textbok answer

1. Breathing is the exchange of air between an individual and the environment and it involves the breathing
in and breathing out processes. Respiration, on the other hand, is the oxidation or ‘burning’ of food to
produce carbon dioxide and water, and to release energy.

2. The air is filtered and warmed when it passes through the nostrils.
3.

Inhaled air Exhaled air

More oxygen Less oxygen
Less carbon dioxide More carbon dioxide
Temperature of the environment Temperature of the body
Less water vapour More water vapour

1. It has a large surface area.
Its wall is one-cell thick.
It has a moist layer for the gases to diffuse.

2. Molecules of oxyhaemoglobin break down to release oxygen which then diffuses out through the wall of
the capillaries into the tissues or cells.

3. haemoglobin. oxygen, oxyhaemoglobin

1. A passive smoker is a person who does not smoke but receives second hand smoke from smokers around
him.

2.

Substances Carcinogenic Sources

1. Tar / Cigarette smoke
2. Nicotine / Tobacco
3. Asbestos dust / Asbestos manufacturing factories
4. Carbon monoxide
5. Carbon dioxide Vehicles
6. Sulphur dioxide Industries
7. Nitrogen oxide Industries
Vehicles

Part A

1. C 2. C 3. A 4. D 5. A 6. B
7. A 8. A 9. C 10. C

Part B

1. The person will have difficulty breathing in and breathing out air.
2. right blank – carbon dioxide; left blank – oxygen; bottom blank – blood capillaries

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1. Heart muscles
2. Left ventricle because it has to pump blood to all parts of the body except the lungs.
3. Diffusion. It has a very thin wall which is one cell-thick.
4. Oxygen from the lungs is carried in the form of oxyhaemoglobin by the pulmonary vein to the left atrium

of the heart, then into the left ventricle. When the left ventricle pumps, oxyhaemoglobin is carried out of
the heart by the aorta. It is then carried by an artery to the kidney.
5. Digested food substances like glucose, amino acids, fatty acids and glycerol. Waste materials like carbon
dioxide are also transported by the blood system from the small intestine to the heart.

1. It has a thin membrane for easy diffusion.
It has no nucleus so it can contain more haemoglobin molecules.
It has a biconcave shape which gives it a larger surface area.

2. To protect the body against diseases.
3. Blood group O can be accepted by all blood groups.

1. Phloem

Xylem Transports synthesised food from the
leaves to all parts of the plant
Transports water and mineral salts from
the roots, up the stem to the leaves

2. Stomata are tiny pores found mostly on the surface of leaves. During transpiration, the pores are opened
to allow water vapour to escape.

3. Wind, light intensity, temperature and humidity
4. Transpiration increases with more wind, greater light intensity, rise in temperature, and lower humidity

Part A

1. D 2. A 3. C 4. B
5. B 6. C 7. A

Part B

1. (a) The oxygen molecule diffuses from the alveolus in the lungs into the blood capillary. It then
combines with haemoglobin to form oxyhaemoglobin and is carried by the pulmonary vein back into
the left atrium, then into the left ventricle of the heart. When the left ventricle pumps, the
oxyhaemoglobin leaves the heart through the aorta, and is carried by an artery to the toe.

(b) Glucose diffuses into the blood capillaries inside the villi of the small intestine. It is then carried by a
vein to the liver, then to the right atrium and into the right ventricle. When the right ventricle pumps,
it is carried by the pulmonary artery to the lungs.

2. (a) A – stoma
B – guard cells

(b) On leaf surfaces

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(c) Controls the opening and closing of the stoma
(d) Carbon dioxide goes in. Oxygen and water vapour move out.

To remove excess water from the plant.
To keep the plant cool.
3 (a) nucleus, oxygen, oxyhaemoglobin
(b) open, oxygen, water vapour

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1. By sweating
2. It removes carbon dioxide and water during respiration.
3. Waste products, if allowed to accumulate, will be toxic to the body and may cause illness.

1. (a) /, (b) / and (c) /
2. Protein would have been converted to amino acids before it reached the kidneys.
3. The urine will be concentrated, dark in colour and scanty.

1. (a) Diffusion through the stomata
(b) Formation of crystals
(c) Formation of complex substances

2. oxygen and eucalyptus oil
3. morphine and cocaine
4. camphor and latex

Part A 2. C 3. B 4. D 5. D 6. D

1. D Excretion in plants Excretion in man

Part B Can store waste products Cannot
Oxygen is a waste product Oxygen is not a waste product
1. Waste products may be useful Waste products are not of use to
Points to man economically man economically
(a)
(b)
(c)

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1. Sexual reproduction is the production of a new individual involving the fusion of the male and female
gametes.

2. They are all asexual methods of reproduction.
They only require one parent to reproduce.
They produce new individuals which are identical to the parents.

3. Sexual reproduction results in variations in the young which may be able to stand changes in the
environment better.

4. Binary fission

1. The sperm fuses with the ovum to produce a zygote, which develops into an embryo.

2. (a) A – prostate gland and seminal vesicle, D – urethra,

B – penis, E – sperm duct

C – testis,

(b) (i) C

(ii) D

(iii) A

(iv) B

3. The temperature outside the body is lower and more suitable for the production of the sperms and

keeping them alive.

1. Male gamete – sperm, female gamete – ovum
2. penis
3. vagina
4. It has cytoplasm which contains food.

1. No, because there is no mature ovum.
2. Lining of the uterus wall and blood vessels
3. (a) There is repair of the uterine wall and formation of blood linings.

(b) The uterus wall thickens and there is more blood supply.

1. Gestation

2. No. The blood vessels inside the umbilical cord transport oxygen from the mother to the foetus, and

transport carbon dioxide from the foetus to the mother.

3. Vagina cervix uterus oviduct

4. (a) carbon dioxide and waste materials

(b) oxygen and nutrients

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1. Milk contains:
• protein necessary for the production of new cells during growth
• calcium for the development of bones in the foetus, and for maintaining the healthy condition of the
mother’s bones and teeth

2. Excessive carbohydrates and fats result in an increase in the mother’s body weight. This may result in a
big-sized baby. Lack of fruits and vegetables may affect the health of the mother and may cause
constipation in the mother.

1. For the man – use condoms
For the woman – take contraceptive pills, use IUCD and diaphragm
For both – practise the rhythm method or carry out sexual intercourse during the safe period

2. It may affect the health of the mother and child. A mother needs time to recover after each pregnancy.
She may not spend enough time with each child.

1. To attract pollinating agents like insects and animals so that they can transfer pollen to the stigma for
fertilisation to take place.

2.

Sepals Petals

Form the first whorl of a flower Form the second whorl of a flower
Usually small and green in colour Usually big and brightly coloured
Protect the flower during the bud stage Protect the reproductive organs of the flower

3. Papaya plants have both unisexual and bisexual flowers. Papaya plants that cannot bear fruits are those
that only bear male flowers.

1. Bright colours, presence of nectar, scented
2. They have hairy bodies and legs. When they visit flowers to collect pollen or nectar, the pollen may stick to

the hairs and when they visit the next flower, the pollen may drop on the stigma of the flower, thereby
carrying out pollination.
3. Man acts as artificial pollinating agent in agriculture by transferring pollen from the anther to the stigma of
flowers (for example, oil palm) to make sure cross-pollination takes place.
4. Advantage – it needs only one parent plant
Disadvantage – it does not produce variations

1. X, Z, W, Y

2. Inside the ovule

3. The ovary the fruit

The ovule the seed

The fertilised ovum the zygote

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1. Water, air, warmth
2. Water softens the seed coat so that the radicle and plumule can break through during

germination. Water is an important medium for the enzymes to act on the insoluble food stored and
change it into soluble substances for the germination of seeds.

1. It involves only one parent.
It does not require gametes.
It produces young plants which are identical to the parent plant.

2. The food stored in the tuber is used by the buds present to germinate into new shoots because the three
conditions for germination are present.

3. Advantage – can produce plenty of young plants in a short time all year round
Disadvantage – there is no variation because the young plants are identical to the parent

4. (a) from seeds
(b) from stem cuttings

Part A 2. D 3. B 4. B 5. A
1. D 7. D 8. C 9. A 10. B
6. A 12. A 13. C 14. A 15. C
17. D 18. B 19. D 20. C
11. A
16. D

Part B Ligation
1. (a) To prevent pregnancy/for birth control
The woman loses her ability to reproduce permanently.
(b) By giving him hormones or drugs
(c) In vitro fertilisation. The female is given hormones to stimulate ovulation. The ovum is then
(d) removed from the female and placed inside a petri dish containing nutrient solution. Then the
(e) sperms from her husband are released into the petri dish to allow fertilisation to occur. A fertilised
ovum is then reintroduced into the uterus of the female for implantation to take place.
(f) The rhythm method/natural method

2. (a) A – anther B – stigma C – ovary D – nectar E – petal
(b) (i) From the anther of a flower to the stigma of another flower.
(ii) Pollinating agent
(iii) Cross-pollination
(iv) Fertilisation has taken place in flower 2 but not in flower 3.
(v) Flowers 1 and 2 are of the same species while flower 3 is of a different species from flower 1.
(c) (i) Brightly coloured and scented.
(ii) To collect nectar.
(iii) They act as pollinating agents.

3. (a) It takes a shorter time to produce a new plant. The new plant is identical to the parent plant.
(b) The ginger has buds which can grow into new shoots and store food.
(c) Cross-pollination and tissue culture

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1. body size, number of cells and weight.
2. Both growth curves have the same sigmoid shape. During infancy and childhood, both have the same

curves. Starting from 4 years old, boys grow slightly faster than girls. Between the age of 12 and 14 years,
girls grow taller than boys. After 14 years old, boys grow faster than girls.

Part A 2. D 3. A 4. D
1. D

Part B
1. The irreversible increase in size, number of cells, weight, change in shape and function of an organism.
2. 12 years old
3. Infancy, childhood, adolescence, adulthood and old age.
4. It contributes to the physical and mental development of children.

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1. compounds, composition

heat

2. Lead sulphide + oxygen lead oxide + sulphur dioxide

heat

Magnesium carbonate magnesium oxide + carbon dioxide

3. Chemical name Element composition
Mineral Iron oxide Copper, carbon, oxygen

Haematite Lead, sulphur
Galena

1. Magnesium and aluminium
2. Iron pyrite
3. (a) Zinc oxide

(b) sulphur

1. second, element, compounds
2. Silica and silicates
3. It is used in making glass by heating a mixture of sand and metal carbonates.

It is used to make concrete pillars and walls.
Silica, in the form of quartz, is used to make electronic chips

1. (a) carbon, oxygen
(b) quicklime

2. Marble, animal shell and coral
3. It changes to calcium oxide and gives off carbon dioxide.
4. It is used by farmers to neutralise the acidic conditions of the soil.

It is used as a commercial alkali to make soda lime which is an efficient acid gas absorber.

1. Petroleum, natural gas and coal
2. Coal is a hydrocarbon and when heated, it burns to produce energy. Coal is formed from trees, ferns and

mosses covered by swamps millions of years ago.
3. Crude petroleum contains many types of hydrocarbons mixed together. The hydrocarbons have to be

separated before they can be used as fuel. Petrol is a ready to burn fuel.

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4. Setting the indicator of the water heater to low heat whenever possible.
Not using the water heater unnecessarily.

Part A

1. C 2. A 3. B 4. D 5. D 6. A

Part B

1. (a) Elements: Gold, sulphur, copper

Compounds: Quartz, calcite, galena, haematite, cassiterite, china clay, calcium silicate

(b) Hardness of the minerals

2. (a) M: oxygen zinc sulphide
N: sulphur zinc oxide

(b) Process K = zinc + sulphur
Process L = zinc + oxygen

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1. By introducing friction on the material
2. Electroscope
3. Directs current to the ground without damaging the building
4. (a) attract

(b) repel
(c) repel

1. Power stations, dry cells, lead-acid accumulators and mercury cells
2. Electrons flow from the negative terminal to the positive terminal.

Current flows from the positive terminal to the negative terminal.
3. (a) Current – the rate of flow of charges

(b) Voltage – the electrical energy needed to move electric charges from one point to another point in a
conductor.

(c) Resistance – the characteristic of resisting the flow of electric current in an electrical conductor.

1. Voltmeter – measures voltage
Ammeter – measures current

2. Voltage – volt
Current – ampere
Resistance – ohm

3. Connect the ammeter in series
4.

1. Inversely proportional
2. Directly proportional
3. \F(voltage,current) = resistance

1. A closed circuit that allows an electric current to flow.
2. (a) Series circuit and parallel circuit

(b)

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(c)

1. Advantages - identical bulbs will light up with equal brightness
- the voltage across the circuit increases if more cells are connected

Disadvantages - current flows in one path only
- light will become dimmer if more bulbs are connected

2. (a) 3V (b) (i) 0.6 A (ii) 1.8 V; 1.2 V (c) 5 ohm

1. 1.5 V

2. Each electrical component can be controlled by separate switches. The brightness of the bulbs remains

unchanged if more bulbs are connected

3. The bulbs in Figure 7.19 (b) are brighter.

4. (a) 2 A (b) 1.33 ohm (c) 4 V

1. The greater the strength of a magnet, the closer its magnetic field lines

2. A magnet will always come to rest in the north – south direction

3. (a) N (b) (i) (ii) (iii) X

S NS N
S arrowhead from N to S

1. A temporary magnet that is produced when electric current flows through a solenoid
2. Magnetic field

Part A

1. C 2. B 3. C 4. B 5. D 6. A

Part B 1.5 V
1. (a) same brightness
1.5 V
(b) connect the two 1.5V dry cells in series
(c)
(d)

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1. thermal generator, hydroelectric generator, diesel generator, nuclear generator and gas turbine generator
2. biomass and solar energy
3. fossil fuels, water, solar energy, biomass

1. alternating current
2. When an alternating current is applied to the primary coil, electrical energy from the primary coil is

transferred to the secondary coil through the changing magnetic field. This induces an alternating current
in the secondary coil.
3. The voltage across the primary coil is smaller than the voltage across the secondary coil.

1. Step-up transformer
2. To lessen the loss of energy in the form of heat
3. To step-down the voltage

1. 240 V
2. Live wire (brown), neutral wire (blue) and earth wire (yellow with green stripes)
3. Main switch – disconnects the electrical power supply from the main supply cable when electrical energy is

not needed.
Circuit breaker – cuts off the electric current flowing through a circuit under abnormal conditions.

1. 480 W
2. 0.5 A
3. 40 s
4. RM7.85

1. The fuse wire melts when current exceeding its rating flows through it. This breaks the circuit.
2. It allows a large current to escape to the earth without passing through the person.
3. 10 A

1. Carelessness and ignorance of the users of electrical energy; damaged insulating wires.
2. A circuit breaker automatically trips the switch when current higher than its rating flows through it.

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3. Fuse – a wire with current rating. This wire melts and breaks the electric circuit when current higher than
its rating flows through it. The wire needs to be replaced so a fuse of the same rating needs to be
replaced.

Circuit breaker – consists of switches. It automatically switches off when the current flowing is higher than
its rating. The circuit breaker can be reset.

4. To avoid electrical shocks and fires.

1. Use energy efficient electrical appliances.
Carry out research and development on renewable energy sources.

2. Use fluorescent lamps.
Switch off electrical appliances when not in use.
Keep the room door and window closed when the air conditioner is switched on.
Use energy efficient electrical appliances.

Part A

1. A 2. B 3. C 4. C 5. D
6. B 7. C 8. C 9. D 10. A
11. C 12. D 13. A

Part B X– live wire, brown
1. (a) Y– neutral wire, blue
Z – earth, yellow with green stripes
(b) breaks the circuit when current exceeding the fuse rating flows through it
(c) (i) There will be current in the metal casing or external part of the kettle.
(ii) The current flows to the earth through the earth wire Z and does not flow through the person
(d)
who touches the kettle.
(i) Wire Z
(ii) The external part of the hair dryer is made of an insulator such as plastic.

2. (a) ELCB – Earth Leakage Circuit Breaker
MCB – Miniature Circuit Breaker

(b) Breaks a circuit if too much current flows in the circuit
(c) Automatically switches off when current flowing through it is higher than its rating

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1. Prominence
Flare Corona
Chromosphere
Core
Sunspot Photosphere

2. The flares cause disturbance to telecommunications and changes to climate on Earth.
3. Through nuclear fusion of hydrogen atoms to form helium. This releases huge amounts of energy.
4. It is relatively close to the Earth

1. (a) galaxy
(b) Milky Way
(c) black hole
(d) nebula

2. The Sun can be seen during the daytime, as hot and bright because of its closeness to Earth whereas most
other stars are far away and are not easily seen. It occurs as a lone star, not in pairs or groups as in the
case of most other stars.

3. Stars are formed from nebulae in outer space. A nebula is a cloud of dust and gases like hydrogen and
helium. The gravitational attraction between particles of the gases and dust pulls them together. As more
and more particles are pulled together, the gravitational attraction gets stronger until a star is created.

1. ‘Big bang’ means an enormous explosion that occurred in the Universe where all the energy and matter in
it were thrown out far and wide into space.

2. It is an important source of energy for all living things.

Part A

1. D 2. D 3. B 4. D 5. B

Part B

1. (a) Nuclear fusion of hydrogen atoms to form helium that generates tremendous amount of light and
heat

(b) sunspots
(c) corona

2. (a) nuclear fusion
(b) It provides warmth, light and food directly or indirectly to all living things

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1. (a) Involved in telecommunication, satellite TV, live telecast, Internet
(b) To monitor and warn of drastic climatic changes, for example, storms and other natural disasters
(c) To help guide ships, to locate a person’s whereabouts on Earth, and for air traffic control

2. To be a scientifically advanced nation, and be a key player in the aerospace industry

Part A

1. D 2. A 3. A

Part B

1. (a) space shuttle
(b) bringing tourists for space travel

2. Through telecommunication satellites
3. The invention of various types of telescopes, the launch of rockets, space shuttles, satellites, space stations

and space probes

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