Full answers textbook science form 2 (3) (2)

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Chapter 1
Formative Practice 1.1
1. The diversity of organisms, whether
animals, plants or microorganisms.
2. Biodiversity supplies raw materials such as
timber, oil palm and rubber, herbs for the
manufacture of medicines and cosmetics,
as well as places for recreation.
3. Definition: a natural or exclusive species
that is found in a particular area only.
Ways: Replant trees and tighten laws
(Any other answers are accepted)
4. Orang utan// Malayan tiger// hedgehog//
mousedeer// hornbill// rafflesia// pitcher
plant.
1.
Vertebrates
Fish
Eel
Mammals
Orang
utan
Dolphin
Platypus
Amphibians
Frog
Toad
Birds
Penguin
Duck
Reptiles
Crocodile
Tortoise
2. Similarity: Both plants produce seeds
Differences:
(a) the paddy plant is a monocotyledon
plant whereas the sunflower plant is a
dicotyledon plant.
(b) the paddy plant has fibrous roots
whereas the sunflower plant has a tap
root.
(c) the paddy plant has parallel vein
leaves whereas the sunflower plant
has network-like vein leaves.
3. (a) The leaves of the monocotyledon plant
have parallel veins whereas the leaves
of the dicotyledon plant have network-
like veins.
(b) Monotcotyledon plants have fibrous
roots whereas dicotyledon plants
have tap roots.
Summative Practice 1
1. (a) Biodiversity
(b) Poikilothermic
(c) Dichotomous
(d) Vertebrates
(e) Gills
(f) Iguana
2. (a) 7 (b)
3 (c)
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3. (a) (i) Without wings
(ii) Thick, hard wings
(iii) Dragonfly (Q)
(iv) More than three pairs of legs
(v) Body with many segments
(b) Have legs
(c) Animal P has three pairs of legs,
animal S has four pairs of legs
whereas animal T has more than four
pairs of legs.
4. (a) Root, leaf, stem, number of cotyledons
(b) (i) Leaves with parallel veins
(ii) Fibrous root
(iii) Both have non-woody stem
5. Correct. The animals are invertebrates
because all three have no backbone.
6. Differences:
(i) Segmented body, not segmented body
(ii) Has legs, no legs
Dichotomous key:
Invertebrate
Without segmented body With segmented body
Planaria
Without legs
Earthworm Butterfly
With legs

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HOTS Mastery 1
7. (a) To build new settlements
(b) To construct highways
(c) To open new industrial areas
(d) To open new agricultural areas
8. Endemic animals are animals that are
threatened by extinction. Hunting and
killing these animals will cause them to
become extinct. Future generations will
not know this animal if it becomes extinct.
Chapter 2
1. Producer: cabbage
Primary consumer: caterpillar
Secondary consumer: chicken
Tertiary consumer: snake
2. (a)
Paddy
plant
Caterpillar Sparrow
Grasshopper
Owl
Rat
(b) Food decreases, consumers
migrate to another place and animal
population decreases.
1. Carbon cycle, oxygen cycle and water
cycle
2. Evaporation and condensation
3. Plants and animals use oxygen and
release carbon dioxide during respiration.
Through the process of photosynthesis,
plants absorb carbon dioxide and produce
oxygen. Apart from that, decomposition
of organisms and burning of fossil fuels
also release carbon dioxide. All these
processes maintain the balance of oxygen
and carbon dioxide in the atmosphere.
4. (a) Collect rain water for everyday use
such as watering plants or washing
cars
(b) Ensure pipes are not leaking
(c) Wash cars using water in a pail
Activity 2.3
3. Prevent organisms from extinction
(Question 1, 2 and 4 based on student’s
findings)
1. (a) Population (c) Habitat
(b) Community (d) Ecosystem
2. (a) Competition (b) Commensalism
(c) Parasitism
1. Logging, open burning, illegal hunting,
unrestricted catching of fish
2. (a) (i) Destruction of habitat
(ii) Migration or death of animals
(b) (i) Increase of carbon dioxide levels
in the atmosphere
(ii) Acid rain that destroys
decomposer bacteria in the
ground
(c) (i) Flow of fertiliser into rivers that
affects aquatic life
(ii) Use of pesticides kills other
organisms apart from the pests
(d) (i) Breeding of pests such as rats
(ii) Disposal of rubbish into drains
causes flash floods
3. Rear owls to to eat the rats that destroy
crops.
4. (a) Open burning/ smoke from car
exhausts/ smoke from factories
(b) Cough/ flu/ asthma getting worse/
limited range of vision / greenhouse
effect/ global warming
(c) (i) Enforce laws
(ii) Conduct awareness campaigns
(iii) Highlight the issue of haze in
school
5. (a) Protect species from extinction so that
future generations can see them.
(b) Animals and plants are needed for
food and oxygen.

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1. (a) Sapling ➝ Rat ➝ Fox
Sapling ➝ Rabbit ➝ Fox
Grass ➝ Rabbit ➝ Fox
(b) Because grass can make its own food
(c) Parasitism
(d) The number of rabbits and rats will
increase.
The number of grass and saplings will
decrease.
2. (a) Outbreak of diseases
(b) Disposal of rubbish, especially food
scraps in an unsystematic way
(c) (i) Scheduled collection of garbage//
fines
(ii) Organise community clean-up
events and cleaning campaigns.
Take care of the cleanliness
of the house environment and
business premises.
3. Azah is correct. Without decomposers,
nutrients such as phosphorus and
nitrogen will remain in the dead body
of organisms and cannot be used by
plants. Plants become infertile and may
eventually die without enough nutrients.
4. The rat population increased because
its predator, the eagles, had been shot.
Razak needs to breed owls at his farm as
a biological control to destroy the rats.
HOTS Mastery 2
5. Trees absorb carbon dioxide that is
released by vehicle exhausts to carry
out photosynthesis and release oxygen.
Trees are also the habitat for organisms
such as birds. Tree roots hold the soil and
prevent erosion. The surrounding areas
become shady and the moisture in the
earth can be maintained.
6. (Accept any suitable design with
explanations)
Chapter 3
Activity 3.1
Activity Observation
A The solution changes to dark blue
B A brick red precipitate forms
C A brick red precipitate forms
D A white colour suspension forms
1. To make sure the samples are at a
constant temperature.
2. First, mix the food sample in powder
form with distilled water. Then, carry out
the Iodine, Benedict, Millon and alcohol
emulsion tests.
3. Activity A: The sample will change colour
to dark blue because of the presence of
starch.
Activity B: A brick red precipitate will form
because of the presence of reducing sugar.
Activity C: A brick red precipitate will form
because of the presence of protein.
Activity D: A white colour suspension will
form because of the presence of fat.
1. (a) Water, fat (c) Carbohydrate
(b) Protein (d) Vitamin
2. (a) Night blindness// Skin diseases
(b) Beri-beri// Anaemia
(c) Scurvy
(d) Rickets // Toothache // Skin diseases
3. (a) Goiter
(b) Anaemia
(c) Rickets // Brittle teeth // Cannot build
DNA and RNA
1. A balanced diet is a diet that contains all
classes of food required by the body in the
right quantities.
2. Gender, body size, health condition, age,
work and climate
3. The energy needs of a 50-year-old man is
higher because he generally does more
heavy work compared to a 50-year-old
woman.

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4. Calorific value of food is the total energy
that is released when 1 g of food burns
completely in the body.
5. Total calories consumed by Suraya:
Food
Calorific value
(kcal)
Cornflakes 160
Milk 130
Nasi lemak (full
serving)
400
Green apple 60
Total 750 kcal
Yes, because the breakfast eaten by
Suraya has all the food classes and is
suitable for the activities she does.
6. The climate in Switzerland is different
from Malaysia. The temperature in
Switzerland is much lower. More calories
are required to maintain the body
temperature there.
Activity 3.7
1. 37ºC is the optimum for action of
enzymes/ human body temperature
2. Digested into maltose
3. Amylase
1. Digestion is the process of breaking down
large and complex food into small and
simple molecules.
2. (a) Mouth (e) Small intestine
(b) Oesophagus (f) Large intestine
(c) Stomach (g) Rectum
(d) Duodenum (h) Anus
3. (a) Amylase: To digest starch
(b) Protease: To digest protein
(c) Lipase: To digest fat
4. Protease, lipase and amylase cannot
be produced. Therefore, protein, fat and
starch cannot be digested effectively.
Experiment 3.1
1. Small intestine, blood
2. (a) Tie the Visking tubes securely
(b) Wash the Visking tubes thoroughly
before putting them into the distilled
water.
3. (a) Iodine solution remains brown
because the size of starch molecules
is big and cannot diffuse through the
Visking tube.
(b) Benedict's solution forms brick red
precipitate because the size of
glucose is small and can diffuse
through the Visking tube.
4. Starch consists of big molecules that
cannot diffuse through the Visking tube.
Glucose consists of small molecules that
can diffuse through the Visking tube.
1. (a) Rectum; stores faeces before it is
eliminated
(b) Peristalsis movement
(c) Water
2. Causes constipation.
1. (a) Eggs, meat, soy bean, chicken, fish
(b) For growth// To build cells and body
tissues
(c) (i) Practise healthy intake of food//
Exercise// Drink more plain water
(ii) Bread, chocolate milk and
half-boiled eggs
(iii) Amri probably had too much
snacks and carbonated drinks.
Snacks have high content of fat.
Carbonated drinks contain a lot
of sugar. Excessive fat can cause
obesity and excessive sugar can
cause diabetes.
2. (a) Consume a diet that is high in fat.
(b) To keep her body warm. Excess fat
will be stored under the skin as heat
insulator.
3. (a) P: Mouth

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Q: Liver
R: Large intestine
S: Oesophagus
T: Stomach
U: Duodenum
V: Small intestine
W: Anus
(b) (i) Mouth
(ii) Stomach
(iii) Duodenum
4. (a) (i) Food sample is placed into a
boiling tube
(ii) 2 ml of Benedict’s solution is
added
(iii) The mixture is heated using a
water bath
(iv) A change of colour is observed.
(b) Food Test Observation
Rice
Iodine
Benedict
Honey
Iodine
Benedict
(c) Rice contains starch. Honey contains
reducing sugars.
5. (a) Temperature of amylase
(b) Volume of amylase and volume of
starch suspension
(c) Yes. When heated, Benedict's solution
does not form a brick red precipitate in
boiling tube A. This shows that there
is no reducing sugar present. The
high temperature destroys amylase.
Starch cannot be broken down into
maltose.
HOTS Mastery 3
6. (a) (Student's answer)
(b) (Student's answer)
7. (a) (Student's answer)
(b) (Student's answer)
Chapter 4
1. A pathogen is an organism that causes
diseases. A vector is an organism that
transmits pathogens from one host to
another new host.
2. (a) Cholera
(b) H1N1// Dengue
(c) Tinea// ringworm
3. Infectious diseases: SARS// H1N1//
Tuberculosis// flu
Non-infectious diseases: Diabetes// high
blood pressure// cancer
4. Infectious diseases are spread through
vectors, and mediums such as water, air
and through contact.
1. Specific defence mechanism and non-
specific defence mechanism.
2. An antigen is a foreign substance or
a substance outside the body that
stimulates the body’s immune system.
An antibody is a protein produced by
white blood cells into the bloodstream in
response to antigen.
Immunity is the ability of the body to fight
against pathogens when the body is
infected with pathogens.
3. (a) P: Passive natural immunity
Q: Active natural immunity
(b) Similarity: Both immunities are
obtained naturally without external
help.
Difference: Immunity P is obtained
when the body receives antibodies
from breast milk or from the mother’s
blood that flows across the placenta,
whereas immunity Q occurs when
antibodies are produced in an
individual who has recovered from a
disease.
(c) Immunity Q is better because the
concentration of antibody in the
blood remains above the immunity
level, whereas for immunity P, the
concentration of antibody in the blood
drops below the immunity level after a
certain period.
4. Smoking, undergoing unnecessary
surgeries, eating imbalanced diet.

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5. Infectious diseases are the main cause
of defect and death among babies and
children. Immunisation is important
because it can stimulate the baby to
produce antibodies to fight against
pathogens. Babies and children will
be safe from infectious diseases and
complications.
1. (a) Group 1: Diabetes, hypertension,
heart attack, cancer
Group 2: Flu, chickenpox,
Leptospirosis, Zika, cholera, tinea
(b) Non-infectious diseases and
infectious diseases
(c) (i) Tinea
(ii) Leptospirosis
(iii) Flu
(iv) Diabetes// hypertension// heart
attack
(d) Chickenpox
2. (a) Dengue virus, Aedes mosquito
(b) Zika// Chikungunya
(c) Dengue haemorrhagic fever spreads
when an Aedes mosquito bites and
sucks the blood of a patient who
has dengue virus. The mosquito will
transmit the virus to another individual
that it bites.
3. Besides producing unpleasant smell, the
exposed garbage will attract cockroaches,
flies and rats. These animals can be the
vectors for diseases such as cholera,
typhoid and leptospirosis.
4. (a) The body reacts to fight viral infection
by producing antibodies in the blood
to kill the virus.
(b) 16 to 17 days after the infection.
(c) The virus is killed and the body gets
immunity against the disease.
5. (a) Similarity: Both mechanisms function
to prevent infection of diseases.
Difference: Specific defence
mechanism attacks certain
pathogens, whereas non-specific
defence mechanism attacks all
pathogens.
(b) (i) Pathogens are destroyed by
antibodies produced by white
blood cells.
(ii) The entrance of pathogens
is prevented by the skin and
mucous membranes, whereas
pathogens that have successfully
entered the body are destroyed
through phagocytosis.
(c) (i) Active natural immunity
(ii) Active artificial immunity
(iii) Passive natural immunity
(iv) Passive artificial immunity
6. (a) Sever the transmission of infection
by detecting the cases actively
and passively such as giving initial
treatment to the patients and
separating the patients from others.
(b) (i) What activities did you do
within the two weeks before the
infection?
(ii) Did you go into the forest or swim
in the waterfall before getting
sick?
(c) (i) Avoid meeting the patients
(ii) Take precautionary steps when
meeting the patients like wearing
a face mask to cover the nose
and mouth.
(iii) Improve personal hygiene,
and cleanliness of house and
environment.
(iv) Take vector control measures.
(Any other answers are
accepted)
(d) Quarantine the patients is a wise step
to prevent the public from meeting the
patients. This is because transmission
of bacteria or viruses can occur
through air, water, vectors and also
through contact.

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HOTS Mastery 4
7. a) • Inference 1: The new food causes the
disease.
•
Inference 2: The new hens have
spread the disease.
b) • Hypothesis 1: If the new food has
caused the disease, then the hens will
recover after eating the original food.
• Testing hypothesis 1: Separate the
sick hens into a different coop. Give
the original food for all the hens.
• Observe all the hens after one
week. If the hens are still sick, then
hypothesis 1 cannot be accepted.
• Hypothesis 2: If the new hens have
spread the disease, then the lab test
on the blood and stool of the hens can
prove this.
• Testing hypothesis 2: Carry out lab
test on the blood and stool of the
hens.
• If the results show the presence of
pathogens in the blood or stool of
the hens, then hypothesis 2 can
be accepted. The hens should
be injected with antibiotics as a
treatment.
Chapter 5
Activity 5.2
1. K – Oxygen
L – Hydrogen
2. (a) The ratio of gas K to gas L is 1:2
(b) One molecule of water is made up of
one oxygen atom and two hydrogen
atoms.
3. Dilute hydrochloric acid allows the current
to flow better through water because water
is a poor conductor of electricity.
Activity 5.3
1. Ice particles absorb heat energy from the
surrounding and start to vibrate faster. The
forces of attraction between the particles
are overcome, causing the ice particles
to move faster and randomly. Hence the
state of matter of ice changes from solid
to liquid.
2. The boiling point of distilled water is lower
than the boiling point of distilled water
mixed with salt because the presence of
impurities (salt) increase the boiling point
of water.
3. Impurities increase the boiling point and
decrease the melting point.
Experiment 5.1
1. Water moisturises the air in bell jar R
while anhydrous calcium chloride absorbs
water vapour in bell jar S so that the air
will become dry.
2. The filament lamp is used as a source of
heat energy.
3. The larger the surface area exposed, the
higher the rate of evaporation of water.
4. To increase the movement of air.
1. • Boil the water – pure water boils at
100°C.
• Determine the density of the water –
density of pure water is 1 g cm–3
2. The movement of water molecules at
room temperature is faster than the
movement of water molecules at 0°C.
This is because high temperature causes
the water molecules to gain more energy
and move faster than the water molecules
at 0°C.
3. Sweat glands secrete sweat onto the
surface of the skin to increase the loss of
heat through evaporation. Evaporation of
sweat cools the human body.
Activity 5.5
1. P: Dilute solution
Q: Concentrated solution
R: Saturated solution
2. Solute – Copper(II) sulphate
Solvent – Distilled water
Solution – Copper(II) sulphate solution
3. Copper(II) sulphate has dissolved to the

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maximum in the distilled water. Thus, the
excess copper(II) sulphate remains as a
precipitate.
Activity 5.6
1. The mixture of water and chalk powder
looks cloudy.
2. When a mixture of solute and solvent
produces a clear solution, this allows
light to pass through the solution. A bright
spot of light will be observed on the white
screen. When a mixture of solute and
solvent does not produce a clear solution,
a suspension is formed. The light cannot
pass through. A dim spot of light will be
observed on the white screen.
3. Copper(II) sulphate solution that is filtered
does not leave any residue because the
particles of copper(II) sulphate crystals
(solute) dissolve evenly throughout the
water (solvent). The mixture of water and
chalk powder leaves residue on the filter
paper because the mixture produces a
suspension that contains the particles of
insoluble chalk powder.
1. Sugar dissolves in water forming sugar
water.
Sugar is a solute, a substance that
dissolves in a liquid.
Water is a solvent, a liquid that dissolves
a solute.
Sugar water is a solution, a mixture of
solute and solvent.
2. The particles of a solute in a solution
are dispersed evenly throughout the
solvent, but the particles of a solute in a
suspension are dispersed unevenly.
3. Rust – lime juice// vinegar
Blood – common salt solution
Ink – hair spray// vinegar
4. Hot water increases the rate of solubility
of coffee powder. The higher the
temperature of water, the higher the rate
of solubility of coffee powder.
Activity 5.7
1. Distillation
2. Chlorine kills the microorganisms in the
water in Petri dish E.
3. The nutrient agar in Petri dish B contains
microbial colonies because filtration only
removes suspended particles but not
microorganisms. The nutrient agar in
Petri dish C is free from microorganisms
because distillation removes suspended
particles, dissolved substances and
microorganisms.
1. Dissolved mineral salts, solid suspended
particles and microorganisms.
2. Filtration and distillation
3. Oil spillage and disposal of industrial
waste.
4. (a) False (b) True (c) False
5. – Develop a waste disposal system.
– Encourage the usage of
biodegradable fertiliser in agricultural
sector.
– Strict law enforcement
1. Water has a strong surface tension due to
the cohesive force between the molecules
of water at the surface. Johan should
have dived into the water by keeping his
hands together straight to the front, and
both legs together straight to the back.
This can reduce the effect of surface
tension of water on him.
2. (a) (i) Salt particle
Water
molecule
(ii) Salt particle
Water molecule

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(b) Yes. Heat can increase the rate of
movement of salt particles. Hence, the
salt particles can move faster to fill the
spaces between the water molecules.
3. (a) The water particles at the surface
of water vibrate faster upon gaining
heat energy from the surrounding and
escape from the water surface.
(b) Humidity, movement of air,
surrounding temperature and exposed
surface area.
– The higher the humidity, the lower
the rate of evaporation of water.
– The higher the surrounding
temperature, the higher the rate of
evaporation of water.
– The faster the movement of air, the
higher the rate of evaporation of
water.
– The wider the surface area
exposed, the higher the rate of
evaporation of water.
(Choose any two answers)
(c) (i)
4. Colloid: (a) (c) (f)
Suspension: (b) (e)
Solution: (d) (g)
5. Alcohol
6. (a) N, K, M, L
(b) Alum – To coagulate suspended
particles in water
Slaked lime – To reduce the acidity of
water
Chlorine - To kill the microorganisms
in water.
(Choose any two answers)
(c) Alum is added to coagulate
suspended particles in water. Slaked
lime is added to reduce the acidity of
water.
(d) Suspended particles mix with the
water and the water becomes cloudy.
7. (a) Sample C
(b) Sample B and D
(c) Sample C
(d) Sample B, C and D
HOTS Mastery 5
8. (Student’s answer)
9. – Is the mixture clear or cloudy?
– Is the mixture transparent?
– Does the mixture leave any residue
when filtered with a filter paper?
Chapter 6
Activity 6.1
1. pH 8 – pH 14
2. The reaction between acid and metal
releases hydrogen gas because acid
contains hydrogen ions.
3. Magnesium ribbon exposed to air will
be oxidised. Therefore, the magnesium
ribbon should be cleaned with sandpaper
to remove the oxidised parts.
4. Vinegar – Sour
Neem – Bitter
5. An acid is a chemical that turns a blue
litmus paper red.
An alkali is a chemical that turns a red
litmus paper blue.
Activity 6.2
1. Universal indicator can show the pH
value of a substance. Litmus paper
cannot show the pH value but it can
determine whether a substance is acidic
or alkaline.
2. The substance has a pH value of 7
because the substance is neutral.
Activity 6.3
1. Strong acid has low pH value.
2. (a) Hydrochloric acid
(b) Sodium hydroxide solution
(c) Ethanoic acid
(d) Ammonia
(e) Salt water
3. The pH value is below 7 because acidic
gases emitted from the factory will
dissolve in rain water. Thus, the rain
water will become acidic.

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1. Bitter gourd juice, mineral water, orange
juice, hydrochloric acid
2. Acids and alkalis are corrosive
3. (a) Acidic
(b) Red
4. Fresh milk, pineapple juice, vinegar
Activity 6.5
1. (Answer based on the student’s finding)
2. Hydrochloric acid + Sodium hydroxide ➝
Sodium chloride + Water
1. (a) Acid + Alkali ➝ Salt + Water
(b) Sulphuric acid + Sodium hydroxide ➝
Sodium sulphate + Water
2. The reaction of bacteria and the food
residue on the tooth produces acid that
corrodes the tooth and causes dental
caries. Toothpaste which is alkaline can
neutralise this acid and prevent dental
caries.
3. Yes. Hair conditioner which is acidic can
neutralise the residue of shampoo on hair
which is alkaline. This makes the hair
look soft and shiny.
1. (a) Formic acid, malic acid
(b) (i) Formic acid
(ii) Malic acid
(c) No changes
2. (a) Flow the ammonia gas into water.
Test the solution with a suitable
indicator. Record the pH of the
solution.
(b) pH paper can determine the pH value
of a substance tested. Litmus paper
cannot determine the pH value of a
substance tested.
(c) (i) Yes. Phenolphthalein remains
colourless in acidic and neutral
conditions and turns pink in
alkaline condition.
(ii) Put red and blue litmus papers
into solution M. If the colour of
blue litmus paper changes to
red, solution M is acidic. If the
colour of red litmus paper does
not change colour, solution M is
acidic.
(Any other answers are
accepted)
3. (a) Acidic: P and R
Alkaline: Q
(b) P, R
– Tastes sour
– pH value less than 7
Q
– Tastes bitter
– pH value more than 7
(c) i) P – Vinegar// Lime juice
ii)
Q – Shampoo// Soap// Detergent
4. (a) Jellyfish's sting venom is alkaline,
therefore soap and toothpaste which
are alkaline cannot neutralise the
venom, but will increase the pain
caused by the venom.
(b) Apply pineapple juice/ vinegar/ acidic
substance to neutralise the alkaline
venom.
HOTS Mastery 6
5. (a) The fishy smell can be removed by
cleaning the fish using lime juice or
bilimbi fruit (belimbing buluh) which
is acidic. The body of dead fish has
tissues that produce ammonia which
is alkaline and has a fishy smell.
(b) Add a few drops of universal indicator
into the vinegar, then add sodium
hydroxide solution little by little until
the colour of the solution changes
to green. At this point, the vinegar is
neutralised.
(Student can use other indicators
and the change in the colour at the
neutral point depends on the type of
indicator)
6. (a) The farmer’s soil is too acidic. This
is proven when the soil dissolved in
water and reacted with baking soda

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to release gas.
(b) Soil that is too acidic is infertile
because it lacks mineral salts required
for the growth of plants. Mineral salts
become less in acidic soil because
they easily dissolve in rain water and
are washed away to other places.
(c) Add slaked lime to the soil. Slaked
lime which is alkaline will reduce the
acidity of the soil.
Chapter 7
Activity 7.2
1. The pieces of shredded paper are
attracted to the object because the object
that has been rubbed with woollen cloth
will have electrostatic effect.
2 i. Rub 2 balloons filled with air against
dry hair.
ii. After a few minutes, place the
balloons close to each other.
iii. The balloons will repel each other.
iv. This shows that both balloons have
collected the same charges when
rubbed with the hair.
Activity 7.3
1. Sparks are produced when the sphere is
brought closer to the dome.
2. The gold leaf diverges.
Activity 7.5
1. The pointer of the galvanometer deflects.
This shows that there is a flow of charges
to the Earth.
2. Place the metal cap of an electroscope
close to the dome of the Van de Graaff
generator. The divergence of the gold
leaf shows the presence of charges.
3. Electric current is the rate of electric
charges flowing through a conductor.
Activity 7.6
1. When the number of dry cells increase,
the current increases.
2. When the number of dry cells increase,
the voltage increases.
3. The brightness of the bulb increases
because the current in the circuit
increases.
4. When the voltage increases, the current
increases and the brightness of the bulb
increases.
Experiment 7.1
A 1. When the length of the nichrome wire
increases, the resistance increases.
2. When the length of the nichrome wire
increases, the current flowing through
the circuit decreases.
3. When the resistance increases, electric
current decreases.
B 1. When the number of dry cells increases,
the reading of the voltmeter increases.
2. When voltage increases, electric current
increases.
1. (i) Heat energy
(ii) Kinetic energy
(iii) Elastic potential energy
2. The clouds and the air graze each other
and cause positive charges to gather
on the top part of the cloud and the
negative charges gather on the lower
part of the cloud. The movement of
negative charges from the cloud to the
earth causes electricity discharge and
produces lightning.
3. R =
12 V
0.025 A
= 480 Ω
The current produced is steady because
it is supplied by voltage from the
accumulator.
Activity 7.7
1. The current that flows through every point
is the same.
2. The other bulb does not light up. When
one bulb is removed, the circuit is broken.

12
Activity 7.8
1. The voltages of bulb M and N are the
same because the voltage in the parallel
circuit is the same.
2. The advantages of a parallel circuit
(a) Each device can be controlled by its
own switch.
(b) The damage in one device does
not interrupt the function of another
device.
The disadvantage of a parallel circuit
The voltage in each device cannot be
controlled.
1.
2. (a) R = 1 Ω + 3 Ω + 5 Ω
= 9 Ω
(b) I =
9 V
9 Ω
= 1 A
(c) 1 Ω Resistor
V = 1 A x 1 Ω
= 1 V
3 Ω Resistor
= 1 A x 3 Ω
= 3 V
5 Ω Resistor
V = 1 A x 5 Ω
= 5 V
3. (a) R = 2 Ω
(b) V = 4 V
(c) Current in 3 Ω Resistor
I =
4 V
3 Ω
= 1.3 A
Current in 6 Ω Resistor
I =
4 V
6 Ω
= 0.67 A
Activity 7.9
1. At both poles of the magnet.
2. From the north pole to the south pole.
3. The closer the magnetic field lines, the
stronger the magnetic field.
Activity 7.10
1. Iron filings are used to show the magnetic
field patterns and the compass is used to
show the direction of the magnetic field.
2. Straight wire, coiled wire and solenoid
produce different magnetic field patterns.
3. When the direction of the electric current
flow is reversed, the direction of the
magnetic field line is also reversed.
However, the pattern of the magnetic field
remains the same.
1. The area surrounding the magnet under
the influence of the magnetic force.
2. (a) The nail becomes an electromagnet

(b)

P
Q
(c) P – North, Q – South
(d) The strength of the magnetic field
increases
3. (a) True (b) True
1. (c)
2. (a) Imran will feel a mild electric shock
caused by the electricity discharged
from his body.
(b) By wearing shoes with rubber soles.
3. (a) The large amount of water vapour
formed in the air during damp
weather prevents the gathering of
charges on an object.
(b) The current from the Van de Graaff
generator is less compared to the

13
domestic electric power supply.
4. (a) – Current (d) – Parallel
(b) – Conductor (e) – Resistor
(c) – Ohm
5. Parallel circuit. So, the alarm can be
switched on by a heat detecting switch
from any different locations in the same
building.
6. A1
= 2.4 A
A2
= 1.2 A
V1
= V2
= 12 V
HOTS Mastery 7
7. The copper coil is able to produce a
powerful electromagnetic effect. This
enables the removal of loads of scrap
metals at a time.
Chapter 8
Activity 8.1
1. Activity A: Gravitational force
Activity B: Weight, normal force and
frictional force
Activity C: Elastic force
Activity D: Buoyant force
2. Weight, normal force and frictional force
3. Frictional force
Activity 8.2
A 1. Force 2. newton (N)
3. Reading of the spring balance
increases because the number of
weight increases.
B 1. Frictional force
2. Reading of spring balance when
wooden block is pulled on the surface
of the table is lower compared to when
the wooden block is pulled on the
surface of sandpaper. Frictional force
causes the difference in the readings.
1. (a) Gravitational force
(b) Frictional force
(c) Buoyant force
2. Pushing force
Point of application of force
3. (a) Action force and reaction force
(b)
Action force
Reaction
force
Activity 8.4
1. When buoyant force is equal to the
weight of the object, the object floats.
When the buoyant force is less than
the weight of the object, the object
submerges.
Experiment 8.1
1. Copper, aluminium
2. The block which is more dense than
water will submerge in water.
Activity 8.6
2. Position X requires a bigger force.
Position Y results in a bigger moment of
force.
Experiment 8.2
1. The depth of dent produced is less when
surface area increases.
2. Surface area increases, pressure
decreases.
3. Depth of dent formed by metal block P
is larger than Q because metal block P
exerts a higher pressure.
4. The operational definition of pressure
is the depth of dent produced when two
metal blocks of different surface areas
drop on the plasticine.

14
Activity 8.8
This is because the atmospheric pressure
acting on the card is strong enough to support
the weight of the water in the glass.
Activity 8.9
A When volume of air in the syringe
decreases, air pressure increases.
B When temperature increases, air
pressure increases.
Activity 8.10
1. Push Pull
Atmospheric
pressure
2. Seal
Vacuum
Seal
Pull
Pull
Atmospheric
pressure
3.
Atmospheric pressure
4.
Water
Rubber tube
Level of
water surface
End of the
tube
Atmospheric pressure
5.
Atmospheric
pressure
6.
Atmospheric
pressure
Activity 8.11
1. Size of air bubbles at the bottom of the
basin is smaller than the size of air bubbles
nearer to the water surface.
2. Volume of air bubbles decreases as the
depth of water increases.
3. Pressure in liquid increases as the depth
of liquid increases.
1. 20 N
2. (a) Surface C
(b) Pressure A = 0.03 N cm–2
/ 333 N m–2
Pressure B = 0.0167 N cm–2
/ 166.7 N m–2
Pressure C = 0.1 N cm–2
/ 1 000 N m–2
3. (a) The density of helium gas in the
balloon is less than density of air
(b) The size of the balloon increases
because air pressure decreases

15
(c)
Weight
Buoyant force
1. (a) Elastic force
(b) Gravitational force
2. Measuring device: Spring balance
S.I. unit: newton (N)

4. Inhaling air into lungs and drinking water
from a straw
5. 0.75 N m
6. (a) 2 500 N m–2
Total pressure by car
=
1 000
4(0.1)
= 2 500 N m–2
(b) Pressure exerted by each tyre
=
2 500
4
= 625 N m–2
7. (a) 5 N
(b) 5 N
(c) Weight of stone is greater than the
upthrust force.
8. Close the hole with her finger to prevent
atmospheric pressure from entering the
straw so that water will rise when sucked.
9. Shoe Q because it has bigger surface
area which will decrease the pressure
exerted on the field. The shoe will not
sink into the soft ground.

10. The tube is not filled with water and the
end of tube in beaker A is higher than in
beaker B.
Modification:
1. Make the position of beaker B higher.
2. Fill the tube with water until full.

Wooden
block
Flow of
water
B
A
HOTS Mastery 8
11. Nurul should sit further from the fulcrum,
so that the moment of force increases to
balance the moment of force by Wan.

12. Modification: Use a wheel with a bigger
surface area.
Explanation: Pressure reduces when the
surface area increases.
Chapter 9
1. joule, J
2. No, sense of touch is not a reliable
method to be used because the
temperature cannot be observed in this
manner.
3. (a)
Activity 9.1
1. Thumbtack K on the copper rod falls off
first because it is the closest to the heat
source.
2.
3. The convection current can be seen
clearly.
4. Place a thermometer to the surface of
the bell jar.
.
Experiment 9.1
1. The temperature of water decreases
the most in flat-bottom flask N because
Action
force
Reaction
force

16
aluminium is not a good heat insulator
and transfers heat from the water faster.
2. Flat-bottom flask K is used as a control
to be compared with the result of the
experiment.
1. The heating of water begins around
the coil of the heater. Hot water
moves upwards and cold water moves
downwards. This convection process
enables the water to be heated faster.
2. The aluminium foil is a good heat
conductor that can hasten the process of
cooking the chicken.
3. A polystyrene container is a heat insulator
that prevents heat from the surroundings
reaching the ice cubes. So, the process
of melting of the ice cubes can be slowed
down.
4. The blanket functions as a heat insulator.
The heat from the body is trapped in
the blanket and it controls the body
temperature so that it is not too cold.
Activity 9.4
1. The metal bar that has been heated
cannot be inserted into the gauge
because the metal bar has expanded.
2. Coloured water is used so that the
change in the water level is easily visible.
3. Expansion and contraction of air inside
the balloon cause the size of the balloon
to change.
1. The volume of water increases.
2. The cable contracts when it is cold, so it
will not cause any damages.
3. Yes. Expansion and contraction can
damage the structure of buildings and
cause the walls to crack.
Experiment 9.2
A 1. Can K
2. The temperature in can K increases
more after 10 minutes because dark
objects absorb heat faster than white
objects.
B 1. Can K
2. The temperature in can K decreases
more after 10 minutes because dark
objects radiate heat faster than white
objects.
3. Radiation
4. (Student's answer)
1. Bright colours are poor heat absorbers,
therefore we feel cooler.
2. The shiny inner surface enables heat
from the hot water to be reflected again
inside and the temperature of the hot
water is maintained.
3. Heat absorber: The cooling agent of the
car engine and ice pack
Heat radiator: Candles and pots
1. (a) The windscreen of the car cracked
because a sudden change in the
temperature causes a non-uniform
contraction of the layer of the
windscreen.
(b) Wind down the windows of the car
before turning on the air conditioner
to allow the hot air from inside the car
to escape first.
2. High heat caused by hot weather or
burning of rubbish would increase the
pressure inside the can and cause it to
explode.
3. Switch on a bulb inside a vacuum flask.
After a few minutes the flask will become
hot. This proves that heat can transfer
without a medium through radiation.
4. (a) The convection current is caused
by the change in the density of fluid
particles. The hot fluid particles will
expand, become lighter, then rise.
Whereas, the cold fluid particles
become more dense and move
downwards. The continuous flow of
this fluid causes convection.

17
(b) Radiation is the fastest heat transfer
method because it does not need any
medium for propagation.
HOTS Mastery 9
5. Dayah can use two thin blankets sewn
together to solve this problem. Two thin
blankets sewn together trap heat between
them. Air, which is a heat insulator (poor
conductor of heat), prevents body heat
from escaping to its surroundings.
6. • Open the lid of the polystyrene for the
heat to be released to its surroundings
through the surface of water.
• Place the beaker in a container with ice
for the heat to be released quickly.
Chapter 10
Activity 10.1
A 1. Sound is not heard because there is no
medium for sound to propagate.
2. Air, water and flour
B 1. (a) Towel
(b) Metal sheet
2. Glass is a good reflector of sound.
1. Vibration of insect wings, vibration of
plucked guitar strings, vibration of air in
a trumpet and a pipe, vibration of a voice
box.
2. (c)
3. They absorb and prevent reflection of
sound.
Activity 10.2
1. (a) Loudness increases when amplitude
increases.
(b) Pitch of sound increases when
frequency increases.
2. When amplitude increases, size of
vibration of wave also increases. A louder
sound is produced.
3. A louder and higher pitch of sound is
produced.
Activity 10.4
1. Pitch of sound increases.
2. The nearer the distance between sound
source and observer, the higher the
frequency of sound.
3. No, because there is no relative
movement from the person who carries
the sound source and the sound source.
1. The voice box of women produces sound
with higher frequency compared to the
voice box of men. So, women’s voice has
a higher pitch.
2. (a)
3. (a)
1. Yes, distance of source that is far from
the surface causes sound to lose energy,
resulting in a weaker echo.
2. The rough walls of a cave causes
reflection of sound in all directions. This
causes echo to be heard repeatedly.
3. (i) To examine condition of foetus in the
womb.
(ii) To estimate depth of sea.
1. Use two polystyrene cups connected with
a string.
– The polystyrene cups trap sound
waves.
– The string will help to transfer the
sound waves.
2. (a) (b)
3. Sound will propagate faster in air of
higher temperature because transfer of
sound energy can occur faster due to the
higher kinetic energy of air molecules.
4. (a) Sound is reflected by a hard surface,
such as the wall.
(b) Furniture will absorb some sounds

18
and reduce the effect of reflection.
5. (a) – Ultrasound waves are transmitted
by a scanner probe that is moved
across the belly of a pregnant
mother.
– The ultrasound waves are
reflected when it hits the foetus in
the womb.
– Information from the reflection
will be shown as an image on the
monitor screen.
(b) Advantages of ultrasound:
– Not harmful to the foetus in the
womb.
– Can be done more often or
repeatedly.
– Painless
– Does not use radiation
– Results can be obtained
immediately
(c) – To determine the depth of sea.
– To locate schools of fish in the sea.
– To detect cracks inside engines
– To clean jewellery
6. (a) Pitch of sound increases because
tighter guitar string produces higher
frequency of vibration.
(b) Strength of sound increases because
amplitude of vibration increases.
HOTS Mastery 10
7. – Install layers of sound absorber from
soft material to reduce reflection of
loud sound.
– Layer of sound absorber from
materials such as sponge, cushion
and softwood to reduce the effect of
reflection of sound waves.
8. Use high frequency signals such as
lasers that operate at frequency of light.
Data in digital form will be changed
to analogue and can be detected by
receiver through transmission of laser
light.
Chapter 11
1. A galaxy is a set of bodies that are made
up of millions of stars together with gas
and dust.
2. The birth of a star is believed to
have happened through the Nebular
Hypothesis:
i. The nebula cloud that contains gas
and dust begins to compress due to
the gravity action on it.
ii. Stronger gravity causes the gas and
dust to be compressed in the center
and start to rotate.
iii. As time passes, this object becomes
bigger, more compact and its gravity
increases. Its rotation also becomes
faster.
iv. The nebula begins to shrink and form
a hot and high density core.
v. This hot core releases its heat
and light as a result of the nuclear
reaction, and then it forms a star.
3. (a) The Earth’s temperature will become
very low because there is no heat
from the Sun.
(b) There will be no day and night
phenomenon because the Earth has
no source of light.
(c) Living things on Earth will die due to
extremely low temperature.
4. Size, colour, temperature, brightness and
distance from Earth.
5. The temperature of a star is determined
through observation of the colour of the
star as seen from Earth using a telescope
1. (a) A star
(b) 6 000 K to 7 500 K
(c) When the temperature and pressure
at the core become too high, a
nuclear reaction will take place.
Hydrogen gas is converted into
helium. A lot of heat and light energy
will be released.

19
2. (a) Yes, the Sun emits its own light.
(b) This is because the Sun is the closest
star to Earth.
3. In my opinion, the mission would not be
successful because the diameter of a
galaxy such as the Milky Way can reach
up to hundreds of light years. In addition,
the distance between the Milky Way
galaxy and the Andromeda galaxy can
also reach up to thousands of light years.
Therefore, taking into consideration the
factor of human age that can only reach
approximately 100 years, an astronaut
would not be able to stay alive and make
it to the Andromeda Galaxy.
HOTS Mastery 11
4. (i) The spaceship has to be designed
using materials that can reflect heat
and withstand heat of more than
10 000 K.
(ii) This material needs to reflect heat
because the temperature in the
spaceship cannot get too high as
the human body is not be able to
withstand high temperatures.
(iii) Other than that, this vehicle needs
to be a high speed vehicle because
factors such as human age and long
distance will not enable the astronauts
to make it to the Sun.
Chapter 12
Activity 12.1
Table 12.1
Planets
Distance
from Sun
(km)
Distance
from Sun
(A.U.)
Distance
from Sun
(ly)
Mercury 5.79 × 107
0.39 6.09 × 10–6
Venus 1.08 × 108
0.72 1.14 × 10–5
Earth 1.50 × 108
1.0 1.58 × 10–5
Mars 2.28 × 108
1.52 2.4 × 10–5
Jupiter 7.78 × 108
5.19 8.19 × 10–5
Saturn 1.43 × 109
9.5 1.51 × 10–4
Uranus 2.87 × 109
19.1 3.02 × 10–4
Neptune 4.5 × 109
30 4.74 × 10–4
1. A.U. and ly are used because the
distance of the planets in the solar system
is too great and can reach up to millions
of kilometres. Therefore, relative units
such as A.U. and ly are used so that the
numbers in the calculation of distance
between planets would not be too big.
2. Mercury
3. The further the distance between a
planet and the Sun, the lower its surface
temperature.
1. (a) Eight planets
(b) The planet that is closest to the Sun is
Mercury and the planet that is furthest
from the Sun is Neptune.
(c) Mercury is the closest planet to the
Sun. The closer the planet is to the
Sun, the faster the planet orbits the
Sun.
2. (a) The Earth rotates from west to east.
(b) On Venus, the Sun rises in the west
and sets in the east.
(c) If the Earth stops rotating,
– longer days occur on the surface
that faces the Sun while longer
nights occur on the surface that is
away from the Sun.
– the area of the Earth that faces the
Sun will experience dry seasons.
3. (a) Distance = 4.37 ly
Distance in km
= Distance in ly × 9.5 × 1012
km
= 4.37 × 9.5 × 1012
= 4.15 × 1013
km
(b) Distance = 4.15 × 1013
km
Distance in A.U. =
4.15 × 1013
km
1.5 × 108
km
= 2.76 × 105
A.U.

20
4. (Student’s answer. All products may be
accepted if it uses recyclable materials).
5. (a) The hottest planet is planet P, the
coldest planet is planet Q. This is
because planet P is the closest to the
Sun while planet Q is the furthest from
the Sun.
(b) Planet Q. The further a planet is from
the Sun, the more time it needs to
travel around the Sun in one orbit.
HOTS Mastery 12
6. (a) Venus does not have enough water
and oxygen necessary for living things
(refer to table 12.2).
(b) The statement made by Pei Lui is
correct. Venus is the hottest planet
in the solar system. This is because
Venus has a high carbon dioxide
content in its atmosphere. This
causes the reflected heat to be
trapped in the atmosphere, therefore
it increases the surface temperature
of the planet.
7. Europa has a possibility of having living
things because it has seawater which is
needed for living things.
Chapter 13
1. When a meteoroid moves close to the
Earth, it will enter the atmosphere of the
Earth due to the gravity of the Earth.
When a meteoroid enters the atmosphere
of the Earth and burns, it will be known
as a meteor. If the meteor does not stop
burning in the atmosphere, and reaches
the Earth as rock fragments, the meteor
will then be known as a meteorite.
2. Collisions between an asteroid and
the Earth happen because the path
of the asteroid path intersects with or
is very close to the orbit of the Earth.
If an asteroid and the Earth are at the
intersection point at the same time, a
collision might happen.
3. When the path of a comet is close to the
Sun, the high temperature of the Sun
will cause part of the ice structure of the
comet to change into gas, which shapes
the tail of the comet. Due to the fact
that the area with gas has a lower mass
than the head portion, the tail portion will
always be away from the Sun because of
the effect of the gravity of the Sun on the
comet.
1. (a) Kuiper (d) Jupiter
(b) Meteoroid (e) Amor
(c) Comet (f) Asteroid
2. Meteorite. A meteorite is a rock that hits
the surface of the Earth. A meteor would
not reach the Earth as it would have
burned out before it reaches the Earth.
3. Meteor. A meteor shower happens when
many meteors enter the Earth at the
same time.
4. (a) If a large asteroid less than 10 km
in size enters the atmosphere, the
species at the area of impact and
about 100 kilometres around the area
will be destroyed. However, if the
asteroid is 10 km or bigger in size, the
entire species on the Earth will face
extinction (as what happened to the
dinosaurs.).
(b) (i) It can be avoided by changing the
course of the asteroid or breaking
it into smaller rock fragments.
(ii) A spaceship can be used to
attach explosives to the asteroid
or shoot it with bombs that have
strong explosive powers before it
reaches Earth.
(c) (i) The asteroid impact 65 million
years ago destroyed living
things and caused a change in
temperature. The temperature
in one area reduced drastically
while the temperature in another
area increased drastically,
causing the death of dinosaurs.

21
(ii) This opinion is acceptable. This
is because each scientists have
their own opinion and theory
about events that happened
millions of years ago.
If there are any signs or
evidence, a theory can be
debated and scientists can study
it again.
5. Yes, it can. This is because some
asteroids have their own gravity while
some don’t. For an asteroid that has its
own gravity, its mass has the ability to
continue expanding and attracting other
asteroids nearby to combine. When the
asteroid becomes too large, this asteroid
can become a planet.
6. Meteors in space are larger in size and
have higher speeds. When they reach
the Earth, their size and speed reduce
due to the friction with the atmosphere.
Therefore, the effects of collision will be
worse in space as compared to the Earth.
HOTS Mastery 13
7. In my opinion, the collision can happen
after they pass Mars and before they
reach Jupiter. This is because there is an
asteroid belt in the area which can cause
collision.
8. Yes. This is because if there is a collision
with a large object, the rotation of the
Earth on its axis can change. When the
speed of rotation is affected, the gravity
of the Sun and other planets will influence
the Earth and pull the Earth towards it.
This phenomenon can cause the Earth to
slip from its orbit.

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