1. SUBJECT: SCIENCE FORM: 5
TOPIC: MICROORGANISMS AND THEIR EFFECTS ON LIVING THINGS
 CLASSIFICATIONS OF MICROORGANISMS
o Type of microorganisms
- Definition:
Tiny living things that cannot be seen by naked eyes, but can be seen by electron
microscopes. They are also known as microbes.
Some of microbes are harmful, but some of them are useful too
- Classification:
There are 5 main groups for microbes:
a) Bacteria Beruk
b) Protozoa Pergi
c) Fungi Filipina
d) Algae Angkat
e) Viruses Van
o Characteristics of various type of microorganisms
1. Bacteria
Definition:
2nd smallest living things can be seen by electron microscope, have the simplest
structure, and have the largest number among the five groups of microbes.
Size:
Consists only one cell (about 0.5 to 10 micrometer)

2. Shape:
There are four general shapes:
a) Cocci Cium
b) Bacili Baboon
c) Spirilia Sampai
d) Vibrio Vietnam
Structure:
Nutrition:
Some bacteria have chlorophyll, so they can make their own food by
photosynthesis process. Some of bacteria don’t have chlorophyll, so they have to be:
a) Saprophytes - get food from decaying matters
b) Parasites - get food from other living organisms
Respiration:
Some of bacteria carry out aerobic respiration, and some of them carry out
anaerobic respiration.
Reproduction:
a) By binary fission

3. b) By spores
Habitat:
Bacteria live in any damp places.
2. Protozoa
Definition:
Animals which are made up of only one cell. They are unicellular. Example:
amoeba, paramecium and etc.
Size:
Consists only one cell (about 5 to 250 micrometer)
Shape:
Have various shapes, but mostly they have irregular shape (no fixed shape)
Structure:
Nutrition:
Some of protozoa live as parasites. E.g: plasmodium. Some of them obtain food
from their surroundings. E.g: amoeba and paramecium. Some of protozoa make
their own food.
Respiration:

4. All of protozoa carry out aerobic respiration
Reproduction:
a) By binary fission
b) By asexual reproduction (spore formation)
c) By sexual reproduction (conjugation)
Habitat:
Protozoa live independently in any ponds, river, damp soils or in other organisms,
and they lives in colonies
Exercise:
1. Name the five main groups of microorganisms
2. Bacteria can live in unfavorable conditions. Under such conditions, they…………….
3. Label the part of bacteria below
4. Size of protozoa is about……………………
5. What is the shape of paramecium? ............................

5. 3. Fungi
Definition:
Plants which do not have chlorophyll. They include mushrooms, moulds and yeast.
They do not have root, stems or leaves
Size:
Some of them are large (i.e mushroom), and some of them are tiny (i.e moulds and
yeast)
Shape:
Have various shapes: i- round ball
ii- long filaments
iii- oval-shaped
Structure:
Nutrition:
Most of fungi live as parasites (i.e moulds) or saprophytes (i.e mucor) .
Respiration:
Most of fungi carry out aerobic respiration
Reproduction:
a) By spores
Fungi such a mushrooms form spores within their caps. Mucor form sporangium
(containing spores). When it ripe, it bursts open and disperses the spore.
b) By budding

6. Habitat:
Fungi live in damp dark habitats.
Example: Mucor grows on damp stale bread placed in the dark
4. Algae
Definition:
Very simple plants which have chlorophyll. Algae do not have root, stems or leaves
Size:
Some of them are large (i.e seaweed), and some of them are tiny (i.e diatoms, euglena
and etc)
Shape:
Have various shapes: i- round ball
ii- long filaments
iii- oval-shaped
iv- network-like structure
Structure:
Nutrition:
Algae possess chlorophyll, so that they can make their own food by photosynthesis.
Respiration:
Most of fungi carry out aerobic respiration
Reproduction:
a) By asexual reproduction (binary fission)

7. b) By asexual reproduction (fragmentation)
Algae reproduced by breaking a long filament into two.
c) By sexual reproduction (conjugation)
Habitat:
Algae live in fresh water, salt water, damp soil or on damp bark of trees.
5. Virus
Definition:
Smallest microorganisms and it do not respire, do not excrete waste products, and
do not possess nucleus, cell membrane and cytoplasm
Size:
About 0.02 – 0.4 micrometer, and can be seen only by electron microscope
Shape:
Have various shapes, maybe in spherical, rectangular or rod-shaped
Structure:

8. Nutrition:
Viruses live as parasites in living cell.
Reproduction:
Habitat:
Viruses live only in living cell.
Exercise:
1. How do fungi continue its generation under adverse condition?
2. Why algae look greenish?
3. What a different between algae and tree?
4. Which of microorganisms cannot survive outside living cells?
A. Bacteria C. Viruses
B. Algae D. Protozoa
6. State 3 properties of viruses which are not characteristics of living things

9.  FACTOR WHICH AFFECTS TO THE GROWTH OF MICROORGANISM
There are 5 main factors that affect the growth of microorganism:
1. Nutrients
Microorganisms need nutrient to live, and they get it by being:
a) autotrophic
b) saprophytic
c) parasitic
2. Humidity
Microorganisms need living place with high level of humidity. That means, they need
moisture or water to live, and they will die if they do not get water for a period of
time.
However, some bacteria can live in a place without water’s presence by forming
spores. For amoeba, they form cyst (spore with outer ring).
3. Light
Most of virus, fungi and protozoa and some of bacteria prefer dim or dark habitat,
while algae and few of bacteria tend to live in bright place since they have
chlorophyll to carry out photosynthesis process.
4. Temperature
Most suitable temperature for the microorganism’s growth and live is about 37ºC
(human’s body temperature).
High temperature will kill microorganisms, while low temperature makes them
inactive.
5. pH value
Most of microorganisms prefer to live in neutral medium (pH = 7)
In very acidic (pH = 1 to 3) and very alkaline (pH = 12 to 14) conditions, most of
microorganisms will be killed.

10.  USEFUL MICROORGANISMS
1. In the Digestion of Food
Some bacteria and protozoa help herbivores (e.g: rabbit, goat, cows and etc) and
termites digest their food
They produce an enzyme called cellulose to help herbivores and termites digest
cellulose into glucose
enzyme
cellulose cellulase glucose
2. In Decay
2.1 Formation of humus
Some of saprophytic bacteria and fungi decompose organic matter into humus
2.2 Production of biogas and fertilizers
Some of saprophytic bacteria decompose organic waste (e.g: waste from oil palm,
paddy and coconut) and turn it into methane gas
2.3 Disposal of oil spills
Some of bacteria break up oil spills and decompose it into less harmful substance.
3. In Medicine
3.1 Antibiotics
There are 2 common antibiotics in world, which are:
a) Penicillin (prepared from penicillium notatum bacteria)
b) Streptomycin (prepared from streptomyces griseus bacteria)
Antibiotics can only kill bacteria
3.2 Vaccines
Vaccines are prepared from dead or very weak bacteria and viruses. It used to
stimulate the body to produce antibodies.
Vaccination refers to an injection containing certain vaccines that can prevent a
person being infected to a certain disease. Example: BCG injection for dry cough
disease.

11. 4. In Agriculture
4.1 Maturing of tobacco leaves
Bacteria used to make tobacco leaves mature, so that they can emit desirable smell
and taste.
4.2 Nitrogen cycle Nitrogen-fixing bacteria
Denitrifying Nitrogen gas
bacteria
Nitrates Plant and animal proteins
Nitrifying
bacteria
Ammonium compounds Bacteria of decay
Figure 4.2- A (Simple nitrogen cycle)
4.3 Productions of chemicals from algae
Some algae used to produce beneficial chemicals for human beings. For the example:
a) beta-carotene – which has anti cancer properties
b) fatty acids – which make cholesterol level in human’s blood become low
5. In Industry
5.1 Making breads and cakes
Yeast is used in the making breads and cakes. It is mixed with flour, sugar and water;
and made into dough
Yeast will reacts with sugar to produce alcohol (ethanol), carbon dioxide and
energy. By the way, this process is known as fermentation.
enzyme
yeast + sugar zymase carbon dioxide + ethanol + energy
Carbon dioxide released makes the dough rise, so that breads and cakes become very
soft.

12. 5.2 Making ethanol
Yeast is also used to produce alcohol (ethanol) instead of carbon dioxide.
5.3 Production of vinegar, and yoghurt
Vinegar (ethanoic acid) is prepared by using bacteria to change ethanol into ethanoic
acid.
bacteria
ethanol (alcohol) + oxygen ethanoic acid (vinegar) + water
Yoghurt (contains lactic acid) is prepared by the action of bacteria on milk. Bacteria
will reacts with lactose in milk and turns it into lactic acid.
bacteria
lactose lactic acid
5.4 Production of soy sauce
Soy sauce is produced from the fermentation of a mixture containing mould, yeast,
flour and soy beans. Salt is added to make it become salty.
Exercise:
1. List all factors affect to the growth of microorganism
2. Which microorganisms that can live in bright place?
3. Tell the range of air humidity which most of microorganisms are very active.
4. What is true about microorganisms?
A. High temperature will kills microorganisms but low temperature will make them
inactive
B. All microorganism grow faster in dry conditions
C. All microorganism cannot produce their own nutrients
D. All microorganism can be seen under light microscope
5. In which bacteria cultures in petri dishes A, B, C or D is the highest density of the
bacteria colony?
Petri dish pH Light Moisture
A 3 Bright Moist
B 7 Bright Dry
C 7 Dark Moist
D 10 Dark Dry

13.  HARMFUL EFFECT BY MICROORGANISMS
- Microorganisms which can cause disease called pathogens. They can be either bacteria
or viruses or fungi or protozoa.
- Before that, disease can be defined as any conditions which actively harm the
normal functioning of the body.
1. Diseases Caused by Bacteria
METHOD OF
DISEASE SYMPTOM TREATMENT/PREVENTION
INFECTION
1.Tuberculosis 1. Through food 1. Patient loss 1. Can be treated by using antibiotics
(Batuk kering) 2. Through infected weight and appetite (i.e streptomycin and isoniazid)
air breathed into the for food 2. Can be prevented through
lung 2. Patient coughs immunization by BCG vaccine
often, and in
advanced he coughs
out of blood.
2. Cholera 1. Through 1. Patient has severe 1. Patient given saline drip and
(Taun) contaminated water diarrhoea and antibiotic
and food. vomits 2. How to prevent from being infected?
2. Patient feels i - Get vaccine
giddy and pain in ii - Boil all drinking water
abdomen iii - Cover all food
3. His body iv - Increase the chlorine content in
becomes water supply
dehydrated.
3. Gonorrhoea 1. Through sexual 1. For male, his 1. Can be treated by using antibiotics
intercourse testis becomes (i.e penicillin)
inflamed and 2. Can be prevented by avoid having
enlarged. He feels sex with prostitutes.
pain during
urination.
2. For female, she
has painful vagina
and uterus.
4. Syphillis 1. Through sexual 1. Patient has fever 1. Can be treated by using antibiotics
intercourse and non-itchy rash (i.e penicillin)
on the body. 2. Can be prevented by avoid having
2. Patient has sores sex with prostitutes.
on the penis or
vagina
3. Patient has sore
throat and pain in
the bones and joint.
5. Tooth decay 1. Through food’s 1. Patient feels pain 1. Can be prevented by:
waste on the teeth’s for infected teeth I - Having a diet low in sugars
surface. since teeth’s pulp is ii - Wash your mouth and brush your
badly inflamed teeth after eating.
Table 9.4 – A (Diseases Caused by Bacteria)

14. 2. Diseases Caused by Viruses
METHOD OF
DISEASE SYMPTOM TREATMENT/PREVENTION
INFECTION
1.Common cold 1. Through 1. Patient gets 1. NO PROPER TREATMENT
(Selsema) contaminated air cough, fever, 2. Can be prevented by:
(when people running nose and i - having proper diet
around sneezes) red or watery eyes ii - have fresh and clean air
2. Patient has a sore iii- keep away from the crowd
throat
3. Patient becomes
weak
2. Dengue fever 1. Through Aedes 1. Patient has high 1. NO PROPER TREATMENT
(Demam denggi) mosquito (inject the fever. 2. How to prevent from being infected?
virus into patient’s 2. Bleeding in nose i - Keep our living place clean
blood) and gums ii - Destroy Aedes mosquito’s habitat
3. Pain in the bones, iii - Fogging
joints, muscles and
eyes
4. Blue marks
appear on the body
3. AIDS 1. Through 3 ways: 1. Patient has fever 1. NO PROPER TREATMENT
(Acquired i -Sexual and diarrhoea, and 2. Can be prevented by having healthy
Immune intercourse coughs very often. clean life.
Deficiency ii - Sharing of 2. Patient has loss
Sydrome) syringes during appetite for food
drug addicts and weight.
iii- Infected
pregnant woman to
her baby.
Table 9.4 – B (Diseases Caused by Viruses)

15. Egg are laid singly in stagnant water
Adult mosquito – has black Egg are hatched and becomes larva
stripes on the abdomen and
legs
Larva grows and becomes pupa
Life Cycle of Aedes Mosquito
3. Diseases Caused by Fungi
METHOD OF
DISEASE SYMPTOM TREATMENT/PREVENTION
INFECTION
1.Tinea 1. Through spore of 1. Whitish patches 1. Can be treated by suitable anti-fungal
(Panau) the fungus appears on the drugs
infected skin 2. Can be prevented by:
(usually face or i - keep the body clean and dry
back of the body) ii - avoid direct contact with infected
person .
iii - do not share towel or comb
2. Ringworm 1. Through spore of 1. A reddish area 1. Can be treated by suitable anti-fungal
(Kurap) the fungus appears on the drugs
infected skin 2. Can be prevented by:
2. Infected skin i - keep the body clean and dry
becomes itchy ii - avoid direct contact with infected
person .
iii - do not share towel or comb
Table 9.4 – C (Diseases Caused by Fungi)
4. Diseases Caused by Protozoa
METHOD OF
DISEASE SYMPTOM TREATMENT/PREVENTION
INFECTION
1.Malaria 1. Through 1. Patient has high 1. Can be treated by suitable drugs such
(Demam kepialu) Anopheles temperature at as plasmoquine, quinine, or
mosquito (inject intervals chloroquine
parasitic protozoon 2. After fever, 2. Can be prevented by:
plasmodium into patient feels very i - fogging
blood) cold and shivers. ii - Keep our living place clean
3. Got rapid pulse
rate
4. Got very liitle
urine, which is very
yellow.

16. Table 9.4 – D (Diseases Caused by Protozoa)
5. The Transmission of Diseases
- Diseases transmitted from one person to another by FIVE ways:
i- By Air
It occurs when infected person sneezes, coughs or talks. So, a spray or tiny droplets of
moistures containing pathogens released into air
Diseases transmitted by air: common cold and tuberculosis
ii- By Water
It occurs when water from ponds, river and sea always contaminated with faeces which
usually contains pathogens. So, these pathogens can spread into water supplies due to
unsanitary conditions / seeped through the soil
Diseases transmitted by water: cholera and hepatitis A
iii- By Food
It occurs when food contaminated by pathogens due to unhygienic handling or houseflies
presence.
Diseases transmitted by food: cholera, food poisoning and hepatitis A
iv- By Contacts
It occurs when there has direct contact between infected people to others or wity objects
handled by infected people
Diseases transmitted by contacts: tinea, ringworm, AIDS, gonorrhoea and syphilis
v- By Vector
Vectors: Animals carry pathogens in their bodies. For example: Aedes mosquito,
houseflies, rats, dogs and etc
Diseases transmitted through their bite into human’s blood or carrying pathogen onto the
food.
Diseases transmitted by vectors: dengue fever, malaria and cholera

17.  PREVENTION OF DISEASES CAUSED BY MICROORGANISMS
1. Prevention through the Control of Vectors
Common vectors, their pathogens and diseases transmitted by them can be shown as
following table:
Vector Pathogen Disease
Aedes mosquito Virus Dengue fever
Anopheles mosquito Protozoa (plasmodium) Malaria
Housefly Bacteria Cholera
Rats Fleas Plague
Table 9.6 – A (Vectors and its diseases)
1.1 Control of Houseflies
To control houseflies, we must:
a) keep our surrounding cleans
b) cover our foods
c) throw organic waste into plastic bags and tied it up for disposal
d) spray insecticides to keep away the adult fly away
e) keep manure and compost heaps far away from houses.
1.2 Control of Mosquitoes
To control mosquitoes, we must:
a) drain marshes and unused ponds
b) clean the house from opened empty tins and coconut shells
c) put anti-larva chemicals or into ponds, drains and stagnant water
d) carry out fogging around living places
e) fix wire gauze at doors and windows
f) sleep under a mosquito net
2. Prevention through Sterilization
Definition of Sterilization:
Destruction of pathogens and their spores in a substance or object
Type of sterilization:
a) heat
b) chemicals

18. c) radiation
2.1 Sterilization using Heat
a) Boiling
- Boiling a substance or an object in water for 20 minutes will kill all bacteria cells and
many spores.
- Surgical instruments in clinics or hospital are usually sterilized in this way.
b) Autoclave
- An autoclave is a steam sterilizer. The things to be sterilized are kept in closed container
and steam under high pressure and temperature of 120ºC for 15-20 minutes
- All the bacteria and spores will be destroyed in this way.
c) Dry air oven
- It can be used to sterilize glassware and metal objects.
- The things to be sterilized are kept in dry air oven at 170ºC for 15-20 minutes
- Effectiveness of sterilization using this way is less compare to using autoclave.
2.2 Sterilization using Chemicals
a) Antiseptics
- It can be used to prevent the growth of some bacteria and destroy some others.
- It usually used for cleaning wounds
- Example: iodine solution, hydrogen peroxide solution and potassium manganate (VII)
solution
b) Disinfectants
- Powerful chemicals to destroy pathogens
- It used for sterilizing instruments, containers, cloths, floors, walls and etc.
- Example: lysol, formaldehyde, phenol and sodium hypochlorite
2.3 Sterilization using Radiation
a) UV light
- Applied to lamp in surgical operating theatre and lab for air sterilizing.
b) Gamma rays
- It used for sterilizing surgical instruments and certain foods

19. - Foods that have been sterilized in this way can be kept for a long period of time and it is
safe to eat.
3. Prevention through Immunization
Definition of Immunization:
Process of increasing a person’s resistance to a particular infection by using antibodies
Definition of Antibodies:
- Chemical substance produced from white blood cells to destroy pathogen or neutralize
the toxins produced by pathogen. Each of antibody acts on a particular pathogen.
Type of immunity:
a) Natural
- Refer to situation when a person recovered from an infection, antibodies produced by
the person’s body to fight that infection remains in the person’s blood for months or
even for his/her whole life.
- When same infection comes back again, the person has antibody to fight back
b) Artificial
- Refer to a situation when a person given a vaccination, “injecting a dead or weak
pathogens into the person’s body to stimulate his/her body to produce antibody”
- Artificial immunity also can be gained when a person is given an injection contains
antibody.
c) Passive
- Part of artificial immunity
- Can be done by injecting antibody (usually contains antiserum) directly into a person’s
body
- Effect of this immunity is fast but temporary.
d) Active
- Can be either natural or artificial immunity
- Can be done by having antibody after recover from infection or vaccination
- Effect of this immunity is slow but permanent.

20.  TREATMENT OF DISEASES CAUSED BY MICROORGANISMS
1. Antibiotics
2. Antiserum
3. Chemotherapy
4. Radiotherapy
5. Surgery