BIOLOGY FORM 4 NOTES CHAPTER 8 : DYNAMIC ECOSYSTEM

8.1 THE ABIOTIC AND BIOTIC COMPONENTS OF THE ENVIRONMENT

• Ecology

   = the scientific study of the interactions of living organisms with other living organisms and with physical environment

Producers

*autotrophs- green plants

*synthesis organic substances / food from nutrients & sunlight

Consumers

• heterotrophs
• acquire energy ? nutrient by feeding on other organisms

-primary consumers

-secondary consumers

-tertiary consumers

Decomposers

*microorganisms-bacteria / fungi

*break down waste products and dead bodies of other organisms into simple substances

  

pH

*affects the distribution of organisms

Light intensity

*affects the distribution and growths of plants and distribution of animals

Humidity

*affects the rate of water loss by plants and animals

Temperature

*affects the physiological activities of plants and animals

Topography

*altitude- the height

*gradient- steepness of a slope

*aspect- windward / leeward slope

Microclimate

-climate in microhabitat

-affects the number and distribution of organisms

FOOD CHAIN, FOOD WEB AND TROPHIC LEVELS

• Food chain

= a sequences of organisms through which energy is transferred.

-  starts with a producer and ends with a top consumer.

     Grass                                 Grasshoppers                    Frogs                    Snakes

(producers)                              (primary                        (secondary           (tertiary

                                                consumers)                   consumers)        consumers)

     1^st                                             2^nd                                      3^rd                        4^th               

trophic level                             trophic level                    trophic level      trophic level

·         Food web

- Different food chains link up to form a food web.

·         Trophics Level

-       The tropics level of an organism is its position in a food chain.

-       When a primary consumer feeds on a producer, only 10% of the original energy in producer is incorporated into the primary consumer and 90% of it is lost as heat.

-       Similarly, when a primary consumer is eaten by a secondary consumer, only 10% of the original energy in producer is incorporated into the secondary consumer and 90% of it is lost as heat.

THE INTERACTION BETWEEN BIOTIC COMPONENTS IN REACTION TO FEEDING

(i)            Symbiosis

(ii)           Saprophytism

(iii)          Prey-predators

(ii) Saprophytism

      = a type of interaction in which living organisms obtain food from dead and decaying organic matter

-          the organisms secretes enzymes to digest dead organisms before absorbing the digested compound.

-          Examples:

(a)          Saprophyte

-     any plants that depends fully on dead organisms for food

       ~ mushroom, fungi

(b)          Saprozoite

-          any animal that obtains food from dead organisms

      ~ Earthworm, paramecium, saprophytic bacteria

(iii) Prey-predator

= an interaction between two organisms in which an organism (the prey) is hunted and killed by the other (the predator) for food.

- helps to control the population of organisms in an ecosystem and maintain the balance of the nature

-          At the beginning, the rats (prey) have plenty of food, and they survive to breed and their population rises.

-          Increases in the population of rats means more food for owls (predator), so they survive to breed and their population rises.

-          With more owls, the population of rats goes down because the rats are eaten by the owls.

-          With less rats, fewer owls survive to breed and their population declines. Some of the owls migrate to other places.

-          With fewer owls, more rats will survive to breed and their population rises, so the cycle repeats itself.

-          The predator-prey cycles are self regulating and keep the populations of both predator and prey in a dynamic equilibrium.

INTERACTION BETWEEN BIOTIC COMPONENTS IN REACTION TO COMPETITION

• Competiton

=an interaction between organisms living together in a habitat and competing for limited resources, such as

(i)    food

(ii)   shelter                    

(iii)  breeding mates

(iv) light

(v)  nutrients

(vi) water                          

(vii)space

• Two type of competition:

(i) Intraspecific Competition

-          a competiton between individuals of the same species

-          The two species of paramecium aurelia and paramecium caudatum are cultured in two separate culture dishes but given the same amount of food.

-          The population of paramecium aurelia and paramecium caudatum in each culture dish increased and then reached a maximum.

(ii)   Interspecific Competition

-          a competiton between individuals of two or more different species

-           in this type of competition, the species that

             *loses: either dies, or is forced to move out of the habitat

             *wins : stays and become dominant in that habitat

-          When paramecium aurelia and paramecium caudatum are cultured in a same culture dish with the fixed amount of food and space, paramecium caudatum lost out to paramecium aurelia in this competition for food and space.

-          The population of paramecium caudatum initially rose and then decreased while the population of paramecium aurelia rose and finally became the dominant species.

8.2 COLONISATION AND SUCCESSION IN AN ECOSYSTEM

8.2.1      Ecosystem

An ecosystem

= a system formed by the interactions of a community of organisms with their non-living environment and function as a unit.

-  is a dynamic system where all the biotic components are in balance with one another and with the abiotic components.

8.2.2      Niche, Habitat, Community And Population Of An Ecosystem

1.    Niche

-          A niche is the role that an organism plays in the ecosystem.

-          Is the way of life of an organism in its natural surrounding

-          Example: the niche of a grasshopper – it hops and flies around the grass field, feeds on grass, mates and becomes food for others.

2.    Habitat

a.    A habitat is a place where an organism lives.

3.    Community

a.    A community consists of all the different populations of plants and animals living together and interacting within a defined area of habitat.

4.    Population

a.    A population is a group of organisms of the same species living in the same habitat at the same time.

8.2.3      Colonisation and Succession

1.    Colonisation is a process whereby living organisms move into the newly formed area which is completely devoid of life.

2.    The species organisms that colonise the newly formed area called pioneer species.

3.    Characteristics of pioneer species:

b.    usually hardy plants

c.    able to survive on dry or nutrient-poor soil or sand.

5.    Succession of a habitat take places when species move into the modified environment, compete and gradually replace the pioneer species.

6.    Successor species grow larger than the pioneer species, thus cutting off light, nutrients and space of pioneer species and finally eliminating the pioneers.

7.    The succession process continues gradually. Finally after many levels of succession, a climax community (a balanced and stable community) forms.

8.2.1.1  Colonisation and Succession In A Pond

Pioneer Stage a.    Phytoplankton, zooplankton and submerged aquatic plants (Hydrilla, Utricularia and Cabomba) are the pioneers. b.    These submerged aquatic plants have long fibrous roots to penetrate the soil and to absorb nutrients. c.    When the pioneer plants die and decompose, the organic matter settles to the bottom of the pond. This organic matter, together with the eroded soil from the bank of the pond gradually settles to the bottom, making the pond shallower and more suitable for floating plants.
Succession by aquatic floating plants d.    Floating plants (Pistia, Eichornia and Lemna) gradually multiply and cover the surface of the pond and prevent sunlight from entering it. e.    This causes the submerged aquatic plants to die as they cannot carry out photosynthesis. f.     The dead plants decompose and add on to the layer of organic matter at the bottom of the pond. g.    The dead plants together with the eroded soil from the bank of the pond gradually raise the floor of the pond, making it too swallow for the floating plants.
Succession by emergent (amphibious) plants h.    Emergent plants (Firmbristylis sp, Scirpus sp and Cyperus sp) which can live in water and on dry land succeed the floating plants. i.      The emergent plants multiply and change the habitat of the pond. j.      Some of the emergent plants die, their decomposed remains add on to the sediment making the pond even swallower and eventually dry it up.
Succession by land plants k.    Land plants (creepers, herbaceous and woody plants) replace the emergent plants and gradually from a jungle
Climax community l.      The process of succession will stop when a level of balance is achieved. m.   The climax community takes a few hundred years to form.

8.2.3.2 Colonisation and Succession In Mangrove Swamp

Avicennia sp. and Sonneratia sp. Zone	Rhizophora sp. zone	Bruguiera sp. zone
Pionner stage: Avicennia sp. and Sonneratia sp. are pioneers. Adaptations: a.     The pioneer plants have vertical aerial roots known as pneumatophores. b.     At the end of the pneumatophores are aerenchyma tissues for gaseous exchange.	Succession by Rhizophora sp.: Pneumatophores trap mud and organic sediment and the amount of soil increases and becomes more compact and firm as time passes, making the habitat more suitable for Rhizophora sp. Adaptations: (a)   Rhizophora sp. has stilt roots (prop roots) for support in the soft and unstable mud. c.     The stilt roots help the plants to breathe as they are permeable to gas. (b)   Have viviparous seedling that start to germinate while still being attached to the parent on the tree branch. (c)    Hydathodes (found on the edges of the leaves to get rid of excess salt from the tree through guttation) (d)   Thick and fleshy leaves (to store water) (e)   Waxy cuticle (protects the epidermis from excessive losing of water)	Succession by Bruguiera sp.: The stilt roots of Rhizophora sp. trap the deposit floating debris, wood, sand and mud brought in by the tide. Over time, these deposition creates firmer soil, raises the ground level and makes it drier, making the habitat more suitable for Bruguiera sp. Adaptations: (a)   Bruguiera sp. has buttress roots and pneumatophores that are knee-shaped. d.     The buttress roots form loops that protrude the soil, providing strong support and trapping more silt. (b)   Other adaptations: e.     viviparous seedling f.      Hydathodes g.     Thick and fleshy leaves h.     Waxy cuticles

8.2       POPULATION ECOLOGY

8.2.1      What is population ecology?

1. Population ecology:

      = the study of the relationship between

(a) different populations

(b) populations and the environment

2. Measuring the population size:

      (a) plants – by quadrat sampling technique

                  (b) animals – by the capture, mark, release and recapture technique.

8.2.2      Quadrat Sampling Technique

1.    Procedure:

1.    The distribution of organisms can be determined by:

8.2.1      Capture, Mark, Release And Recapture Technique

1.    Procedure:

1.    Populaton size:

Formula:_____________________________________________________

1.    Assumptions:

(a)  The marked individuals can mix randomly in the population before the second sample is taken;

(b)  Marked and unmarked animals in the sample are caught at random.

(c)  The marks on the animals of the first sample cannot be deleted easily and are no danger on the sampled animals.

(d)  There are no predators of the sampled animals in the area surveryed.

(e)  The population sampled is stable and does not experience any sudden changes.

(f)   The mortility rate and the birth rate are about the same.

8.2.1      The abiotic factors which influence the distribution of an organism.

a.    The distribution of an organism is influenced by abiotic factors such as:

(a) light intensity                (b) temperature

(c) humidity                       (d) pH

(e) aspect

Experiment: To study the effect of change pH on a plant population. Objective: To study the effect of change pH on the population growth rate of Lemna sp. Problem statement: What is the effect of change pH on the population growth rate of Lemna sp? Hypothesis: In a neutral medium the population growth rate of Lemna sp. is the fastest. Variables: Manipulated variable: pH of water Responding variable: Number of Lemna sp. Fixed variable: Light intensity Materials: Dilute hydrochloric acid, dilute sodium hydroxide solution, pond water, distilled water and Lemna sp. Apparatus: Beakers Procedure: 1.       Nine beakers are labelled as A1,A2,A3,B1,B2,B3 and C1, C2, C3.. 2.       Each beaker is filled with 200 ml of pond water. 3.       10 ml of dilute hydrochloric acid is poured into beaker A1,A2 and A3. 4.       10 ml of dilute sodium hydroxide solution is poured into beaker B1,B2 and B3. 5.       10 ml of distilled water is poured into beaker C1,C2 and C3. 6.       20 Lemna sp. plants are put into each beaker. 7.       Each beaker is placed in an area of evenly distributed light. 8.       After 5 days, the number of Lemna sp. plant in each beaker is counted. 9.       The result is recorded in a table. 10.    The average reading of number of plants at the end of experiment is taken. Precautional step: 1.       Make sure all the beakers are exposed to the same light intensity. Presentation of data Beaker Condition (pH) Number of plants Beginning of experiment End of experiment A1 Acidic A2 A3 B1 Alkaline B2 B3 C1 Neutral C2 C3 Conclusion: The population growth rate of  Lemna sp. is affected by a change in pH. Lemna sp. grows best in a neutral environment. The hypothesis is accepted.

8.2       BIODIVERSITY

8.2.1      What is biodiversity?

1.    Biodiversity:

= the diverse variety of plants and animals in the different ecosystem on the earth.

8.2.2      Classification of organisms

Kingdom	Characteristics	Examples
Monera / Prokaryotae
Protista
Fungi
Plantae
Animalia

The hierarchy in the classification of organism

1. The naming of organisms or biological nomenclature is based on the Linnaeus binomial system.

2. In this system, each organism has two names in Latin.

The first name: begins with capital letter, refers to the name of genus

The second name: begins with small letter, refers to the name of species.

3. Example: the scientific name of humans is Homo sapiens or Homo sapiens.

4. Scientific names of some animals and plants:

Common name	Scientific name
Durian
Hibiscus
Maize
Frog
Fruit fly

8.2.1      The importance of biodiversity

1.    Source of medicine

a.    Plants in tropical provides raw material for medicine, for example, in the treatment of cancer.

2.    Shelter and food

b.    People and animals depend on their ecosystem for shelter, food and basic needs.

3.    Environmental services

c.    Environmental services, such as nitrogen cycle, pollination, and regulation of atmospheric temperature are provided due to the diversity of plants and animals, and the interactions between various organisms.

4.    Economic resources

d.    Eco-tourism contributes to the economy.

e.    Timber, rubber and organic oils plays important roles in economy.

8.2       THE IMPACT OF MICROORGANISMS

8.2.1      Types of microorganisms

1.    A microorganism (or microbe) is an organism (unicellular animal or plant) that is very small and cannot be seen by unaided eye. It can only be seen with the help of a microscope.

2.    The various type of microorganisms

Types of microorganisms	Characteristics	Examples
Bacteria	·      Unicellular organisms ·      Have cell wall ·      Do not have nuclear membrane ·      Asexual reproduction through binary fusion ·      Form spores in unfavorable condition ·      4 ways of nutrition: (a)     Photosynthesis (b)     Chemosynthesis (c)     Saprophytic (d)     Parasitic	Lactobacillus Streptococcus E. coli
Algae	·      Semi-aquatic plant, autotrophs. ·      Have chlorophyll and chloroplast ·      No leaves, stems or roots. ·      The cell walls are made of cellulose ·      Live in moist and extremely low light area ·      Sexual and asexual reproduction through spores or separation of vegetative cell. ·      Carry out aerobic respiration.	Phytoplankton, Spirogyra sp.
Types of microorganisms	Characteristics	Examples
Fungi	·      Unicellular or multicellular plant. ·      Heterotrophs ·      Do not have chlorophyll, leaves, stems or roots. ·      The cell walls are made of chitin ·      Sexual and asexual reproduction through spores and budding ·      Live in dark and moist area or upon the death or decaying organism.	Mucor sp. Yeast
Protozoa	·      Aquatic unicellular organism ·      Have a nucleus, cytoplasm, and a plasma membrane ·      Carry out life processes, such as respiration, reproduction and excretion. ·      Sexual and asexual reproduction through spores and budding or binary fusion	Paramecium, Amoeba, Euglena
Virus	·      Smallest microorganism, can only be seen under electronic microscope ·      Non-living cell – because it cannot survive or reproduce on its own outside the cells of its host. ·      Depend on host for nutrition, reproduction and respiration. ·      Have two parts: (a)  Inner core – composed of nucleic acid: DNA or RNA (b)  Outer capsid of protein ·      Can be purified or crytallised	Influenza virus, Poliomyelitis virus, Tobacco mosaic virus

8.2.1      The effects of abiotic components on the activity of microorganisms

1.    The activity of microorganisms are affected by:

(a)  Nutrients and water

a.    Microorganisms need water and nutrient for reproduction and grow.

b.    Without water, the microorganisms will die or form spores.

(b)  pH

c.    Each species of microorganisms has its own optimum pH.

d.    Most bacteria prefer slightly alkaline conditions (pH 7.4), while yeast and protozoa prefer acidic conditions (pH 4.5 – 4.0).

(c)  Temperature

e.    Most a microorganisms are inactive in low temperature.

f.     The optimum temperature for microorganisms is between      35 ⁰C – 40 ⁰C

g.    Beyond 60 ⁰C, the growth of the microorganisms is inhibited.

h.    Microorganisms and their spores can only be destroyed when they are sterilized at 121 ⁰C.

(d)  Light intensity

i.      Microorganisms prefer dark or low light intensities.

j.      High intensities of sun light or ultraviolet rays can kill microorganisms.

k.    Photosynthetic algae and bacteria are more active under high light intensities to carry out photosynthesis.

(e)  Presence or absence of oxygen

l.      most microorganism (aerobes) require oxygen for respiration and metabolism.

m.   Certain bacteria and fungi are facultative anaerobes, they are able to grow in either presence or absence of oxygen.

n.    Obligate anaerobes can only survive in the absence of oxygen.

Experiment: To investigate the effect of nutrients on the rate of respiration in yeast Objective To investigate the effect of nutrients on the rate of respiration in yeast. Problem statement What is the effect of nutrients on the rate of respiration in yeast? Hypothesis The higher the nutrients, the higher the rate of respiration / the shorter the time taken for the lime water to turn chalky. Variables Manipulated variable: concentration of nutrients Responding variable: time taken for lime water to turn cloudy/rate of respiration Fixed variable : surrounding temperature, pH, light intensity, volume of lime water Materials Yeast suspension, glucose solution, lime water and distilled water Apparatus Thermometers, boiling tubes, test tubes, stoppers, delivery tubes, and beakers technique Using stopwatch, record time taken for lime water to turn chalky. Procedure Five boiling tubes are labelled as A, B, C, D and E. Each boiling tube is filled as given below. Boiling tube Contents A 10 ml of yeast suspension + 10 ml of distilled water B 10 ml of yeast suspension + 10 ml of 5% glucose solution C 10 ml of yeast suspension + 10 ml of 10% glucose solution D 10 ml of yeast suspension + 10 ml of 15% glucose solution E 10 ml of yeast suspension + 10 ml of 20% glucose solution the apparatus is set up as shown as below. Each boiling tube is placed in a water bath at a temperature of 35oC The time taken for the lime water to turn cloudy is recorded. Precautional steps: §  make sure all joints are air-tight §  repeat experiment to get average readings §  Add paraffin oil. Results: Boiling tube Concentration of glucose (%) Time taken for lime water to turn cloudy (minutes) A 0 B 5 C 10 D 15 E 20 Conclusions When the concentration of nutrients increases, the rate of respiration of yeast increases.  The hypothesis is accepted.

The role of Useful Microorganisms in the Ecosystem

Area	Usage / Examples
Digestion	The alimentary canal of herbivores, contain bacteria which produces cellulose enzyme to digest cellulose. The digestion of cellulose in termite is done by protozoa that produces cellulose enzyme to digest cellulose. In human colon, some mutualistic bacteria can synthesis Vitamin B 12 (to prevent anaemia and Vitamin K for blood clotting)
Medicine	Fungi are used in the production of antibiotics. o   Example: Penicillin produced by fungus Penicillium natotum is used to treat diseases such as gonorrhoea, syphlilis and lung infection. Vaccines which formed by weakened or dead bacteria or viruses are used to stimulate the body’s immunity agaist diseases. o   Example: B.C.G. vaccine is used to produce immunity agaist TB.
Decomposition	Bacteria and saprophytic fungi decompose the dead animals and plants into simple compounds and elements. Microorganisms are used to treat waste from industries. Decomposers play an importance role in natural cycles of elements such as carbon cycle and nitrogen cycle. a.    the decaying process returns elements such as carbon, nitrogen and sulphur back to the soil. b.    These substances are then reabsorbed by plants and move through the ecosystem again.
Industry	1.    Production of alcohol a.    Yeast is used to produce alcohol through fermentation of sugar, starch or grains. 2.    Production of vinegar a.    The bacterium, Acetobector, acts on the alcohol to produce vinegar. 3.    Making of bread a.    Yeast is used to raise the dough. 4.    Production of butter a.    The bacteria split the proteins from the fat of the cream to enable the fat molecules to stick together when the mixture is stirred strongly. 5.    Production of fermented milk a.    The bacteria, Lactobacillus sp. and Streptococcus sp. together with yeast act on thick milk to produce fermented milk. 6.    Production of vitamins a.    Microorganisms such as yeast can be used to produce vitamin B2 and vitamin D. 7.    Textile industry a.    Bacteria are used to decompose the soft plant tissues leaving the plant fibres.
The Nitrogen Cycle	Nitrosomonas sp. and Nitrococcus sp. convert ammonia into nitrites. Nitrobacter sp. converts nitrites into nitrates that go into the soil, which are absorbed by the roots of plants. Rhizobium and Azotobacter sp.  converts nitrogen into nitrates.

1. There are three main processes which involve the activity of microorganism in nitrogen cycle.

(a)  decomposition

(b)  nitrogen fixation

(c)  denitrification

2. Decomposition

a.    organic matter such as animal carcasses, dead plants and animal wastes are converted by the saprophytic organism (bacteria and fungi) into ammonia.

b.    Ammonia is converted into nitrites by Nitrosomonas sp. and Nitrococcus sp.

c.    Nitrobacter sp. then converts nitrites into nitrates that go into the soil, which are absorbed by the roots of plants and converted into proteins.

3. Nitrogen fixation

d.    Nitrogen fixation is a process whereby atmospheric nitrogen is converted into nitrates.

e.    It can be carried out by:

(a)  industry fixation

(b)  biological fixation

(c)  atmospheric fixation

f.     Industry fixation

a.    Ammonia nitrate is produced through nitrogen-based fertilizer

g.    Biological fixation

a.    Biological fixation is carried out by nitrogen-fixing bacteria and blue-green algae

b.    Azotobacter sp. and Clostridium sp. (free-living bacteria in the soil) convert nitrogen into nitrates.

c.    Rhizobium that lives in the root nodules of leguminous plants, also converting nitrogen gas into nitrates.

d.    Noctoc sp. is a blue-green algae in the soil that fixes nitrogen gas into nitrates.

h.    Atmospheric fixation

a.    During thunderstorm, lightning causes nitrogen gas and oxygen gas to combine to produce nitrogen dioxide.

b.    The nitrogen dioxide gas dissolves in rain water to form nitrous acid and nitric acid.

c.    These acids react with bases found in the soil to form nitrates.

4. Denitrification

i.      The denitrifying bacteria reduce nitrates to free nitrogen and oxygen gas.

j.      The nitrogen gas returns to atmosphere while oxygen is used by the denitrifying bacteria for respiration.

8.2.1      The effects of harmful microorganisms

k.    There are many microorganisms that cause harmful effects. These include:

(a)  causing infections and diseases

(b)  spoilage of food, clothing and other sustances

l.      Pathogens are organisms or viruses that can invade the body of living hosts and cause diseases.

8.2.2      How diseases spread

m.           Diseases are transmitted in five ways, through

(a)          Air

·         Through cough, sneezes, talk or breathe

·         Examples of diseases: TB, diphtheria and viral diseases such as pneumonia, influenza, cold and mumps

·         Ways to prevent:

(i)    refrain from spitting

(ii)   refrain from coughing near other people

(iii)  use handkerchief or tissue paper when sneezing

(b)          Food

·         Through dirty hands, exposed food, pests, raw food

·         Examples of diseases: typhoid, amoebic dysentery, cholera, worm infection

·         Ways to prevent:

(i)    Cooking food

(ii)   Covering food

(iii)  Keeping food in refrigerator

(c)          Water

·         Through contaminated water

·         Examples of diseases: typhoid, amoebic dysentery, cholera

·         Ways to prevent:

(i)    Boiling the drinking water

(ii)   Chlorinating the water in the reservoirs

(d)          Physical contact

·         Through direct contact, indirect contact, sexual intercourse and cuts

·         Examples of diseases: ringworm, TB, measles, chickenpox, sexually transmitted diseases (gonorrhoea, syphilis and AIDS)

·         Ways to prevent:

(i)    Do not share personal belongings

(ii)   Adopt hygienic habits

(iii)  Abstain from immoral activities and drug abuse

(iv) Abstain from immoral sexual relationships

(e)          Vectors

·         Through insects (mosquito, housefly and lice), through animals (rats, dogs)

·         Examples of diseases: Malaria (by Anopheles sp. mosquito), Dengue fever (by Aedes sp. mosquito), Cholera (by housefly)

8.2.3      Methods of controlling pathogens

1.    Antibiotics

n.    Antibiotics are chemical substances produced by certain microorganisms.

o.    Function: To kill and inhibit the growth of bacteria and fungi.

p.    Examples:

(i)    Penicillin is used to treat diseases caused by bacteria, such as syphilis

(ii)   Streptomycin is used to treat diseases such as TB.

2.   Antiseptics

-     Antiseptics are chemical used to kill and inhibit the growth of microorganisms on cuts or wound.

-     Examples:

      iodine solution, potassium permanganate solution, acriflavin, alcohol

3.   Disinfectants

-     Disinfectants are chemical solution used to kill microorganisms on the surface of floors, buildings, furniture, toilet bowls and clothing.

-     Examples:

Phenol, carbolic acid, creasol, and formaldehyde

2.    Vaccines

q.    Vaccines are weakened or killed viruses and bacteria which injected to the body to stimulate the production of antibodies.

r.     Examples:

BCG vaccine is used to immunize a person against TB.

8.2.1      The use of microorganism in biotechnology

1.    Cleaning of oil spills	b.  Genetically engineered bacteria are used in cleaning oil spills. c.  The bacteria together with a nutrient solution are sprayed onto the oil. d.  The bacteria break down the oil into less harmful substances such as carbon dioxide and water.
2.   Management of waste	e.    Toxic and non-toxic industrial wastes are converted by microorganisms into safe substances for the environment. f.     Certain species of bacteria are used to decompose compounds of hydrocarbons and sulphur in toxic solution and in septic tanks. g.    Degrading fungi are used to convert wood pulp and other useful products.
3.   Processing of food	h.    Yeast is used in the making of bread and wine. i.      Yogurt is made from the fermentation of milk, using bacteria such as Lactobacillus sp. ad Streptococcus sp.
4.   Production of bioplastics	j.      Bioplastic is biodegradable plastic which can be easily decomposed. k.    Bioplastic is produced by culturing bacteria in a nutrient-rich medium. Bacteria in the nutrient medium react by synthesizing a natural plastic. l.      The bioplastic is extracted from the bacteria to make bags, bottles, spoons and forks.
5.   Production of energy from biomass	m.   Anaerobic bacteria are used to break down organic waste to produce biogas and gasohol. n.    The biogas produced can be used as domestic fuel or fuel for vehicles.