Definition

• Is the study of
interrelationships or
interactions within
organisms and with
their environment.
 Application of knowledge
gained from studying ecology.
Promote ecotourism.
Pollution control.
In prediction of adverse weather
patterns.
Conservation of biodiversity and
natural resources.
Pests and disease control.
Sustained food production.
 Concepts/terminologies
used in ecology.
1) Habitat – Place in ecosystem
with specific conditions where
organism lives. eg Terrestrial,
aquatic habitat.
2) Ecological niche – Is specific
physical position an organism
occupies in habitat and its role
and interactions in that position
eg feeding with other species.
 Habitat images.

Terrestrial
Aquatic
 Niche Images
Describe each niche
3) Biotic factors – Are factors in
ecosystem caused by activities of
living things eg competition, parasitism
predation, symbiosis etc.
4) Abiotic factors – Are non-living
environmental factors that affect
organisms in ecosystem eg wind, light,
temperature etc.
5) Ecosystem – A self sustaining natural
unit consisting of interacting biotic
and A biotic factors. eg grassland,
forest, pond, lake ecosystem…
Ecosystem images. Identify the
biotic factors, biotic factors and
the interactions in each picture.
6) Population – Is number of organisms
of same species in a specific place at
a given time. eg population of rats,
cockroaches, black jack, jacaranda,
humans, earthworms, bacteria, etc.
7) Community – Is all organisms of
different species or different
populations interacting in a given
habitat.
8) Biosphere/ecosphere – Is part of
earth and atmosphere that supports
life.
Population images.
 Community images
Identify the different species in
each community below:
 Community images
Identify the different species in
each community below:
 Community images
Identify the different species in
each community below:
 Community images (Is this also a community?)
Identify the different species in this community:
9) Autecology – Is ecological study of
of one specific species.
10) Synecology – Is ecological study of
many species.
11) Biomass – Is dry weight of organism
per unit area at specific trophic level.

12) Carrying capacity – Is maximum

number of organisms that can be
sustained in a given area without
exhausting the resources.
Explain the problems caused by Exceeding
carrying capacity in the photos below:
Explain the problems caused by Exceeding
carrying capacity in the photo below:
Explain the problems caused by Exceeding
carrying capacity in the photo below:
 FACTORS IN ECOSYSTEM.
I) ABIOTIC FACTORS ll) BIOTIC

• ABIOTIC FACTORS:
• Includes light, temperature,
humidity, wind, atmospheric
pressure, salinity, topography,
altitude, edaphic factors…
 1. LIGHT.
• Importance- Is main source of
energy in the ecosystem
– Light energy is used in
photosynthesis by plants, algae,
and photosynthetic bacteria.
• Light affects the following in the
ecosystem:
a) Distribution of organisms eg Bats,
cockroaches,…live in the dark. While
humans, birds…live where light is.
b) Rate of photosynthesis- High light
intensity increases while low light
intensity decreases rate of
photosynthesis.
c) Behavior and activity of organisms
- Some are active at night eg bats
while others are more active in light
during the day eg humans, birds…
d) Flowering
e) Reproduction
f) Hibernation
g) Migration
Photographic light meter is used for
measuring light intensity.
In water body light intensity decreases
with depth.
Light intensity in water body is
measured using seechi disc.
In closed canopy forest, organisms along
the ground get less light while those in
open canopy forest get more light. Thus
 Light meter images
• Examples:
 Secchi disk images.
• Examples:
 Closed and open canopy
• Closed canopy
OPEN
CANOPY
 2. Temperature
• Is measured using thermometer
-units used is °C, °F or K

• Temperature range is measured

using maximum and minimum
thermometer.
 Thermometers
• Examples:
 Effect of temperature on
organisms in ecosystem.
i. Affect metabolic activities
-Optimum temperature activates
enzymes thus making metabolic
rate to increase.
-Temperatures above or below
optimum reduces rate of
metabolism since enzymes are
denatured or inactivated
respectively.
ii. Affect distribution of organisms.
-The Beer lives in cold area while the
-Carmel, scorpion… live in hot areas.
iii. Affect rate of transpiration.
-The higher the temperatures
the higher the rate of transpiration
and vice versa.
 Aquatic habitat doesn’t experience
much temperature changes since
water has high specific heat capacity.
 Temp and distribution of
organisms
• Images:
 3. Relative humidity.
• Refers to amount of water vapour
in the atmosphere.
• Measured using hygrometer (See
page 35 Klb).
-Anhydrous blue cobalt chloride
paper can also be used. If it turns
pink at faster rate then the
relative humidity is high.
 Hygrometer images
•
 Effect of relative humidity
a) Influences rate of transpiration.
(Explain how).
b) Influences the rate of uptake of water
and mineral salts by root hairs of
plants. This is possible due to
influence of RH on rate of transpiration

c) Affects distribution of organisms.

-Earthworms, moss plants,… live or
grow in moist areas with low RH
while scorpions… live in areas with
low RH.
Earthworms in high humidity
 4. Wind
• Wind vane and wind sock are used
to determine direction of wind.
• Anemometer is used to measure
speed of wind.
• EFFECT OF WIND IN ECOSYSTEM:
a) Affect rate of transpiration in
plants.
b) Affect rate of evaporation
c) Influences rainfall – Dry winds
cause less rain…
Wind images
Wind vane/ wind sock
d) Promotes seed dispersal.
e) Promote pollination in plants.
f) Promotes formation of sand dunes in
deserts on which plants can then grow.
g) Influence migration in migratory birds.
h) Promote aeration of water bodies by
causing water currents and waves.
i) Enable predator to get scent of prey
and so be able to trace the prey.
j) Influences temperature by the blowing
of cool or warm air.
 5. Atmospheric pressure
• Is the pressure exerted by the
atmosphere on the earth’s
surface.
• Is measured using Barometer.
• High altitude areas have low
atmospheric pressure while low
altitude areas have high
atmospheric pressure.
Barometer
 Effects of atmospheric pressure on
Ecosystem.
a) Affects rate of transpiration– The rate
is low at high atmospheric pressure
since the high atm pressure prevents
water vapour from evaporating from
plant stoma…
The rate is high at low atmospheric
pressure… (why?)
b) Influences amount of O2 and CO2 in
the air. Areas with low atm pressure
have low concn of O2 and CO2 thus
low rate of photosynthesis and
Mountain plants image
respiration while areas with high atm
pressure have high concn of O2 and CO2
thus high rate of photosynthesis and
respiration.
c) Affects distribution of organisms
eg areas with high atm pressure have
more CO2 and O2 and thus has more
organisms.
In water bodies, water pressure
increases with depth. Animals with
ability to withstand high pressure
will be found at the bottom while
those that can’t will be near surface.
 6. Salinity.
• Refers to degree/concentration of
salts in water bodies.
• It is measured by chemical
titration experiments.
• Affects distribution of organisms
eg crocodiles, tilapia live in fresh
water with low salinity while
sharks, whale, etc live in marine
ie salty water.
 7. pH
• Refers to degree of acidity or
alkalinity of a substance.

• Affects mainly soil and aquatic

environment.

• Is measured using indicators and

indicator colour charts.
Soil pH determination
Soil pH determination
 Effects of pH in ecosystem

a) Influences distribution of organisms.

Some plants grow only in acidic soils
eg rice

b) Affect metabolic activities in

organisms by activating or denaturing
enzymes.(Mainly in aquating organisms
 8. Topography.
• Refers to landforms.
• Influences rainfall distribution
–Windward sides get more rain
than leeward side of mountains.
• Influence distribution of
organisms ie more plants and
animals on windward side (why?)
• Influence fertility of soil. – Valleys
have more fertile soil.
 9. Altitude.
Affects concentration of O2 and
CO2 in air(High altitude has lower
concentrations of O2 and CO2 …
Affect distribution of organisms.
Influences temperature. High
altitude areas have lower
temperatures than low altitude
areas.
 1. Predation
• Is interaction between two
animals where one (the predator)
kills the other (prey) for food.
• Example of predator – praying
mantis, lion, eagle, snake, etc.
• Example of prey – Antelope, rat…
• Define predator and prey.
Adaptations of predators:
a) Sharp claws catching and tearing
prey.
b) Strong legs for fast running to be
able to catch the prey.
c) Sharp eye sight to be able to
locate the prey from far.
d) Sharp sense of smell to be to
locate prey from far.
e) Sharp large canines for tearing
prey.
f) Has colours that camouflage with the
surrounding environment to avoid
being noticed by the prey.
g) Strong jaws and large carnassial
teeth for effective chewing of prey.
h) Some have poison glands that secrete
and release poison into prey to
paralyse and kill prey.
 Describe the adaptations of
predators shown in the 10 phots
below:
 Adaptations of prey.
a) Has colours that camouflage
with the surrounding
environment to avoid being seen
by the predator.
b) Strong long legs to enable it to
run fast to escape from predator.
c) Acting dead to avoid being killed
by predator eg millipede.
d) Some mimic dead dry substances to
avoid being noticed by predator.
(ie have structures that imitate
appearance of …) Eg stick insect that
resemble dry sticks.
e) Have scaring structures to scare
predators eg snakes have scaring
patterns on skin…
f) Have protective devices to prevent
predator from killing them. Eg tortoise
has shell…
g) Strong legs for producing strong
kicks for defense eg zebra.
-Sharp horns for defense.

h) Release toxic liquid and bad smell

for repelling away predators.
 Describe the adaptations of
predators shown in the 10 phots
below:
Stick insect
 Graph of prey and predator
population.
35
E D G
30
B
Population

25

20
C F
15
-Prey
10
A -Predator
5

0
0 2 4 6 8 10
Time
 A-B –There is increase in number of
prey since they reproduce and
predators feeding on them are few.
Predators increase since they have
enough food (prey).
 B-C –Prey decrease in numbers due to
the large number of predators feeding
on them.
 C-F –Predator decrease in numbers due
to less prey thus less food for them.
 Qn – Explain the trend in curve at C-D
and F-G
 2. Competition.
• Is the relationship that occurs
between organisms that share the
same resource which is in limited
supply.
• Organisms can compete for light,
mate, food, space…
 Types of competition.
• 1. Intraspecific 2. Interspecific
1) Intraspecific competition
- Is competition between
members of same species.
2) Interspecific competition
- Is competition between
members of different species.
For competition to occur the organisms
involved must be living in same habitat
and sharing same resource.

In a competition the strong well adapted

Organisms get more of the resource,
survive and increase in numbers while
the weak poorly adapted members get
less of the resource, some die and
decrease in numbers.
 Graph of interspecific competition of
two species of paramecium
(P. aurelia and P. caudatum)
Population (relative numbers)

90
80
70

Y-P.aurela
60
50
Y-P.caudatum
40
30
20
10
0
0 5 10 15

Time (hrs)
P. Aurelia species is well adapted and
strong and so it outcompetes
P. caudatum.
For P. aurelia, the numbers become
constant after time 6hrs since the
number of new ones formed equal to
number of those dying.
Graph of intraspecific competition eg of
rats put in a cage of fixed size and
supplied with same amount of food
daily, would appear as shown below:
 Rat population against time
35
B D
Population (relative numbers)

30

25

20
C
15

10
A
5

0
0 5 10 15

Time (weeks)
At A-B: The food and space was enough
So the rats reproduced and increased.
At B-C: Competition for food and space
occurred due to high numbers of rats
so some poorly adapted rats died thus
decrease in population.
At C-D: The number of rats was low so
no competition for food and space thus
they reproduced and increased in
number.
Explain likely outcome of competition
shown in the 3 photos below:
Dealing with competition images
 How are these animals
overcoming competition?
 How organisms overcome
competition:
i. By migration.
ii. In herbivores: some are grazers eg
sheep, antelope and feed on grass
while others like giraffe and goats
are browsers and feed on leaves.
iii. By co-existing: ie feed at different
times. Hippo and cattle are both
herbivores. Hippos feed at night
while cattle feed during the day.
iv. By feeding on different forms of same
type of food eg antelopes feed on old
hard grass while Zebra feeds on soft
young grass but both are grazers.

v. Feeding on different type of food at

different stages of development. Eg
adult butterfly feeds on leaves while
their larva feed on flower nectar.
3. Saprophytism
 3. Saprophytism
 Is nutritional relationship between
organisms where an organism
feeds on dead decaying organic
matter of other organisms.
 Examples: Fungi, Some bacteria…
 Importance: Leads to recycling of
nutrients. How?
 4. parasitism.
• Is relationship between organisms
where an organism (parasite)
obtains nutrients from another
live organism (host) without
killing it.
• Ectoparasites- are parasites that
live on surface of host.
• Endoparasite- Are parasites that
live inside the host.
Explain how these Parasites shown in
the 7 photo below affects the
organisms:
Effect of parasite on host.
a. Inject pathogens into host which
cause disease in host.
b. Irritation.
c. Anemia by sucking host’s blood.
d. Obstruction of host’s gut, ducts,
or blood vessels
e. Competes with host for food thus
causing malnutrition.
 5. Symbiosis
• Is association between organisms
of different species where both
organisms benefit from each
other.
• Examples:
i. Bacteria in gut of humans
synthesis vit-K as humans
provide them with shelter and
nutrients.
 Explain the benefits of each
organism in the symbiotic
relationships in the photos below:
ii. Rhizobium bacteria in root nodules of
legumes. Legumes provide shelter and
nutrients to Rhizobium while the
Rhizobium bacteria makes nitrates for
the plant.
iii. Lichen. Lichen is a composite
organism consisting of two organisms
Algae and Fungi. Algae manufactures
food for fungi while fungi provides
anchorage and takes up water and
salts for algae.
iv. Weaver birds and crocodile. Weaver
birds feed on food remnants between
crocodiles teeth and so clean up the
crocodiles teeth as croc protects them.
v. Bacteria in rumen of ruminants digest
cellulose while the ruminant offers
it with shelter.
vi. Cattle and ox-pecker…
6. Human activities
-They include cultivation, conservation,
mining, constructions, industrialisation
-Some of this destroy ecosystem and
organisms while others conserve.
 Nitrogen cycle
• Is the cycling of Nitrogen and
nitrogen compounds in nature
• IMPORTANCE OF NITROGEN
• It is very important since it is used
in making of proteins in both plants
and animals.
• Proteins are very important in living
things. They form hormones,
enzymes, pigments, muscles, cell
membrane, antibodies etc.
Though 78% of air is Nitrogen plants can
still suffer N-deficiency because plants
don’t take Nitrogen in gaseous form.
The Nitrogen has to be converted into
nitrate or ammonium then plants will
absorb them via root hair.
The plants will use this Nitrogen which
is in the NOˉ3 and NH4 to combine with
the simple sugars made in
photosynthesis to form amino acids and
plant proteins.
Animals get Nitrogen by feeding on plant
proteins, digest and absorb them in villi
as amino acids, then use it to make animal
proteins eg muscles, enzymes, …
The different forms in which
Nitrogen exists.
PLACE FORM OF NITROGEN
Air Nitrogen gas – N2
Soil Nitrate – NO3, Ammonium –
NH4, N2 gas
Plants Plant proteins eg…
Animals Animal proteins eg…
Excretory Urea [CO(NH2)2]
wastes
 The 3 main stages in
Nitrogen cycle.
1. Nitrogen fixation
a)Non-biological Nitrogen fixation
b) Biological Nitrogen fixation.

2. Nitrification.

3. Denitrification.
 1.Nitrogen fixation.
• Is where Nitrogen gas in
atmosphere and in soil air is
converted to Nitrate- NOˉ3 or
ammonium- NH4
• Occurs in 2 ways:
a) Non-biological.
b) Biological fixation.
 a) Non-biological nitrogen fixation
– Done by lightning energy which causes
the following series of reactions in air:

N2+O2 NO2

NO2+H2O HNO3

-
NO3
b) Biological Nitrogen fixation:

• Done by bacteria of two kinds:

i. Symbiotic bacteria like
Rhizobium in the root nodules of
legumes. They convert N2 in soil
to nitrate.
ii. Non-symbiotic free living
bacteria in the soil eg
Azotobacter and Clistridium. -
They convert N2 in soil to NO3
 2. Nitrification.
• Is process through which ammonia
+
and NH4 is converted to nitrite
[NOˉ2] and then to Nitrate.
• Conversion of ammonium to nitrite
is done by nitrifying bacteria called
Nitrosomonas and Nitrococcus
• Conversion of NOˉ2 to nitrate is by
Nitrifying bacteria called
Nitrobacter.
 3. Denitrification.
• Is the conversion of ammonium and
nitrate back to Nitrogen gas.
• Done by Denitrifying bacteria like
Pseudomonas denitrificans and
Thiobacillus denitrificans.
• Denitrification occurs mostly in
water logged soils with anaerobic
conditions where these anaerobic
bacteria thrive.
• Qn. Why do water logged soils have
less fertility and less Nitrate?
Denitrification is disadvantageous since
it lowers soil fertility by loss of nitrate.
Advantage of denitrification:
-Releases free Nitrogen gas to
atmosphere for recycling thus complete
the nitrogen cycle.
Some plants that grow in nitrate
deficient soils feed on insects to obtain
nitrogen ie are insectivorous eg Venus
fly trap plant.
Other processes involved in
Nitrogen cycle include:
a) Absorption – Is the uptake of
Nitrate from soil by plant root
hair. It is then used to make plant
proteins.
b) Feeding – Where animals eat
plants to obtain and assimilate
plant proteins which have
nitrogen and use it to make
animal proteins.
c)Excretion – Is where animals eliminate
nitrogenous metabolic wastes like urea
ammonia… which undergo nitrification
to form Nitrate.

d) Death of organisms and decay

process by saprophytes – Through this,
the nitrogen in plant and animal
proteins is converted to ammonia which
undergoes nitrification to form nitrates.

*NOTE: Draw Nitrogen cycle from the

text book – F3klb pg 41
Energy flow in ecosystem
• Main source of energy in ecosystem
is the SUN
• Plants use light energy from sun in
photosynthesis to make food.
• Plants through photosynthesis,
convert light energy into chemical
energy in food.
• Food manufactured by plants has
chemical energy. This energy then
flows from plants to herbivores, then
carnivores… through feeding.
 Trophic levels.
• Are feeding levels through which
energy flows in ecosystem from
one organism to the next.
• There are 5 main trophic levels:
1) Producers – Are the organisms
that manufacture their own food.
Eg plants, algae, photosynthetic
bacteria. They are the main
source of food in ecosystem.
2) Primary consumers – Are the
organisms that feed on producers eg
herbivores like cattle, antelope, rats…
3) Secondary consumer – Are organisms
that feed on primary consumers eg
carnivore like lion, snake, cat, eagle…
4) Tertiary consumer – Are organisms
that feed on secondary consumers eg
the scavengers like Hyena, vultures,…
5) Quaternary consumers – Are
organisms that feed on tertiary
consumers ie the decomposers like
fungi, bacteria…
Energy flow in ecosystem from one
trophic level to the next through feeding
can be presented in 3 main ways:
1. Food chain

2. Food web

3. Pyramids
 1. Food chain.
• Is linear presentation of flow of
energy in ecosystem.
• It must start with producer in the
following order:
• Producer Primary consumer sec cons T. cons Q. consumer

• Where means eaten by.

• Construct food chain using the
following organisms:
 Examples of food chain.
i. Rabbit, grass, dog.
• Grass Rabbit Dog
 ii. Snake, grass, Hawk, rat.
 Grass Rat Snake Hawk
 iii. Zooplanktons, Crabs, small
fish, phytoplanktons, Shark.
 Phytoplanktons Zooplanktons Small fish Crabs Shark

 iv)Antelope, grass, goat, lion,

Hyena, wildebeest, leopard.
 2. Food web.
• Is a presentation of energy flow in
ecosystem comprising of a
combination of several
interconnected food chains.
• QN. Construct a food web using
the organisms in Qn iv) of food
chain.
Qn. 2(a) Construct a food web using the
organisms: Vulture, Rabbit, wolf, python,
grass, sheep, Antelope, Leopard.
b) From the food web, construct food chain:
i) Ending with vulture as sec consumer.
ii) Ending with python as sec consumer.
iii) Ending with vulture as tertiary consumer.
c) Explain what would happen to the number
of organisms in this ecosystem if:
i) All pythons and wolves are eliminated.
ii) Lions and cheetahs were introduced.
d) How many preys does wolf have?
e) How many predators does sheep have?
• f) DDT insecticide was applied on
the grass to control some pests
that had invaded this area. Name
the organism that will have the
highest accumulation of DDT in its
tissues after 3 months. Give a
reason.
Qn2 ans. a)
Vulture

Leopard Wolf Python

Antelope Rabbit Sheep

Grass
Ans b)
i) Grass sheep Vulture
ii) Grass Rabbit Python
iii) Grass Antelope Leopard Vulture
C i) Rabbit, Sheep, Antelope, will
increase.
i) Antelope, rabbit, sheep, will
decrease initially; later competition
will cause decrease in sec consumers
d) Three
e) Three
• f) Vultures.
• Reason: - Accumulation of DDT
will increase as we move from
producers … to Quaternary
consumers through feeding
relationship…
Examples of food web
 3. Ecological pyramids.
• Is presentation of energy flow
(feeding) in ecosystem from one
trophic level to the next using block
pictorial diagrams.
• Each trophic level is represented by
a rectangular block.
• The length of the block matches the
number of organisms or biomass at
that trophic level.
• Producers are always at the bottom
followed upward by p.cons, sec
cons, t. cons, Quaternary consumer.
 Types of pyramids.
• 1. Pyramid of numbers 2. Pyramid
of biomass 3. pyramid of energy.
1. PYRAMID OF NUMBERS.
 Constructed by considering the
number of organisms at each
trophic level.
  Examples: - Construct pyramids
of numbers using the following
organisms.
a) Grass, birds, grasshopper.

Birds
Grasshopper
Grass
 b) Monkeys, Tree, Fleas

• Ans:

Fleas
Monkey
Tree

This is inverted pyramid.

 2. Pyramid of biomass.
• Is constructed by considering
biomass of organisms at each
trophic level
• Biomass is dry weight per unit area.
• Biomass is got by obtaining
organisms of same trophic level
from a unit area then drying till
there is no further decrease in
weight.
 General structure of pyramid of
biomass
• Pyramid of biomass has only one
basic structure:

Q. Cons
T. Consumer
Sec consumer
P. consumer
Producer
Biomass decreases up the pyramid.
Reasons:
 Not all the food eaten by the
consumer is retained in the body
instead:
i. Some is lost in dung.
ii. Some is lost as heat after
respiration.
iii. Some is lost in excretion.
 Biomass of producer is higher than
that of consumers so as to be able
to support the consumer with
enough food.
 3. Pyramid of Energy.
• Is constructed by considering
amount of energy at each trophic
level.
• Structure of pyramid of energy is
same as that of pyramid of
biomass.
• Reasons for decrease in energy
up the pyramid is same as those
written in pyramid of biomass.
 Note:
• Plants get energy to make food from
light energy (from sun).
• Not all energy that lands on leaf is
used in photosynthesis. Some is
reflected away and some is lost as
heat.
• Task – Construct a) pyramid of
numbers.
b) pyramid of biomass using the
following organisms:
• Cow, Tick, Grass, protozoa (in tick).
 Population
• Is the total number of organisms of
same species in a given area at a
specific time.
• Population density – Is population of
organisms per unit area.
• Population dispersal – Is spread and
distribution of organisms in the
habitat.
• Population growth – Is rate of
increase in number of organisms of
same species.
Factors affecting population growth
rate:
1. Food availability
2. Space availability.
3. Diseases and pests.
4. Climate.
5. Predators.
6. Natural disasters.
• Sample is a small number of
organisms of a given species
counted from a small area of
habitat as a representative of the
whole population.
• Is done where the area of the
habitat to be studied is large.
 The 4 population sampling
methods (For small organisms)
1) Quadrat method.

2) Line transect.

3) Belt transect.

4) Capture recapture.
 1. Quadrat.
• For estimating population of small
plants and small less mobile
animals.
• Procedure:
• Determine the specific organisms
you want to study.
• Go to area of study.
• Throw the quadrat atrandom
(backward) to avoid being biased.
• Count the number of organisms under
study within the quadrat.
• Make several throws and keep counting
the organisms under study in each
throw.
• Get average population of each
organism under study.
Note: Quadrat is a square metal or
wooden frame measuring 1m by 1m.
Plant Throws: 1 2 3 4 Average
species ppln
A-Black jack 6 9 4 9 7

B-Nut grass 3 5 8 4 5

C-Pig weed 9 2 5 4 5
 2. Line transect.
Procedure:
Identify plant/organism species
you want to study.
Go to area of study
Establish a diagonal line transect
(Can use a rope).
Put a quadrat at start of line
transect and count the number of
organisms under study within the
quadrat.
Move the quadrat along the transect
line at equal distance interval.
Count the number of organisms under
study at each interval A, B, C, D…
and record.
 This method is for estimating
population of small plants and less
mobile small animals.
Diagram of line transect.
• Line transect.

Quadrat
 Example of data from line
transect method:

Plant Quadrat: A B C D Average

species ppln
Black jack 6 9 4 9 7

Nut grass 3 5 8 4 5

Pig weed 9 2 5 4 5
• (For determining population of
small plants and small less mobile
animals.)
• Determine the organism you want
to study.
• Go to area of study.
• Establish a belt transect using
two ropes along diagonal of area
of study.
Diagram of belt transect.
Example: let the ropes be 10m long each
and 2m apart thus belt area=20m²
• Count all of each type of plant/animal
species you want to study within the
belt transect.
Eg- You count 120 black jacks.
Population estimate=120
Population density of black jack
=Population/area = 120/20 = 6 per m²
• For estimating population of small
fast moving animals and flying
insects.
• For animals like fish, fast crawling
insects, grasshoppers…
 Procedure.

• Determine the organism you want

to estimate population (Lets use
grasshoppers).
 Go to area of study.
 Use sweep net to make first
capture of grasshoppers.
 Count and mark all in 1st capture
and release them back.
 (if it were fish we put a tag on
the tail fin)
 After 24 – 48 hrs go back to same area
of study and make second capture of
same type of organism (don’t mark
them).
 In this second capture, count those
with previous mark, then count those
without the mark and total of all in
second capture.

 Calculate population using the

formula:
 First capture marked X Second capture
Population=
Second captured marked

= FCM X SC
SCM
Qn. F3 boys of Jomo K boys High.School
made first capture and marked 360
grasshoppers. After 24 hrs they went to
same area of study and made second
capture of 40 grasshoppers that had
previous mark and 240 that didn’t have
mark. Calculate population of g/hoppers
in the area of study.
 Assumptions made in capture
recapture method:
1. That the ink used to mark the
insects won’t harm or kill it.
2. That the organisms will interact
and mix freely after 1st capture.
3. That there will be no migrations or
immigrations.
4. That no organisms under study will
die between 1st and 2nd capture.
5. That there will be no new births
between 1st and 2nd capture.
6. That the ink or tag won’t come off.
 End of population.

Ecology is now half way.

Ecology continues.
AMEN.
 The 4 main groups of plants:

1. Xerophytes – Adapted to grow in

arid conditions.
2. Mesophytes – Adapted to grow in
terrestrial habitat with sufficient
water/rain.
3. Hydrophytes – Adapted to grow in
fresh water habitat.
4. Halophytes – Adapted to grow in
salty water/marine water.
Xerophytes
Identify this adaptation
Identify this adaptation
Identify this adaptation
Identify this
adaptation
Identify this adaptation
Identify this adaptation
 1. Xerophytes.
Adaptations:
a) Has deep roots to reach water
table.
b) Has widely spread peripheral roots
to absorb surface water after short
rains.
c) Leaves have thick waxy cuticle to
increase diffusion distance for
water vapour thus reduce cuticular
transpiration.
• Leave’s thick cuticle also insulates
leave against heat.
d) Leaves are reduced in size, some to
needlike, others to spikes so as to
reduce surface area for transpiration.
e) Has mucilage fluid in leaves and stem
which has high osmotic pressure thus
enables plant to attract and retain
water.
f) Has few stomata on upper leaf
epidermis and more on lower epidermis
so as to reduce stomatal transpiration.
g) Have sunken stomata that trap
moisture and so reduce diffusion
gradient for water vapour and reduce
transpiration rate.
These are reduced leaves NOT leaves
Reduced to thorns
These are needlelike leaves NOT
Leaves Reduced to thorns
Spike leaves NOT
Leaves Reduced to thorns
Scaly leaves NOT Leaves Reduced
to thorns eg Cypress
h) Stomata has epidermal hairs that trap
moisture to reduce diffusion gradient
for water vapour between leaf and air
thus reduce the rate of stomatal
transpiration.
i) Shade leaves during dry season so as
to reduce surface area for transpiration.
j) Succulent thick leaves, roots and
stems to store water.
k) Leaves undergo leaf rolling during dry
season to trap moisture and reduce
diffusion distance for water vapour
between leaf and air thus reduce
transpiration.
Mesophyte leaf TS
Sunken stomata and epidermal
hairs image.
Rolled leaf TS.
l) Have reversed stomatal rhythm
ie stomata close during the day and
open at night so as to reduce rate of
stomatal transpiration.
j) Their cells and tissues have high
tolerance to high temperatures and
less water.
k) Some have toxic milky latex
(eg Euphorbia) while others have
thorns to protect them from browsed
on and destroyed by herbivores.
Mucilage
Mucilage
Toxic milky latex
Toxic milky latex
Problems in arid areas to which
xerophytes adapt to overcome include:
1. High temperatures.
2. High rate of transpiration.
3. Less water availability.
a) Leaves have thin lamina to reduce
diffusion distance for water vapour
thus increase rate of transpiration.
b) Broad leaf blade to increase rate of
transpiration.
c) Leaves exhibit leaf mosaic
arrangement to expose all cells to
light to maximize photosynthesis.
d) Fairly equal number of stomata on
upper and lower epidermis of leaf to
promote transpiration and gaseous
exchange.
e) Spongy mesophyl cells have more air
spaces to promote gaseous exchange,
photosynthesis and transpiration.
f) Thin cuticle to reduce diffusion
distance for water vapour between leaf
and atmosphere and thus increase rate
of cuticular transpiration.
g) Leaves of plants at the base of forest
have more chloroplast to increase rate
of photosynthesis.
h) Some have buttress roots and others
with prop roots for support.
i) Waxy cuticle on leaves to drip off rain
water.
Task – i) List the general conditions in
which mesophytes grow.
ii) What are epiphytes and
climbers
(pg 51 F3 klb)
Buttress root
system
Buttress root
system
• There are 3 types of Hydrophytes.
A. Floating hydrophytes.
B. Submerged hydrophytes. – Are fully
immersed in water.
C. Emergent hydrophytes. – Roots are
attached on the floor of the water
body while the leaves and flowers
float on water eg water lily…
 List conditions in which
hydrophytes grow. (pg 52 F3 klb).
 A. Floating hydrophytes.
Adaptations:
i. Large broad leaves to increase
surface area for transpiration.
ii. Have many stomata on upper leaf
epidermis to increase rate of
transpiration.
iii. Have aerenchyma tissue that forms
air spaces for buoyancy.
iv. Leaves have thin cuticle to reduce
diffusion distance for water vapour
between leaf and atmosphere thus
increase rate of transpiration.
Mesophyte leaf TS
Hydrophyte leaf TS
Hydrophyte leaf TS
v) Small shallow roots to reduce uptake
of water.

B. Emergent hydrophytes.
-Has all adaptations of floating
hydrophytes. In addition:
i) Has long flower stalk to enable flower
to emerge out of the water.
ii) Has long leaf stalk to enable leaf to
emerge above the water.
iii) Has numerous adventitious roots on
the submerged rhizome for anchorage.
Identify the hydrophyte adaptations below
• Have aerenchyma tissue that
forms air spaces for gaseous
exchange.
• Thread-like leaves to increase
surface area for photosynthesis.
• Has more sensitive chlorophyll to
maximize absorption of light for
photosynthesis.
• Thin cuticle to reduce diffusion
distance for gases to easily
diffuse into plant.
Submerged hydrophyte
4. Halophytes.(eg the mangroove)
Adaptations:
a) Their tissues have high tolerance
to high salt concentrations.
b) Leaves have bladder cells that
accumulate salts and excrete
them out of leaf.
c) Have buttress roots and tilt roots
for firm anchorage in the loose
muddy soils.
d) Have pneumatophore roots that
pop out of soil for gaseous
exchange.
Pnuematophores
Tilt roots
Mangrove buttress
roots
Excess salts excreted out of leaf
 e) Some have slender seeds with sharp
end to piece into soil when fruit falls
in the mud to prevent it from being
swept away by water.
g) Their root hair cells have ability of
accumulating a lot of salts that enables
them to take in water by osmosis from
the surrounding salty water.
f) Some form fruits with aerenchyma
tissue that form air spaces for buoyancy

Draw diag of hydrophytes on

pg 52 – 53 F3 klb.
Fruits with long sharp extensions
Conditions that halophytes
(Mainly Mangroves) grow in
1. Marine/salty waters like sea,
oceans which can dehydrate
them
2. Muddy loose soils that provide
poor anchorage for plant and
seed germination
3. Soils with less Oxygen
4. Accumulation of excess salts in
tissues
 Definition:
• Is the emission of substances into
the environment to levels that are
toxic to living things.
• Pollutants – Are substances that
cause pollution.
• Pollutants occur as a result of
human activities and some natural
occurrences like volcanicity.
1. Air pollution

2. Water pollution

3. Soil/Land pollution

4. Noise pollution
Identify the type of pollution
in the pictures bellow:
• Is the emission of substances into
air to levels that are harmful/toxic to
organisms.
• AIR POLLUTANTS include:
• i) Smoke and fumes ii) Dust.
• iii) Sulphur based gases.
• iv) Oxides of Nitrogen
• v) Aerosols vi) Noise.
• vii) Lead fumes.
Identify the air pollutants
shown below:
• Source of smoke:
Burning of wood products.
Combustion of petroleum
products.
• Contain pollutants like:
a) Excess carbon(iv)oxide
b) Carbon(ii)oxide
c) Carbon particles
• Blocks plant leaf stomata thus
reducing gaseous exchange and
photosynthesis.
• Damages respiratory track in
humans when inhaled for long.
• Form soot that dirtify surfaces.
• CO forms as a result of
incomplete combustion of fuels.
• When inhaled it combines with
haemoglobin in red blood cells to
form carboxyhaemoglobin which
doesn’t dissociate and so
prevents O2 from combining with
haemoglobin, This causes
suffocation, comma and even
death.
a) Irritation of eyes
b) Suffocation
c) Headache
d) Respiratory difficulties
e) Smog formation.
f) Global warming. Effects…
 Identify the effect of
CO2/smoke + fog shown below:
• Smoke + fog = smog
• Effects:
a) Poor visibility
b) Irritation of respiratory system.
c) Lower rate of photosynthesis due
to poor light penetration.
Identify the effect of excess
CO2 shown below:
• Caused by excess CO2 in air.
• A layer of the excess CO2 forms in
the atmosphere.
• This layer prevents warm air from
rising. Accumulation of warm air on
earths surface leads to rise in
temperatures. This is called Global
warming or Green house effect.
• This can cause excessive melting of
mountain snow leading to flooding.
• This also causes climate change,
desertification…
• Include:

• Sulphur(iv)oxide gas – SO2

• Hydrogen sulphide gas – H2S

 Identify the sources of Sulphur and
Nitrogen based oxides shown below:
• Source:
Food preservative factories.

Sulphuric acid factories.

 Combustion of sulphur based

petroleum products eg in engines.
a) Cause diseases like pneumonia,
Bronchitis, heart failure…
b) Dissolves in rain water to form acid
rain which makes soils acidic, kills
soil microorganisms, affect plant
growth, and cause leaching of Mg,
Ca ions from soil.
c) Corrodes iron sheets, paints…
d) Damages cilia in trachea thus
cause irritation of alveolus by solid
particles which pass trachea
untrapped to alveolus.
e) Damages plants.
 Hydrogen sulphide.
• Source: Volcanic activities, Rotting
garbage, Geothermal stations, mines..
• Effects:
i. Irritation of respiratory system.
ii. Corrosion of writings and paintings.
iii.Lung problems
iv. Burns on skin
v. Contaminates blood.
vi. Can cause infertility in some
animals. Eg sheep.
 3. Oxides of Nitrogen.
eg Nitrogen(iv)oxide – NO2
• Source:
• Factories manufacturing nitrate
fertilizers and nitric acid.
• Exhaust fumes from engine during
combustion of petroleum products
 Effects of NO2
• Dissolves in rain water to form
acid rain which…
• Cause respiratory difficulties.
• Can cause cancer (ie is
carcinogenic).
• Cause poor visibility.
• Source: Road works, cement works,
Quarrying, chalk, cultivation…
• Effects: - Makes environment dirty.
• Block stomata and lower
photosynthesis.
• Cause respiratory difficulty.
• Cause poor visibility.
• Affect eyes.
• Are substances that consist of very
fine liquid and solid particles
suspended in gas and are applied in
spray form. Eg pesticides, some paint,
herbicides, perfumes, air refresheners
• Aerosols contain pollutants like:
a) CFC – Chlorofluorocarbons which is
added to increase dispersal of spray.
b) Heavy metals like copper, Pb, Hg…
Identify CFC sources below:
Effect of Aerosol components
eg CFCs and heavy metals
Not necessary
a) Effect of CFCs:
i. Damages ozone layer thus making
Ultra Violet rays from sun to reach
earth’s surface.
–Effect of UV –cause skin cancer,
skin burns, and damage plants.
ii. Cause irritation of respiratory
system.
i. Copper fumes:
 - Source: -Aerosols eg in
fungicides.
-Fumes from copper mines and
copper platting works.
 – Effect: - Prolonged inhaling of…
accumulates Cu in body organs
and so damages body organs.
• Source: -Skin lightening
cosmetics – Coal works – Muddy
swamps – Fungicides – Factories
that manufacture chlorine and
sodium hydroxide – combustion of
petroleum oils – Making of vinyl
plastics – Ore works.
 Effects of mercury(Hg) fumes:

i)Prevents skin melanin formation.

This exposes skin to harmful UV rays
which then causes skin cancer and
burns.
ii) Accumulate in vital organs like
brain, liver, kidney, cause their
malfunctioning, damage and can lead
to death.
iii) Paralysis iv) Blindness
• Source: Fumes from welding
works.
• Effects:
 Can cause Emphysema (lung
disease).
 Can cause high blood pressure.
 Weaken bones by causing
decalcification of bones.
• Source: Exhaust fumes from petrol
engines. (Pb is usually added to petrol
in form of triethyllead to prevent
engine knock).
• Effects:
Weak bone formation (since lead
competes Ca in bone formation).
Liver and kidney problems.
Blocks stomata in plants…
1) By inhalation during breathing.
2) Through skin eg Hg in some cosmetics.
3) Through food. – The pesticides and
herbicides and other fumes containing
this heavy metals dissolve in water, get
absorbed by plants where they
accumulate. Some are washed to water
bodies and get absorbed by fish.
• These heavy metals then get into
animals and humans as they feed on
this plants, then accumulate to harmful
levels and cause defects.
Control of air pollution.
1) Afforestation and reafforestation
– Trees act as carbon sink by
utilising CO2 in photosynthesis.
2) Use of gas masks in factories
and when welding.
3) Use unleaded petrol in engines.
4) Use sulphur free diesel and
petrol in engines.
5) Use CFC free aerosols.
 Control of air pollution cont…

o 6) Proper maintenance of
engines.
o 7) Ban unroadworthy vehicles.
o 8) Use biological and cultural
pest control methods instead of
pesticides.
o 9) Encourage public transport
instead of personal cars.
 Control of air pollution cont…

• 10. Ban smoking in public.

• 11. Use alternative renewable sources
of energy like solar, wind, electricity…
• 12. Factory and vehicle exhaust
system should be fitted with catalytic
converters to convert toxic gases to
harmless forms.
• 13 Legislation eg
• 14. Educate public on dangers of air
pollution, causes and control.
Identify the type of pollution
below:
 NOISE POLLUTION
• Definition: Is the emission of
unwanted sounds in the
environment in a manner that is
harmful to humans and other
organisms.
• Unit used to measure sound is
Decibels (dB)
• Loud sound above 80dB is harmful
• Source of noise pollution:
• Automobiles, sirens
• Aeroplanes and jets
• Nuisance unwanted sounds
• Loud music from Discos, public
rallies
• Industries
• Animals natural sounds
• Natural occurrences like volcanic
eruptions, lightening,
• Weapons and fights eg Bombs,
gunshots
Effects of noise pollution
• Cause stress and anxiety and its
related health complications
• Headache
• Ulcers
• Hypertension
• Arteriosclerosis
• Deafness
• Can destroy structures, buildings
eg loud bomb and jet sounds
Control of noise pollution
• Wear ear muffs/ear plugs
• Good maintenance and servicing
of machinery
• Legislation to ban loud sounds in
residential places
• Use sound absorbers in disco
halls and bars
• Develop less noisy machines and
weapons
• Avoid areas with loud noise
Ear plugs/muffs – control noise pollution.
• Is release of substances or
energy forms into water bodies to
levels that is harmful to
organisms.
• Domestic effluent/Sewage.
• Industrial effluent.
• Agrochemicals.
• Oil spillage.
• Soil erosion.
• Heavy metals.
DOMESTIC EFFLUENT/SEWAGE

• Causes pollution when raw

sewage from households in urban
areas gets discharged into a river.

• Sewage consists of household,

kitchen and toilet wastes.
1) Can cause spread of water bone
diseases eg Cholera, typhoid…
2) Can kill aquatic organisms at
point of discharge into river since
it is toxic.
3) Reduce light penetration in water
4) Causes Eutrophication. This is
reduction of oxygen in water
body that leading to suffocation
and death of aquatic
organisms/fish
 Qn. How does eutrophication occur?

• Ans:
• Sewage has organic matter which on
decomposing increases nutrients in
the water.
• This causes high growth and increase
in water plants and algae.
• When this large number of plants and
algae die, a lot of oxygen in water is
used to decompose them thus O2
reduces leading to suffocation and
death of water organisms.
Eutrophication - images
 Graphical presentation of levels of various
substances in river water downstream from
point of sewage discharge.
35
A B C
30
Levels of substances

Aquatic animals
25
O2 Level
20

15

10 Organic matter
Bacteria
5 Algae and aquatic
plants
0
0 2 4 6 8 10 12
Distance downstream (km)
1) Oxygen: At A – Normal level
At B – Decrease in O2 since it is
used by bacteria to decompose
the organic matter.
At C – Rises to normal level since
decomposition is over.
• At A – Normal numbers.
• At B – Decrease in level.
Reason – Toxins and polluting
effect of sewage killed them.
– There was low O2 thus aquatic
animals suffocated and some
died.
• At C – Rise to normal level since
sewage decomposition is over.
3. Level of algae and aquatic plants

• At A – Normal level.
• At B – Increase
-Reason – Plants and algae get
more nutrients from
decomposition of sewage and
grew and increased in numbers.
• At C – Normal level- why?
 4. Level of bacteria.

• At A – Normal level.
• At B – Increase.
Reason – There is enough food
(sewage) for the bacteria so they
reproduced and increased.
• At C – Decreased to normal since
sewage has reduced thus less
food for bacteria.
 5. Level of organic matter.

• At A – Normal level.
• At B – Increase in level.
Reason – Sewage is discharged to
the river and the sewage has a lot
of organic materials.
• At C – Drop to normal.
Reason – Decomposition of the
sewage is over thus decrease in
organic matter to normal.
 Industrial effluent.

• Contains pollutants like toxic

compounds, Heavy metals, acids
and bases and hot water.
• Effect:
• They are toxic and so directly kill
aquatic organisms.
• Change water pH thus interfere
with enzymatic processes in in
aquatic organisms.
• Some cause eutrophication.
Industrial effluent - Are wastes in solution
And liquid form from industries
Note : This toxins and heavy metals gets
absorbed by aquatic plants then through
feeding they move to next trophic level
ie to fish up to humans where they
accumulate to harmful levels.
• Source:
• Industries that channel their hot water
to water bodies.
• Effect:
• Kill aquatic organisms due to high
temperatures.
• Makes water to loose O2 and CO2 thus
reduces photosynthesis in aquatic
plants and suffocate aquatic
organisms to death.
 Agrochemicals.
• Include: Fertilizers, Herbicides,
Pesticides. Which have pollutants like
CFCs, Heavy metals, which are
washed by rain runoff to water bodies.
• Effect:
a) Fertilizers cause eutrophication.
b) Some are non-biodegradable thus
accumulate in water to toxic levels.
c) Change water pH and salinity thus
interfering with metabolic activities of
aquatic organisms.
d) Some are toxic and kill aquatic
organisms.
e) Heavy metals damage the organs of
animals and can cause death.
Oil spillage images
• Source: Garage works, Tanker
accidents, Leakage in tankers and
ships.
• Effect:
• Prevents entry of O2 into water thus
suffocating aquatic organisms.
• Reduce light penetration into water
thus reduce phts in aquatic plants.
• Clogs fish gills thus lead to death.
 Soil erosion
• Rain run-off water washes soil
sediments and silt to water bodies
• Effects: -Silt can clog fish gills and kill
fish by reducing gaseous exchange.
• -Reduce photosynthesis by by aquatic
plants by reducing light entry to water
• -Silt fills up water body thus interfere
with navigation and displace fish.
Erosion
• Comes under sewage/domestic
effluent.
• Detergents eg omo, toss…
• Effects:
a) Have Sulphates and phosphate thus
cause eutrophication.
b) Change water pH…
c) They are non-biodegradable thus
accumulate in water body to toxic
level.
• Includes Hg, Cd, Cu, Pb,…
• Are in pesticides, herbicides and
when applied on plants they can
be washed into water bodies and
be absorbed by water plants then
to fish and humans through
feeding.
• Effects – Are as stated in air
pollution (But don’t use the term
fumes)
1) Sewage treatment in sewage
treatment plants.
2) Proper repair and maintenance of
oil tankers to avoid leakages and
accidents.
3) Create awareness on causes,
dangers and control of water
pollution.
 Control of oil spills
– apply biodegradable detergents
 Control of oil spills –
aerial biodegradable detergent spraying
Sewage treatment
Sewage treatment
4) Avoid using detergents or use
biodegradable detergents or soap.
5) Use biological or cultural pest and
weed control methods.
6) Legislation to ban discharge of
industrial and domestic effluent into
water bodies.
7) Use organic manure instead of
inorganic manures (fertilizers).
8) Control soil erosion by terracing,
contour ploughing, gabions etc.
9) Cool industrial water before
discharging into water bodies.
10) Treat industrial effluent to convert
them into harmless forms.
• Pollutants/source of soil pollution:
Solid wastes
Oils/petroleum products
Agrochemicals
Oxides of sulphur and Nitrogen.
Aerosols
• Include household and industrial
wastes like polythene, solid food
remains, papers, plastics, tins,
bottles, vegetation…
• Effects:
a) Polythene and plastics are
non-biodegradable therefore form
layer in soil that prevent water
drainage and aeration in soil.
b) Provide breeding site for mosquitos
and pests which cause diseases ie
broken plastics, bottles, tins…
c) Cause injuries eg broken bottles.
d) Dirtify and destroy aesthetic state of
environment.
e) Bad smell, (produce H2S) by rotting of
food remains and other organic wastes.
 2. Oils.
• Source: Garages, factory spills
tanker accidents…
• Effects:
a) Lower soil aeration.
b) Block respiratory system of soil
organisms thus killing them.
c) Cover plant leaves of plants on
ground thus hinder
photosynthesis and gaseous
exchange
• Source: Fertilisers, herbicides, pe-
sticides.
• Effect:
a) Changes soil pH thus harm soil
organisms.
b) Can change soil structure and
affect soil drainage, aeration,
organic matter and erosion.
c) Heavy metals in them are toxic.
 4.Oxides of sulphur and
Nitrogen.
• Source: As in air pollution.
• Effect :
a) Destroy soil structure
b) Form acid rain that makes soils
acidic and kill soil organisms.
c) Acidity cause leaching thus lower
soil fertility.
d) Acidity lower production of crops
that grow in alkaline soils.
• Effects :
a) Kill soil organisms thus lower soil
fertility.
b) Accumulate in soil and are taken
up by plants and passed to
animals through feeding from one
trophic level to the other and
harm animals.
 Control of soil pollution.
1) Control solid wastes by:
a) Recycling eg Polythene and
plastics to make posts…
b) Sort organic waste and make
manure.
c) Re-use eg bottles, metals
d) Incineration (burn).
Good Garbage collection system
Good Garbage dump site system
Good Garbage sorting system
Sorted packed waste for recycling
2) Use organic manure instead of
fertilizers.
3) Use biological and cultural pest and
weed control methods.
4) Use pipeline to transport oils/petrol.
5) Legislation on use of polythene, and
management of solid wastes.
RADIOACTIVE EMISSIONS
• Radioactivity – is the breakdown
of atoms/nucleus of heavy metals
of large atomic mass to release
high energy radiations/to release
nuclear energy.
• Examples of such heavy metals
are Uranium, radium, germanium,
Plutonium, Hydrosonium…
 Use of nuclear energy
• Electricity generation
• As Nuclear weapons/atomic
bombs
• Propel nuclear war planes, war
ships and submarines
 Effect of radioactive
emissions
• Leads to inheritable genetic
abnormalities through mutation
• Cause bone and leukemia cancer
• The high energy emitted destroys
structures and organisms
• CONTROL
• Dialogue between nations to prevent
use of nuclear weapons in war.
• Legislation to ban use of nuclear
weapons
• Regulate and limit use of nuclear
energy only in electricity generation
 HUMAN DISEASES
• · DISEASE: Means any disorder in
the body of an organism that
disrupts the normal physical,
physiological and psychological
steady state of wellbeing of the
body.
• · HEALTH: is a state of normal
physical, mental and
emotional/psychological wellbeing
in the body of the organism.
• Diseases are caused by
pathogens and parasites.
• Pathogens are disease causing
microorganism like bacteria,
viruses, protozoa and fungi.
• Parasites are organisms which
live and derive nutrients on or in
the body of another organisms.
(Parasites can be ectoparasites or
endoparasites).
• Vectors are animals in which
pathogens live and they transmit
the pathogen from one
organism/person to another. Some
vectors are also parasites eg
ticks, mosquitos while others ore
not eg snails…
 Categories of human diseases

• We are going to study only the

following at F3:
1. Bacterial diseases (Cholera and
typhoid).
2. Protozoan diseases (Amoebic
dysentery and Malaria).
3. Parasitic worms (Ascaris
lumbricoides and Schistosoma).
 Bacterial diseases
• 1. Cholera
• Cause: Bacteria – Vibrio cholerae
• Transmission:
• - Water bone and food bone
• – Faeces from infected people can
get into water bodies. Flies
transmit this bacteria from
infected water or faeces to human
food.
• People get infected when they eat
such infected food and water.
• Incubation period:
• - 1 – 6 days
• Symptoms:
• - Violent diarrhoea
• - Severe abdominal pain
• (This is because the bacteria
damages intestinal wall leading to
loss of water from body and
diarrhoea - Can kill within 24hrs)
• Treatment:
• - Take oral rehydration salts
• - Administer appropriate antibiotics
• Control:
• Proper sanitary disposal of faeces
• Proper cooking of food before
eating.
• Proper water treatment and
boiling before taking.
• Observe proper hygiene both
personal, toilet and environment.
• 2. Typhoid:
• Cause: Bacteria called Salmonella
typhi
• Incubation period: two weeks
• Transmission:
• - Through faeces and urine of
infected person to water bodies
then transmitted to people by
taking infected food and water
and by flies.
• Through saliva and sweat in
cloths and beddings.
• Symptoms:
• - Fever, headache, loss of
appetite, muscular pain and sore
throat
• - Rashes then red spots on chest.
• - Diarrhoea
• (The bacteria attacks the
intestinal wall, causes sores and
enter blood. Sores may lead to
perforation of intestine and cause
death)
• Treatment:
• Administer appropriate antibiotics
• Control:
• - Proper faeces and urine disposal
• - Proper hygiene
• - treat and boil water and cook food
well before eating.
• - Wash hands, fruits before eating
• - Food handlers in school, hotels to
undergo regular check ups
• - Vaccination offers immunity for
only two years thus is not effective
control.
 Protozoan diseases

• 1. Amoebic dysentery
• Cause:
• Protozoa called – Entamoeba
histolica
• Transmission:
• Ingesting food or water containing
the Entamoeba histolica cysts.
Information not necessary
• Symptoms:
• - Severe abdomen pain (the protozoa
cyst wall is digested thus releasing
the protozoa which attacks colon
wall and release histolysin enzyme
that damages the colon wall causing
pain, ulcer wounds and blood loss)
• - Blood stained diarrhoea
• - Pain when passing out stool
• - Fever
• - Inflammation in other body organs
like liver, lungs and brain if the
protozoa reaches them where it
causes abscess formation (pus).
• Treatment:
• Administer amoebicides
• Control:
• - Treat and boil water and food
before eating.
• - Proper disposal of faeces and urine
• - Rehydration
• - Proper food storage
• 2. Malaria
• Cause:
• Protozoa called Plasmodium
• There are different species of
plasmodium that cause malaria
– P. vivax, P. Ovale, P. falciparium
and P. malariae
• Transmission:
• - By a vector – female anopheles
mosquito which sucks blood
containing the plasmodium from
infected person. The plasmodium
then develops into infective stage
while in the mosquito and is
transmitted to a healthy person via
its saliva.
• Incubation period:
• 7 – 10 days (within which
Plasmodium moves to liver,
reproduce, cause enlargement of
liver and spleen. then gets
released into blood where they
attack red blood cells, reproduce
further and destroy red blood
cells thus leading to anaemia and
reduced oxygen transport. The
toxins released by the
plasmodium into blood causes
fever)
Plasmodium life cycle
• Symptoms:
• - Headache
• - Loss of appetite
• - High regular fever with chills,
sweating and shivers
• - Vomiting
• - Muscle and joint pain
• - Feeling weak
• - Convulsions may occur in
children
• Treatment:
• - Administer full dose of appropriate
anti malaria drug.
• Prevention/control:
• Use mosquito repellants
• Sleep under treated mosquito nets
• Spray mosquito breeding sites and
residential areas with appropriate
insecticide
• Drain stagnant water and clear
vegetation and bushes near
residential areas to destroy
breeding sites for mosquitos
• Clear broken bottles, tins, plastics
and polyethene that hold water and
act as mosquito breeding site
• Apply oil/powders on stagnant water
to suffocate and kill mosquito larva
• Biological control:
• – by using sterile male mosquitos to
mate with females
• - By using fish in ponds to feed on
mosquito larva
• Take antimalarial/prevention dose
before travelling to malaria prone
areas
• Hindrances to effective control:
• Presence of alternative mosquito
reservoirs like livestock and
monkeys
• Mosquitos developing resistance
to insecticides
• Less funding of malaria control
• Warm tropical climate promote
breeding of mosquitos
 Parasitic worms

• Parasitic worms include Ascaris

lumbricoides and Schistosoma.
• 1. Ascaris lumbricoides
• Is a parasitic worm belonging to
Kingdom Animalia and Phylum
Nematoda
• It attacks human and pig’s
intestines and other organs
• Transmission and life cycle:
• Adult female lives in ileum where it
obtains nutrients and lays eggs
(about 200,000 eggs per day)
• The tiny eggs are passed out in
faeces and may be passed to
vegetables, fruits and food by flies
• The eggs form embryos in them
• The eggs in contaminated food are
ingested by humans and move down
to stomach then to small intestine
• In small intestine the eggs hatch
into tiny larva which burrows across
intestine wall to blood.
• In the blood several larva get
transported to other organs like
the lungs where they move across
alveolus wall to bronchioles,
bronchus, trachea then to throat
where they are swallowed
together with saliva or food to
oesophagus then moves to
stomach then to small intestine
where they grow into mature
adults.
• The adults mate and lay eggs…
• The cycle takes 60 – 70 days.
• Effect of Ascaris on host/symptoms:
• Irritation of trachea
• Bruise trachea exposing it to infection
by bacteria
• Coughing and fever
• Malnutrition since they compete and
consume host’s nutrients
• Anaemia since larva consumes host’s
blood
• Blockage of hosts intestines leading to
swollen abdomen (in heavy infestation)
• Blockage of bile duct, pancreatic duct
by the larva
• Treatment:
• Administer appropriate drugs to kill
the worms and inactivate the eggs.
• Control/prevention:
• Water treatment and boiling before
drinking
• Thorough cooking and boiling food
before eating
• Proper hygiene – Wash hands, fruits
before eating; wash hands after
visiting toilet
• Proper disposal of faeces and toilet
cleanliness.
• Adaptations of Ascaris
lumbricoides to parasite life:
• Lays many eggs to promote
survival
• Eggs have a protective shell to
protect them from destruction in
harsh environment
• Has to hosts pigs and humans to
promote survival
• Its tissues are tolerant to low
oxygen concentration and so can
survive in the gut where oxygen
concentrations are low
• Has muscular pharynx for sucking
in digested food from the ileum
• Has thick cuticle to protect it
from being digested by digesting
enzymes in the gut.
• 2. Schistosoma
• Is a parasitic flatworm of the blood
(Blood flukes) belonging to Kingdom
Animalia, Phylum Platyhelminthes and
genus Schistosoma which include
Schistosoma mansoni
Schistosoma haematobium
Schistosoma japonicum
(They occur in pairs with the larger
male holding the slender female)
They exist in blood veins, intestine and
urinary bladder.
• They cause a disease called
Schistosomiasis (Bilharzia)
• Transmission/life cycle:
• Cercariae (Larva) stage emerge
from snails into water.
• When humans step in snail infested
water, the cercariae will penetrate
across the skin of humans and enter
into blood stream where they are
transported to the liver where they
mature and mate then form eggs.
• The adult worms shed the eggs into
blood where they move to intestine
• The eggs get released from humans
in faeces and urine then into water
where they hatch into larva called
Miracidia
• Miracidia penetrate into snails
(Intermediate host) where they
develop into infective stage called
Cercariae
• Cercariae moves out of the snail
to water and enter (final host)
humans who walk, bath or take
such water.
• Effects/symptoms:
• Causes injuries in urinary bladder,
intestines and blood veins. This is
as a result of the sharp spines of
the adult worms scratching the
urinary bladder, intestines and blood
vessels as it moves.
• Other infections develop as a result
of the scratches made by the adult
Schistosoma worms.
• Itching and skin damage as the
secariae penetrates across human
skin
• Fever as a result of toxic chemical
substances released by larva and
adult worm in human body
• Treatment:
• Administer appropriate drugs
prescribed by a doctor
• Control/prevention:
• Proper sanitary disposal of faeces
and urine. (not in rivers or lakes)
• Treat or boil water before taking
• Avoid bathing in snail infested
water.
• Wear protective gum boots, gloves
and clothes when working in
swampy water
• Spray molluscicides to snail infested
area/water to kill snails
• Adaptations of Schistosoma to
parasitic life:
• It has different stages of
development (adult, miracidia,
cercariae, eggs) thus difficult to
control
• The adult worm produces
chemical substances on its coat
to protect it from host’s defence
system
• Has suckers for attaching firmly
to host to avoid being dislodged
• Cercariae larva form cyst that
makes it remain dormant but viable
for long time till it gets human host
• Has two hosts (snail and humans) to
promote its survival
• The male Schistosoma has a canal
(gynecophoric canal) where it
carries the female this ensures
efficient fertilization of eggs
• Cercariae and eggs have glands that
secrete lytic enzymes that soften
tissues of skin and snail to allow for
easy penetration into the host
• NOTE: Ensure you study your text
books and add more information
to these notes from the text books
and from your teacher.
• Strictly follow your biology
teacher’s notes and guidelines
alongside these notes
• Also study diagrams from your
text book.
• Physically answer many
questions on these form three
topics and carry out practicals so
as to get well grounded in
biology.
 End of
ECOLOGY
God bless you