CHAPTER 1: Respiration

Respiration takes place in all living things. Humans obtain oxygen and remove carbon dioxide through

the respiratory system.

HUMAN BREATHING MECHANISM

Living things get their oxygen supply from the air around them. We breathe in oxygen for

respiration and breathe out carbon dioxide and water vapour produced during respiration.

Human respiratory system

Figure 1.1 shows the structure of the human respiratory system

Figure 1.2 shows the structure of the lung in greater detail.

TRANSPORT OF OXYGEN IN THE HUMAN BODY

Our lungs consist of millions of alveoli. Each alveolus has one cell thick wall. On the inside there is a

thin film of moisture and on the outside, it is covered with blood capillaries (Figure 1.6).

The inhaled air which is rich in oxygen is found inside the alveolus. The oxygen dissolves in the

moist lining of the alveolus and then diffuses into the blood capillaries. Diffusion of oxygen takes

place from an area of higher concentration of the gas to an area of lower concentration of the gas.

The blood inside the capillaries contains red blood cells which are rich in a substance called

haemoglobin. The oxygen combines with the haemoglobin in the red blood cells to form

oxyhaemoglobin. The blood rich in oxygen then leaves the lungs and is carried by bigger blood

vessels to the heart.

When the heart pumps, the oxygenated blood is distributed to all parts of the body. When the

blood reaches tissues or cells that do not have enough oxygen, the oxyhaemoglobin is broken down

and oxygen is released. The oxygen then diffuses through the walls of the capillaries into the cells.

At the same time carbon dioxide from the cells diffuses into the capillaries to be carried back to

the lungs.

Figure 1.7 shows the transport of oxygen in the form of oxyhaemoglobin.

THE IMPORTANCE OF A HEALTHY RESPIRATORY SYSTEM

The oxygen that is needed for respiration comes from the atmosphere. Due to air pollution, the air

that we breathe may contain substances which are harmful to our respiratory system. The air we

breathe in may also contain bacteria, viruses and other microorganisms.

Substances that are harmful to the respiratory system

Several substances harm the human respiratory system. For example, cigarette smoke damages the

respiratory system. Other harmful substances are industrial waste products, pollutants from motor

vehicles, bacteria, viruses and other microorganisms.

Effects of harmful substances

Cigarette smoke can cause emphysema, heart diseases, bronchitis and lung cancer. It can also

worsen respiratory problems such as asthma and pneumonia.

Cigarette smoke contains poisonous chemicals that include tar, nicotine and carbon monoxide. Tar

collects in the lungs. It is a mixture of many toxic chemicals. Many of these substances are

carcinogens, that is, they cause cancer. Nicotine in the tobacco causes addiction to smoking. Carbon

monoxide is a highly poisonous gas. It reduces the amount of oxygen in the blood. Sulphur dioxide is

acidic and can damage lung tissues.

A non smoker may inhale the cigarette smoke from smokers. This smoke is called secondary smoke

and it will harm the non-smoker. This is called passive smoking by the non-smoker.

The lungs of a smoker suffering from a smoking related disease such as emphysema show unhealthy

tissue compared to that of a non-smoker.

Effects of harmful substances

Chemical substance Sources Damaging effects

Tar Cigarette smoke Causes lung cancer

Nicotine Cigarette smoke Causes addiction to smoking

Carbon monoxide Cigarette smoke, car exhaust Reduces amount of oxygen in the blood

Sulphur dioxide Industry, vehicles Damages lung tissues

Hydrocarbons Industry, vehicles Cause cancer

Nitrogen oxide Industry, vehicles Interacts with hydrocarbons to form haze

Haze Industry, vehicles, open burning Causes breathing difficulties

Other harmful substances that may enter our respiratory system are industrial waste like coal

dust, sulphur dioxide and asbestos dust, as well as pollutants from motor vehicles like carbon

monoxide, nitrogen oxide, and hydrocarbons. All these have been related to respiratory problems

like chronic bronchitis, emphysema, asthma and even cancer. They directly or indirectly cause haze.

Haze can cause throat irritation and inflammation of the upper respiratory tract, and difficulty in

breathing.

Effects of smoking

Questions

1. What does the cotton wool in the U-tube represent?

The cotton wool in the U-tube represents the lungs

2. What is the function of the litmus solution?

The function of litmus solution is to investigate the presence of acidic substances in cigarette

smoke

3. What are the substances in cigarette smoke that cause the cotton wool and litmus solution to

change colour?

Tar and the acidic substances in cigarette smoke cause the cotton wool and litmus solution to

change colour

4. What can you conclude about the effects of cigarette smoking?

Cigarette smoke can damage the lungs because it contains tar, produces acidic substances and

heat

CHAPTER 2: Blood Circulation and Transport

The human body has an efficient transport system which is made up of the heart and blood vessels.

Plants, like humans, also need a transport system.

TRANSPORT SYSTEM IN HUMANS

The transport system in humans is called the circulatory system. It is made up of the heart and

blood vessels that carry the blood in our body. The blood vessels are all link up.

Structure of the heart

The human heart is a muscular, cone-shaped organ. It is located in the chest cavity between the

lungs. It is the size of your fist. The heart is made up of cardiac muscles which can contract

automatically without being stimulated by nerves. The heart has four chambers. The two upper

chambers are the right ventricle and the left ventricle.

Function of the heart

The function of the heart is to pump blood to all parts of the body. The right side of the heart

pumps blood to the lungs, while the left side pumps blood to the other parts of the body. The heart

pumps blood by contracting and relaxing its muscles. The contractions can be heard as heartbeats.

The left and right side of the heart work in harmony. The atria contract and relax at the same

time. So do the two ventricles. A valve separates each atrium from the ventricle below it. There are

also valves at the exit of the ventricles. This ensures that the blood flows only in one direction,

from an atrium to a ventricle, then from a ventricle into a blood vessel.

Blood vessels and their functions

When the heart pumps, the blood flows around the body in a system of tubes called blood vessels.

There are three types of blood vessels. They are arteries, veins and capillaries.

Difference in characteristics of blood vessels

Blood Vessel Characteristic

Arteries Carry blood away from the heart to all parts of the body. All arteries (except those

to the lungs) carry blood rich in oxygen. Arteries have thick muscular walls and

relatively small lumen. This is because the heart forces blood into them, and they

need to maintain the pressure of the blood. The branch into very small tubes called

capillaries.

Veins Carry blood to the heart from all parts of the body. All veins (except those from

the lungs) carry blood with little oxygen. They have thinner and less muscular walls

than arteries because the pressure of the blood is lower in the veins. They have

relatively large lumen and valves to ensure one-way flow of blood.

Capillaries They have one cell thick walls that allow substances to pass through them into cells

and from cells into the blood. Capillaries join to form bigger tubes called veins.

Capillaries are also involved in the release of excess heat from the body.

Path of blood flow in the circulatory system

The circulatory system carries blood to and from different parts of the body.

Humans have a double circulatory system. Blood passes through the heart twice as it circulates in

the body.

Paths of blood flow

Path 1: From the heart to the lungs and back again to the heart

The right atrium receives deoxygenated blood from different parts of the body and pushes it into

the right ventricle. The right side of the heart then pumps blood to the lungs to collect oxygen and

remove carbon dioxide

Path 2: From the heart to the rest of the body and back again to the heart

The oxygenated blood returns to the left atrium and flows into the left ventricle. Then the left

side of the heart pumps blood to the rest of the body to supply oxygen to the cells and to collect

carbon dioxide.

Role of blood in transport

Our circulatory system transports or carries useful substances like oxygen and nutrients, and

removes wastes like carbon dioxide and urea. It also transports chemicals like hormones and

antibodies.

Substances transported in blood

Substance transported From To

Oxygen in the form of oxyhaemoglobin

inside red blood cells

Lungs All body cells

Carbon dioxide in blood plasma All body cells Lungs

Digested food such as glucose, amino

acids in blood plasma

Small intestines Liver and all body cells

Waste materials (urea) in blood plasma Cells and liver Kidneys

Hormones in blood plasma Endocrine glands Target organs in the

body

Importance of a healthy heart

The heart is a very important organ. It transports oxygen to all parts of our body. An unhealthy

heart leads to various health problems. Examples are coronary heart disease, heart attack, high

blood pressure and stroke. These illnesses may even cause death.

HUMAN BLOOD

An adult human has about 5 litres of blood which is about 9% of his body weight. Blood is the main

carrier of the body’s transport system. It carries nutrients and oxygen to the body cells and

transport carbon dioxide and waste products away from the cells. It also fights diseases and helps

to maintain a constant body temperature.

Blood constituents and their functions

Blood is made up of blood cells and platelets suspended in a liquid. The liquid part is called plasma

and forms about 55% of the volume of blood. It carries dissolved substances. The blood cells and

platelets form 45% of blood.

Blood performs the following functions.

1. It acts as a transport medium that carries gases and dissolved substances from one part of the

body to another. Red blood cells carry oxygen. Blood plasma carries dissolved substances.

2. White blood cells protect the body against diseases.

3. Blood maintains the body temperature at 37oC.

Blood group and compatibility

Blood can be classified into groups. There are four main blood groups namely A, B, AB and O. Each

of us belongs to a particular blood group or blood type. The blood group is determined by a protein

on the surface of the red blood cells. A lot of blood may be lost during an operation or an accident.

To replace the lost blood, a person needs a supply of blood from a donor. The transfer of blood

from a donor to a recipient is called blood transfusion. The donor’s blood and the recipient’s blood

must be compatible. Otherwise, the blood will agglutinate inside the blood vessels of the recipient.

This may cause the death of the recipient.

Compatibility of different blood groups

Recipient’s blood group

Donor’s blood group

A B AB O

A

B

AB

O

A person with blood O is known as a universal donor because his blood can be accepted by all blood

groups. A person of blood group AB is known as a universal recipient because the person can receive

blood from all blood groups. However, he can only donate blood to people of blood group AB.

() compatible

() incompatible

Importance of blood donation

Many patients of different age groups require blood transfusion. This is needed when they undergo

major operations, battle long-term diseases, or are the victims of accidents. For example, blood is

needed during surgery, childbirth, or cancer treatment. As a result, hospitals in Malaysia require a

lot of blood to meet the needs for blood transfusion.

Blood is a living and renewable tissue. Donating blood does not harm anyone, but it can save lives. A

healthy person can donate blood every 56 days or about four to six times per year.

Storage and handling of donated blood

To ensure that donated blood is safe for transfusion, the following measures are taken.

The donor is interviewed and given medical counselling

The donated blood is tested or screened for Hepatitis B and C, sexually transmitted diseases

and human immunodeficiency virus (HIV). This is to make sure that infected blood is not given

Blood can be separated into plasma, red blood cells, white blood cells, and platelets. Depending on

the illness, a patient can be given the constituents of blood required.

The donated blood is collected in a plastic bag which prevents a substance that prevents the blood

from coagulating. These bags are then sent to the hospitals where they are stored in blood banks at

4oC. There are two types of blood in the blood banks. Fresh blood which can last for 24 hours, and

the stored blood at 4oC which can last for about 40 days. Before the blood is used for transfusion,

the bags are taken out and left at room temperature for two hours.

TRANSPORT SYSTEM IN PLANTS

Plants, like animals or humans, need a transport system that consists of thin tubes called vascular

tissues in the roots, stems and leaves

Transport tissues in plants

There are two types of tissues that are involved in the transport system of plants. These are xylem

and the phloem. Xylem tissues carry water and dissolved minerals absorbed in the roots, up the

stem and to the leaves. Phloem tissues carry glucose, produce by the leaves during photosynthesis,

from the leaves to all parts of the plant.

CHAPTER 3: Excretion

If rubbish is allowed to accumulate, it will harm the environment. Similarly, our body also produce

waste product which are harmful. Plants, like humans and animals, also produce waste products.

HUMAN EXCRETION

Many chemical reactions in the body produce waste products. The body needs to remove these

waste products to stay healthy. The process of removing waste products, produced during chemical

processes in the cells, is called excretion.

Excretion helps to remove waste produced by cells. If wastes are not removed, toxic substances

build up and these can damage organs in the body. This can lead to death.

Excretory organs and excretory products

The skin, which is known as a sensory organ is also an excretory organ. The skin excretes water,

mineral salts and some urea through sweating. Sweat is salty. From the sweat gland just below the

skin, water, mineral salts and urea are excreted along the sweat duct and pass out the sweat pore

that lies on the skin surface. For example, on a hot day, there is more sweat on the skin.

Evaporation of the sweat cools the skin and hence the body.

The waste products of respiration, carbon dioxide and water, are expelled from the lungs.

Therefore, the lungs are also excretory organs.

The kidney, the main excretory organ in humans, removes urea, a waste formed in the liver from

excess amino acids in the body. The urea is excreted in urine. Besides urea, urine also contains

water and traces of mineral salts.

Excretory organs and excretory products

Excretory organ Excretory products

Kidney Water, mineral salts, urea

Skin Water, mineral salts, urea

Lung Water and carbon dioxide

The importance of excretion

Excretion helps to maintain a healthy body. For example, carbon dioxide from respiration must be

removed quickly because a high level of this gas will increase the acidity of blood. Urea is another

waste product. Urea, if left to accumulate in the body, will become toxic. In addition, excretion of

excess water and mineral salts by the kidneys helps to maintain the balance of water content,

chemical composition and pH in the body system.

THE URINARY SYSTEM IN HUMANS

The human urinary system is made up of several parts. These parts help to remove waste products

like urea, water and mineral salts.

The kidneys are located at the back at the body and form the main organs of the urinary system.

The kidneys are found at the back of the abdominal cavity, just below the diaphragm.

Urea from the liver is sent to the urinary system. The flow of the urea into the urinary system

starts from the kidney, to the ureter, then to the bladder, and lastly to the urethra before being

removed in urine.

Structure of the kidney

The kidneys are bean-shaped and roughly the size of a fist. They are protected by the lower rib

cage. The outer transparent coat of the kidney is fairly tough and is called the capsule.

When the kidney is cut longitudinally, it is seen to consist of two parts; an outer darker protective

part that is known as the cortex and an inner lighter layer called the medulla. The cortex makes up

about one-third of the kidney. The inner boundary of the medulla forms several pyramids which

open into a sac-like cavity called the pelvis. From the pelvis, a long, narrow tube called the ureter,

leads to the bladder.

Functions of the kidney

The most important function of the kidney is to filter blood and remove urea, excess mineral salts

and water to form urine.

The kidneys regulate the water and chemical balance in the body. The amount of the water that is

reabsorbed depends on the amount of water required in the body. If the body have too much water,

reabsorption will be less. The urine produced will be diluted. On the other hand, when the body

system lacks water, more water will be reabsorbed into the blood. The urine will be concentrated.

Importance of maintaining healthy kidneys

It is important to maintain healthy kidneys. Besides excreting urea, water and mineral salts, the

kidneys also excrete many harmful substances that are consumed. The kidney is a relatively strong

organ. However, it may be harmed in several ways. The food we take may contain toxic substances

like mercury, lead and arsenic that can damage the kidney.

One should maintain healthy kidneys by drinking plenty of water. A high intake of salt and sugar may

cause diseases such as high blood pressure and diabetes. These diseases may lead to kidney failure.

We should avoid taking food and medicine that can harm the kidney. Kidneys may also be harmed by

infection. Usually, the infection begins in the bladder. However, it can spread to the ureter and

kidneys.

Living with kidney failure

Kidney failure is a common disease nowadays. Although we can live with only one kidney, failure of

both can result in death. However, kidney failure can be treated through dialysis or kidney

transplant. Dialysis is a more common treatment for kidney failure and is carried out with the use

of a machine.

Dialysis is a technique of separating particles of different sizes in a liquid mixture. In dialysis,

blood is filtered through an artificial membrane in the dialysis machine.

A patient’s blood needs to pass through the dialysis machine many times to make sure all wastes are

removed. As such, the patient must be connected to the machine for about five hours, two or three

times a week. Dialysis is not cheap. Dialysis does not cure the damaged kidney. It is only an artificial

substitute for the original kidney.

EXCRETION IN PLANTS

Plants also need to excrete their waste products. The waste products of plants are water, carbon

dioxide, oxygen, mineral salts and nitrogenous wastes. These products are excreted mainly through

the stomata.

How plants remove their excretory products

Plants excrete their waste products mainly by simple diffusion. This is done through the cell wall

and through the stomata.

Mineral salts are mainly retained within the plant body. As crystals, for example, calcium carbonate

and calcium oxalate crystals. Minerals like silicon salts are deposited in the leaves of the grass

family, to strengthen the leaf blade.

Nitrogenous waste products are removed as complex substances. These substances are released

when the plants shed their leaves, flowers or bark.

Excretory products of plants

Unlike humans or animals, plants have little nitrogenous wastes. Nitrogenous wastes are usually

converted into insoluble and harmless granules which are retained within the plants cells. Some of

them are useful to humans while others are poisonous.

The majority of nitrogenous wastes are extremely poisonous but may be extracted to produce

medicine. Drugs like morphine, opium and cocaine are excretory products of plants. There are other

waste products like tannins which collect in the bark and can be used by humans to make ink. Other

waste products like oil droplets may be made into perfumes.

CHAPTER 4: Reproduction

All living organisms reproduce to increase their numbers. Animals lay eggs or give birth to young.

Plants reproduce by seeds, spores, or special plant parts.

UNDERSTANDING SEXUAL AND ASEXUAL REPRODUCTION

Reproduction is the process of producing new individuals from living organisms. It is a

characteristic of all living organisms.

Importance of reproduction

Reproduction is the way to increase the number of individuals or offspring of the same species. It

replaces those that die. It also ensures that the species does not become extinct, but continues to

produce new individuals for survival.

Types of reproduction

Reproduction can be divided into two types: sexual reproduction and asexual reproduction. Sexual

reproduction is the reproduction of new individuals by living organisms, involving sex cells. These

sex cells are called gametes. This type of reproduction is shown by humans, and higher animals such

as fish, amphibians, birds, reptiles, mammals and most invertebrates. Flowering plants such as the

rambutan, papaya and hibiscus also show this type of reproduction.

Asexual reproduction is the production of new individuals by living organisms, without involving sex

cells. It occurs in simple organisms such as Amoeba, Paramecium and Hydra. Plants like onion, ginger

and potato can also reproduce this way.

Reproduction

Sexual reproduction

Asexual reproduction

binary fission spore formation budding vegetative

reproduction regeneration

MALE REPRODUCTIVE SYSTEM

Humans carry out sexual reproduction which involves gametes. The male reproductive system

produces plenty of male gametes called sperms.

The male reproductive system consists of a pair of testes, the scrotum, two sperm ducts, a pair of

seminal vesicles, prostate gland, urethra and penis.

Description and function of different parts of the male reproductive system

Part Decription and function

Sex glands These include the seminal vesicle and prostate gland. Sex glands secrete

fluid which contains nutrients from the sperm

Sperm duct A tube which transport sperms from the testis to the urethra inside the

body

Testis Produce the male gametes (sperms) and male sex hormones

Scrotum A sac which hangs outside the body

It holds and protects the testes

Urethra A tube which runs through the penis

It is a passage that allows sperms to flow out of the body

It is a passage that allows urine from the bladder to be excreted to the

outside of the body

Penis Male sex organ which is made up of soft tissues and rich in blood vessels

It transfer semen into the vagina of the female during copulation

Structure and function of sperm

The male sex cell produced by the testis is called sperm. It is the smallest cell in the body. It is

shaped like a tadpole. It consists of a head, neck, middle piece and tail. The head contains the

nucleus. The nucleus consists of genetic material to be transferred to the offspring or children.

The tail enables the sperm to move or swim in the semen inside the vagina, uterus and oviduct of

the female reproductive system.

FEMALE REPRODUCTIVE SYSTEM

The female reproductive system consists of a pair of ovaries, two fallopian tubes or oviducts,

uterus, vagina and cervix.

Description and function of different parts of the female reproductive system

Part Decription and function

Ovary Female sex organ that produces female gametes (ova) and female

sex hormones

Fallopian tubes (oviduct) A muscular tube where fertilisation takes place

Uterus (womb) Pear-shaped with thick muscular walls

Place where the foetus develops and grows

Uterus wall is rich in blood vessels

Cervix Neck of the uterus. Widens during childbirth

Vagina (birth canal) Muscular tube which opens to the outside of the female body as

the vulva

Place where the sperms are transferred during copulation

Structure and function of the ovum

The female sex gamete is called an ovum or egg. It is spherical in shape with a diameter of about 0.1

millimetres. It is the largest cell in the human body. The nucleus contains genetic material which is

passed from the mother to the child. The ovum is not able to move by itself.

FERTILISATION AND PREGNANCY

During copulation millions of sperms are transferred into the vagina. The sperms swim through the

cervix into the uterus and up the oviduct to meet the ovum. If the ovum is present in the oviduct,

fertilisation takes place.

During ovulation, a mature ovum is release. The ovum moves along the fallopian tube or oviduct

towards the uterus. Millions of sperms are release during copulation. However, only about 100 will

reach the ovum. Of these, only one is able to fuse with the ovum.

The fusion between the sperm and the ovum is called fertilisation. Fertilisation produces a zygote.

The zygote divides into two, then into four, and so on. After six days, a ball of cells, now called an

embryo, is formed.

The correct sequence of ovulation, fertilisation and implantation of the embryo in the uterus wall is

shown in the figure below. When implantation is successful, the woman is said to be pregnant. It

takes nine months from the time the zygote is formed until the foetus is ready to be born.

SEXUAL REPRODUCTIVE SYSTEM OF FLOWERING PLANTS

In flowering plants, flowers form the reproductive system of the plant. They produce male and

female gametes for sexual reproduction.

A typical flower consists of sepals, petals, stamens and a pistil, which are arrange in whorls or rings

at the end of a flower stalk.

Parts of a flower

Structure Characteristic Function

Sepal Outermost whorl of a flower, usually

green in colour

Protects the flower during the bud stage

Petal Second whorl of a flower, usually

coloured

Attracts insects and animals

Stamen Consists of the filament and anther Male reproductive part of a flower

Pistil Made up of the stigma, style and ovary Female reproductive part of a flower

POLLINATION

For sexual reproduction in flowering plants to occur, the pollen must first reach the stigma. The

process of transferring ripe pollen from the anther to the stigma is called pollination.

Pollination is the transfer of pollen grains from an anther to a stigma. When the anther is mature

and ripe, it burst open. This releases the pollen grains. Some of the pollen may drop onto the ground

and some may be carried away by pollinating agents to the stigma. There are two types of

pollination; self-pollination and cross-pollination.

Self-pollination takes place when the pollen from the anther of a flower is transferred to the

stigma of the same flower or to the stigma of another flower on the same plant. Cross-pollination is

the transfer of pollen from the anther of the flower to the stigma of another flower on a different

plant of the same species.

Comparison between self-pollination and cross-pollination

Self-pollination Cross-pollination

Involves only one plant Involves two plants of the same species

Requires one or two flowers of the same

plant

Requires two flowers from different

plants of the same species

If it involves one flower, both the anther

and the stigma must mature at the same

time. If it involves two flowers, the anther

and stigma can mature at different times

The anther and stigma can mature at

different times

Less variety in new plants More variety in new plants

OBSERVATION

Studying various types of flowers like hibiscus, maize, morning glory or lily

APPARATUS AND MATERIALS

Hand lens and different types of flowers like hibiscus, maize, morning glory or lily

PROCEDURE

1. Carry out this activity in groups. Each group should bring the various specimens listed above, or

other types of flowers

2. Examine the characteristics of the various flowers. Then identify their pollinating agents.

3. Copy the table below in your science notebook and record all your observations.

Name of

flower

Characteristics of flowers Pollinating

agent Colour

of

petal

Size

of

petal

Filament Stigma Anther

and

pollen

Smell Nectar

Hibiscus

QUESTIONS

1. What conclusion can you make about the characteristics of the flowers and their pollinating

agents?

_______________________________________________________________________

_____________________________________________________________________

2. Why do wind-pollinated flowers produce plenty of pollen?

_______________________________________________________________________

_____________________________________________________________________

Pollinating agents

For pollination to occur, pollinating agents are needed to transfer the pollen grains. The various

pollinating agents are wind, insects, animals and water.

Wind is a pollinating agent for most monocotyledonous plants like maize, grass and paddy. Wind-

pollinated flowers are usually white or light in colour, small, have no smell and no nectar. They have

long filaments to expose the pollen to the wind. They produce plenty of small, light and smooth

pollen. Such pollen is easily carried by the wind. The styles and stigma are long. The stigma is

feathery to trap the pollen carried by the wind.

Insects, like bees and butterflies, are important pollinating agents. Insects are attracted by big,

colourful and scented flowers. When the insects lands on the flower to suck nectar for food, pollen

sticks to the hairy legs and body of the insect.

When the insect lands on another flower to collect food, the pollen may drop off and stick on the

stigma of that flower. Insect-pollinated flowers produce small amounts of pollen. Such pollen is big,

sticky, heavy and rough. Their styles are short and the stigma has a sticky surface.

Animals, like birds and bats, pollinate flowers when they suck nectar from the flowers. Such

flowers are usually big, colourful, scented and produce rough sticky pollen. The pollen sticks to the

beak or body of the animals. When a bird sucks out nectar with its long and pointed beak, pollen

sticks to the beak.

Water is a pollinating agent for water plants like the Elodea and Hydrilla. The flower floats on the

water surface. The water carries the pollen from the anther to the stigma.

Comparison between wind and insect pollinated flowers

Wind-pollinated flower Insect-pollinated flower

Small, pale coloured, not scented, no nectar Big, brightly coloured, scented, nectar

present

Long filament with big anther at the end,

filament sways in the wind and pollen

disperses

Short filament and small anther at the end

Plenty of small, light and smooth pollen Big, rough, sticky and less amount of pollen

Long style Short style

Long and feathery stigma Short and sticky stigma

GERMINATION OF SEEDS

After fertilisation, most of the flower parts wither and die. The ovules grow inside the ovary until

they develop into seeds. A seed is made up of an embryo and a food store wrapped in a protective

seed coat or testa.

Structure and function of a seed

Seeds from different plants (monocotyledonous or dicotyledonous) are differnt in size, shape and

colour. They all have the same basic parts like the seed coat, food store and embryo. The

endosperm, which acts as a food store, is found only in the monocotyledonous seed. In the

dicotyledonous seed, Food is stored in the cotyledons for the embryo.

Physical changes of seedlings during germination

If a seed lands on the ground under suitable conditions, like the presence of water, air and optimum

temperature, it will grow into a new plant.

Germination occurs when the embryo grows into a seedling. The embryo is made up of the plumule

and the radicle. The embryo needs food for growth. It obtains it from the food store in the

cotyledons or the endosperm. The plumule grows upwards to form a new shoot. The radicle grows

downwards into the soil to form the root. It is now called a seedling. The seedling continues to

absorb food from the food store until it forms green leaves to produce its own food by

photosynthesis.

VEGETATIVE REPRODUCTION IN FLOWERING PLANTS

Besides sexual reproduction, many flowering plants can reproduce vegetatively. This type of

reproduction requires only one parent plant. Buds on the vegetative plants may grow into new plants.

Vegetative reproduction is a method of producing new plants from any vegetative part of the parent

plant, other than the flower. It is a type of asexual reproduction because it only requires only one

parent plant. The young plant are exactly like the parent plant because they have the same genetic

material. Parts of the plants that can reproduce vegetatively are the stem, leaf and root. Most of

these vegetative parts contain stored food and buds. The bud uses that stored food and grows into

a new plant. Soon it will produce its own food by photosynthesis.

Vegetative reproduction

Vegetative parts Example of plants

Roots

Stems

underground stems

stems that run

horizontally, or

runners

modified stem, or bulb

Leaves

CHAPTER 5: Growth

Nutrition plays an important role in growth. The food that we eat is digested and absorbed by the

body cells where part of it is used to build new cells.

HUMAN GROWTH PATTERN

Growth is an increase in body size, number of cells, weight and change in body shape as well as in

the function of an organism. Growth is irreversible and permanent.

The characteristics of human growth

Our body weight increase and we grow taller until we reach a particular height. Our body shape also

changes. Apart from physical changes, human growth also involves mental, social and emotional

changes. We become more mature.

In human, growth can be determined by measuring physical characteristic such as height and

weight, at suitable intervals over a period of time. These measurements are plotted against time to

obtain a growth curve. The gradient of this curve at a particular time shows the rate of growth at

that time.

In humans, the growth curve can be divided into five stages. These are infancy, childhood,

adolescence, adulthood and old age. Rapid growth occurs during infancy which lasts until about 3

years of age. This is followed by a period of slower growth during chilhood.

Childhood lasts until puberty , which begins at around 12 years old for girls and 14 years old for

boys. Adolescence is the period of rapid growth when sexual maturity or puberty is achieved. This

is followed by minimal growth during adulthood. Adulthood starts from about 20 years of age.

During old age there is negative growth, that is, a loss in height because tissue break down more

quickly than they can be repaired. The age groups of the different stages of growth differ from

one individual to another

Growth curves of boys and girls

CHAPTER 6: Land and Its Resources

Our country is blessed with various natural fuel resources. Examples of these resources are coal,

petroleum, natural gas and wood. Metals are found in the Earth’s crust as elements and compounds.

MINERALS IN THE EARTH’S CRUST

Some of the most abundant elements in the Earth's crust

oxygen

silicon

aluminium

iron

calcium

sodium

potassium

magnesium

all others

REACTIONS BETWEEN METALS AND NON-METALS

Reaction of metals with oxygen

1. Metals react with oxygen in the air to form metal oxides. This process is called oxidation.

2. Magnesium + oxygen heat

magnesium oxide

3. Usage of:

(1) Potassium manganate(VII) crystals

Supplies oxygen

(2) Glass wool To prevent the potassium manganate(VII) crystals from mixing with the metal filings

(3) Glass wool To prevent oxygen from escaping to the surroundings

Metal + oxygen metal oxide

Reactions of metals with oxygen

Metal Reaction rate Product of reaction

Magnesium Very fast Magnesium oxide

Aluminium Very fast Aluminium oxide

Zinc Fast Zinc oxide

Iron Fast Iron oxide

Copper Slow Copper oxide

Reactions of metals with sulphur

Metal Reaction rate Product of reaction

Magnesium Very fast Magnesium sulphur

Aluminium Very fast Aluminium sulphur

Zinc Fast Zinc sulphur

Iron Fast Iron sulphur

Copper Slow Copper sulphur

SILICON COMPOUNDS

Silicon is the second most abundant element in the Earth’s crust. Silicon does not exist as a free

element in its natural state. However it exists in the form of compounds. Silicon compounds that

exist in the Earth’s crust are silica and silicates. Silica is silicon dioxide consisting of silicon and

oxygen. Silicates are silicon compounds that are made up of silicon, metal and oxygen.

Silicon compounds and their examples

Silicon compound Example

Silica Sand, quartz

Silicate Asbestos, jade, clay, mica

Properties of silica and silicates

Silicon compound Material Solubility in water Action with acid Effect of heat

Silica Sand

Quartz

Silicate Mica

Clay

CALCIUM COMPOUNDS

1. Calcium exists naturally as calcium compounds such as calcium carbonate.

2. Calcium carbonate consists of calcium, oxygen and carbon.

3. Examples of natural calcium carbonate include marble, limestone, stalagmites, stalactites in

limestone caves, coral reefs, animal bones and shells.

NATURAL FUEL RESOURCES AND THEIR IMPORTANCE

Petroleum fractions and their uses

CHAPTER 7: Electricity

ELECTRICITY

1. Electrical energy (electricity) is a form of energy.

2. There are two main electrical sources:

Electric cells (dry cells, lithium cells, nickel-cadmium cells, mercury cells and acid-lead

accumulators convert chemical energy into electrical energy)

Electric generators

Current, Voltage and Resistance

1. Electric current is the flow of electrons or negative charges through a circuit.

2. (a) Electric current flows from the positive terminal of a battery to the negative terminal of

the electrical source.

(b) Electrons flow from the negative terminal to the positive terminal of an electrical source.

3. The flow of electrical charges can be observed by using a Van de Graaff generator and a

galvanometer.

4. A Van de Graaff generator is a device that produces electrical charges at high voltages and it’s

dome.

(a) When the Van de Graaff generator is started, the dome is positively charged.

(b) Sparks are produced when a metal sphere is brought closer to the dome.

(c) The galvanometer needle is deflected.

ELECTRIC CURRENT, VOLTAGE AND RESISTANCE

Quantity Electric current Electric voltage

Definition The rate of flow of charges. The voltage across two points is the

electrical energy needed for the

electrical charges to flow between

the two points.

Voltage is the force which ‘pushes’

the electrons through a wire

Symbol I V

SI unit Ampere or A

1 ampere =

1 000 milliamperes (mA)

1 milliamperes (mA) =

1 000 microamperes (μA)

Volt or V

Device used

to measure

the quantity

Ammeter

Voltmeter

How the

device is

connected in

a circuit

In series to other electrical

components in a circuit.

The positive terminal of the

ammeter is connected to the

positive terminal of the battery.

The negative terminal of the

ammeter is connected to the

negative terminal of the battery.

In parallel across a battery or other

electrical components in a circuit.

The positive and negative terminals of

the voltmeter are on the same side of

the circuit as the positive and

negative terminals of the battery.

Resistance

1. Resistance, R is the property of an electrical conductor that opposes the flow of electrons

through it.

2. The SI unit of resistance is ohms (Ω).

3. Relationship with electric current

(a) The higher the resistance, the smaller the current that flows through the circuit.

(b) The lower the resistance, the larger the current that flows through the circuit

4. Factors affecting resistance

(a) Resistance is affected by the

length of the conductor

diameter of the conductor

type of conductor

(b) The longer the conductor, the higher its resistance.

(c) The thicker the diameter of the conductor, the lower its resistance

(d) A good conductor has low resistance. Copper wire has a lower resistance than iron wire.

A poor conductor has a high resistance. Example: nichrome wire

5. A resistor reduces the current flowing through the circuit.

There are two types of resistors:

(a) A fixed resistors has one fixed resistance that cannot be changed.

(b) A variable resistor or rheostat has resistance that can be change to give variable

resistances.

Variable resistors are used to control the volume of a radio or a television, the speed of a

fan, and the temperature of an oven.

For example: If the knob on the speed regulator of a fan is turned from number 5 to

number 1, the resistance is increased. Hence, the current is reduced and the speed of the

fan reduces.

THE RELATIONSHIP BETWEEN CURRENT, VOLTAGE AND RESISTANCE

Ohm’s Law

1. Ohm’s law states that the current (I) that flows through a metal conductor is directly

proportional to the voltage (V) across it, if the resistance remains constant.

2. Therefore, Ohm’s law is expressed as follows:

3. Ohm’s law is used to calculate the values of electric current, resistance and voltage in a circuit.

4. Ohm’s law is often remembered as a triangle. Cover up the letter representing what you want to

find and use the equation it shows.

V : voltage in volts (V)

I : Current in amperes (A)

R : Resistance in ohm (Ω)

ELECTRIC CIRCUITS

1. Electrical components are represented by certain symbols to simplify the drawing of electric

circuit diagrams.

Electrical components Symbol

Electric cell

Battery

Rheostat (variable

resistor)

Fixed resistor

Fuse

Switch

Bulb

Ammeter

Galvanometer

Voltmeter

2. A complete or closed circuit consists of connecting wires and electrical components which allow

electric current to flow through.

3. An incomplete or open circuits has a break in the circuit which does not allow the flow of

electric current.

4. A switch is used to connect or disconnect a circuit.

ELECTROMAGNETISM

When current flows through a straight wire, the wire becomes magnetised. The magnetic field lines

form concentric circles around the wire. The magnetic field becomes stronger if a larger current

flows through the wire. The magnetic field lines will also be closer but they do not cut across one

another.

An electromagnet is a type of magnet in which its magnetism is produced by the flow of electric

current. It needs electrical energy to work. It loses its magnetism once the electrical energy supply

is switched off. This means that the electromagnet is a temporary magnet.

CHAPTER 8: Generation of Electricity

Electrical energy (electricity) has become a basic need in our everyday life. Electrical energy is

generated at power stations before it is transmitted to consumers. Many modern appliances use

electrical energy to work.

TRANSFORMERS

1. A transformer is a device that can change the voltage of alternating current.

2. An alternating current (a.c.) is a current that flows back and forth in periodic cycles.

3. Transformers are used in the transmission and distribution of electrical power from power

stations to the consumers in homes and industries.

4. A high voltage is needed in the transmission of electrical energy in power stations to reduce the

loss of electrical energy during the transmission of electricity.

5. A basic transformer consists of two sets of insulated coiled wires wrapped around on both sides

of a soft iron core.

6. A soft iron core is made up of many thin layers of iron called laminations and is not a solid bar.

7. There are two types of transformers:

Step-up transformers

Step-down transformers

Step-up and step-down transformers

When there are fewer turns in the secondary coil than the primary coil, the secondary voltage will

be lower than the primary voltage. This type of transformer is called a step-down transformer.

When there are fewer turns in the primary coil than the secondary coil, the secondary voltage will

be higher than the primary voltage. This type of transformer is called a step-up transformer.

ELECTRICAL POWER SUPPLY AND WIRING SYSTEM IN HOMES

Electrical power is supplied to our homes through the main supply cables from the substation. There

are two type of current: direct current and alternating current. The type of current supplied to our

homes is alternating current with a voltage of 240 V.

The electrical wiring system

Every house has an electrical wiring system that supplies electrical power from the mains to the

electrical appliances. The electrical wiring system consists of the main fuse, electric meter, main

switch, circuit breakers, live wire, neutal wire and earth wire.

Parts and functions of the elctrical wiring system

Parts Functions

Main fuse Breaks the circuit if the current exceeds a safe value

Main switch Disconnects the electrical power supply from the mains when electrical

energy is not needed

Circuit breaker Cuts of the electric current flowing through a circuit under abnormal

conditions

Live wire Carries the electric current from the substation to the house

Neutal wire Carries the electric current from the house back to the substation

Earth wire Connects an electrical appliance directly to the earth

Electric meter Measures the amount of electrical energy used

CHAPTER 9: Stars and Galaxies

There are billions of galaxies in the Universe consisting of stars and planets. All living things

depend on the Sun’s energy.

THE SUN

The Sun is the main source of energy for the Earth. There can be no life on Earth without the Sun.

The Sun is a giant ball of hot glowing gases and it spins around in space.

The Sun was formed from a huge cloud of dust and gas floating in space. Among the many stars in

space, the Sun is the closest to Earth. This is why we can see the Sun during the day.

Characteristics of the Sun

The Sun is very much larger than the Earth. Its diameter is about 109 times than of the Earth. Its

mass is 333 420 times the mass of the Earth.

Characteristics of the Sun as compared to Earth

Properties Characteristics of Sun Characteristics compared to Earth

Diameter 1 392 000 km 109 times the diameter of Earth

Mass 1.989 x 1034 kg 333 420 times the mass of Earth

Density 1485 kg/m3 0.27 times the density of Earth

Surface temperature 5100-6000oC 227-273 times the temperature of Earth

Composition Hydrogen (70%-80%) and

helium

Earth’s atmosphere contains oxygen,

nitrogen, carbon dioxide and inert gases

Structure of the Sun

1. The surface of the Sun consists of three gaseous layers: photosphere, chromosphere and

corona.

2. The photosphere

The innermost atmospheric layer of dense gases

It is considered as the surface of the Sun

The visible light that reach Earth from the Sun originates from the photosphere

Sometimes, interactions with the Sun’s magnetic field results in the appereance of sunspots

on the photosphere

3. The chromosphere

The chromosphere is the layer above the visible photosphere

The chromosphere glows red because hydrogen gives off a reddish colour at these high

temperatures.

It is invisible and can only be seen during a total solar eclipse

Solar flares arise from the chromosphere layer

4. The corona

The corona is the extremely hot outermost layer above the chromosphere

The corona forms rings of whitish-blue light. The corona can only be seen during total solar

eclipses

5. The core

The core is the innermost layer of the Sun

The temperature of this layer can be as high as 15 x 106 oC

STARS AND GALAXIES IN THE UNIVERSE

The Universe

The Universe consists of all the matter, energy and space that exists. It contains billions of

galaxies, stars, planets and particles. The solar system, which includes the Sun and the Earth, is

part of the Universe.

Constellation

A constellation is a group of stars arranged in a specific pattern that is visible from Earth.

CHAPTER 10: Space Exploration

MEASAT 1 and MEASAT 2 are the two Malaysian satellites. Satellites are used in areas such as

communication, weather, monitoring, defence, navigation and environmental monitoring.

DEVELOPMENTS IN THE FIELD OF ASTRONOMY

Astronomy is one of the oldest fields in science. It involves the study of objects in the Universelike

planets, stars and galaxies.

Applications of technology related to space exploration and astronomy

1. Space enables scientists to conduct scientific experiments that benefit mankind.

2. This is because the vacuum and zero gravity conditions in outer space make research that

cannot be conducted on Earth possible.

3. Research in space has led to the development of

special metals and microchips

nutritional food

special medicines

pure vaccines

advanced medical equipment

4. The application of space technology have helped to improve the quality of life and economy.

Although space exploration is costly, it benefits outweigh the cost, which is why space

exploration needs to be continued.

The uses of satellites

1. Telecommunications

Communications satellites enable global communications via telephones, radio and television

channels all over the world

Malaysia has MEASAT satellites in space to transmit live telecasts on televisions in homes

2. Navigation

Navigation satellites help ships and airplanes to determine their positions and directions

anywhere on Earth.

3. Military purposes

Military satellites help countries in security and defence, locate personnel and targets.

4. Remote sensing

Remote sensing collects data and information about the conditions and activities on Earth. For

example, to prevent natural disasters, to locate natural resources and to monitor floods.

5. Weather forecast

Meteorological satellites predict the weather, monitor changes in weather conditions such as

wind direction, temperatures and pressure in the Earth’s atmosphere.

6. Detection of natural resources

Environmental satellites are a means to study the world’s resources. These satellites help to

detect the locations of natural resources such as petroleum, coal, natural gas and minerals.