1.1 The classification of microorganisms

• Microorganisms : Living things which are so small that cannot be seen with the naked eye and only visible under the microscope.

• Can be classified into 5 groups :

a) Bacteria d) Virus

b) Algae e) protozoa

c) Fungi

Various types of microorganisms(refer note in Ms word )

Exercise 1.1

1) What are microorganisms?

2) Draw the diagram to show that bacteria reproduce by

a) Binary fission

b) Conjugation

Refer textbook page 5

1.2 Factors that affect the growth of microorganisms

The growth of

microorganisms

is affected by

nutrient humidity pH value light temperature

A ) pH VALUE

• Three groups of pH value which are :

• pH 1-6 ( less than 7 ) : acidic – microorganisms die

• pH 7 : neutral – the best pH value for the growth of microorganisms

• pH 8 -14 ( more than 7) : alkaline – microorganisms die

B ) TEMPERATURE

37°C ( Human body temperature ) – the best temperature for the growth of microorganisms

Temperature too low or too high – microorganisms will inactive or killed

C ) LIGHT

Microorganisms can grow better in dark places than light places.

D) HUMIDITYMicroorganisms can grow better in damp places or wet places.

E) NUTRIENTS ( FOOD)

Microorganisms need nutrient to grow well.

Exercise 1.2

1. State five factors that affect the growth of microorganisms.

2. How does the ph value of vinegar affect the growth of microorganisms?

3. What was the optimum temperature at which the microbes reproduce?

1.3 Useful Microorganisms

A) DIGESTION OF FOOD• Make vitamin K and B• Herbivors such as cows which do not produce

enzymes rely on bacteria and protozoa in their digestive system to produce cellulase which helps to break down cellulose into simple sugars.

B) DECOMPOSITION AND RECYCLING OF MATERIALS• Dead organisms such as plants and animals undergo a

process called decomposition. This process is caused by microorganisms such as bacteria and fungi

C) MEDICINE AND HEALTH SUPLEMENTS•Antibiotics – medicine used for treating various types of diseases. Example : Penicillin ( made up of fungus )

•Vaccine : consists of dead bacteria and virus used to protect human from disease. Example : BCG injection used to prevent tuberculosis.

D) AGRICULTURE•Nitrogen-fixing bacteria living in leguminous plants help in maintaining soil fertility by forming nitrates in the soil.

E) INDUSTRIES•In the food industry : yeast ( fungi ) acts on carbohydrate to produce carbon dioxide that will causes breads and cakes to rises.

•Bacteria are used to treat skins of animals to eliminate tissues and fat.

Exercise 1.3

1. Fill in the blanks with suitable words on the use of microorganisms.

( a) ________ and ________ are used to make vaccine. ( b) ________ fix nitrogen in the air and converts it into nitrate in the soil. ( c) ________ help to digest cellulose in the gut of

herbivore animals. ( d) saprophytic ________ and _______ eliminate dead organic substances from the surface of the Earth. ( e) ___________ is used to make bread and cake dough rise while ________ is used to make food like

vinegar, yogurt and cheese.

1.4 The Harmful Effects of microorganisms

• Pathogens – Microorganisms that cause diseases

• Table below shows the diseases with symptoms that cause by bacteria, virus, fungi, protozoa and algae

Pathogen Diseases Symptoms

Bacteria Cholera ( taun) Diarrhoea (cirit birit), vomiting(muntah)thirsty, severe cramps in the limbs ( kejang di beberapa bahagian badan)

Tuberculosis – TB ( batuk kering)

Cough, sputum streaked with blood, weight loss

Syphilis Painless sores, non-itchy rashes, deformed joints

Gonorrhoea Male : pain when urinating

Female : pain in the reproductive organs.

Pathogen Diseases Symptoms

Protozoa Dysentery

(disenteri)

Diarrhoea, weak feeling, liquid faeces ( najis cair)

Malaria High fever, anaemia, fatigue, pale skin, headache

Pathogen Diseases Symptoms

Virus Common cold / influenza

Running nose, fever, headache, sore throat, watery eyes

Dengue fever Red spots appear on the skin, bleeding in the nose, mouth, skin, internal organ

Hepatitis A and B Fever, tired, weak feeling, loss of appetite, vomiting, jaundice, joints and muscular pain

Measles Cold, cough, fever, red rash, sneezing, conjunctivitis

Poliomyelitis Weak muscles, nerves, paralysis of the limbs

AIDS Fever, diarrhoea, loss of appetite, weight loss, muscular aches and pains, destroyed immune system

Pathogen Diseases Symptoms

Fungi Ringworm

( kurap )

Scaly patches usually itchy, become red

Tinea ( panau ) Itchy white rash

How diseases spread? ( Bagaimana penyakit merebak?)

• Through the air

• Through the water

• Through contaminated food (makanan tercemar)

• Through contact ( sentuhan )

• Through vectors like flies and mosquitoes

Exercise 1.41. Name two diseases that spread by

pathogens through a) air c) waterb) contact d) vector

2. (a) What is the meaning of vector? (b) Give two examples of vector other than flies and mosquitoes.

Refer textbook

1.5 Ways To Prevent Infection Caused By Microorganisms

Infections

caused

by pathogens

Vector

control Sterilisation Immunity

Vector control

• A vector – an organism that transmits pathogens from one person to another

• Vector control – to reduce the number of vectors by killing or stopping the reproduction of the vectors

Control of Mosquitoes

• The life cycle of the mosquito ( draw the diagram from textbook page 23)

Methods of control used for each stage of the life cycle of the mosquito

Stage Methods

Egg Cleaning or draining swamps, ponds and containers filled with water

Larva Spraying oil or insecticide on the water surface / rearing fish

Pupa Spraying oil or insecticide on the water surface / rearing fish

Adult Cleaning and lighting up the places, spraying insecticide, use mosquito nets

Exercise 1.5 (A)1.Figure 1 shows the life cycle of a housefly.

(a) Name stages

i.X ii. y

(b) Name one disease spread by houseflies (c) How do houseflies spread disease?

(d) State two ways how houseflies at the

adult stage are controlled.

(e) Why are houseflies considered to be

vectors?

adult

Y

pupa

X

STERILIZATION

STERILIZATION（ Process which

destroyed/ removed pathogens from

an object or environment）

HEATHeatingBoiling

Autoclave / pressure cooker

RADIATIONGamma rays

Ultraviolet rays

CHEMICALSAntisepticsDisinfectant

THE USE OF HEAT

METHOD

EXAMPLES OF SUBSTANCES THAT

STERILIZED

Heating the food can kill the microorganism

Surgical tools ， milk bottle ， cups ， spoon ， forks

Boiling drinking water by 100°C for 20 minutes kills almost all the microorganism except their spores

Surgical tools ， milk bottle ， cups ， spoon ， forks

Use an autoclave or pressure cooker with temperature of 120°C or above （ steam under high pressure ） can kill all microorganism including their spores

Surgical tools ， nutrient agar ， laboratory apparatus

THE USE OF RADIATION

METHOD EXAMPLE OF SUBSTANCE THAT STERILISED

Gamma rays Used to sterilise medical equipment

Ultraviolet rays Used to sterilise operation theatres ， laboratories and tissue culture room

THE USE OF CHEMICALS

METHOD EXAMPLE OF CHEMICALS

Antiseptics is used to clean wounds to prevent infection of living tissues

Iodine solution

Disinfectants are powerful chemicals used to kill pathogens on objects such as medical equipment ， floors ， blanket

Formalin ， lysol

Exercise 1.5 (B)

1) Why does boiled water still contain bacterial spores?

2) What is the disadvantage of using heat to sterilise glassware?

3) Why is autoclaving the most effective method of sterilisation?

4) How is drinking water treatment plants and water in swimming pools treated?

IMMUNITY

• Immunity is the ability of the body to kill pathogens before they can cause disease

• Immunisation is the process of increasing a person‘s resistance through artificial means to help a person fight against a disease

• Immunity is due to the presence of white blood cell because white blood cells can produce antibodies

• Immunity protects our body from being infected by certain diseases

IMMUNITY

active passive

natural artificial natural artificial

NATURAL ACTIVE IMMUNITY

• Antibodies are produced by the body itself

• Antibodies are produced after a person has recovered from an infection

• This antibodies will fight the infection again if the pathogens return

• Will lasts for a long period of time• Example ： chickenpox and measles( draw figure 1.19 page 27)

ARTIFICIAL ACTIVE IMMUNITY

• By getting vaccinated

• A vaccine is a solution that consists of harmless toxins of pathogens ， dead antigens or weakened pathogens

• A vaccine is injected into the body to stimulate it to produce antibodies

• Lasts for a long period of time( draw figure 1.20 page 27)

NATURAL PASSIVE IMMUNITY

• Immunity is attained naturally• Antibodies are obtained from an outside

source• Acquired by a foetus from his/her mother

when antibodies are passed through the placenta

• The baby gets this immunity after birth by feeding on its mother‘s milk

• Lasts for a short period of time

ARTIFICIAL PASSIVE IMMUNITY

• Is gained by directly injecting antiserum into an infected person

• Antiserum is a mixture of serum （ the plasma of blood ） and antibodies extracted from animals/ people have been infected with the disease

• Lasts for a short period of time( draw figure 1.21 page 28)

Exercise 1.5 ( C )

Figure below shows a graph showing the varying antibodyconcentration in the blood of a youth once vaccination isgiven.(a) What is meant by vaccination?(b) On which day will he receive his second vaccination?(c) On which day will he obtain immunity from the

vaccination?(d) Why does he need a second injection?(e) Name the types of immunity obtained by him.(f) Name one disease that needs more than one

vaccination to be prevented.

1.6 TREATING DISEASES CAUSED BY MICROORGANISM• Medicine – the field of science that

specialises in treating diseases and keeping our body fit and healthy

Medical treatment for diseases

traditional modern

TRADITIONAL MEDICAL TREATMENT

• Herbal treatment – use parts of plants such as barks ， roots ， leaves ， fruits and flowers

• Acupunture – special thin needles are pushed into the skin in particular parts of the body

• Yoga and meditation – to improve general mental and physical health to relieves aches and pains

MODERN MEDICAL TREATMENT

• Antiserum – given to person who is already suffering from the disease

• Chemotheraphy – use of synthetic drugs in treating diseases （ malaria ， ringworm ， dysentery ）

• Radiotheraphy – use of radioactive rays to treat certain diseases （ skin diseases ， cancer ， tumours ）

•Surgery – used if certain parts or organs are seriously infected

•Antibiotics – complex chemical substances that kill bacteria or slow down their growth without harming the body cells

Antibiotics Diseases

Penicilin Gonorhoea ， syphilis

Streptomycin Tuberculosis

Tetracylin Cholera ， typhus ， dysentery

Chloramphenicol Cholera ， typhus

Exercise 1.6

Essay question(a) A student wants to build up his body’s immunity towards

hepatitis B. Explain how the student can achieve this. ( 4 marks)

(b) Pak Ali’s son experiences diarrhoea and vomitting without feeling nauseous. The doctor confirms that he has cholera. Explain how Pak Ali can prevent this disease from spreading among his other family members. Your answer should include the following:

(i) Identify the problem(ii) Clarification of the problem(iii) Solving methods ( 6 marks)