SA1 Revision 2 2012 Answer Notes

SA1 REVISION 2 2012
P6 Science

Booklet A

 What to do
 Understand the concept for each
question.
 Underline the key words (question).
 Understand the explanations for each
question.
 Write down the correct answer as
correction.

Question 1 – Answer (1)
 Concept:
 Classification of plants
 Key words (Question)
 classify

 Explanation
 Tomato and love grass are dispersed by animals.
 Coconut and pong pong are dispersed by water.

 Pong pong and love grass are inedible plants.

 Tomato and coconut are edible plants.

 Concept:
 Classification of materials
 Explanation

 Concept:
 Life cycle of butterfly
 Stage X, Stage Y
 Explanation
Caterpillar moults a
number of times

Pupa is the stage where
it does not eat at all

 Concept:
 Seed dispersal
 most likely
 Explanation
 Plant S – found near the sea, so most likely
dispersed by water.
 Plant T – found near each other, so most likely
dispersed by splitting.
 Plant U – found scattered all over the island, so
most likely dispersed by animals.

 Concept:
 Hereditary (passing down of characteristic traits)
 adopted, most likely
 Explanation
 Since both Mr and Mrs Tng have double eyelids,
it is not likely for their children to have single
eyelid. Thus, Arnold is most likely the adopted
child.

 Concept: bryophyllum

 Reproduction of plants
 most likely
heliconia
 Explanation
 W – ferns reproduce from spores Water chestnut

 X – Bryophyllum is able to
reproduce from leaves
 Y – Water chestnut is an
underground stem
 Z – Heliconia reproduce from
suckers

 Concept:
 Water cycle
 Water cycle
 Explanation

 Concept:
 Environment

 same amount, same amount, different, find out
 Explanation
 The water level drops because water is able to
flow and occupy the air spaces.

 Concept:
 Water boiling
 Most likely, true
 Explanation
 A is false – different amount of water means the water will
boil at different times since the amount of heat supplied is
the same.
 B is false – both have 2 burners, thus heat energy is the
same.
 C is true – boiling temperature is always 100oC no matter
the amount of water.

 Concept:
 Function of the stomata in plants
 Layer of cooking oil on both surfaces, died
 Explanation
 Since the stomata is blocked by the oil, it cannot
take in carbon dioxide (for photosynthesis) and
oxygen (for respiration).
 Since oil is transparent, light can still pass
through.
 Since oil is not an insulator of heat, warmth can

 Concept:
 Carbon dioxide is taken in during photosynthesis and
given out during respiration.
 Amount of carbon dioxide, 12 midnight to 12 noon
 Explanation
 At night, photosynthesis does not occur (due to the
lack of light), therefore carbon dioxide level will be
high.
 In the daytime, photosynthesis occurs, thus carbon
dioxide level will drop.

 Concept:
 Blood in humans
 Blood, helps
 Explanation
 One of the function of blood is to transport
nutrients from the small intestine to all parts of the
body as well as to carry waste to the rectum.
 Blood also carries oxygen (from lungs) and carbon
dioxide (to lungs).

 Concept:
 Heart rate
 heartbeat

 Explanation
 Playing soccer will cause his heart rate to
increase the most.
 Resting will lower his heart rate

 Walking will increase his heart rate again but not
as high as playing soccer.

 Concept:
 Plant cells and its parts
 Structures, all
 Explanation
 Allplant cells have cell wall, cytoplasm and cell
membrane.
 Not all plant cells have chloroplasts (e.g. root
cells) since only the leaves make food.

 Concept:
 Cell division (every cell divides itself into 2)
 Every 15 seconds, 128
 Explanation
Cell Count Time (seconds)
8 45
16 60
32 75
64 90
128 105

 Concept:
 Cell parts and function
 true
 Explanation
 A is true – cell Z cannot make food as it does not have
chloroplast.
 B is false – all cells can reproduce (all living things can
reproduce)
 C is true – Cell Z does not have cell wall

 D is true – Since cell Z does not have cell wall it must be an
animal cell.

 Concept:
 Electricity

 X, blow
 Explanation
 when a bulb
blows, it forms
an open circuit

 Concept:
 Electricity conductors
 Conductors of electricity
 Explanation
 Pencil lead is a conductor of electricity but not a
good one (thus the light produced is dim)
 Plastic ruler and glass fibre is not a conductor of
electricity (thus no light produced)
 Steel nail is a good conductor of electricity (thus
very bright light produced by bulb)

 Concept:
 Electrical circuit
 false
 Explanation
 A is false – Set up Y is a series circuit

 B is false – When batteries are arranged in series, it will
have more electrical energy as compared to a parallel
circuit, thus Y will be brighter.
 C is true – When a bulb in series blows, the whole circuit
will fail to work.
 D is false – When a bulb in parallel blows, the other bulbs
will continue to light up.

 Concept:
 Interaction of organisms (how one affect the other)

 rapidly

 Explanation
 A will happen – Water hyacinth is a floating plant, if there are too
many, they will cover the surface of the river and block sunlight
from reaching the submerged plants (thus these submerged
plants cannot photosynthesize and produce oxygen.)
 B will happen – The water hyacinth will create obstacles for the
boats to travel.
 C will happen – Sunlight blocked preventing submerged plants
from making food (same reason as A)

 Concept:
 Photosynthesis of plants
 Most adapted, hot and dry
 Explanation
 P is more adapted to survive in hot and dry
space as it is able to retain the most amount of
water.

 Concept:
 Food web (how change in one organism affects the
others)
more predators
 Changes, D increases
 Explanation

less
organisms
eating

more food
more predators

 Concept:
 Environment – overcrowding, fair test
 overcrowding

 Explanation
 Variable to change – size of pot
 Variable to keep the same – Number of seeds
and type of soil

 Concept:
 Forces
 true
 Explanation
 A is true – Gravitational force acts from a distance
 B is true – Magnets only exert magnetic force on magnetic
objects
 C is true – Weight is due to gravitational force acting on it

 D is false – (common misconception) An object remains
stationary because frictional force is acting on it, otherwise
it will start moving.

 Concept:
 Magnets with stronger magnetic force is able to attract pins from a
longer distance
 Strings of different length, true
 Explanation
1. False – Although B attracted the most pins, it is also the nearest to
the pins
2. False – Although C attracted the least number of pins, it is the
furthest away from the pins, thus its magnetic force is not the
weakest
3. True – D and A attracted the same number of pins, but since D is
nearer to the pins, D’s magnetic force is weaker than A’s
4. False – same reason as (3)

 Concept:
 Extension of the spring is proportional to the mass of
the load
 Original length, 8 cm, extension, 90g
 Explanation
 Every 10 g causes the length of spring to increase by 2
cm
 Therefore, 90 g  26 cm (length of spring)

 Thus extention  26 – 8 = 18

 Concept:
 Hardness of metals
 Descending order of hardness
 Explanation
A material is hard if it is able to scratch another
material
 Y is hardest  can scratch W, X and Z

 W is 2nd hardest  can scratch X and Z

 Z is 3rd hardest  can scratch X

 X is softest  cannot scratch any of the 3

 Concept:
 Light and shadow
 Smaller shadow
 Explanation
 The nearer an object to the screen the smaller the
shadow
 When you move the light source away from the
object, the shadow becomes smaller as well

 Concept:
 Heat gain, heat loss – Heat travels from hot to cold
 Cold milk, hot water, correct
 Explanation
A is incorrect – cold milk gains heat from the hot
water
 B is correct – the hot water loses heat to the cold
milk, thus the temperature will drop
 C is correct – the mug is cooler than the hot water,
thus it gains heat

 Concept:
 Heat travels
 Irrelevant
 Explanation
1. A is relevant – this experiment shows that heat travels
through matter
2. B is irrelevant – whether matter expends when heated
does not affect the outcome of this experiment
3. C is irrelevant – this experiment is to investigate
whether air, water or metal is a better conductor of
heat
4. D is relevant - this experiment is to investigate
whether air, water or metal is a better conductor of
heat

Booklet B

 What to do
 Understand the concept for each
question.
 Underline the key words (question).
 Write down the key words (answer) for
each question (that you did not get full
marks) as correction.

Question 31
 Key Concept:
 Classification of materials
 Key Words or Phrases

Question Answer
a) Suggest, Natural Materials
heading
b) Wrongly Silk, silkworm
classfied, explain

Silk comes from an animal (0m) (not specific enough)

Question 32
 Key Concept:
 (a) Seed germination, (b) life cycle of animal
Question Answer
a) Tick T, NPTT, F, F
b) How many 4 stages
stages
c) How many days, 11 days
adult

Question 33
 Key Concept:
 Water does not have definite shape

Question Answer
a) Reason, overflow Gaps in sand, water can
occupy the space
b) Property Does not have definite
shape

Question 34a
 Key Concept:
 Testing for presence of starch
Question Answer
i) Which, dark Cell B
blue
ii) Reason Chloroplast, make food

Question 34b
 Key Concept:
 Celldivision (we grow because our cells are
dividing)
Question Answer
i) Size, explain, Cell division cause increase in
wrong height
ii) State, wrong Replacement of damaged cells

Question 35
 Key Concept:
 Factors that affect the survival of an organism
Question Answer
a) Complete, graph
See next slide

b) State 2 factors, 1. Sudden change in
increase, deaths, temperature
September 2. Predators introduced
3. Adult guppy ate smaller
guppy

Question 36
 Key Concept:
 Environment – soil erosion (Plants hold the soil
together to prevent soil erosion)
Question Answer
a) Observed More soil in drain Y than X
b) Reason No grass (prevent soil
erosion)
c) Hill resort, apply Grow grass
http://youtu.be/1D1V-t3UTHA

Question 37
 Key Concept:
 Forces – Gravitational force

Question Answer
a) What, force Gravitational force

b) Who, easier Ben

c) Explain Moving load downwards, same
direction as gravity

Question 38
 Key Concept:
 Extension of spring
Question Answer
a) Line graph

See next slide

b) Relationship The greater the mass of the weights
hung on the spring balance, the
greater the extension of the spring

Question 39
 Key Concept:
 Electromagnet

Question Answer
a) value of x, reason 0o,, no battery to turn rod into
electromagnet.
b) Explain, moved Steel rod is now electromagnet,
away iron thumbtack attracted to steel rod

Question 40
 Key Concept:
 Light and shadow
Question Answer
a) Light can pass Soya Sause – Q (translucent)
through Cooking oil – R
Identify, suggest Mineral water – S (transparent)
Black coffee / dark ink – T
(opaque)
b) bases, aligned,
draw, shadow

Question 41
 Key Concept:
 Water - boiling
Question Answer
a) How, boiling Temperature reach 100oC
point
b) Right, white No. Steam is gaseous state,
cloud, steam, cannot be seen
explain

Question 42
 Key Concept:
 Heat transfer | Cold contracts
 Important – Coldness cannot travel. Heat
travels from hot to cold. Heat from rod travels
to ice.
Question Answer
a) Explain, cool end S Rod is good conductor of heat,
coldness transferred
b) Another change Contracts
c) Increased gradually Gain heat from surroundings
to 20oC, explain

Question 43
 Key Concept:
 Heat expands
Question Answer
a) Why, open Lid expanded

b) Explain Gain heat from warm water

Question 44
 Key Concept:
 Heat expands
Question Answer
a) What, after Stopper pop out
some time
b) Explain Air in flask expanded when
heated, force stopper out

SA1 Revision 2 2012 Answer Notes

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SA1 Revision 2 2012 Answer Notes