This document describes the process of ecological succession in ecosystems. It provides the example of succession in a mangrove swamp ecosystem, where pioneer species like Avicennia help build soil conditions over time through their root systems to allow later successor species like Rhizophora and Bruguiera to colonize. The document also outlines the five stages of succession that occur as a pond gradually shallows over time, from pioneer aquatic plants to eventual colonization by woody plants as the pond transforms into land.

1. Chapter 8 Dynamic Ecosystem
Ong Yee Sing
2017

2. Chapter index
• 8.1 The Abiotic and Biotic Components of the Environment
• 8.2 Colonisation and Succession in an Ecosystem
• 8.3 Population Ecology
• 8.4 Biodiversity
• 8.5 The Impact of Microorganisms on Life
• 8.6 Appreciating Biodiversity

3. 8.1 The Abiotic and
Biotic Components
of the Environment

4. Components of Ecosystem
Altitude
Slope Gradient
Aspect
Microclimate
土壤
地形
方面

5. Abiotic factors
• pH value
• a drastic change in pH of the soil and water
may kill the organisms
• Temperature
• affects the physiological activities of organisms
• most of organisms cannot tolerate extremes
temperatures
• Light intensity
• affects the distribution and growth of
organisms
• the sun is the source of energy for plants
• most animal need sunlight but some show
adaptation to live in the dark
• Humidity
• is the amount of water vapour in the air
• plant and animal that live in wet or dry climate
have special adaptation
The amount of light
which different levels of
a forest may receive
varies.
Hydrangea flower color is influenced by soil pH. In soil with low pH, aluminum ions
(Al3
+) are more available for uptake by plants, altering the flower pigments to reflect
more blue as myrtillin (red pigment) forms complexes with metal ion.

6. Abiotic factors
• Water
• some organisms are able to survive under
condition where there is a limited supply of
water such as camel and cactus
• Microclimate
• Refers to local climate in a small area
• humidity, temperature and light intensity
affect the microclimates
• Topography
• physical feature of the land
• influence local climate and soil
development
• higher altitude: lower atmospheric pressure
and temperature
• steeper slope cause a faster drainage and
run-off (thinner soil)
• gentle-slope areas receive more sunlight
compared to valley
• aspect (direction of the slope) influences
the microclimate intensively
• Facing the direction of wind – more rain
• Facing south – more sunlight
Slope effect, a vegetational
result of aspect, in evidence
in the coastal sage scrub
community of
southern California's Santa
Monica Mtns. The slope on
the left side is north-facing,
thus moister and dominated
by Ceanothus sp.. The
south-facing slope on the
right side is much drier
(receiving more direct sun),
and is more sparsely
vegetated with the more
drought tolerant Artemisia
californica and Yucca
whipplei.
The presence of
concrete paths, brick
walls and ponds will act
as heat sinks, absorbing
the sun's heat during the
day and slowly releasing
it at night. They can offer
good protection against
frost on cool nights to
prevent frost.

7. Quiz
• An ecosystem possesses _________.
A. only living components
B. only non-living components
C. both living and non-living components

8. Food chain and food web
• Food chain食物链 is a series of
organisms through which energy
is transferred in the form of food.
• Food web食物网 are interconnected
food chains.

9. Trophic level
• Trophic level营养级别
represents each stages
in the food chain.

10. Pyramid of numbers
• Trophic level can be shown as
a pyramid of numbers.
• Pyramid of numbers数字金字塔
shows the population of each
organism in a food chain can
be shown in a sort of stacked
bar chart.

11. Energy flow
• When the energy is
transferred to the
next trophic level, a
lot of energy is lost
(through undigested
matter, excretory
products, lost as heat
during respiration)
• 90% : energy is lost
• 10% : transfer from
one trophic level to
the next

12. Quiz
• Energy flows through an ecosystem because when one form of energy
is transformed into another form, and there is always a loss of some
energy as heat.
A. True
B. False

13. Quiz
• When numerous food chains link to each other in an ecosystem, it is
known as a(n) _________.
A. food pyramid
B. food web
C. food cluster
D. feeding guild
E. energy pyramid

14. Quiz
• All organisms that feed at each link in a food chain comprise a/an
______.
• trophic level
• biomass
• food pyramid
• energy pyramid
• calorie

15. Quiz
• A pyramid of energy shows that there is an increasing amount of
energy available at each successive trophic level.
A. True
B. False

16. Quiz
• It is generally stated that only about ______ % of the energy available
at one trophic level is incorporated into the tissues of animals at the
next level.
A. 10
B. 20
C. 30
D. 40
E. 80

17. INTERACTION BETWEEN
ORGANISMS
Symbiosis Saprophytism Prey-predator Competition
Commensalism Mutualism Parasitism
Intraspecific Interspecific

18. Symbiosis
共生生物
Commensalism
• ( + , 0 )
• example
- clown fish &
sea anemones
- pigeon orchid
Mutualism
• ( + , + )
• example
- lichens
- root nodules
Parasitism
• ( + , - )
• example
- flea
- tapeworm
+ : benefits
0 : neither benefit
nor harm
- : harm
Epiphytes
(plant)
Epizoics
(animal)
Ectoparasite Endoparasite
Interaction in which there is a close and permanent
relationship between two specific organisms
片利共生 互利共生 寄生
附生植物 附生动物 内寄生外寄生

19. Saprophytism
• A type of interaction in which living
organisms obtain food from dead and
decaying organic matter
• Enzymes are secreted onto the food
and digestion occurs outside the cell
• Example :
• saprophyte (plant) : fungus
• saprozoite (animal) : earthworm, maggot
腐生

20. Prey-predator
(+ ,- )
• Predator
• kills other animal for food
• larger and fewer in number than
its prey
• the number of predator affects
the size of prey population
• Prey
• the animal that kill by the
predator
• must be able to protect itself from
being killed
• Example : owls & snakes, frogs
& snakes
捕食

21. Competition
• An interaction between organisms which
live together in a habitat and compete for
the same resources (light, water, space
and nutrients) that are in limited supply.
• Species that lost in the competition either
migrate to other areas or die.
• Intraspecific competition: between
individuals of the same species e.g.
plantlets from a Bryophyllum sp. leaf
• Interspecific competition: between
individuals of different species e.g.
Paramecium aurelia & Paramecium
caudatum
plantlets from a
Bryophyllum sp.
leaf The niche of Paramecium aurelia and Paramecium
caudatum overlap very much. Therefore, it brings to the
extinction of the failing competitor, Paramecium
caudatum.

22. Quiz
• Which of the following statements is true?
A. Symbiosis refers to different organisms living together.
B. Members of a symbiotic relationship cannot live without each
other.
C. Symbiosis refers to different organisms living together and
benefiting from each other.
D. A parasite is not in a symbiosis with its host.

23. Quiz
• An association in which one population of organisms benefits while
the other is neither harmed nor helped is called a(n) _____
association.
A. parasitic
B. commensalistic
C. mutualistic
D. prey-predator

24. Quiz
• Which of the following associations is characterized by one organism
attaching or engulfing the other?
A. predation.
B. commensalism.
C. mutualism.
D. competition.

25. Quiz
• Which of the following associations is characterized by some degree
of coexistence whereby one organism benefits at the expense of the
other?
A. predation.
B. commensalism.
C. parasitism.
D. mutualism.

26. Quiz
• What is the
relationship between
Hieracium pilosella
and Plantago
lanceolata?
• Interspecific
competition
• What are the
relationships
between mycorrhizae
with Hieracium
pilosella and
Plantago lanceolata?
• mutualism
Mix
population
non-mycorrhiza
mycorrhizal

27. 8.2 Colonisation
and Succession in
an Ecosystem

28. Ecosystem生态系统
• A dynamic system formed by
the interaction of living
organisms and their non-
living environment
• Example : Mangrove, swamp,
desert, marine forest
Some example of ecosystems.

29. Components of an ecosystem

30. Term Description
Habitat栖息地 A habitat is the natural environment in which an organism lives and
obtains its basic resources such as food and shelter.
Biosphere生物圈 A biosphere is the global ecological system integrating all living
beings and their relationships, including their interaction with the
elements of the lithosphere, geosphere, hydrosphere, & atmosphere.
Biome生物群系 A biome is a a large naturally occurring community of flora and fauna
occupying a major habitat, e.g., forest or tundra.
Community群落 A community consists of different populations of plants and animals
living and interacting in the habitat of an ecosystem.
Population族群 A population consists of organisms of the same species living in the
same habitat at the same time.
Species物种 A species is a group of organisms which can interbreed to produce
fertile offspring.

31. Niche生态位
• Niche is the function of an organism
in the habitat
• Organisms can live in the same
habitat but they occupy different
niches.
• A niche comprises:
• its habitat
• its activity patterns (interactions with
others, the range of temperature, the
spaces it occupies, period of activity)
• resources it consume
• Example: a caterpillar and aphid live
in the same habitat but occupy
different niche (caterpillar eats the
leaf but aphid sucks sap from the
leaf).
Each species utilizes a different aspect of the tree's habitat to
reduce competition with other species. This allows multiple
species to extract resources from the same location.

32. Colonisation移植 and succession演替
• Colonisation takes
place in newly
formed areas where
no life previously
existed.
• Succession is the
gradual process
through which one
community changes
its environment so
that it is replaced by
another community.
Colonisation
The process of succession

34. Succession also occurs in animals

35. Pioneer species先锋物种
• The first species of organisms to
colonise a new habitat is called the
pioneer species.
• Special adaptation of pioneer species
• hardy plant
• have good dense root system (bind sand
particles and hold water + humus)
• have short life cycle
• when they die, their remains add to
humus content
• Examples : grasses, ferns & sedges
Pioneer plants on a lava flow.
Lichen on rocks.Abandoned Mamut Copper Mine in Sabah.

36. Successor species后继物种
• Succession leads to a final and stable
community which is in equilibrium
with its environment and is known as
climax community顶极群落
• Successor species : a series of plant
that replaced the pioneer species
(herbaceous plant)
• Successor :
• grow bigger than pioneer thus reduced
the amount of sunlight available
• have small wind- dispersable seeds (able
to spread and grow rapidly)
• can change the structure and quality of
soil for larger plant to grow
• Example: herbaceous shrubs
Ragweed
Shrubby fields

37. Dominant species优势种
• Dominant species grow faster and
dominate the slower growing pioneer
and successor species.
• Dominant species turn modify the
environment which allows larger tree
to grow
• The larger trees provide shade and
the shrubs cannot compete and are
replaced by forest floor species.
• Ecological succession leads to a
relatively stable community which is
a climax community.
• Example: tropical rain forest
Pine as a dominant species.
Pine-Oak-Hickory Forest as a climax community,

38. Example: mangrove swamp
• Found in tropical and subtropical regions
where freshwater meets salt water.
• Characteristics :
1) Soft & muddy soil
2) High concentration of salt
3) Low level of oxygen
4) Exposed to high intensities of sunlight
and strong wind
• 4 species of mangrove :
1) Avicennia sp.
2) Sonneratia sp.
3) Rhizophora sp.
4) Brugeria sp.
• The mangrove plants are well adapted to the
harsh conditions of these regions.

39. Distribution of Mangrove Trees in the Banks of Rivermouth

40. Colonisation and succession in mangrove
swamps
COLONISATION
• The pioneer species : Avicennia sp. and Sonneratia sp.
• The extensive roots system of Avicennia sp. and Sonneratia sp. collect sediments &
organic matter
• As times passes, the soil become more compact & firm
SUCCESSION
• Rhizophora sp. replaces the pioneer species
• The arcing roots of Rhizophora sp. trap silt and mud, creating a firmer soil structure.
• As times passes, the ground becomes higher & the soil becomes drier
• Bruguiera sp. replaces Rhizophora sp.
• The buttress roots of Bruguiera sp. form loops which protrude from the soil to trap more
silt and mud. The soil structure changes.
• Over time, terrestrial plants (Nypa fruticans & Pandanus sp.) replace Bruguiera sp.
• As times passes, the tropical plants replace the terrestrial plants to form climax
community.

41. Pioneer species
Adaptations :
• pnematophores
• aerenchyma tissue
• viviparous seedlings
Successor species
Adaptations:
• props roots
Successor species
Adaptations :
• buttress roots
• viviparous seedlings
• hydatodes
• thick & succulent leaves
• waxy cuticles

42. Props roots
Excretion of crystalline
salt from hydathodes
Viviparity
Pneumatophores
Cable roots

43. Adaptation of mangrove plants
PROBLEMS ADAPTATIONS
Soft, muddy soil
Strong coastal wind
Avicennia sp. : underground cable roots (long & branch)
Rhizophora sp. : prop roots (aerial roots)- for anchor & aeration
Waterlogged conditions of soil (↓
amount of O2)
Avicennia sp. : breathing roots (pneumatophores), grow
vertically upwards
Gaseous exchange through lenticels (on the bark)
Direct exposure to the sun
(↑ rate of transpiration)
Leaves are covered by a thick layer of cuticle
Leaves are thick & succulent (able to store water)
High salinity of the sea water
(soil hypertonic compared to the cell
sap of the root cells)
The cell sap in the roots cells has a higher osmotic pressure
(hypertonic) than the soil.
The excess salt is excreted as crystalline salt from hydatodes
(pores on the lower epidermis)
Seeds which fall onto the ground die
(submerged in the soft &
waterlogged)
Viviparity : seeds are able to germinate while still attached to
the mother plant

44. Processes of Colonisation and Succession in a
Pond

45. Shallowing of a pond

46. 1. Pioneer stage
• When pioneer plants die and decompose,
the organic matter settle to the bottom of
the pond and make the pond shallower.
• This produce suitable conditions for aquatic
floating plants.
2. Succession by aquatic floating plants
• Floating plants cover the surface of the pond
and prevent light from entering the pond.
• Pioneer plants cannot perform
photosynthesis and die. These dead plants
will sink to the bottom and increase the
organic matter layer of the bottom.

47. 3. Succession by amphibious plants
• Dead aquatic floating plants and eroded
soil from the pond banks will raise the
pond floor and make the pond too
shallow for aquatic plants to float.
• The aquatic plants are succeeded by
amphibious plants.
4. Succession by herbaceous plants
• The continued deposition of organic
matter enables grass to gradually replace
amphibious plants.

48. 5. Succession by woody plants
• The death of amphibious plants caused
continued deposition of organic matter
and evaporation of pond water will
make the pond very shallow and
eventually dry it up.
• Finally land plants and other woody
plants will replace the amphibious
plants and form a jungle.
6. Climax community
• The succession will stop when a level of
balance is achieved.

49. Quiz
• Which of the following describes a population?
A. The function of an organism or the role it plays in an ecosystem
B. The natural environment in which an organism lives
C. A group of organisms of the same species living in the same habitat
at the same time
D. A natural collection of plant and animal species living within a
habitat in an ecosystem

50. Quiz
Which gives the correct sequence of plants involved in the process of
succession in a disused pond?
A. Emergent plants  floating plants  land plants  submerged plants
B. Floating plants  submerged plants  land plants  emergent plants
C. Submerged plants  floating plants  emergent plants  land plants
D. Land plants  emergent plants  floating plants  submerged plant

51. Quiz
Over many years a forest can be found on an initially barren piece of
land left behind by a volcanic eruption. What is the correct sequence of
ecological processes that have taken place?
A. Colonisation, succession, climax community
B. Colonisation, climax community, succession
C. Succession, colonisation, climax communiity
D. Succession, climax community, colonisation

52. Quiz
Phytoplankton, zooplankton and algae are often among the first
species to establish themselves in a mining pond. As time passes,
submerged and floating plants will grow, followed by amphibious
plants, grasses, small shrubs, bushes and eventually trees.
This is an example of
A. colonisation
B. competition
C. evolution
D. succession

53. Quiz
• During primary succession, lichen
or algae would be considered __?
A. pioneer species
B. volunteer species
C. founder species
D. conqueror species

54. 8.3
Population
Ecology

55. Population ecology种群生态学
• Population ecology: a branch of ecology
that studies the structure and dynamics
of populations
• Population density: the number of
organisms per unit area of the habitat
• Population density is affected by abiotic,
biotic, birth rate, death rate immigration
and emigration.
• Direct counting allow us to know the
exact number of the organisms in a
population.
• Sampling techniques allow us to use a
small sample to estimate the total
population size of the organisms.
Direct counting
Sampling

56. Sampling technique
• Sampling technique: estimate the
total population size of the
organisms
• Type of sampling technique:
1. quadrat sampling technique样方
抽样技术
2. the capture, mark, release &
recapture technique記號再捕捉法
Quadrat sampling technique
Mark and recapture technique

57. Quadrat sampling technique
• Generally used to estimating the
size of plant populations.
• Made from a metal or a wooden
frame to forms a square of a
known area.
• The quadrat is placed randomly
in the ecosystem.

58. Function of the quadrat sampling technique
• Frequency: the number of times a particular species is found present
when a quadrat is thrown a certain number of times
Frequency : Number of quadrats containing the species
Number of quadrats
• Density: the mean number of individuals of a species per unit area
Density : Total number of individuals of a species in all quadrats
Number of quadrats X quadrat area
• Percentage coverage : an indication of how much area of the quadrat is
occupied by a species.
Percentage coverage : Aerial coverage of all quadrats (m2)
Number of quadrats X quadrat area
X 100%

59. Capture, mark, release and recapture
technique
• Used to estimate the
populations of mobile animals
• The method :
1. A specific animal sample is
captured
2. The animal is marked (a ring,
a tag or waterproof coloured
ink/paint).
3. The marked animals are
released into the general
population
4. After suitable period of time,
a second sample are
recaptured
5. The number of marked
animal is recorded

60. Formula to calculate population size
Population size : (no. of individuals in the 1st sample) X (no. of individuals in the 2nd sample)
no. of marked individuals recaptured

61. Quiz
• The quadrat sampling technique can be used in the study of the
populations of
A. birds
B. earthworms
C. grasshoppers
D. rabbits

62. Quiz
• Which of the following steps need to be taken to improve the
accuracy of the capture, mark, release and recapture technique ?
A. Put a bigger mark.
B. Capture more animals.
C. Capture the bigger animals.
D. Do recapture after one month.

63. Quiz
• The following information is about the capture, mark, release and recapture
technique.
P – Mark the captured animals.
Q – A second sample is captured.
R – Release the marked animals.
S – An initial sample is captured.
Which of the following is the correct sequence of the capture, mark, release and
recapture technique?
A. PRSQ
B. PSRQ
C. SPRQ
D. SRQP

64. The table shows the results obtained from an investigation into the
distribution of mimosa plants on a school field.
Table 1
The percentage frequency of the mimosa plants is
A. 25%
B. 36%
C. 66%
D. 80%
Quadrat 1 2 3 4 5 6 7 8 9 10
Number
of plants
5 2 0 1 8 2 0 3 4 5
Quiz

65. 8.4 Biodiversity

66. Biodiversity and classification
• Biodiversity is the diverse species
of plants and animals interacting
with one another on Earth.
• Taxonomy is a branch of biology
concerned with identifying,
describing and naming organisms.
• Organism are classified into 5
major kingdoms :
1) Monera
2) Protista
3) Fungi
4) Plantae
5) Animalia

67. Five kingdom classification

68. Kingdom Characteristics Example
Monera原核生物界 • prokaryotic organisms (unicellular organisms)
• no distinct nuclear membrane
• cell wall is present but lack of both membrane-bound nuclei and organelles
• no tissues formation
• photosynthetic and non-photosynthetic
• bacteria
• cynobacteria
Protista原生生物界 • have a nuclear and membrane-bound organelles
• may be unicellular or multicellular (algae and protozoa)
• they can either be heterotrophic or autotrophic or even both
• the cell are not specialised to perform specific functions in the organisms
• some have both plant and animal characteristic
• Amoeba
• Paramecium
• Spirogyra
• Chlamydomonas
Fungi真菌界 • heterotrophic multicellular but some are unicellular
• the cell walls contain chitin
• the main bodies consists of network of thread-like hyphae called mycelium
• do not have chlorophyll
• produce spores for reproduction
• saprophytic but some are parasitic
• mold (Mucor)
• mushrooms
• yeast
Plantae植物界 • include all land plants
• have a chlorophyll and carry out photosynthesis
• multicellular
• cells are specialise into tissues
• mosses
• fern
• flowering plant
• non-flowering plant
Animalia动物界 • multicellular, heterotrophic and eukaryotes
• do not have cell wall
• mobile
• do not have chlorophyll
• invertebrate
• fish
• reptiles
• bird
• mammals

69. The Hierarchy in the
Classification of
Organisms 生物分类
• Living organisms are classified
according to certain basic
features.
• Note:
• Phylum (sg.), phyla (pl.)
• Genus (sg.), genera (pl.)
• Species (sg.), species (pl.)
域，界，門，綱，目，科，属，种

70. Linnaeus Binomial System二名法
• The Linnaeus Binomial System of classification uses two words to
name every species of organisms found.
• the first word in the name refers to the genus
• the second word is the specific name
• The characteristics of the system are as follows:
• both names are Latin words.
• the name of the genus is written first and the first letter should be in upper
case.
• the name of the species is written in lower case.
• both names are in italics if typed or underlined if written

71. Scientific
names of some
local organisms
Common
name
Scientific name
Paddy Oryza sativa
Durian Durio zibethinus
Oil palm Elaeis guineensis
Rambutan Nephelium lappacium
Sugar
cane
Saccharum officinarum
Chicken Gallus domesticus
Toad Bufo melanosticus
Frog Rana erythraeu

72. The importance of biodiversity
Shelter
Clean drinking
water
Economic resources
Clean air
Sources of food
Sources of medicine
Importance of
Biodiversity

73. 8.5 The impact of
microorganisms
on life

74. Microorganisms
• Microorganisms are tiny organisms
that can only seen clearly under the
microscope
• Microorganism are classified into 5
major types :
1) Virus
2) Bacteria
3) Algae
4) Protozoa
5) Fungi

76. Name Characteristics Examples
Bacteria • unicellular prokaryotic organisms
• have a cell walls made of a polymer called peptidoglycan
• certain bacteria form spores under unfavourable conditions
• in spherical (coccus), rod (bacillus) or spiral (spirilium) shape
• Lactobacillus sp.
• Staphylococcus
sp.
Algae • photosynthetic eukaryotic plant-like organisms in the kingdom protista
• have a chlorophyll and chloroplast
• cell walls are made of cellulose
• do not have leaves, stems or roots
• phytoplankton
• Spirogyra sp.
Fungi • heterotrophic multicellular or unicellular
• do not have chlorophyll
• have a cell walls made up of chitin
• sapophytic
• Mucor sp.
• yeast
Protozoa • unicellular organism
• have nucleus, cytoplasm and plasma membrane
• have flagella, cilia or pseudopodia to move
• Euglena sp.
Paramecium sp.
• Amoeba sp.
Viruses • is not a living cell because it cannot survive or reproduce on its own
outside the host
• is composed of DNA and RNA, surrounded by a protein coat
• can be crystallised
• T4 bacteriophage
• tobacco mosaic
virus

77. The effect of abiotic components on the
activity of microorganisms
• Concentration of nutrient
• all microorganisms except viruses
need nutrient and water for
reproduction and growth.
• without nutrient and water,
microorganisms will die or form
spores
• Light intensity
• microorganisms prefer place which
are dark or have a low light intensity
• a high intensity of sunlight and
ultraviolet rays can kill
microorganisms
• however, algae and photosynthetic
bacteria need light to photosynthesis
• Temperature
• most microorganisms are inactive at low
temperatures
• optimum temperature for most
microorganisms is between 35 ⁰C and 40
⁰C
• beyond 60 ⁰C the growth of
microorganisms is inhibited
• microorganisms and their spores can
only be destroyed when they are
sterilized at a temperature of about 121
⁰C
• pH
• most bacteria -pH around 7.4
• moulds, yeast and protozoa - pH 4.5 and
5.0

78. The role of useful microorganisms in the
ecosystem
• Digestion:
• in stomach, intestine or caecum of
herbivors have bacteria that
produce cellulases enzymes to
digest cellulose
• Termite have a Trichonympha sp.
(flagellated protozoan) to digest
cellulose from the wood
• Human have bacteria in the colon
that synthesise vitamin B12 and K
• Medicine
• fungi – produce antibiotic (prevent
the growth of bacteria)
• Penicillium notatum produce
antibodies to treat gonorrhoea,
syphilis, lung infection
• Streptomycine produce antibodies to
treat tuberculosis (TB)
• dead bacteria or viruses – produce
vaccine
• BCG for TB

79. • Decomposition:
• bacteria and saprophytic fungus
are microorganisms that feed on
dead organic matter to get energy
for their life processes.
• play an importance role in the
natural cycles of the elements
such as the carbon cycle and
nitrogen cycle
• Nitrogen cycle
• Nitrogen Fixation
• fix atmosphere nitrogen into nitrate NO3
-
• Rhizobium sp. (in root nodule)
• Nostoc sp. (cyanobacteria in the soil)
• Decomposition
• decomposition of organic matter into
ammonia NH3
• fungi
• Nitrification
• Changes ammonia into nitrite, NO2
-
• Nitrosomonas sp.
• Nitrococcus sp.
• Changes nitrite into nitrate, NO3
-
• Nitrobacter sp.
• Denitrifying
• changes nitrate into nitrogen
The role of useful microorganisms in the
ecosystem

80. Nitrogen
cycle
-)
, Nostoc

81. • Industry
• production of alcohol – using yeast
through the fermentation process
of sugar, starch or grains
• production of vinegar – the
bacterium, Acetobacter, acts on
alcohol to produce vinegar
(ethanoic acid)
• Making bread – using yeast and
sodium bicarbonate to produce
carbon dioxide to rises the bread
dough
• Production of butter – cream is
made sour by the action of
bacteria.
• production of fermented milk –
tairu and yogurt using bacteria,
Lactobacillus sp. and
Streptococcus sp. and yeast
• production of vitamins – Vitamin
B2 – yeast, Vitamin D – yeast and
bacterium
• textile industry – bacteria are use
to decomposed the soft plant
tissues leaving the plant fibres
The role of useful microorganisms in the
ecosystem

84. Pathogens, Vectors and Symptoms of Some
Diseases
Disease Pathogens Vector Symptoms Method of infection
TB Bacteria - -Feeling tired
-Constant coughing
-Coughing out blood
Droplet infection, dust, food
and drinks that are
contaminated
Cholera Bacteria (Vibrio sp.) House fly -Vomiting
-Serious diarrhea
Water or food that is
contaminated
Food
poisoning
Bacteria, fungi House fly -Vomiting
-Diarrhoea
-Abdominal pains
-Fever
Water or food that is
contaminated
Cold Virus - - Fever, Headache
- Muscle pain
Through the air
Ringworm Fungi - - Red spot on the skin
- Itchiness
Touch

85. Pathogens, Vectors and Symptoms of Some
Diseases
Disease Pathogens Vector Symptoms Method of
infection
Dengue Virus Mosquito,
Aedes aegypti
- High fever
- Headache
- Rashes
- Pain at the joint
- Bleeding from the nose, gums and tooth sockets
Mosquito
bite
Mumps Virus - - Fever
- Painful feeling when eating
-Difficulty opening the mouth
-Soft swelling in front and below the ears
Through
the air
Malaria Protozoa
(Plasmodium)
Mosquito - Fever
-Headache
- Muscle pain
-Shivering
Mosquito
bite

86. Pathogens, Vectors and Symptoms of Some
Diseases
Disease Pathogens Vector Symptoms Method of infection
AIDS Virus
(HIV 1 and
HIV 2)
- - Fever
- Loss of body weight
-Tiredness
-Candidiasis around the mouth and throat
-Pneumonia
-Kaposis’s sarcoma
-Through sexual contact with
a person infected with HIV
- Transfusion of blood from a
HIV victim
-Sharing of injection needles
SARS Virus - -High fever
-Cry cough
-Shortness of breath or breathing difficulty
-Pneumonia
-Headache, muscular stiffness
-Loss of appetite
-Rash, diarrhoea
-Droplet infection touch
- Close contact with someone
who has SARS
-Body secretion

87. Transmission of Disease
• The air
• Droplet transmission
• Airborne transmission
• Touch
• Food
• Vectors
• Water

88. Controlling Pathogens
Methods of controlling
pathogens
Antibiotics抗细菌药
Penicillin and streptomycin
are chemicals produced by
microorganisms which
inhibit the growth or kill
other microorganisms,
especially bacteria
Vaccines疫苗
Are modified or weakened
forms of bacteria or viruses. Is
a suspension of dead bacteria
or viruses which is inoculated
into our body to induce the
production of antibodies.
Examples of vaccine are Sabine
vaccine and BCG
Antiseptics消毒剂
Are used on cuts and
wounds to kill and inhibit
the growth of
microorganisms. Examples
of antiseptics are acriflavin
and iodine solution
Disinfectants消毒剂
Use to kill microorganisms on
the floor, buildings or furniture
and sterilise surgical
equipment. Example : phenol,
formaldehyde and carbolic acid