, suggest two advantages of
the nest for the sufVival of E. Explain your answer. [2J

(Go on to the next page)

0000128
 6

33 (a) Organism Pis made of oneoell and it lives in a pond.

nij [eus

....
- :.,
cell membraoo--------'"-i',

Organism P

Organism P can make Its own food.

Whichpart of the cellenables it to make its own food? (1]

Fiona placed soma pond water with organism P in a dish as shown in Diagram 1. She
cut twoholes in a sheet of aluminium foil andcovered the dish as shown in Diagram 2.

..,..--... organism P hole

dish with ,-
pond water .:::::::::: aluminium
foil
Diagram 1 Diagram 2

She left tile dish under bright light for some time. Diagram 3 shows what she observed
when'sheremoved the aluminium foil.

Dlsgram3

(b) State the characlerlstic of living things!hat is shown by organism P. [1I

(c) Suggestwhy organism P behaved as observed by Fiona. f1(

0009/28
 7

34 Insect M lays anegg inthe ovaryof a flower of plant Y and rubspollen grains
onthestigma of the same flower.

Theegg of insect M hatches in thedeveloping ovary and its youngieeds onthe seeds of
plant Y.

seed
young of insect M

inside of fruit ol plant Y

(a) State thepart of the flower that thefruitof plant Y developsfrom. [1)

(b) Explain how rubbing pollen grains on the stigma of the flower benefits both
theplant and·iniact M. [2)

35 Ali sprayed some handsanitiser onhis hand.

(a) Slatewhy Ali's handbecame dry veryquickly. [1)

(b) All sprayed hand sanitiser- on his hand again and blew on It. Explain why his
hand felt colder than before. [2]

(Go onlo thenext page)

0009/2B
 8

36 Thomas carried oyt a·n experiment with a toy boat. He turnecj the propeller to twist. the
rubber band before releasing the boat into a bathtub filled with water. He meas.ured the
distance moved by the boat There was no wind•during the experiment.

rubber b81)

His resultsare as stiown.

No. Distance moved (cm)

oflurns of First try .
Seoond try
propeller
10 1J;.5 14.4
20 24.6 26.3
30 39.2 36:0

(a) State how the number of turns of the propeller affected the distance movedby
the boat. [f]

(b) Fill in lf>eboxes.to sh:ow the enelgy conversion when the boat is moving. {2]
rubberband propeller boat
: · , ,
' :,
---+ + I
'
+
'
·-' •
- ' - - -
- - - J :

(c) Suggesta ·reason why the-disiance moved for both tries are different for 20
tum.s.of the propeller when Thomas released the boat at the same edge of the
bathtub.

[1)

0009/2B
 9

0009/2B
 1
0

37 Meimeicookedsomevegetablesusing oil Fin a heatedpan.She measured thetemperature

of the pan before adding the vegetables untilafter the pan was washed. Her results are
as shown.
temperature of pan ('CJ

180
1
60
r I
' -
140 -- -·
· -·
120
-·
- \ -
1.00
80 -
- I ' \
\
I
I

o - .
; -

40 --· '\. -

I.I- I . Ume (min)

'-· 1 2 3 4 5 6 7 8 9 10

(a) Stafe the room temperature. (1)

(b) State the time.at w11ich she put the vegetables into the pan. [1)

After oooking, she poured the hot oil into the sink. Oil F hasa melting point of 40'C.

hot oil
sink

sink protector X
to catch solid waste

wa er pipe

(c) Several months later, the water pipe b low the sink wasblockedby a solidat X.
Explain why a solid was formed In th.a water pipe even though tire sink
protector prevented solid waste from entering. (2)

(Go on to tho nextpage}

0009/2B
 10

·38 In the circuit shown, P and Qare identical bulbs. All components are

woli<ing. fixed iron cylinder -r-, p Q

, m.etal contact
B •'
•'• '-,
metal contact JS
iron bar
-'

metal.contact metal contact

When switch Sis closed, the ironbar movesup anddownbetween pointsAand B, andbulb
P turns on andoff repeatedly.

(a) Explainwhy the iron ar moves between A ant! B repeatedly. [2)

(b) Statewhich bulb(s) is/a.re lighted when the.iron bar is at A. [1l

(c) When the ironbar ; ·at B, state how the brightness of bulb Q.changes. Explain your
answer, [2]

0009/2B
 11

39 Kenneth sets up an electric circuit ina toy using identical bulbsand batterie,; as
shown. All the circuit components are wooong.

fixed metal plates

battery

fixed metalplate

Whenhe closed the sw'rtch, tilebulbs did not light

up. Use a pencil to complete the circuit below.

• Correct the mistake(s)
• Connect thebulbs such that
if one blows, tile other willsijll belit and
the bulbs willlight up only when the switch is dosed. (3)

8
(
'
-
>
> l
L'- '-
,

(Go onto thenext page)

0009/2B
 12

40 (a) State what bollingmeans. (1)

An engineer wanted to test if an eleciric pol can be used on a table with a thick glass
top. He heated water in the pot for one hour.

water

(b) (i) Explain why part A of the glass top washotter than part.B. (1)

(ii) The glass top cracked after some time. Explain why. (ti

End of Paper

0009/2B
PSLE YEARLY
SCIENCE
ANSWERS
2023 6. (3)
Booklet A
Explanation:
Though the amount of bacteria Q
1. (2)
Explgnqtion: is highest Qt 3-8 °c, this is also the
Deforestation leads to fewer trees temperoture where the omoullt of
ovoiloble to toke in corbon dioxide bacteria P is very low. The omount
for photosynthesis. Also, during of boctE!riOP is highest ot 30°C. The
deforestation, the trees ore cut omouot of bocterio Q is very high ot
30 •c.
and burnt, releosing morecarbon
dioxide into the oir.
7. (3)
2. (2) Exolonation:
Exi:ilonation: The food-carrying tubes ore found
Chicken, frog, grosshopper and in all ports of the plant. Food mode
cockrooch hove a thrnc-stoge life in the leoves ore transported to all
cycle. Beetle ond butterfly hove l)(lrts of the plant through the food
o four-stage life qJcle. carrying tubes.

3. (4) 8. (2)
flcolanation: Explanation:
Both structures assist in the Pollen grains land on stigma {P)
dispersal during pollination.Fertilisation occurs
of seeds. in the ovary (R). After fertilisation,
the ovary develops into o fruit and
4. (4)
the ovulesdevelopsintoseeds (in
Explanation: the
The amount of undigested food in
OVO'lJ).
themouth (A) and the gullet (B) is
the highest and the some as
9. (2)
nodigestion tokes place in the
gullet. Jn the stomoch, some E!!pJan :
digestion tokes ploce and less The changed vodable is presence of
undigested food is found here. In substance S. So, container Q should
the small intestine, digestion is not contain substances.
completed. Thus the amount of
undigested food i.s the lowest ond 10. (3)
the some in the smoll intestine (D) .ExplOl)Otion:
ond the large intestine (E). As seen ir"l the graph, the rote of
photosyothesis increases when the
5. (2) amount of light increases from O to
ExplQl'lOtion: 1500 units.Above1500units, the rote
Webbed feet shows that onimol X of photo$Yn1hesis remains constant
con swim.Hoving a beokand feothets even wher"l the amount of light
show1hotonimol Xisa birdond birds increases.
lay eggs to reproduce.

1
PSLE Yearly Science - Answers
11. (1) 14, (4)
f J lonotion: .Explouation:
A popufotion is defined as a gmvp The number oi fruit flies increased
of orgonisms of the some kind from Doy 1 to Dou 17 showing !
hot living together and reproducing in living thingsreproduce. From Doy 17
o porticulor place. Grasshoppers eot to Doy 25, there is a huge
decreose plonb, so they ore not predators. in the number of fruit flies,
posslbly A habi1ot is the home of on animal due to disease. The nettingwith
hOles or a plant. sugg ts thot 1here is plentiful air
Acommunity isagroupof popu1CJtiohs supply for the fruit flies.
of different organisms living in the
some area at a given time. 15. (3)
Explonotion:
12. (2) MotedoI W must bestrong in o,der
to Exofonotion: support the body and to protect
U1e With no oil on leaf A, the water loss internal organsof the crab. Ability
to through the stomoto is thegreatest. Roat, fle.xibility andbeing
waterproof Thus, leaf A willhove the least moss. wiU not support the body or
protect With oil on the top surfoce of leaf the internal organs of the crab.
C, there islossof water through the
stomoto on the bottomsurfoce of the 16. (2)
leof. Thus, leaf Cwillhove less water Explanation:
lossando greatermosscompared to Water from the river evoporotes to
leof A. form water vapour which rises up
With oil on the bottom surto,e of to the sky. The water vopour then
leaf 8 (v1.•hich hos more stomata), condenses to form tiny water
droplets leof B will hove less woter toss ond {known os clouds). When the clouds
a greater mosscompared to feof C. get heovy. the tiny woter droplets
With oil on both toP ond bottom combine to foll as rain.
surfaces of leof 0, the woter Joss is
the leost,·.sothe mossof leaf O is the 17. (4)
grootest. .bllla!:'otion:
Grovitotior1ol forc;e olwoys octs on
13. (3) objects on Earth. Frictional force
xplonotion: must be present, otherwise
magnet The seeds were placed in rooms ot 8 will not come to a stop.
Mognetic thesometemperoture, thusit cannot repulsion existsos magnet 8
stopped show that seeds need warmth ior at o distance from magnet
A. gerrnlnotion. Seeds in both rooms
germinoted, showing that light is 18. (3)
not needed for ge-rminotion of seed$. fxQl,anotipn:
The heightqf the seedlingsplaced in The material used to make the net
the dork room is greater than that needs to be strong so that it will
not of the seedlings placed in the well- beeasily broken, flexible sothatit con
lit room, showing thot the seedlings be tolled up, and not allow light to
grow foster in the dor<k. poss through $0 that people ,an
see
the netting and be ke-pt out of th@
work area.

2
 PSLE Yearly Science - An-swers
19. (1)
24. (4)
Explanation: ploootioo:
When the rim is heated, it e.xponds When object Pisplaced oboveobject
and becomes larger than the X. there is no change in the moss
wheel. This allows the rim to be of object X., this suggests that
fitted on the wheel easily. there is no magnetic
repulsion/attraction between
20. (3) objects Pand X.
Explonoti9,Q: When object Q isploced
As poper isapoor conductor of aboveobject X, the moss of object
heot, it connot conduct heat away X increases:, suggesting magnetic
quickly. Thus, port X which is repulsion between objects Q and X.
closest to the flame willabsorb Therefore objectsQondXmust
more heatandburn. bemugnetsand object P must be
non-magnetic.
21. (4)
Explanation: 25. (1)
The bulb blew because there is too lonation:
much current flowing in the circuit. Matter hos massand tokes up space.
Thus, fewer batteriesmust beused Light is o form of energy. andit
to reducetheamount of current does not have moss. and will not
flowing in the circuit. 1oke up space.

22. (4) 26. (1)

fxplongtion: pJanation:
Gravitational force is constantly X is exposed to one unit of weight
acting on'the boll, causing it to on it but Y is exposed to two units
slow downofter on initial of weight and also the weight of
upwardsforceat point P. At point Q, X. However, both springs ended up
the gravitational force causes the with the same length, suggesting Y
boll to start to foll downwards. is stiffer than X. This means that in
order to hove the some amount of
23. (4) elostic spring force, X would need
Explanotion: to be compressed more than Y.
Adding a bulb or switch at B will
not hove any effect of the 27. (t)
brightness of bulb L. Explonotion:
Adding a battery with opposite Jn order to prove that force
terminals facing the other bottety needed to move on object is not
at A will leod to bulb L to become affected by the surfoce oreo of the
brighter, as more current flows obje<.t in contact withthe table, we
through the circuit. willchoose different surfoce areas
Adding battery with some terminals of object in
facing the other battery ot A will .contact with the table {changed
lead to bulb L to not light up, as variable). All other vor•ables ore to
no current flows through the be kept constant (for example,
circuit. moss of object, type of toble
Plo<ing o light bulb ot A will lead surface).
to bulb l to become less bright.
Plodng o switch at A will not
change the brightness of bulb L.

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PSLE Yearly Sdence -
Answel'$
28. (4l intesHne, less digested foodcon
£xplonotion: enter the bloodstream.
Walking towords or away from the
lamp postandjumping up anddown
neor the lamp post will cause the
shodow of Evato increasc/deCfease in
length. Standing stm neor the fixed
light source will hove the length of
the shadow remaining the same.

(bl Three pairs of legs I Three

body parts/A pair of leeler>(Any
one)
(c) During global worming, the
temperature of the
surtoundings increases. From
the grnph,osthe temperature of
thesurroundings increases,
thereorefewernumber o1days in
o completelifecycleof
themosquitoes. This meons
that the mosquitoes grow into
adults in fewer days, leading to
more adult mosquitoes.

30. {a} WhEm jogging, more energy

is needed bythe legs. Theheart
will pump more blood to
transport more oxygen and
more digested food to the legs
so that more respiration can
take place to produce more
energu. At the
$0metime, more corbon
dioxide con be corried owoy
fromthelegs to the lungs to be
exhaled from the body.
(b} There will be less absorption of
digested food during jagging.
More bloodistransported to the
leg muscles instead of the
small intestine of the digestfve
system. Therefore,ot the small
4
31. (a) The different lokes.
Note: Eoch lake hos
different omovnt'Sof dirt in
it.
(b) The experiment was
repeated three times for
each lake.
(c) Loke S. The disc con be seen
up to on overo-ge depth of
750 cm, whic:his the deepest
of the three lokes. This
means there is least dirt in
lake S to block light from
entering the lake.

32. (al /""-,..

F E G

C
/
(b) When i1s nest is built in
woter, organism E con hide
from predator G which lives on
land. Organism £ con eat
organi.sm.s B ond C which
liYe in water.

33. (a) Chloroplast

(bl Living thingsrespond to
changes. (c} Orgonism P needs
light to make
food.

34. (al Ovary

(b) Rubbing pollen grains on
the stigma tesvlt:$in
pollination and subsequently
fertilisation of the flower.
Fruits of plant Y con be
developed from the ovary
after fertilisation. The
continuity of plant Y is
ensured. The young of
insectM con feed on the
seedsof plant Y.
 PSLE Yearly Science - Answers
35. (a) The liquid hond sonitiser goins 38. (a) When switch S was closed, o
heot from Ali's hand and dosed circuit is formed and
PSLEevaporates to- fotm o vapour.
Yearly Sdence ollows electric current to flow
Answel'$
(b) The presence of windspeeds up through bulbs P and Q and the
the rate of evoporotion. More fixedironcylinder whichbecomes
heat is goined by the hand on electromognet. Bulbs P and
sanitiser to evaporate foster into Q light up. The electromagnet
o vopour. ottrocts the iron bor which
Exglonotion: moves to point B and
touches When Ali blew on the hond the metal contacts. This
causes sanitiser, moving air (wind) is electric current to stop
flowing prese-nt. throughbulbPand thefoced iron
cylinder. Bulb P no longer lights
36. (o) The gre01er the ,,umber of turns up. The fixed iron cylinder stops
of the propeller, the longer the workingasonelectromagnet and
distonce moved by the boot. no longer attracts the iron bor.
(b) E:!ostk potential energ!l kinetic The iron bor falls boc.k to
point energy + sound energy+ kinetic A. touches the metal contacts
energy anddoses the circuit. The
process Note: When thepro ller moves, thenrepeots, ondironbar moves
$0Und con be heard from the up and down between points A
movement. and 8, and bulb P turns on
ond
(c) The humon reoction time con off repeatedly.
affect the releose of the boot. / (b) Bulbs P and Q
Thewater couldbe movingwhen (c) Bulb Q is brighter when ironbor
the boot wos releosed. (Accept is at 8. Bulb Q roceives current
ony relevant answer.) from the two botteries in the
citcuit. Withmorecurrentpos.:sing
37. (o) 3o•c through bulb Q, it lights up
Explanation: After the pan s brighter.
woshed, the temperature of the
pan is at room temperature.
(b) At time 1 min
(c) When thehot oil wospoured
into the sink, n flowed through
the sink protector into woter
pipe.
Heat from the hot oil Is lo$t to
the cooler water in the water
pipe, ond the oil changes to
solid state. over time, more
solid oil is
occumuloted ot X. .
ti,ote: The melting point is olso
the free2:in9pointof osubstonce.

5 0 Educ.-riQn;al Pli,li$!ling 1-bis,e Pte Ltd

6
PSLE Yearly Science - At'1$l'-'CfS

39.

fxRlaomiQn:In Kenr"!
eth'soriginol electric circuit. the
bulbs ore connected by the
Wi(es only ot the metal tips,
her\ce, this will not allow
electric current to flow through
the bulbs. The botterie:sore
arrcnged such that thenegative
terminalsore facing each other.
No current will be flowing
th(ough the circuit.

40. (a) Boiling isoprocesswherealiquid

gain$he<rt and changes to a
gas ot its boiling point.
(b) (I) Heot is transferred from the
electricpot to the thick gloss
top. As port A i.s nearer to
the electric pot, it gains
heot foster fromthe pot
compared to port B.
ExploootiQO: As the gloss
is thick. heat willtoke a
longer time to flow from
part A to
all other ports of the glass.
(ii) Port A gained heat and
expanded foster than po(t
8.
Theunevenexpansioncauses
the cr0<king of the gloss
top.