10 Chapter 9 Teacher Copy F5 BI

Siratun Najah Fi Ilmi Al Insan Chapter 9: Ecosystem

CHAPTER 9

Ecosystem

“Dan binatang-binatang ternak itu, Ia juga
menciptakannya untuk kamu; terdapat padanya
benda-benda yang memanaskan tubuh dari sejuk
dan beberapa faedah yang lain; dan daripadanya

juga kamu makan”

Surah Al-Nahl: Ayat 10

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9.1 COMMUNITY AND ECOSYSTEM

Species Population Community Ecosystem

Terminology Explanation
Niche
Role of an organism in an ecosystem
Includes its behaviour and interactions with biotic and abiotic
components in the surrounding of its habitat
Consists two components;
Ecological niche - Role of a species in its surroundings.

Species niche - Way in which a species interacts with biotic
and abiotic components within its
surroundings

Example;
o Goat grazing grass at field (Ecological niche)
o Hunted by tiger for food (Species niche)

Habitat Natural surrounding or the living place of an organism

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Terminology Explanation
Species
Population A group of similar organisms which able to interbreed and produce
Community offspring
A group of organisms of the same species which live in the same
Ecosystem habitat
Populations of all organisms from different species living in the
same habitat
Interacting with each other

Few communities that live together in a habitat and interact with
each other including non-living components (abiotic) such as water,
air and soil

Biotic and Abiotic Components in an Ecosystem

1. Ecosystem consists of two main components;
Biotic components - Interaction of organism with each other in an
ecosystem

Abiotic components - Non-living elements including their physical and
chemical characteristics that can

Affect an organism in an ecosystem

Ecosystem Tree
map

Living component Non-living component

Biotic components Abiotic components
Producers
Consumers pH value
Decomposers Temperature
Light intensity
Microclimate
Topography
Air humidity

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Abiotic Components

pH value

1. pH value of soil strongly influences the distribution of living organisms in a habitat
2. Most organisms living adequately in a pH value is either neutral or almost neutral
3. Soil is a habitat for hundred million of worms and microorganisms such as bacteria, fungi

and protozoa
4. A little change in pH value disrupts the activities of microorganisms that live in the soil

Reduces soil fertility.

Temperature

1. Surrounding temperature affects the physiological activities of plants and animals
2. A little change in temperature causes a reduction in the metabolic rate of organisms

• Reduce rate of enzyme reaction that catalyse physiological responses
3. Most organisms can live within the temperature range of 20 °C to 40 °C
4. Some organisms can live in extreme temperatures

Polar bears (Tundra) Foxes (Desert)
Temperature of –14 °C 45 °C during the day

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Light Intensity

1. Light intensity and duration of sunlight received influence the distribution of organisms
2. Plants require light to carry out photosynthesis
3. Taller plants in rainforest exposed to high light intensity form a canopy

Providing low light intensity underneath
Only small plants such as ferns can grow under the canopy
4. Plants in coniferous forests are shorter as well as smaller in size
Temperate climate has low light intensity
Causing lower density of plants

Coniferous forest Rainforest

Topography

1. Physical characteristics on the surface of the Earth
2. Which include;

Altitude
Gradient
Aspect
3. Topography determines humidity, temperature and light intensity in an ecosystem

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1. Altitude

The higher the altitude, the lower the Alpine
relative humidity, atmospheric pressure and zone
oxygen content.

Plants at different levels of altitudes are Temperate
different in types, sizes and density. zone
For example;
Rainforest
o Pine trees that grow at higher zone
altitudes are smaller in size

o Meranti trees that grow in tropical

rainforest are larger in size

2. Gradient

Steeper mountain slopes are easily eroded
due to swift water movement.
Soil layer becomes thinner and drier.
This area has less growth of plants
Except for some short, thorny shrubs with
small and pointed leaves

3. Aspect

Refers to the direction in which wind blows Sea
and the rays of sunlight.
A mountain slope which faces the sea has
denser plants compared to the one facing
towards the land.
This slope also gains more rainfall
distribution.
The slope that receives more sunlight is
denser with plants
Rain distribution at Bukit Larut - 3500mm/
year
Rain distribution at Jelebu - 2000mm/ year

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Microclimate

1. Refers to the climate condition of a small area which is different from the surrounding area.
2. Can take place under the rocks, or beneath the shades of bigger plants of the forest

canopy
3. Depends on temperature, humidity, light intensity, heat balance, atmospheric pressure,

water evaporation and ability of soil to retain water around an area in order to maintain
humidity

High temperature

Death tree

Low temperature

Air Humidity

1. Quantity of water vapour in the air which affects the distribution of organisms in a habitat
2. More organisms occupying areas of high humidity than in dry areas
3. Low air humidity increases water loss in a stoma through transpiration

Enhances the absorption of water and mineral salts from the soil
Provides a cooling effect
Plants can maintain optimum temperature for enzyme action.

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Autotrophic and Heterotrophic Nutrition

1. Nutrition is a way for an organism to obtain nutrients and energy from the food
2. Nutrient is a substance that provide nourishment and energy to living organism
3. There are two types of nutrition;

Nutrition

Autotroph Heterotroph
Organism which can Organism which can’t
synthesis they own food synthesis they own food
Obtain energy from eating
and digesting organic
substances

Photosynthesis Chemosynthesis
Green plant that Bacteria which synthesise
synthesises complex organic compounds without
organic compounds from using light
carbon dioxide together Gain energy from the
with light energy oxidation of inorganic
Via the process of substances such as
photosynthesis hydrogen sulphide and
ammonia

Holozoic Saprotrophic Parasitic
Organism that eating Saprotroph’s organisms Parasites are organisms
solid organic substances which gain their nutrients that absorb nutrients from
Then digested and from dead and decaying the hosts
absorbed into the body organic substances. For example, fleas and
Most animals including Digestion occurs outside tapeworms get nutrients
human beings are the body of an organism from their human hosts.
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Biotic Components According to Trophic Levels

1. Biotic components are the organisms that need energy to carry out life processes.
2. Main source of energy for all organisms comes from the sun
3. There are three groups in biotic components

Producers
Consumers
Decomposers
4. Trophic level refers to the position of organisms which can be linked by the energy flow in
a food chain.

Biotic component Explanation
Producer
Autotroph’s synthesis organic substances from inorganic
Primary consumer substances
Producers consist of green plants which synthesise
glucose from water and carbon dioxide
With the help of energy from sunlight

Herbivores which gain energy by feeding on producers.

Secondary consumer Carnivores which feed on primary consumers or omnivores
which feed on primary consumers and producers.

Tertiary consumers Carnivores which feed on secondary consumers.

Decomposer Microorganisms decompose waste substances as well as
dead or decaying organisms
Into simpler organic substances
Such as carbon dioxide and ammonia

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Energy Flow in the Food Chain

1. Organisms in an ecosystem interact with each other in the form of a feeding relationship
2. Can be shown in the food chain
3. Food chain is the sequence of energy transfer from one trophic level to another trophic

level
4. In a food chain:

Starts with the producer and ends with either a secondary consumer or a tertiary
consumer
Organisms feed on organisms from the previous trophic level.
Energy is transferred from the consumed organisms to the feeding organisms.
Energy is transferred between trophic levels when an organism eats other organisms
from which it gains its energy.
Energy is transferred to the organism after it has digested and assimilated the food
To form new substances in the body

Paddy Rat Snake Owl
Producer Primary consumer Secondary consumer Tertiary consummer

First trophic level Second trophic level Third trophic level Forth trophic level

5. Most of the animals feed on more than one type of organisms in natural conditions
6. For example, birds eat caterpillars as well as grasshoppers and paddies
7. Birds form a few food chains and occupy different trophic levels
8. Bird can be placed at the second trophic level as a primary consumer by feeding on paddy
9. The same bird can also exist at the third trophic level as a secondary consumer when

feeding on grasshoppers

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10. Several food chains to be interconnected to form a food web.
11. In a food web:

Shows the feeding relationships in a community.
Consists of several food chains
Organisms in all food chains rely on each other in feeding aspects.
Starts with photosynthetic producers which convert light energy from the sun into
chemical energy
Food in producer is stored in organs such as roots, fruits, stems or leaves

State all the food chain based on diagram above

Plant Grasshopper Frog Owl
Plant Mouse Owl
Owl
Plant Mouse Snake Snake

Plant Grasshopper Frog Owl
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Ecological Pyramids

Siratun Najah Fi Ilmi Al Insan Chapter 9: Ecosystem

1. Food chains and food webs show the feeding relationships among organisms
2. Energy transfer occurs when an organism feeds on another organism
3. When a trophic level increases, the number of individuals, biomass and total energy

contained in each individual for each trophic level will change
4. All these factors can be described in the form of ecological pyramids
5. Consist of;

Pyramid of numbers,
Pyramid of biomass
Pyramid of energy.

Pyramid of Numbers

1. Diagram which shows the number of organisms at every trophic level in a food chain
2. Base of the pyramid is the largest part which accommodates the first trophic level
3. Representing the number of producers
4. Next tiers of the pyramid are the sections for the second, third and fourth trophic levels
5. Represent the number of primary consumers, secondary consumers and tertiary

consumers.
6. Number of organisms decreases whereas the size of organisms at each level gets bigger

when ascending the pyramid

Tertiary
consumer

Secondary
consumer

Primary
consumer

Producer

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Pyramid of Biomass

1. Diagram which shows the total biomass per unit area of all organisms in every trophic level
2. Biomass is a total quantity or weight of organisms in a given area

Measured by using dry mass
3. Pyramid shows the biomass that can be supplied to the organisms in the next trophic level
4. Total biomass of producers that can be eaten by primary consumers is higher than the

total biomass of primary consumers in the ecosystem
5. Total biomass of secondary consumers is lower than primary consumers
6. Ascending the pyramid, the total amount of biomass per unit area decreases

400 kg/km2
2100 kg/km2
21000 kg/km2

2.1 x 107 kg/km2

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Pyramid of Energy

1. Pyramid of energy demonstrates the total energy which is present in an ecosystem
2. Light energy from the sun is the energy source in an ecosystem
3. Absorbed by green plants to carry out photosynthesis

Convert it into chemical energy
4. Energy will be transferred to the next trophic level when a primary consumer feeds on a

producer
5. Energy contained inside the food molecules stored in the body tissues
6. Only 10% of the energy is transferred to the next trophic level
7. 90% of the energy is dissipated into the environment through;

Heat (Cellular respiration)
Living processes (Growth)
Excretion (Faeces and urine)
8. Organisms that belong to lower trophic levels have greater energy compared to organisms
at higher trophic levels.

Tertiary 0.1% Energy released
consumer as heat
1.0%
Secondary
consumer 10%
Organisms’
Primary energy 100%
consumer

Producer

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Calculate the energy received by the snake

Energy input from
the sun during
photosynthesis

100 000 kJ 90% energy 90% energy 90% energy
lost lost lost

Paddy Grasshopper Frog Snake

10 X 100 000 kJ 10 X 10 000 kJ 10 X 1000 kJ
100 100 100

= 10 000 kJ = 1000 kJ = 100 kJ

Inverted Pyramids of Numbers and Pyramid of Biomass

Inverted Pyramids of Numbers Inverted Pyramid of Biomass

Tertiary
consumer

Secondary
consumer

Primary
consumer

Producer

Found in parasitic food chain Often found in marine ecosystem
Single plant may support the growth of Because the producers are very small and
many herbivores have limited mass
Each herbivore in turn may provide They also reproduce and die quickly
nutrition to several parasites Less biomass at any given time compared
Each parasite can support many hyper to consumers
parasites
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Types of Interaction Among Biotic Components Tree
map
Types of Interaction Among Biotic
Components

Saprophytism Symbiosis Predation Competition
Interaction involving
Interaction in which Interaction when predator that eats Organisms in a
an organism gets different species prey habitat compete in
its food from dead that live together order to get basic
organic materials. interact with each needs such as food,
other water, light and
mates

Mutualism Commensalism Parasitism

Interspecific Intraspecific
competition competition

Mutualism
1. Interaction that gives benefits to both organisms
2. For example;

Myna gets its food (lice) from the body of a buffalo
Buffalo is free from the lice

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Commensalism

1. Interaction that provides benefits to only one organism without causing any harm to the
other organism.

2. For example
Shark does not gain any benefit
Remora fish gets scraps of the shark's food.

Parasitism

1. Interaction that benefits one organism but harms the other organism
2. For example;

Tapeworm becomes a parasite in the intestines of a human being
Absorbing nutrients and causes the human (host) to lack in nutrients.

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Competition Interspecific competition
Intraspecific competition

1. Competition among same species of 1. Competition among different species of
organism to get basic need organism to get basic need

2. For example, paddy plant competing to 2. For example, paddy plant and maize
each other to obtain sunlight plant are competing to obtain sunlight

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Mangrove Ecosystem

Abiotic Components

1. Mangrove trees are tropical plants which are usually found in estuaries
Place where the sea and river meet

2. These plants have successfully adapted themselves to the extreme abiotic components

Bubble
map

Germination of Exposed to waves
seedlings in and water tides.
tidal area.

Soil with high salt Abiotic Soft, silted and muddy
content as well as Components soil that lacks
very low content of of Mangrove aeration.
dissolved oxygen in Ecosystem

water.

Exposed to very Exposed to strong
strong light wind blows.
intensities.

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Biotic Components

1. Mangrove swamp is dominated by mangrove plants as a producers
2. Species of flora and fauna adapt themselves to live in the mangrove forest and make the

mangrove forest as a habitat
3. There are also decomposers such as bacteria and fungi

Decompose dead organisms into nutrients for the plants
4. These organisms form a food web
5. Helps to maintain the dynamic balance of the mangrove forest.

Proboscis monkey

Horseshoe
crap

Biotic Stork
Components
of Mangrove
Ecosystem

Mangrove tree

Mudskipper Crab

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Adaptation Features of the Mangrove Trees

Parts of Adaptation features
mangrove trees
Leaves Have thick cuticles and sunken stomata
• Can reduce the rate of transpiration.
Pneumatophore roots
Have succulent leaves
• Can store water

Has hydathode pores
• To eliminate excess salt.

Mature leaves can store salt
• Will fall off when the concentration of salt stored is too
high.

Roots are short root projections from the soil surface for
aeration in water-submerged areas
Allows the gas exchange between the submerged root and
atmosphere through lenticels
Example: Avicennia sp.

Prop roots Roots branch out from the lower part of the stem of a
mangrove tree
Roots are firmly planted in the soil to support the tree
To overcome strong winds and waves.
Example: Rhizophora sp.

Buttress roots Roots with a thick structure
Add in widening the base of a tree.
Provide support to the tree that grows on soft soil which
borders with solid land.
Example: Bruguière sp.

Viviparous Seeds Seeds germinate and grow when they are still on the parent
plant.
Enables fallen seedlings to stick into the muddy soil
Will not be uprooted by waves.

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Colonisation and Succession

1. An ecosystem can change due to;
Natural phenomena - Such as volcano eruption, earthquakes and draughts

Human activities - Such as mining

2. Mining can cause organisms to die or migrate to other habitats
3. After a long period of time, this deserted area starts to have inhabitants
4. Known as pioneer species

Species that begins to colonise an area
Where there are no other living things
5. Colonisation is a process when plants start to conquer an uninhabited area, breed and
form colonies in that area
6. Succession is a process when a few species of dominant plants in a habitat are gradually
being replaced by other species called successor.

Colonisation and Succession in Mangrove Swamp

Coastal zone Middle zone Inland zone

High tide

Low tide

Muddy Enlarge root system/ Prop root in Butress root in
bank Pneumatophore in Rhizophora sp. Bruguiera sp
Avicennia sp. and

Sonneratia sp.

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Coastal zone

1. Area that is most exposed to big waves
2. This zone is dominated by pioneer species, which are Avicennia sp. (Api-api tree) and

Sonneratia sp. (mangrove apple)
3. Enlarged root system and pneumatophores help the trees to trap mud and organic

substances which are brought by high tides
4. Mud accumulation slowly begins
5. Soil becomes higher and denser
6. Soil not suitable for the growth of Avicennia sp. and Sonneratia sp.
7. More suitable for the growth of Rhizophora sp.
8. Rhizophora sp. succeeds and replaces the pioneer species.

Middle zone

1. Area situated along the river, closer to the estuaries.
2. Inhabited by Rhizophora sp. plants (bakau minyak tree) that have tangled prop roots.
3. These roots trap twigs and mud which are washed away and block the flow of water
4. trapped mud causes sedimentation to occur much faster
5. River bank becomes higher and drier because less seawater overflows during high tides
6. Soil becomes less suitable for the growth of Rhizophora sp
7. More suitable for the growth of Bruguiera sp
8. Bruguiera sp. succeeds and replaces Rhizophora sp.

Inland zone

1. Area situated further into the land
2. Soil becomes higher, harder and only flows with seawater during high tides
3. Area is inhabited by Bruguiera sp. (tumu merah tree)
4. Have buttress roots to trap more mud and silt
5. Sedimentation process forms a new swamp that projects out towards the sea
6. One-time shore gets further away from the sea and the ground changes into a land
7. More suitable for land trees such as Nypa fruticans and Pandanus sp
8. Land trees succeed and replace Bruguiera sp.

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The Importance of the Mangrove Ecosystem

Importance Explanation
1. Become a natural barrier
2. Protected site for aquatic Lessen the impact of strong waves and wind that
reach the seashore are
animal Protect aquatic organism from predator and swift
3. Protected site for bird current and waves
4. Generate income
Preserved areas where various species of migratory
5. Building material birds
6. Source of energy
Sea products such as fish, shrimps, crabs and sea
snails become a source of income
Mangrove areas are conducive for fish rearing in
floating cages and also for breeding commercial
species
Mangrove woods used to make handicrafts

Mangrove woods can be used to build boats, fish traps
and building frames

Mangrove wood is burnt in the furnace to charcoal

7. Source of food Fruit of Avicennia sp. can be consumed as a
8. Source of medicine vegetable
Fruit of Sonneratia sp. is used in the production of
drinks
Fruit of Nypa sp. can be eaten and water from the fruit
can be used in the production of vinegar and nira
Bark of 142ruguier asp. tree can be used to treat
diarrhoea

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9.2 POPULATION ECOLOGY
Factors Affecting Population Distribution
1. Population distribution shows how the organisms of the same species are able to spread

out in a habitat

Factor The effects towards plants
Temperature
Optimum temperature for plant growth is between 25 °C to 30
Water °C.
Light High temperatures can cause enzymes to denature
pH of soil Biochemical processes in plants are disrupted
Mineral salt content Causing plant to;
o Stunt the growth of plants.
o Increase the rate of water evaporation by transpiration.
o Slow the rate of photosynthesis.
Low temperatures reduce the activities of enzymes
Slow down the biochemical reactions.
Water is needed for enzyme activities, photosynthesis,
transport and support in herbaceous plants.
Desert, tundra and poles have low population distribution and
density of plants.
Light is very important for the process of photosynthesis
Areas which receive little light have a lower number of plants

pH of soil is important for nutrient absorption by the roots
pH is either too acidic or too alkaline will cause lower absorption
of nutrients by plants.
growth of plants will be disrupted due to lack of nutrient
Salt content affects the absorption of water through osmosis by
the roots.
High salt content in soil will cause plants to lose water through
osmosis.
Minerals are needed for the production of proteins, enzymes,
nucleotides, vitamins and others compounds.
Example, phosphorus is used to form phospholipids (in the
formation of cell membrane).

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Factor The effects towards Animal
Temperature
Areas which are exposed to high temperatures in a habitat are less
Water inhabited
Breeding site Such as worms and snails.
Food supply Animals are concentrated in areas that have enough water sources
For drinking and cooling the body.
Safe and suitable breeding site is needed by animals
To raise their offspring
Food is important for survival
Animals are heterotrophs
Depend on plants and other animals for food

Patterns of Population Distribution

Clumped Patterns of Population Distribution Random
Uniform

Clumped organisms form Organisms are distributed Organisms are distributed in
separated groups. all over an inhabited area. a free pattern in an area.
Caused by uneven Every individual in species Involves species that have
distribution of resources in competes for limited little interaction among
an area resources in an area individuals

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Estimation of Organism Population Size

1. Two important factors for studying population ecology

Population size - Number of organisms present in a population
- Can be estimated by a random sampling technique
- Studied area is large and difficult to obtain data

Population density - Number of individuals of a species per unit area of a habitat

Quadrat Sampling Technique

1. To estimate the population size of land plants or animals which are inactive or move slowly
2. Number of organisms in the quadrat areas is the sample which represents the whole area

of study
3. Data obtained from all quadrats can be used to estimate the population in the area of study
4. Quadrat is a square-framed structure which is made of wood, iron or plastic
5. Quadrat normally subdivided into a few parts of the same size to estimate the coverage

percentage of any species
6. Size of the quadrat depends on the types and size of organisms, the area of study as well

as the distribution and density of the plants being studied
7. For example, a one-metre-squared quadrat is suitable to estimate the population of plants

in a school field.
8. Quadrat sampling technique can estimate the frequency, density and coverage plant

species

Quadrat frame Subdivided quadrat frame
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Frequency
Probability to get an individual of any plant species in every quadrat

Frequency = The number of quadrats containing studied species X 100%

Total number of quadrats used

1M

1M Second quadrat = X Third quadrat = ⁄
First quadrat = ⁄

Calculate the frequency of Mimosa pudica sp.

Frequency = 2 X 100%
3

= 67%

Density
Average number of individuals in any species per unit area of study.
Total number of individual species studied in all quadrats
Density = Total number of quadrats used X Area of a quadrat

1M Second quadrat = 0 Third quadrat = 3

1M
First quadrat = 1

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Calculate the density of Mimosa pudica sp.

1+3
Density =

3 x (1m x 1m)
= 1.3 m-2

Coverage Percentage
Percentage of soil surface covered by the plants

Coverage Area covered by studied species in all quadrats X 100%

percentage = Total number of quadrats used X Area of a quadrat

First quadrat = 30 Second quadrat = 45 Third quadrat = 60

Coverage (30 + 45 + 60)cm2 X 100%

percentage = 3 X (10cm x 10cm)

= 135 cm2 X 100%
300 cm2

= 45%

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Capture-Mark-Release-Recapture Technique

1. Can estimate the population size of organism that can move freely
2. Such as foxes, sharks, snails, millipedes, insects and butterflies which in the studied
3. Carried out by following steps

Animals under study are captured randomly in the area of study (natural habitat)
Number of animals captured is recorded (first capture)
Every animal captured is marked by using nail polish, paint or Indian ink
Marked animals are then released into the same area of study
Second capture is done randomly in the same area of study after a certain period
of time
Total number of animals captured the second time recorded for both marked and
unmarked

Population size = First capture X Second capture

Second capture with mark

A group of students have conducted an experiment to determine the population size of snail
at the school garden. Calculate the population size of snail at the school garden.

Area Snail Capture Numbers of
snail capture

First 30
capture 25

School
garden

Second X
capture X

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Key:

Represent 5 snail

X Represent 5 snail with mark

Population size = 30 X 25

10

= 75

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