sa1 revision 2 2012 answer notes
TRANSCRIPT
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.
Question 2 – Answer (3)
Concept:
Classification of materials
Explanation
Question 3 – Answer (1)
Concept:
Life cycle of butterfly
Key words (Question)
Stage X, Stage Y
Explanation
Caterpillar moults a
number of times
Pupa is the stage where
it does not eat at all
Question 4 – Answer (3)
Concept:
Seed dispersal
Key words (Question)
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.
Question 5 – Answer (1)
Concept:
Hereditary (passing down of characteristic traits)
Key words (Question)
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.
Question 6 – Answer (3)
Concept:
Reproduction of plants
Key words (Question)
most likely
Explanation
W – ferns reproduce from spores
X – Bryophyllum is able to
reproduce from leaves
Y – Water chestnut is an
underground stem
Z – Heliconia reproduce from
suckers
bryophyllum
Water chestnut
heliconia
Question 7 – Answer (4)
Concept:
Water cycle
Key words (Question)
Water cycle
Explanation
Question 8 – Answer (4)
Concept:
Environment
Key words (Question)
same amount, same amount, different, find out
Explanation
The water level drops because water is able to
flow and occupy the air spaces.
Question 9 – Answer (1)
Concept:
Water boiling
Key words (Question)
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.
D is false – same reason as C
Question 10 – Answer (1)
Concept:
Function of the stomata in plants
Key words (Question)
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
still pass through.
Question 11 – Answer (4)
Concept:
Carbon dioxide is taken in during photosynthesis and
given out during respiration.
Key words (Question)
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.
Question 12 – Answer (2)
Concept:
Blood in humans
Key words (Question)
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).
Question 13 – Answer (4)
Concept:
Heart rate
Key words (Question)
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.
Question 14 – Answer (2)
Concept:
Plant cells and its parts
Key words (Question)
Structures, all
Explanation
All plant cells have cell wall, cytoplasm and cell
membrane.
Not all plant cells have chloroplasts (e.g. root
cells) since only the leaves make food.
Question 15 – Answer (4)
Concept:
Cell division (every cell divides itself into 2)
Key words (Question)
Every 15 seconds, 128
Explanation
Cell Count Time (seconds)
8 45
16 60
32 75
64 90
128 105
Question 16 – Answer (3)
Concept:
Cell parts and function
Key words (Question)
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.
Question 17 – Answer (4)
Concept:
Electricity
Key words (Question)
X, blow
Explanation
when a bulb
blows, it forms
an open circuit
Question 18 – Answer (4)
Concept:
Electricity conductors
Key words (Question)
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)
Question 19 – Answer (4)
Concept:
Electrical circuit
Key words (Question)
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.
Question 20 – Answer (4)
Concept:
Interaction of organisms (how one affect the other)
Key words (Question)
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)
Question 21 – Answer (1)
Concept:
Photosynthesis of plants
Key words (Question)
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.
Question 22 – Answer (3)
Concept:
Food web (how change in one organism affects the
others)
Key words (Question)
Changes, D increases
Explanation
more predators
more foodmore predators
less
organisms
eating
Question 23 – Answer (4)
Concept:
Environment – overcrowding, fair test
Key words (Question)
overcrowding
Explanation
Variable to change – size of pot
Variable to keep the same – Number of seeds
and type of soil
Question 24 – Answer (3)
Concept:
Forces
Key words (Question)
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.
Question 25 – Answer (3)
Concept:
Magnets with stronger magnetic force is able to attract pins from a
longer distance
Key words (Question)
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)
Question 26 – Answer (2)
Concept:
Extension of the spring is proportional to the mass of
the load
Key words (Question)
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
Question 27 – Answer (3)
Concept:
Hardness of metals
Key words (Question)
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
Question 28 – Answer (2)
Concept:
Light and shadow
Key words (Question)
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
Question 29 – Answer (3)
Concept:
Heat gain, heat loss – Heat travels from hot to cold
Key words (Question)
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
D is incorrect – the hot water loses heat to the cold
Question 30 – Answer (1)
Concept: Heat travels
Key words (Question) Irrelevant
Explanation1. 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,
heading
Natural Materials
b) Wrongly
classfied, explain
Silk, silkworm
Silk comes from an animal (0m) (not specific enough)
Question 32
Key Concept:
(a) Seed germination, (b) life cycle of animal
Key Words or Phrases
Question Answer
a) Tick T, NPTT, F, F
b) How many
stages
4 stages
c) How many days,
adult
11 days
Question 33
Key Concept:
Water does not have definite shape
Key Words or Phrases
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
Key Words or Phrases
Question Answer
i) Which, dark
blue
Cell B
ii) Reason Chloroplast, make food
Question 34b
Key Concept:
Cell division (we grow because our cells are
dividing)
Key Words or PhrasesQuestion Answer
i) Size, explain,
wrong
Cell division cause increase in
height
ii) State, wrong Replacement of damaged cells
Question 35
Key Concept:
Factors that affect the survival of an organism
Key Words or Phrases
Question Answer
a) Complete, graphSee next slide
b) State 2 factors,
increase, deaths,
September
1. Sudden change in
temperature
2. Predators introduced
3. Adult guppy ate smaller
guppy
4. Water pollution
Question 36
Key Concept:
Environment – soil erosion (Plants hold the soil
together to prevent soil erosion)
Key Words or Phrases
Question Answer
a) Observed More soil in drain Y than X
b) Reason No grass (prevent soil
erosion)
c) Hill resort, apply Grow grasshttp://youtu.be/1D1V-t3UTHA
Question 37
Key Concept:
Forces – Gravitational force
Key Words or Phrases
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
Key Words or Phrases
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
Key Words or Phrases
Question Answer
a) value of x, reason 0o,, no battery to turn rod into
electromagnet.
b) Explain, moved
away
Steel rod is now electromagnet,
iron thumbtack attracted to steel rod
Question 40
Key Concept:
Light and shadow
Key Words or Phrases
Question Answer
a) Light can pass
through
Identify, suggest
Soya Sause – Q (translucent)
Cooking oil – R
Mineral water – S (transparent)
Black coffee / dark ink – T
(opaque)
b) bases, aligned,
draw, shadow
Question 41
Key Concept:
Water - boiling
Key Words or Phrases
Question Answer
a) How, boiling
point
Temperature reach 100oC
b) Right, white
cloud, steam,
explain
No. Steam is gaseous state,
cannot be seen
Question 42
Key Concept:
Heat transfer | Cold contracts
Important – Coldness cannot travel. Heat
travels from hot to cold. Heat from rod travels
to ice.
Key Words or PhrasesQuestion Answer
a) Explain, cool end S Rod is good conductor of heat,
coldness transferred
b) Another change Contracts
c) Increased gradually
to 20oC, explain
Gain heat from surroundings
Question 43
Key Concept:
Heat expands
Key Words or Phrases
Question Answer
a) Why, open Lid expanded
b) Explain Gain heat from warm water
Question 44
Key Concept:
Heat expands
Key Words or Phrases
Question Answer
a) What, after
some time
Stopper pop out
b) Explain Air in flask expanded when
heated, force stopper out