MICROORGANISMS AND THEIR EFFECTS ON LIVING THINGS

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					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)
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
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:
    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? ............................
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
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)
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:
   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
   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.
   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               glucose
                                             cellulase
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.
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
                                     Nitrogen gas
                 Denitrifying
                  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                 carbon dioxide + ethanol + energy
                              zymase
   Carbon dioxide released makes the dough rise, so that breads and cakes become very
   soft.
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.

                           lactose     bacteria     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
   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)
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)
                                    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.
                        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
   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
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
- 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.
   TREATMENT OF DISEASES CAUSED BY MICROORGANISMS

1. Antibiotics

2. Antiserum

3. Chemotherapy

4. Radiotherapy

5. Surgery

				
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