This document discusses microorganisms (microbes), which are very small organisms that can only be seen with a microscope. It describes the three kingdoms of microbes - fungi, protoctista, and monera. Fungi reproduce using spores and include useful yeasts as well as harmful molds. Protoctista are single-celled organisms with nuclei that move using flagella, cilia, or pseudopodia. Monera lack nuclei and include bacteria and blue-green algae. The document outlines the characteristics, reproduction methods, and impacts of these microorganisms, including both harmful disease-causing varieties as well as useful ones like yogurt bacteria. It also discusses Louis Pasteur's pioneering work

1. MICRO-ORGANISMS
CHAPTER 4
BIOLOGY

2. MICROORGANISMS (MICROBES) :-
I) MICROORGANISMS ARE VERY SMALL ORGANISMS WHICH CANNOT
BE SEEN WITH THE UNAIDED EYE. THEY CAN BE SEEN ONLY WITH A
MAGNIFYING GLASS OR MICROSCOPE.
II) MICROORGANISMS MAY BE UNICELLULAR OR MULTICELLULAR.
III) MICROORGANISMS MAY EXIST ALONE OR IN COLONIES.
IV) MICROORGANISMS ARE FOUND IN ALL KINDS OF ENVIRONMENT LIKE
ICE COLD CLIMATE, HOT SPRINGS, DESERTS, MARSHY LANDS ETC.
THEY ARE ALSO FOUND INSIDE THE BODIES OF OTHER ORGANISMS.

3. MICRO-ORGANISMS ARE DIVIDED INTO 3
KINGDOMS
Fungi Monera
Protoctis
ta

4. A fungus is any member of the group of
eukaryotic organisms that includes
unicellular microorganisms such as yeasts
and molds, as well as multicellular fungi
that produce familiar fruiting forms known
as mushrooms

5. SPORES
They reproduce in a way different to
plants and animals , it uses spores
to reproduce.
SPORES:
- Carried by air and water.
- Have a protective coat to help
them survive in heat and cold and
dry conditions.
- Does not grow until it finds
suitable conditions.

6. LIFE CYCLE OF FUNGI
- Spores germinate producing
long thin thread called a
hypha (begins to digest
food around it).
- Many hyphae form
mycelium.
- Mycelium produce fruiting
bodies (mushroom).
- The Molds’ mycelium
fruiting bodies are dark
black globes called
sporangia.

7. • With fungi, there are good guys and there
are bad guys. Some make our food go
mouldy, and some cause diseases. But they
also break down dead plants and animals,
keeping the world tidier.
• If you ever get athlete’s foot (a skin
complaint that gives you itchy feet),
then you’ve got a fungus growing
on you! (Don’t worry, it’s not
serious, and you can buy an
ointment that kills the fungus.) The
fungus likes moisture, so drying
between your toes helps to keep it
away.

8. Useful
Yeast- Bread is made by mixing
flour, yeast, water and
sugar into dough.
- The yeast respires in the
dough using the sugar and
produces bubbles of co₂ that
makes the dough rise.
- When bubbles of gas are
heated they expand so the
dough is placed in a warm
cupboard for about half an
hour to make the dough

9. The living things in Protoctista kingdom
have microscopic bodies made from just
one cell which contains a nucleus.
Amoeba Flagellate Ciliate

10. - Protoctista live in aquatic
habitats or damp places
(soil).
- Some make their own food
by photosynthesis and are
called unicellular plants
(Protophyta).
- Other members feed as
animals do and are called
unicellular animals
(Protozoa)

11. HOW PROTOCTISTA MOVE?
Flagellum
- Single long hair (In
flagellates).
- They lash the
flagellum like a whip
to move.
Cilia
- Coating of ting hairs
(In Ciliates).
- They wave the cilia
to and fro to move.
Pseudopodia
- False feet (In
amoeba).
- Make projections
from its body wall to
move.

12. The living things in Monera kingdom are one
celled organisms but they do not have a nucleus.
This kingdom contains 2 groups:
Bacteria
Blue green
algae

13. Blue green
algae- They live in seas, oceans and lakes.
- They can also grow on wet rocks, at the sides
of stream and rivers and the tops of rocky
sea shores.
- When they occur in large numbers they can
be seen.

14. Bacteria
- Bacteria can be found almost everywhere (In
air, water on rocks and inside living things
too).
- They can be spherical, spiral or rod shaped.

15. How do they reproduce?
- By Fission (each bacterium
divides into 2)
- If they have enough
warmth, moisture and food,
some bacteria can
reproduce once every 20
minutes.
- When conditions become
dry and hot and unsuitable
for feeding and breeding
some bacteria can form
spores.
Thick wall
Bacterium
Bacterial spore

16. Diseases caused by harmful bacteria
- Diphtheria
- Whooping cough.
- Cholera.
- Typhoid.
- Tuberculosis.
- Food poisoning.
Useful bacteria
- Yoghurt is made using bacteria.
- Vinegar is made by allowing other
bacteria to feed on ethanol and change

17. Do not have cell structure.
- Viruses can be stored for many years without
changing (they do not eat, respire or excrete).

18. How do Viruses reproduce?
- When they are placed on
living tissue they enter the
cells and reproduce.

19. Diseases caused by viruses
- Each kind of virus attacks
certain cells in the body.
- Ex. Cold virus attacks the
cells that line the inside of
the nose the destructive
action of the virus causes
the nose to run.
- Viruses also cause
influenza, chicken pox,
measles and rabies.

20. Many microorganisms have a very important part in making sure
that life on earth continues.

22. Decomposers
break down dead
plants and
animals into
minerals
(released into the
soil)
Plants take in the
minerals in the
soil to grow.
Animals eat the
plants.
Animals eat the
herbivores.

24. - Louis Pasteur (1822 -1895) was a French scientist
(made many discoveries about microorganisms).
- Before Louis Pasteur began his work people
believed in an idea called the spontaneous
generation.
- Spontaneous generation: Living things come grow
from non-living things.
- Ex.: Maggots came from raw meat.
Mice from wheat.
Beetles from cow dung.

26. - Louis Pasteur (concluded from his experiments that
whatever is causing the change can be carried by
air, but it must be heavier than air because it
settled in the bend in the swan neck.
- He called the tiny objects spores.

27. - After realising that broths where made bad by
microorganisms, Pasteur reasoned that
microorganisms can cause disease in animals and
in humans.
- Pasteur developed the theory called the GERM
THEORY.
- The Germ theory states that many diseases are
cause by microorganisms invading the body.