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PREFACE
This book is compiled for all aspirant scientists
and teachers young at heart!!!
The CAPS-exam guidelines have been followed.
This book is designed to help students to understand Life
Sciences and make it their own.
To my critical fellow educators:
Do not let the simplicity fool you.
The academic standard was not lowered!!
Compiled by: J Grobler
Published by:
Tel: 074 278 8623 / 084 808 9606
Fax: 086 596 1071
Email: [email protected]
a
Warning!!!
Copyright applies to this publication. In terms of the South African copyright law any
person who copies this publication, or any part thereof, or make copies, commit a crime
and run the risk of being fined or put in jail.
CONTENTS
TERM 1
DIVERSITY, CHANGE AND CONTINUITY
1.
BIODIVERSITY AND CLASSIFICATION OF MICRO-ORGANISMS
1.1
Micro-organisms
1
- Viruses
- Protista
- Bacteria
- Immunity
- Fungi
- Biotechnology - brewing of beer
1.2
9
13
18
29
35
Biodiversity of plants
- Bryophytes
- Pteridophytes
- Gymnosperm
- Angiosperm
1.3
37
49
55
62
Biodiversity in the animal kingdom
- Classification and phylums
- Porifera
- Cnidaria
- Platyhelminthes
- Annelida
- Arthropoda
- The roll of invertebrates in agriculture and ecosystems
- Chordata
72
78
80
84
87
90
93
94
TERM 2
LIFE PROCESSES IN PLANTS AND ANIMALS
1.
ENERGY TO SUSTAIN LIFE
1.1
Photosynthesis
- Factors essential for photosynthesis
- The dorsi ventral leaf
- The chemistry of photosynthesis
- The importance of photosynthesis
- Photosynthesis experiments
102
103
105
107
108
1.2
Nutrition in mammals
- Herbivores, carnivores and omnivores
- Structure of the human digestive system
- Homeostatic control of blood sugar
- Mechanical and chemical digestion
- Dietary supplements, alcohol and drugs
1.3
117
117
124
125
129
Cellular respiration
- Aërobic respiration and Anaërobic respiration
- The chemistry of cellular respiration
- Cellular respiration experiments
139
141
144
TERM 3
LIFE PROCESSES IN PLANTS AND ANIMALS CONTINUED
2.
GASEOUS EXCHANGE
2.1
Gaseous exchange in organisms
- In plants and animals
- Effective gaseous exchange area
2.2
The human respiratory system
- The human lung
- Gaseous exchange in the lungs and tissue
- Respiratory diseases
3.
EXCRETION IN THE HUMAN
3.1
Excretion in different organs
- Lungs, kidneys, liver, skin and digestive system
3.2
150
151
152
156
158
165
The human urinary system
- Composition of urine
- The functioning of the nephron
- Homeostatic control of water and salts
- Diseases of the kidney
166
170
171
183
ENVIRONMENTAL STUDIES
1.
POPULATION ECOLOGY / POPULATION DYNAMICS
1.1
Definitions
- Populations, niches, biomass, parameters
1.2
186
Population size
- Factors influencing population size
- Population growth curves
187
190
1.3
Interaction in the environment
- Competition, speciation and predation
192
1.4
Determining population size
198
1.5
Symbioses
- Commensalism, mutualism and parasitism
1.6
Social organisation
- Social behaviour, polymorfism
1.7
209
Ecological succession
- Primary and secondary succession
1.8
205
213
Human population
- Population growth, Age and gender
215
TERM 4
ENVIRONMENTAL STUDIES CONTINUED
2.
HUMAN IMPACT ON THE ENVIRONMENT
2.1
The atmosphere and climate change
- Release of carbon dioxide
- Ecological and carbon foot print
- Deforestation and the greenhouse effect
- Methane release and ozone layer
2.2
Water
- Availability of water, dams
- Wetlands and poor farming methods
- Alien plantations, bore holes, water wastage
- Water quality, mining activities and water pollution
2.3
2.5
222
223
224
225
Food security
- Poor farming methods, pest control
- Soil erosion and fertilizers, alien plants
- Genetic manipulation, impact on gene pools
- Wastage
2.4
217
217
218
220
228
230
231
232
Loss of bio diversity
- Habitat destruction, poaching and indigenous knowledge
233
The processing of solid waste
- Control of dumping sites
- Recycling
- Methane gas, nuclear waste
238
239
239
I
GRAPHS TO BE MASTERED
A.
The line graph
1.
2.
Always add a heading to the graph as well as a key to indicate different graphs
The axis (X and Y) must be correctly calibrated (e.g. 2,4,6,8 or 3,6,9,12 etc.)
- You usually have to start with a 0-value
Relative constant values which are called the INDEPENDENT VARIABLES will be found
on the X-axis e.g. temperature, years, time etc. These values are not easily influenced by
external factors
The values on the Y-axis are influenced by external factors such as those found on the xaxis, and are called the DEPENDENT VARIABLES
The unit of the axis must always be indicated
The data on the graph must be shown clearly
3.
4.
3.
4.
X-axis ( Temperature in °C)
20
30
35
40
45
50
Y-axis ( Reaction rate in mg/min)
2
3,5
4,5
5,5
5,5
1,2
Reaction rate
of enzyme
(mg/min)
Temperature (°C)
B. The Pie graph
1. The total area represents 100%
2. The sum of the segments will equal 100 %
II
C.
The Histogram
1.
2.
3.
4.
Data is represented by individual columns for comparison
A series of data is shown
The columns touch and are of equal width
The axis must be correctly calibrated
Number of
deaths
Age at death (years)
D. The bar graph
1.
2.
The bar graph has spaces between the columns
Each column represents something different, and no series is formed
Composition
(%)
KEY:
1
DIVERSITY, CHANGE AND
CONTINUITY
BIODIVERSITY
MICRO-ORGANISMS
1.
2.
3.
4.
Micro organisms / microbes are organisms that can only be seen through a microscope
The micro organisms contribute to biodiversity in ecosystems, since millions are present in
important food chains
Micro organisms play a daily role in
- Diseases, e.g., tuberculosis, AIDS, cholera, malaria etc.
- Food production, e.g., yeasts in baking, production of wine and cheese etc.
- Decaying of food by fungi and bacteria
- Sewage disposal by bacteria
These include:
- viruses that range in size from 0,01 um to 0,1 um ( 1 um = 0,001 mm)
- bacteria that range between 0,1 um to 5 um
- Protista - unicellular animals such as Amoeba and
- those causing diseases such as Malaria
- fungi - bread mould and mushrooms
VIRUSES
INTRODUCTION
1. Viruses can be seen as inert or dormant. They only become active when they enter living
cells of other organisms. They are therefor not considered as living organisms at all by
some scientists!
2. They are all, without exception, parasites or pathogenic, since they cause diseases
3. In 1918, 20 million people died of a flu epidemic in Europe
- more than in world war one!
4. Viruses only have one function, and that is to REPRODUCE!
- All other metabolic activities are absent!
5. Viruses are transported passively by air, water, physical touch, body fluids and food
THE STRUCTURE OF VIRUSES
1. They are extremely small and are only visible under very high magnification of electron
microscopes
2. The body consists of - a protein coat / capsid consisting of capsomeres which enclose
- a nucleic acid
3. The nucleic acid is
- RNA in viruses found in plant cells
- DNA in viruses found in animal cells
4. They range from cylindrical to spherical (round)
To Contents
2
The influenza (flu) virus
The tobacco mosaic virus
RNA
Capsomere
Helix DNA
Capsid
Typical structure of an animal virus
A cubic wart virus
Capsomere
DNA/RNA
A membrane envelope
The structure of a bacteriophage = a virus pathogenic on bacteria
3
REPRODUCTION / REPLICATION IN VIRUSES
1.
2.
3.
4.
5.
6.
7.
8.
9.
Viruses can only reproduce inside plant or animal cells
The virus attaches to the cell and injects its nucleic acid into the cell
The protein capsid stays on the surface of the cell
Inside the cell, the virus DNA / RNA takes control of the host cell’s DNA / RNA
This changes the chromosomes of the cell and can be seen as a form of mutation!
The virus-DNA/RNA now controls the cell
The cell is controlled to produce new viruses
As soon as the cell is exhausted and filled with new viruses, it bursts open and releases
the new viruses
The newly formed viruses now attack other cells in the organism’s body
Replication of bacteriophage viruses
The virus attaches to host cell
New viruses released
Bacterium
DNA forced inside
- now controls the host
DNA
Host cell filled
with new viruses
Host cell produces
new viruses
BIOLOGICAL IMPORTANCE OF VIRUSES
Viruses cause many diseases in plants, animals and humans
IN PLANTS
1.
2.
Abnormalities in plants cause massive economical losses
The tobacco mosaic virus in tobacco leaves cause CHLOROSIS in the leaves
- The leaves turn yellow since chlorophyll is absent
- This makes the tobacco leaves useless for the market
4
SPREADING OF VIRUSES
1.
Viruses are spread by
- food and water
- contact = coughing, sneezing and sexual contact
- vectors (carriers) such as mosquitos, flees, plant lice and ticks
- Until now the HIV-virus is not transmitted by mosquitoes!
2.
If a person comes in contact with a virus, he builds up an immunity against the virus by
- producing anti bodies which “recognise” and help to eliminate the virus
- That is why babies are vaccinated against different diseases
- The vaccine contains a weakened strain of the virus
- the baby is actually infected with the virus
- to enable him/her to produce antibodies against the particular virus
3. Plants are cultivated to make them resistant against certain viruses
DISEASES CAUSES BY VIRUSES (VIRAL DISEASES)
DISEASE
1.
Rabies
Caused by the
Rabdo virus
2.
AIDS
Caused by the
MIV-virus
A spherical
retrovirus
3.
Colds and flu
4.
German measles /
Rubella
TRANSMISSION AND SYMPTOMS
The animal is infected by the bite of
another rabid animal.
Viruses are transmitted by saliva of
a rabid animal.
The virus attacks the central
nervous system and other organs
The infected animal appears tamed
with a foaming mouth.
It develops hydrophobia-fear of
water.
Hallucinations and confusion are
found in infected humans.
Aids = Acquired immune deficiency
syndrome
The virus is transmitted through
blood, sexual contact and from a
mother to her unborn baby.
The virus attacks the immune
system, by reducing the T-cells that
protect the body against infections.
The person dies of other
opportunistic diseases such as TB
and pneumonia etc.
Infection occurs during low
immunity through direct contact with
the virus. E.g.. Contact with
infected hands by sneezing,
coughing, nose blowing etc.
Causes an abnormal baby if a
woman is infected in the first four
months of her pregnancy.
An abortion is performed.
TREATMENT
Louis Pasteur developed a
vaccine against rabies.
Pets are inoculated every
six months.
Immunisation – weakened
viruses are injected into the
body. Antibodies are produced
against the virus to protect the
body against the disease in the
future
Anti-retroviral drugs are used.
No treatments in the advanced
stages are available.
Prevention is the only
solution to this disease!
Drink lots of water and rest!
Only the symptoms are treated
Immunisation is possible
Immunisation is possible
for pregnant women.
A girl must be infected to build
natural immunity against the
virus.
5
EFFECT AND MANAGEMENT
OF AIDS IN SOUTH AFRICA
A.
THE STAGES OF AIDS AFTER INFECTION WITH THE HIV-VIRUS
1.
Primary HIV infection
- The virus migrates to the lymph nodes and many new HIV viruses are produced
Sero-conversion
- Antibodies against the HIV virus are produced
- Flu-like symptoms, a skin rash and swollen lymph nodes are present
- Night sweats can occur
- The person will test positive for HIV antibodies
- The person is now HIV-positive – all other symptoms disappear
- This stage can last between a few weeks and 13 years!
Opportunistic infections will be experienced - Immune system decline will now occur
- Aids-related diseases such as viral, bacterial and fungal infections will appear
- Weight loss will also take place
- A lowered T-cell count is found (fewer T-cells)
Aids-related diseases become more severe
- Organs are attacked and weight loss becomes severe
- Diarrhoea, fever and fatigue occurs
- The person dies of other diseases such as pneumonia, tuberculosis etc.
2.
3.
4.
B.
AIDS STATISTICS / NUMBERS
WHY ARE AIDS STATISTICS OFTEN INACCURATE?
1.
2.
3.
4.
5.
Many cases are not reported, only specific people are tested
Many people are not aware that they are HIV positive and they are in the window period
Many people that are tested could have emigrated or they could have died
Mistakes are made in the composition of statistics
Statistics are often outdated and therefore inaccurate
FACTORS DECREASING AIDS NUMBERS
1.
2.
3.
4.
5.
6.
More condoms are freely available
Successful training programs are held and consciousness on HIV-spreading increases
Persons are more loyal to their lovers
Abstinence (no sex) becomes fashionable
More people die of AIDS and are not part of the statistics anymore
Fewer mothers transmit the virus to their babies
FACTORS INCREASING AIDS NUMBERS
1.
2.
3.
4.
5.
Increase in licentiousness - more people become sexual active at a young age
Unfaithfulness - having more than one lover
People are uninformed - they don’t believe the HIV-virus can kill
People in desolated areas - people don’t have access to condoms and clinics
Training programs and informing people on the HIV-virus are insufficient
6
SHOULD THE GOVERNMENT TEST ALL PERSONS AND THEN ANNOUNCE THEIR HIVSTATUS?
A.
ADVANTAGES CONNECTED TO IT
1.
2.
3.
4.
5.
Announcing a person’s HIV-status can enable his/her lover to protect her-/himself
Planning for medical care can be done by the government and other companies. Budgets
can be planned ahead
Infected persons can be helped to prevent further infections
Couples will be loyal to each other
More accurate statistics will be available
B.
DISADVANTAGES CONNECTED TO IT
1.
2.
3.
4.
5.
Individuals’ rights to their own privacy are violated
Information can be misused and employers can discriminate against HIV-positive workers
Discrimination and rejection by friends and colleagues can occur
Suicide can increase under HIV-positive individuals
The costs for testing the whole population are very high
ACTIVITY
VIRUSES
1. Why is it illegal to take meat products such as biltong as well as fresh fruit and vegetables
through customs on an airport when you leave or enter a foreign country?
________________________________________________________________________
2. Will it one day be possible for the HIV-virus to be transmitted by mosquitoes?
________________________________________________________________________
3. Can a virus which is pathogenic on plants, also cause diseases in humans? ___________
4. Why must you wash your hands after blowing your nose? _________________________
_______________________________________________________________________
5. Where did the saying “Bless you?!” still used today when someone sneezes, originate?
(Use the internet) _________________________________________________________
6. How are viruses transported inside?
a) animals _______________________ b) plants ________________________________
7. What is meant by “mutations”? Can it be a possible explanation for why you can be
infected with influenza every year? ___________________________________________
_______________________________________________________________________
8.
7
Study the information on AIDS as supplied by the South African Health
Department and answer the questions that follow:
Table 1:
The percentage of HIV-positive women that visited prenatal clinics in
South Africa
Age
< 20
20 – 24
25 – 29
30 – 34
35 – 39
40 – 44
Table 2
1999
16,5
25,6
26,4
21,7
16,2
19,5
8.1
2001
15,4
28,4
31,4
25,6
19,3
26,2
2002
14,8
29,1
34,5
29,5
19,8
26,4
2003
15,8
30,3
35,4
30,9
23,4
25,8
2001
2,5 million
2,2 million
106 109
4.7 million
2002
2,95 million
2,3 million
91 271
5,3 million
2003
3,1 million
2,4 million
96 228
5.6 million
Sex
2004
3,3 million
2,8 million
104 963
6,29 million
The percentage of HIV-positive individuals that were tested at clinics in
South Africa
Where is the highest percentage of HIV-positive people found?
GROUP
Age
2004
16,1
30,8
38,5
34,4
24,5
17,5
The number of HIV-positive individuals that were tested at clinics in South
Africa
Group
Women
Men
Babies
TOTAL
Graph 1:
2000
16,1
29,1
30,6
23,3
15,8
23,1
ANSWER
POSSIBLE EXPLANATION
8.2
8
Where is the lowest percentage of HIV-positive people found?
GROUP
Age
ANSWER
POSSIBLE EXPLANTATION
Sex
8.3
Why does the occurrence of AIDS decrease in higher age groups?
________________________________________________________________
________________________________________________________________
8.4
What is the best solution to decrease the occurrence of AIDS in South Africa?
________________________________________________________________
________________________________________________________________
8.5
Debate the following statement: “Condoms should be freely available in the
bathrooms of schools” _____________________________________________
________________________________________________________________
________________________________________________________________
8.6
How is the AIDS virus transmitted to babies? ____________________________
________________________________________________________________
8.7
Do you think that antiviral medications should be freely available to everybody?
Give a reason for your answer _______________________________________
________________________________________________________________
8.8
In 2004 60 million people in the world were HIV-positive. Which percentage of
this total was found in South Africa? Show all your calculations!
________________________________________________________________
________________________________________________________________
________________________________________________________________
9.
On billboards on the highway is the following slogan: “If you love me, protect me!
Use a condom!” Create your own slogan to make people aware of the dangers
of AIDS
9
PROTISTA
1.
2.
3.
Protista consists of organisms which are eukaryotic, since they have true nuclei and
cell organelles inside a cellular membrane
The Amoeba is an example of one of the simple Protista and is found in the muddy
sediment of clean fresh water ponds
Other examples are green algae such as Spirogyra and Euglena that can
photosynthesize and which are also found in clean fresh water ponds. The Euglena
has flagella to swim with (Is it a plant-like animal or an animal-like plant??)
Spirogyra
4.
5.
6.
Euglena
Many Protists are pathogenic since they cause diseases such as:
- Plasmodium sp. that cause Malaria which is transmitted by the Anopheles mosquito
- Trypanosoma sp. that cause sleeping sickness and is transmitted by the Tsetse fly
The mosquito and Tsetse fly act as vectors since they transmit the parasite
The symptoms of Sleeping sickness are a high fever, anemia, sleepiness and then
death
To Contents
MALARIA
1.
2.
3.
4.
5.
6.
7.
10
Malaria is a tropical disease that is found in 90 countries world wide
- that is caused by a group of unicellular, parasitic organisms (Protista)
- which live on the red blood corpuscles (erythrocytes)
- of reptiles and mammals
There are four malaria species which are pathogenic on the human namely:
- Plasmodium falciparum, P. ovale, P. vivax and P. malariae
P. falciparum is the most dangerous and is also very common in Africa
Plasmodium is transmitted by the female Anopheles mosquito
- which acts as the vector
Malaria kills more than one million people every year, from which 90% of the
deaths are in Africa
Malaria is responsible for one out of four deaths among children
The chemical substance Chloroquine is the safest to use against Malaria, but is
losing its effectiveness against the parasite rapidly
THE LIFE CYCLE OF PLASMODIUM
Two stages are found inside the human body namely
- in the liver and in the erythrocytes
A.
The liver stage
1.
The human is infected by sporozoites which are present in
- the saliva of the female Anopheles mosquito
The sporozoites migrate to the human liver
Each sporozoite produces up to 40 000 merozoites through mitosis
- which are released into the blood stream
2.
3.
B.
The blood stage
4.
5.
Erythrocytes are invaded by the merozoites = Erytrocytic phase
The destruction of the erythrocytes causes anaemia in the infected person
- who feels very tired and listless
Erythrocytes burst open and release merozoites into the blood stream
- This produces a high fever of 40°C as well as flu symptoms
Malaria can usually be detected in the blood stream during this phase
The merozoites invade other liver cells and erythrocytes
The kidneys, liver and milt are overloaded with toxins
- which can cause death
Some merozoites develop into male and female gametocytes
Gametocytes are ingested with the blood by the Anopheles female mosquito
- when an infected person is bitten
The gametocytes develop into gametes in the gut of the mosquito
Male gametes fertilize the female gametes and
- Zygotes are formed which invade the gut wall
The zygote undergoes meiosis and
- forms a cyst in the gut wall
Many sporozoites are produced from one cyst
- which migrate to the salivary glands of the mosquito
The mosquito can now infect the next person
The parasite does not affect the mosquito in any way
Up to 2 million P. falciparum parasites can be present in an infected person
- and 40% of the eythrocytes can be destroyed before death occurs
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
15.
16.
17.
11
THE LIFE CYCLE OF PLASMODIUM (MALARIA PARASITE)
A. IN THE HUMAN
Second mosquito infected
Erythrocyte produces
gametocytes
Male and female
gametocytes
ingested
Merozoites
invade erythrocytes
and liver cells
Erythrocyte
produces
merozoites
First mosquito
Start of the cycle
Sporozoites
injected into
bloodstream and
invade liver cells
and erythrocytes
Erythrocyte
invaded by merozoites
Sporozoites produce merozoites in
liver cells
B. IN THE MOSQUITO
Gametocytes produce gametes inside gut of mosquito
Male and female
gametocyte ingested
Male
Zygote
Female
Sporozoites migrate to
salivary glands of
mosquito
Many Sporozoites are produced in gut wall
Migrates to gut wall
of mosquito
Cyst forms in gut wall
ACTIVITY
12
MALARIA
Study the following information on Malaria and answer the questions:
1.
Malaria is combatted by the following:
- the use of drugs such as chloroquine that prevent Malaria
- the spraying of water masses with insecticides where mosquitoes hatch
- the use of mosquito nets over beds
- the spraying of insecticides inside homes
- the drainage of water masses where mosquitoes hatch
- the use of fish that feed on mosquito larvae
- the development of a natural immunity in people that are often infected
2.
The graph illustrates the occurrence of malaria in South-Africa between 1989
and 2004, as supplied by the Medical Research Unit of South Africa in an
informal settlement.
Number of females
Number of males
1.
Which method of combat is the most harmful to the environment? Explain your
answer _______________________________________________________
______________________________________________________________
2.
Which method of combat is the most environmentally friendly? Explain!
______________________________________________________________
3.
Why are more women infected than men? ____________________________
______________________________________________________________
4.
What caused the abnormal high infection rate between 1998 and 2000?
Keep in mind where mosquitoes breed! ______________________________
______________________________________________________________
5.
Do you think that a person is more vulnerable to malaria if he is infected with
AIDS? Give a reason for your answer _______________________________
______________________________________________________________
13
BACTERIA
INTRODUCTION
1.
2.
3.
Before antibiotics were developed by Alexander Fleming in 1929
- the human race was affected greatly by a vast number of bacterial diseases
Thousands of soldiers died of infections in their wounds before antibiotics were used
Alexander Fleming experienced world war one as well as the second world war. His
antibiotics were only used in the second world war to save thousands of lives
(Can you imagine the pain and hardship during world war I ?)
Interesting
facts
Louis Pasteur witnessed an attack by a rabid dog on the inhabitants of his
hometown in Southern France when he was only nine years old, which
influenced him greatly. He later qualified as a microbiologist. He did valuable
experimental work on viruses as well as bacteria.
Use the Internet or other resources to find out more about his work
PASTEURIZATION
1.
2.
3.
4.
Louis Pasteur is the “father” of pasteurization which is still
- used today to keep our milk fresh for longer
His first experiment was on wine which he boiled and sealed
- to prove that the bacteria responsible for the wine to ferment,
- were found in the surrounding environment
Milk is heated for 15 seconds at 72°C and then cooled
- immediately during the pasteurization process
This process kills all the bacteria in the milk
THE STRUCTURE OF A BACTERIAL CELL
1.
2.
3.
4.
5.
6.
Bacteria are unicellular organisms that form colonies
Bacteria have the basic structure of a plant cell with:
- a cell wall consisting of cellulose = polysaccharide
- a slime sheath/capsule that surrounds the cell wall and protects the cell from drying out
- a cell membrane which is selectively permeable
- a granular protoplasm with vacuoles and dissolved substances
NO nucleus is present - only chromatin granules consisting of DNA are present
- which makes the cell prokaryotic
Food granules are found in the protoplasm
1 to more flagella help with locomotion
Hair-like structures / pili are found on the external surface of the cell
- which help the bacterial cell to attach to its host
- e.g the colon bacillus attaches to the gut of humans by its pili
To Contents
14
THE STRUCTURE OF A BACTERIAL CELL
Flagellum
Slime capsule
Mitochondrion
Cell wall
Cell membrane
Chromatin material (DNA)
Cytoplasm
Vacuole
Food granules
5.
Bacteria are found in different forms:
A. Coccus / spherical
B. Bacillus / rod-shaped
Monococcus
Monobacillus
e.g tuberculosis
Diplococcus
e.g pneumonia
Diplobacillus
Streptococcus
e.g sore throat +
food poisoning
Staphylococcus
e.g boils
C. Spirillum / spiral
shaped
Bacillus with
flagella
e.g syphilis
15
REPRODUCTION IN BACTERIA
1.
2.
3.
4.
5.
Budding : A new bacterial cell grows from the mother cell
Endospores: The slime capsule forms a thick-walled structure that is able to survive
extremely adverse conditions. This is also a dormant/resting stage
Segmentation : The bacterial cell breaks into small segments. Each can survive
individually
Conjugation : Two bacterial cells exchange genetic material (DNA/RNA) in order to survive
- They use their pili to attach to each other
Binary fission /Mitosis: This is the most common and fastest means of reproduction. That
is why bacterial diseases and infections spread so rapidly!
Binary fission / mitosis in a bacterial cell
Two identical
daughter cells are
formed
Mother cell divides by mitosis
THE ECOLOGICAL ROLE OF BACTERIA
A.
BENEFICIAL (USEFUL) BACTERIA
A1. In food
1.
2.
3.
Anaerobic bacteria (Requires no oxygen) convert sugar during fermentation to
- alcohol and carbon dioxide
This process is used in the production of wine, medicine and other alcoholic beverages
such as
- brandy and ginger beer!
Beneficial bacteria are also used in the production of yoghurt, buttermilk and cheese
A2. As Decomposers / saprophytes
1.
2.
3.
4.
Dead organisms are decomposed to again become part of the ecosystem
Roughage in the colon of the human is digested by millions of bacteria
Bacteria help with the digestion of plant material in herbivores
E.coli bacteria in the human colon help with the production of vitamin K which is necessary
for blood clotting
- This symbiosis is seen as mutualism,
- since both organisms benefit from it
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A3. In the nitrogen cycle:
1. Nodular bacteria on legume roots (beans, soya beans and peas)
- fix nitrogen from the atmosphere in the soil
- for plants to build amino acids and proteins
2. These plants are sources of nitrogen for animals and humans
- for the production of amino acids
- to build proteins in their own bodies
- e.g enzymes, hormones, protoplasm of cells etc.
3. Nitrifying and denitrifying bacteria convert nitrates and
- ammonia (from urine and faeces)
- to free nitrogen in the atmosphere (Done in grade 10!)
B. HARMFUL BACTERIA
In the food industry:
1. Bacteria found in spoilt food, can cause serious illnesses
2. The bacteria cause the food to “decompose”!
3. This causes food poisoning which can cause death if not treated
Pathogenic bacteria
USE THE TABLE ON THE FOLLOWING PAGE!