Science Form 3 textbook answer (Chapter 1-4)

ANSWERS

CHAPTER 1 Stimuli and Formative Practice 1.1 (p. 10)
Responses 1. Central nervous system and peripheral

Activity 1.1 (p. 7) nervous system
Questions 2. (a) Voluntary actions are conscious
1. Stimulus: Seeing your partner let go of
actions, carried out according to the
the ruler. wishes of a person and are controlled
Response: Catching the ruler using your by the brain.
Examples of controlled actions are
thumb and index finger. reading, writing, speaking, eating,
This is a voluntary action drinking, walking, running, exercising,
because it is a conscious and singing.
action and is made according (b) Involuntary actions are spontaneous
to the will of the individual actions that happen without being
who received the stimulus realised or thought of beforehand.
and is controlled by the brain. Examples of uncontrolled actions
2. The distance moved by the ruler shows are heartbeat, breathing, peristalsis,
the time taken by the student to catch secretion of saliva and sneezing.
the ruler. The shorter the distance, the 3. Injured nerve cells in the human brain
faster the reaction time. are unable to interpret impulses from
3. Different students usually have different affectors and cannot send impulses to
reaction time. Besides this, the reaction effectors. Due to this, a person who
time of an individual is not constant. sustained brain injury is unable to carry
4. In the daily life of humans, reaction time out voluntary or involuntary actions
plays an important role to coordinate and involving the brain.
control organs and body parts so that 4. The network of nervous system of
they function harmoniously and efficiently. humans functions to control and
coordinate organs and body parts so as
Activity 1.3 (p. 9) to carry out processes in the body and
Questions daily activities.
1. Stimulus: Intensity of light that enters
Brain Teaser (p. 15)
the eye. Excess mucus is produced when a person
Response: Change in size of the pupil. suffers from cold. This excess mucus will
obstruct receptors from being stimulated by
This is an involuntary action chemical substances in the air entering the
because this action occurs nasal cavity.
spontaneously without any
conscious control or prior Brain Teaser (p. 16)
thoughts. A blind person uses the sensitivity of the
2. The higher the intensity of light, the fingertip to read Braille and sensitivity of the
smaller the size of the pupil. hand to detect vibrations of the walking stick
3. This response can help protect the eye when it hits objects to detect any nearby
from injury. obstructions.

Brain Teaser (p. 10)

Muscular system

1

Activity 1.6 (pp. 19, 20) substances in hot food also evaporate to
Questions form vapour which enters the nasal cavity
1. Tip of index finger. It has the largest and stimulates the smell sensory cells.
The combination of sense of taste and
number of receptors. sense of smell causes hot food to taste
2. Elbow. It has the least number of better.

receptors. Formative Practice 1.2 (p. 29)
3. Touch receptor. 1. (a) Cornea
4. Number of touch receptors and thickness (b) Pupil
(c) Retina
of epidermis. (d) Brain
2. Semicircular canals
Activity 1.7 (p. 21) 3. At the upper part of the nasal cavity
Questions 4. Sweet, sour, salty, bitter, umami
1. To ensure no other solutions remain and 5. Number of receptors and thickness of

only the taste of one solution is detected skin epidermis
during each attempt. 6. (a) Five types of taste, touch, pain, hot
2. All areas of the tongue can detect all
tastes of the solutions. objects, cold objects, and pressure.
3. Both sides of the tongue are most (b) Five types of taste can be detected
sensitive towards taste because they
have a large number of taste receptors. by taste receptors in the taste
4. The middle part of the tongue is least buds of the tongue. The tongue is
sensitive to taste because it has a small protected by skin that has touch,
number of taste receptors. pain, heat, cold and pressure
5. The front part of the tongue is more receptors, therefore it can detect
sensitive to sweet taste, the sides of touch, pain, hot objects, cold objects,
the tongue are more sensitive to sour and pressure.
and sweet tastes, the back part of the
tongue is more sensitive to bitter taste Experiment 1.1 (pp. 30 – 33)
and the middle part of the tongue is more A.   Questions (p. 31)
sensitive to umami.
1. Light
Brain Teaser (p. 22) 2. Shoot of the plant
No. After the tongue is cleaned, the tongue 3. The shoot of the plant shows positive
will become more sensitive.
phototropism because shoots of
Activity 1.8 (pp. 22, 23) plants grow towards the direction of
Questions light.
1. Without the nose being pinched.
2. Taste of the cordial drink is more easily B.  Questions (p. 32)
1. So that light cannot influence the
detected using a combination of sense of growth of the seedlings.
taste and sense of smell. 2. (a) Grow upwards against the
3. So that your partner does not use sense direction of gravity.
of sight to determine the taste of the (b) Grow downwards in the direction
cordial drink based on the colour such as of gravity.
purple colour for taste of grape, orange 3. Roots of plants show positive
for taste of orange, yellow for taste of geotropism because the roots of
mango and red for taste of strawberry. plants grow towards the direction of
4. In addition to chemical substances gravity. Shoots of plants show negative
in food which dissolve in saliva and geotropism because shoots of plants
stimulate the taste buds, chemical grow against the direction of gravity.

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C.  Questions (p. 33) cat received by both of Azman’s ears are
1. Water the same. The brain then informs Azman
2. Roots of the plant the direction of the cat making the sound.
3. Absorbs water and moisture in the air
in beaker Y S 1u . m((((acbdm)))) a••××t i ve Practice 1 (pp. 41 – 43)
4. The roots of the plants show positive
hydrotropism because they grow 2. P: Brain
towards water. Q: Spinal cord
R: Peripheral nerve
Formative Practice 1.3 (p. 35) 3. (a) Changes in the size of the pupil of
1. (a) Tropism is a directed response of
the eye.
plants towards stimuli coming from a (b) Intensity of light which enters the eye.
certain direction. (c) The lower the intensity of light
(b) (i) Thigmotropism
(ii) Geotropism directed towards the eye, the larger
(iii) Phototropism the size of the pupil of the eye.
2. (a) (i) Shoots (d) During a solar eclipse, the bright
(ii) Roots rays of the sun will enter the eye and
(iii) Tendrils or winding shoots damage the cells of the retina.
(b) Positive hydrotropism allows roots to 4. (a) Sound → Ear lobe → Ear canal →
obtain water and dissolved mineral Eardrum → Ossicles → Oval window
salts to survive. → Cochlea → Auditory nerve → Brain
3. Similarity: Tropism and nastic response (b) Light → Cornea → Aqueous humour
→ Pupil → Eye lens → Vitreous
are responses of plants humour → Retina → Optic nerve →
towards stimuli. Brain
Difference: Tropism is the directed 5. (a) X: Touch receptor
response of plants towards Y: Pain receptor
stimuli while nastic response (b) Finger tip is more sensitive towards
is the response towards touch stimuli compared to the palm
stimuli without considering of the hand.
their direction. Finger tip has a thinner layer of
epidermis and more touch receptors
Brain Teaser (p. 37) compared to the palm of the hand.
The blind have a more sensitive sense of (c) Agree. The tongue is a sensory
hearing. They make use of sound to detect organ that has receptors known as
location and estimate distance of nearby taste buds on the surface of the
objects. tongue which is protected by skin
epidermis.
Formative Practice 1.4 (pg. 39) 6. (a) The sense of smell helps us to detect
1. Stereoscopic and monocular vision. danger such as leakage of gas that
2. Location of eyes on the head. might occur in the science laboratory.
3. Primary consumer has monocular vision. For example, we can detect the
presence of dangerous gases such
Monocular vision has a wide field of as chlorine and ammonia from their
vision and allows it to detect predators smell.
coming from various directions. (b) Dogs have a very sensitive sense
4. Stereophonic hearing allows us to of smell because they have more
determine the direction of sound sensory cells for smell than human
accurately.
5. Azman uses his stereophonic hearing 3
to determine the cat’s location. The time
and loudness of the sound made by the

and are more efficient to analyse 3. To provide sufficient oxygen and
eliminate carbon dioxide from the air.
smell than human.
4. (a) (i) Rib cage
7. (a) – Positive phototropism (ii) Diaphragm
– Positive hydrotropism (iii) Trachea and bronchus
(b) Positive phototropism ensures shoots (iv) Lungs
(b) – A thin rubber sheet stretches more
and leaves of plants obtain sufficient
easily compared to a thick rubber
sunlight to make food through sheet.
– Therefore, a thin rubber sheet is
photosynthesis. more easily pulled downwards or
pushed upwards.
Positive hydrotropism allows roots (c) (i) Breathing in or inhaling
of plants to grow towords water so (ii) Exhaling
(d) – The structure or volume of the
that they can absorb water to enable glass jar which represents the rib
cage is fixed when the thin rubber
plants to carry out photosynthesis. sheet is pulled downwards or
pushed upwards.
8. (a) Stereoscopic vision – While the structure and volume of
(b) The eagle is a predatory animal. the rib cage changes during the
processes of inhaling or exhaling.
Stereoscopic vision helps the
Formative Practice 2.2 (p. 56)
eagle to hunt its prey by accurately 1. Difference in concentrations of oxygen

determining the location of its prey. gas in the alveolus and blood capillaries.
2. (a) When concentration of oxygen is
9. Explanation:
– Fill the transparent plastic bottle with high, haemoglobin will combine
with oxygen chemically to form
water. oxyhaemoglobin which is unstable.
(b) When concentration of oxygen is low,
– It functions as a convex lens. oxyhaemoglobin will decompose to
– Place it on top of the newspaper. form haemoglobin and oxygen.
– Read the newspaper through it. 3. Glucose + oxygen → carbon dioxide +
water + energy
CHAPTER 2 Respiration 4. Efficiency of exchanging oxygen in the
human body decreases at high altitudes.
Experiment 2.1 (pp. 50 – 52) Concentration of oxygen in the air at high
Question (p. 51) altitudes is low. Because of this, the rate
– The water level in the gas jar containing of diffusion of oxygen from the alveolus
into the blood capillaries is also low.
inhaled air is higher. 5. – Thickness of wall of alveolus and
– Composition of oxygen in inhaled air is blood capillary is one cell thick
– The wall of alveolus is moist
higher than that in exhaled air. – Alveolus with large surface area
– Burning of candle using the oxygen in the – Dense network of capillaries covering
alveolus
gas jar causes water to enter to fill the
space originally filled with oxygen. Brain Teaser (p. 57)
Because forests help to maintain the balance of
Question (p. 52) oxygen and carbon dioxide in the atmosphere.
– Limewater in the conical flask where

exhaled air was passed through turns
cloudy.
– Carbon dioxide in the exhaled air reacts
with the limewater.

Formative Practice 2.1 (p. 53)

1. (a) Trachea

(b) Bronchus

(c) ×Bו×r onchiole
2. (a)
(b)
(c)
(d)

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Brain Teaser (p. 58) body cells result in healthier body cells.
Because smoking endangers the health of Because of this, the health of all systems
the smoker and everyone in the vicinity of the in the body especially the respiratory
smoker. system is maintained.
5. Not smoking, frequent exercise
Brain Teaser (p. 59)
Electric buses do not emit exhaust gases. Brain Teaser (p. 67)
Because of this, air pollution can be reduced. Organ of gaseous exchange.

Experiment 2.2 (pp. 62, 63) Brain Teaser (p. 71)
Questions Air is always moving from one region to
1. Cigarette tar
2. Cigarette smoke is an acidic substance another region. Therefore cooperation from

because it changes the purple colour of the global society is required. Prevention in
litmus solution to red.
3. Ammonia, stearic acid, methane, butane, only one region would not be effective.
methanol, toluene, cadmium, arsenic,
acetone Formative Practice 2.5 (p. 72)

Formative Practice 2.3 (p. 63) 1. Leaves, stem, aerial roots
1. (a) Tar, pollen, haze and dust
(b) Sulphur dioxide, carbon monoxide, 2. P: Guard cell Q: Stomatal pore

nitrogen dioxide 3. (a) Stomata are open during the day.
2. Pollen
3. (a) Pain during breathing Water diffuses into guard cells by
(b) Blood in phlegm
(c) Frequent shortness of breath osmosis causing the guard cells to
(d) Wheezing sound when breathing
4. Lung cancer, emphysema, bronchitis, bend and open the stoma.

(any two) (b) Stomata are closed at night. Water
5. A person who does not smoke but
diffuses out of guard cells by osmosis
who breathes in cigarette smoke from
smokers nearby. causing the guard cells to straighten

Formative Practice 2.4 (p. 66) up and close the stoma.
1. (a) Gills
(b) Trachea (c) Stomata are closed on hot days
(c) Moist outer skin
2. Thin outer skin of frogs, dense network to prevent excessive loss of water

of blood capillaries under the layer of through transpiration.
skin, very permeable to respiratory gases
and moist. 4. Polluted air will reduce the amount of
3. Body cells of insects have a direct
connection with the respiratory surface. sunlight reaching the plants and reduce
Oxygen that enters the tracheole diffuses
directly into the cells while carbon dioxide the rate of photosynthesis. Hence, the
diffuses out.
4. When we exercise, our rate of respiration growth and survival of plants will be
increases. Higher rate of transport of
oxygen to body cells and higher rate jeopardised.
of elimination of carbon dioxide from
Summative Practice 2 (pp. 74 – 77)

1. (a) Alveolus

(b) Bronchus

(c) Nasal cavity

2. P: Trachea

Q: Bronchus

R: A•lveolus
(a) •
3. (b) •
(d)


4. (a) higher

(b) lower

5. (a) Haemoglobin transports oxygen from

the red blood cell to body cells.

(b) Oxyhaemoglobin easily decomposes

into haemoglobin and oxygen when

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it reaches body cells so that oxygen gaseous exchange
can diffuse into the cells. in the alveolus is
6. (a) Azura may be allergic to pollen. In reduced causing
Spring, more pollen is released from shortness of breath.
anthers. When Azura inhales air 8. – Stop smoking.
containing pollen, there is a higher To avoid harmful substances found
risk of her getting an asthma attack. in cigarette smoke from entering the
(b) Any place that is hazy and dusty. lungs and harming the respiratory
Examples: industrial areas, system.
construction sites and others. – Avoid places with polluted air.
Haze and dust also cause asthma To avoid inhaling air that contains
attacks in asthma patients. harmful substances such as cigarette
7. (a) – Thickness of the wall tar, carbon monoxide, sulphur dioxide,
– Moisture of the wall nitrogen dioxide, haze, dust and pollen
– Surface area which are harmful to the respiratory
– Network of capillaries system.
(b) (i) Asthma – Have proper exercise and lead a
Symptom: Shortness of breath healthy lifestyle.
Cause: Excessive release To maintain a healthy respiratory
system.
of mucus on the 9. Users at the waiting areas will become
surface of alveolus passive smokers if there are other users
reduces the surface nearby who smoke. This is harmful to
area and rate of their health.
gaseous exchange in 10. (a) Gaseous exchange is through
the alveolus thereby diffusion into cells.
causing shortness of (b) The respiratory system of insects is
breath. more effective than the respiratory
(ii) Bronchitis system of human.
Symptom: Shortness of breath (c) Gaseous exchange through direct
Cause: Inflammation of the diffusion into the cells of insects is
bronchus in bronchitis easier, quicker and more efficient
patients caused compared to gaseous exchange
by tar and irritants through transport of gases by blood
in cigarette smoke in the human body.
reduces the rate of 1 1. (a) Carbon monoxide
movement of air from (b) When the air in a car which
the nose to the lungs contains carbon monoxide is
through the bronchus. inhaled, the carbon monoxide
This causes bronchitis combines with haemoglobin to form
patients to be carboxyhaemoglobin. Because of
frequently breathless. this, a person in the car will not have
(iii) Emphysema sufficient oxygen supply which can
Symptom: Shortness of breath be fatal.
Cause: The alveolus in 12. (a) (i) 3.0 dm3
emphysema patients (ii) 2.5 dm3
is damaged by (b) (i) 4.0 dm3
dangerous substances (ii) 3.0 dm3
in the air such as (c) The more active the activity that is
irritants in cigarette performed, the larger the maximum
smoke. Hence, the volume of the lungs. From the graphs
surface area for

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in Figures 3(a) and 3(b), the volume – toxic waste products that fail to be
of air in the lungs of runners X and Y eliminated from the body to the outside
increases when they are running. surroundings will poison and kill the
(d) Runner Y. organism.
Cigarette smoke which damages the
alveolus will reduce the maximum Activity 3.2 (p. 84)
volume of air in the human lungs. Fish
Because the maximum volume of – Fish has a single blood circulatory system
air in the lungs of runner Y is less,
therefore runner Y is a smoker. where blood flows through the heart only
(e) Increase in the maximum volume once in one complete cycle to the all the
of the lungs increases the rate of other parts of the body.
respiration because the rate of – Fish’s heart has one atrium and one
gaseous exchange in the lungs is ventricle.
increased. – Deoxygenated blood flows out from
the heart to the gills where gaseous
CHAPTER 3 Transportation exchange occurs in the capillaries of the
gills changing deoxygenated blood to
Formative Practice 3.1 (p. 82) oxygenated blood.
1. The function of the transport system – Oxygenated blood flows from the heart to
the whole body, changes into deoxygenated
is to carry substances needed by cells blood and flows back into the heart.
into organisms and eliminate waste
products from organisms to the outside Amphibians
surroundings. – Amphibians have an incomplete double
2. Examples of substances needed by cells:
Oxygen, nutrients circulatory system where blood flows
Examples of waste products eliminated through the heart twice in one complete
from cells: cycle to the whole body.
Carbon dioxide, water, urea – Amphibian’s heart has two atriums and
3. Importance of the functions of transport one ventricle.
system in organisms are as follows: – Deoxygenated blood flows out from the
– Transport system provides substances amphibian’s heart to the lungs and skin
where gaseous exchange occurs in the
needed by cells such as oxygen and blood capillary walls in the lungs or under
nutrients which are used to produce the skin changing deoxygenated blood to
energy through the process of cellular oxygenated blood.
respiration. – Oxygenated blood flows from the heart to
– Transport system provides substances the brain and a mixture of oxygenated and
needed by plant cells such as carbon deoxygenated blood flows to all other parts
dioxide and water which are used to of the body except the lungs. Oxygenated
carry out photosynthesis. blood changes into deoxygenated blood
– Transport system also eliminates and flows back into the heart.
toxic waste products from the cells of
organisms to the surroundings. Reptiles
4. If the transport system of an organism – Reptiles have an incomplete double
cannot function well,
– cellular respiration cannot be carried circulatory system where blood flows
out. Without energy, living process through the heart twice in one complete
cannot occur in the organism. cycle to the whole body.
– food cannot be made by green plants – Reptile’s heart has two atriums and one
through photosynthesis. Without food, ventricle with a structure which divides the
plants and animals will die. space in the ventricle into two separate
parts.

7

– Deoxygenated blood flows out from 2. Artery
the heart to the lungs where gaseous
exchange occurs in the walls of the Transports oxygenated blood (except
blood capillaries in the lungs changing the pulmonary artery)
deoxygenated blood to oxygenated blood.
Capillary
– Oxygenated blood flows from the heart to
the whole body except the lungs, changes Connects arteries to veins and is a place
to deoxygenated blood and flows back into of exchange of substances between cells
the heart.
Vein
Mammals and birds
– Mammals and birds have a double Transports deoxygenated blood (except
pulmonary vein)
circulatory system where blood flows
through the heart twice in one complete 3. Type of activity, gender, age, health
cycle to the whole body. 4. Caring for our heart is important to
– The heart of mammals and birds have two
atriums and two ventricles. ensure continuity of our life.
– Deoxygenated blood flows out from
the heart to the lungs where gaseous Brain Teaser (p. 99)
exchange occurs in the walls of the An individual who has blood type O can
blood capillaries in the lungs changing
deoxygenated blood to oxygenated blood. donate blood to all individuals irrespective of
– Oxygenated blood flows from the heart to
the whole body except the lungs, changes their blood type because blood type O does
to deoxygenated blood and flows back into
the heart. not have any antigens on its red blood cells.

Brain Teaser (p. 91) Formative Practice 3.3 (p. 101)
Systolic pressure is produced when the
ventricle pumps blood out from the heart to 1. Red blood cells, white blood cells,
the whole body. Blood coming out flows with
high pressure. Diastolic pressure on the other platelets and blood plasma
hand is produced when blood flows into the
heart. Blood flows with lower pressure. 2. Blood plasma

Experiment 3.1 (p. 92) 3. Blood group of
Questions Blood group of recipient
1. The more active the activity, the higher donor
A B AB O
the pulse rate.
2. The rate of intake of oxygen and release A •×•×
B ו•×
of carbon dioxide by body cells increases AB × × • ×
while carrying out active activity. This O ••••
causes the heart to beat more frequently
and increases the pulse rate to transport 4. (a) To save lives
oxygen and carbon dioxide more efficiently. (b) Leukaemia, haemophilia
5. (a) A person of blood group O can
Formative Practice 3.2 (p. 95)
1. Blood circulatory system is a special donate blood any individual because

transport system in complex organisms the person has no A antigen and B
which functions to transport nutrients,
respiratory gases and waste products. antigen.

8 (b) A person of blood group AB can
receive blood from any individual

because his plasma does not contain

antibody Anti-A or Anti-B.

(c) Blood bank is the place where blood
is stored and retrieved.

6. (a) Hospitals, National Blood Centre
(b) Road accidents, war
7. (a) Blood group AB
(b) Presence of virus and other

unwanted substances

(c) Prevents clotting of blood

Activity 3.8 (p. 110) Summative Practice 3 (pp. 116 – 120)
Questions
1. The eosin solution stains to form a 1. (a) PULSE

specific pattern in the leaves, stem and (b) TRANSPIRATION
roots of the plant.
2. Xylem (c) CAPILLARY
3. Passage of water in plants is through a
transport tissue, namely xylem. (d) PHLOEM

Activity 3.9 (p. 111) (e) HEART
Questions
1. (f) ANTIGEN
2. (a)
Part that is swollen (b) •
(c) ×
(d) ×
×
3. (a) Valve

(b) Transport oxygenated blood

(c) (i) Blood vessel Q has thick walls to

Part that is shrivelled withstand high blood pressure.

(ii) Blood vessel R has walls which

are one cell thick to increase
2. Passage of food in plants is through the
the efficiency of exchange of
phloem.
substances between blood and

body cells through diffusion.

Formative Practice 3.4 (p. 112) 4. (a) Oxygen, carbon dioxide, water,
1. Transpiration is a process of loss of
digested food, waste products
water in the form of water vapour from
(b) Oxygen, carbon dioxide, water
the surface of plants to the air through
(c) During the day, plant cells carry out
evaporation.
photosynthesis and produce oxygen.
2. (a) vapour, liquid
(b) xylem, phloem Hence, plant cells do not need
3. Light intensity, air humidity, temperature,
oxygen supply.
air movement
5. (a) (i) dub
4. Passage of water in xylem can be
detected with the use of dye because (ii) lub

water is colourless. (iii) systolic

5. P: Phloem (iv) diastolic
Q: Xylem
R: Xylem (b) Systolic pressure reading is higher
S: Phloem
T: Xylem than diastolic pressure reading.
U: Phloem
Systolic pressure reading is reading

of blood pressure which is higher

when heart ventricle contracts to

force blood out of the heart to be

distributed to the whole body.

Diastolic pressure reading is reading

Formative Practice 3.5 (p. 113) of blood pressure which is lower

1. Similarity: – Both are transport systems when heart ventricle slackens to

– Both transport water, facilitate blood flowing from the whole

nutrients and dissolved body back to the heart.

substances 6. (a) (i) Eric, Roy

– Both exist in complex (ii) Blood will coagulate.The victim

organisms may die.

Difference: Pick one of the differences (b) (i) Individual 2.

shown in Figure 3.31. This is because she fulfils the

2. Organisms cannot continue to live if they age condition of 18 years and

do not have a unique circulatory system above but less than 60 years.

according to their respective needs. She also fulfils the body mass

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condition of more than 45 kg. CHAPTER 4 Reactivity of Metals

(ii) Pregnant women are not suitable Brain Teaser (p. 126)
Mineralogists usually use the name bauxite,
to donate blood. civilians such as mine workers use the name
aluminium ore and scientists use the name
7. (a) Transports food aluminium oxide.

(b) Xylem or Y Activity 4.1 (pp. 126, 127)
Questions
(c) (i) The part above the ring will 1. Carbon dioxide
2. Flow the gas through limewater. If
become swollen. Food collected
the limewater turns cloudy, the gas is
here cannot be transported to the carbon dioxide. On the other hand, if the
limewater does not turn cloudy, the gas is
part below the ring because of not carbon dioxide.
3. (a) Carbon dioxide
the absence of X (phloem). (b) Carbon dioxide
4. (a) calcium chloride + carbon dioxide +
(ii) The plant will dry up and die.
water
8. Set A = 54 g = 0.3 g/min (b) calcium oxide + carbon dioxide
180 mins 5. Calcium, carbon, oxygen

Set B = 36 g = 0.2 g/min Formative Practice 4.1 (p. 128)
180 mins 1. Minerals are naturally occurring solid

9. (a) Badrul. He has the highest pulse rate elements or compounds with definite
immediately after activity. crystalline structures and chemical
compositions.
(b) Azizah. Her pulse rate returns to its 2. (a) Gold, silver, diamond or other mineral
original rate after a time interval of 15
minutes after activity. elements (Any one)
(b) Bauxite, hematite, galena, cassiterite,
10. (a) Location B.
Location A is not suitable for the quartz or other natural mineral
compounds (Any one)
growth of herbs. This is because of 3. Calcium oxide that has properties of a
the absence of light needed by herbs base is used to neutralise acidic soil.
to carry out photosynthesis. Silicon dioxide that has a high melting
Location C is not suitable for the point is used to make glass laboratory
growth of herbs. High temperature in apparatus.
this location will increase the rate of
transpiration of the herbs. Activity 4.3 (pp. 130, 131)
Location B is suitable for the growth Questions
of herbs. Temperature in this dim 1. (a) Magnesium oxide
location is able to maintain the rate (b) Aluminium oxide
of transpiration of the herbs. In (c) Zinc oxide
addition, the presence of sunlight in (d) Iron oxide
the bright location enables the herbs (e) Lead oxide
to carry out photosynthesis. 2. The more reactive the metal towards
(b) Example of constructed model
oxygen, the more vigorous the reaction.
Transparent umbrella which 3. Magnesium → Aluminium → Zinc → Iron
can reduce the intensity of
light that enters → Lead

Tissue Brain Teaser (p. 132)
Carbon + oxygen → carbon dioxide
Water Hydrogen + oxygen → water
Device to regulate air humidity

10

Activity 4.4 (pp. 132, 133) (b) Air pollution. Air pollution can be
Questions avoided by filtering the gases
1. (a) Zinc + Carbon dioxide produced before releasing them to
(b) No change the atmosphere.
(c) Lead + Carbon dioxide
2. Zinc and lead. Summative Practice 4 (pp. 143 – 145)
Oxides of metals which are less reactive
1. (a) Elements: Iron, Silver, Potassium,
than carbon will turn into the metals
when heated with carbon. Tin, Diamond
3. Aluminium
Increasing Carbon Compounds: Quartz, Bauxite,
reactivity Zinc
Galena, Hematite, Limestone
Lead      
(b) Bauxite, Aluminium and oxygen
4. Metal extraction. Metals which are less
reactive than carbon in the reactivity 2. (a) Stanum(IV) oxide
series of metals can be extracted from
their ores through the reduction of the (b) Carbon
oxide of these metals by carbon.
(c) Tin + oxygen → Tin(IV) oxide
5. (a) more 3. (b)
(b) less (c) •
•
Formative Practice 4.2 (p. 136) 4. (a) Oxygen
1. The reactivity series of metals is an
(b) Potassium and sodium are very
arrangement of metals according to their
reactivity towards oxygen. reactive metals. Paraffin prevents
2. (a) Yes. Metal X is reactive towards
potassium and sodium from reacting
oxygen because metal X burns with a
bright flame. with oxygen and water vapour in the
(b) Metal Y is less reactive than metal X.
air.
(c) X
Y 5. (a) Oxygen
Z
(b) To provide oxygen for the reaction.
3. (a) oxygen
(b) potassium (c) Heat the powdered metal until it
(c) extraction
4. (a) Potassium glows before heating potassium
(b) Gold
5. (a) Carbon and hydrogen manganate(VII) to provide oxygen for
(b) Carbon and hydrogen can react with
the reaction.
oxygen.
(d) To construct a reactivity series of
Formative Practice 4.3 (p. 141)
1. (a) Electrolysis metals.
(b) Reduction of iron ore with carbon
2. (a) Tin 6. For metals which are more reactive
(b) (i) Iron ore, limestone, coke
(ii) Hot air than carbon, extraction of the metals
(c) (i) Slag
(ii) Molten iron is through the electrolysis method. For
3. (a) Soil erosion. Problem of soil erosion
metals which are less reactive than
can be solved by replanting trees.
carbon, extraction of the metals is

through reaction of the metal ores with

carbon.

7.

Mixture of iron
powder, limestone
powder and coke Bottle/Plastic bag

Air at room Drinking
temperature straw

Air at room
Hot temperature
Fan Hot air Cooking oil air
blade
Motor
Motor
Water

Paper clip

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Explanation: Represent
Substance Blast furnace
Slag
Bottle Molten iron
Cooking oil Heating device
Water Iron ore
Motor Limestone
Iron powder
Limestone powder

Innovative step: Fan blade is connected
in a direction opposite
to the normal direction
so that sucked air flows
through the motor to be
heated. Motor is also
cooled by this flow of
air.

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