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BIOLOGY NOTES

CHAPTER 1: ECOLOGY SUBTOPIC : 12.1 Introduction to ecology.

LEARNING OUTCOMES: Define basic terminologies in ecology.

- niche, habitat, organism, population, community, ecosystem, biome, biosphere.

.

MAIN IDEAS

/KEY POINT EXPLANATION NOTES

Definition of

ecology

Ecology is the study of how organisms interact with each

other and their environment

Terminologies

Terminologies Definition

Niche Niche is the status or role of an organism

in its habitat /environment.

Habitat

Organism The systems working together with

complexity make up a complex living

organism.

Population

Community All the organisms that inhabit a

particular area; an assemblage of

populations of different species living

close enough together for potential

interaction.

Ecosystem

Biome Any of the world’secosystem types,

often classified according to the

predominant vegetation for terrestrial

biomes and the physical environment for

aquatic bioms, and characterized by

adaptations of organisms to the

particular environment.

Biosphere

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BIOLOGY DIAGRAM

1. Level of organization in an ecosystem.

2. Component of biosphere.

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SUBTOPIC : 12.2 Ecosystem concept

LEARNING OUTCOMES: Explain ecosystem concept.

a) Explain the components of the ecosystem with example:

i. Biotic component

ii. Abiotic components

iii. Interaction between / among biotic components

iv. Interactions between biotic and abiotic components

b) Describe the following ecosystem structures:

i. Lake ecosystem

ii. Terrestrial ecosystem of tropical rainforest

MAIN IDEAS

/KEY POINT EXPLANATION NOTES

Definition of

ecosystem

concept.

Definition according to Odum (1969)

• Basic functional unit of nature including both

organisms and their non-living environment.

• Each interacting with other and influencing each

other’s

• Both necessary for maintenance and development of

the system.

Biotic

components

Autotroph / producer

-An organism that obtains organic food molecules without

eating other organism or substances derived from other

organism.

-In terrestrial ecosystems- green plants are the producers.

-In aquatic ecosystems – phytoplankton

(algae & blue green bacteria).

Heterotroph / consumer

-An organisms that obtains organic food molecules by eating

others organisms or substances derived from them.

-Heterotroph can be divided into 4 type of organisms:

Herbivore

(primary consumer)

Carnivore

(secondary consumer)

- An animal that mainly eats other

animals.

Predators –

Scavengers –

Omnivore

Detritivore An organism (such as an

earthworm or crab) that feed on

small fragments of dead organisms

and on waste matter of animals

and plants.

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MAIN IDEAS

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Decomposer

-An organism that absorb nutrients from nonliving organic

material such as corpses, fallen plant material and the wastes

of living organisms.

Abiotic

components

Atmosphere

-

Hydrosphere

-

Lithosphere

-

Interactions

between/among

biotic

components

Competition

-The interaction among two or more individuals that attempt

to use the same essential resource, such as food, water,

sunlight, or living space.

-can be divided into two:

Interspecific

intraspecific

Parasitisme

-A symbiotic relationship in which one organism (parasite)

benefits and the other (host) is adversely affected.

-can be divided into two:

Endoparasites

Ectoparasites

Commensalisme

-

Mutualisme

-A symbiotic relationship in which both participants benefit.

Predation

-Relationship in which one organism (predator) kills and

devours another organism (prey).

Interactions

between biotic

and abiotic

components

-Ecosystem create biophysical feedback mechanisms between

living (biotic) and non-living (abiotic) components of the

planet.

-These feedback loops regulate and sustain local communities,

continental climate systems, and global biogeochemical cycles

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MAIN IDEAS

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Lake ecosystem -Zonation of lake ecosystem:

i) base on light penetration

ii) base on distance from shore and depth of water

iii) base on open water

i) Base on light penetration

Photic

zone

- Upper part of lake or marine environment

- light is sufficient for photosynthesis

- Biotic components: almost all are the

primary producer (high productivity occurs)

Aphotic

zone

*Compensation point :-

-The depth at which light penetrating the water creates the

same balanced effect

-Point in between photic and aphotic zone .

- Where the rate of photosynthesis equal to the rate of

respiration

ii) Base on distance from shore and depth of water

Littoral

zone

-Area near the shore that receives sunlight,

extending down to the depth where rooted

plants stop growing

- Diversity greatest here:

i) very diverse animal

ii) diversity of plant

Limnetic

zone

-Open surface waters , away from the shore

-It is above the profundal zone

-This is the main photosynthetic body of the

lake

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MAIN IDEAS

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iii) Base on open water

Pelagic

zone

-A portion of freshwater ecosystem that

occurs in open water, away from the shore

Benthic

zone

- Located at the bottom of all aquatic biomes

-Made up of sand and organic and inorganic

sediments

Lake

Stratification

- the separation of lakes horizontally into three layers based

on temperature:

Epilimnion

Thermocline

or

metalimnion

Hypolimnion

Terrestrial

ecosystem of

tropical

rainforest

Strata Type of tree Animal in

community

Emergent

Canopy

Shrub

Herb

Taloid

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BIOLOGY DIAGRAM

3. Lake ecosystem.

4. Lake stratification.

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5. Terrestrial ecosystem of tropical rainforest.

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SUBTOPIC : 12.3 Energy flow through ecosystem

LEARNING OUTCOMES: Describe food chain, food web and ecological pyramid in relation to trophic levels and

energy transfer.

MAIN IDEAS

/KEY POINT EXPLANATION NOTES

Food chain

-In a food chain, energy and nutrients are passed from one

organism to another.

-It represents one path of energy flow through an ecosystem.

Food web

-Most food chains are interconnected.

-Most animals will utilize several food sources.

-Shows the flow of biomass and energy from one trophic level

to the next.

Trophic level

-The position that an organism occupies in a food chain.

-Many animals feed at several different tropic levels.

Trophic level 1 Producer

Eg: Plants

Trophic level 2

Trophic level 3

Trophic level 4

Ecological

pyramid

-A diagram representation of the relative energy value at each

trophic level / the flow of energy through the food chain.

-Three types of pyramid have been used:-

Pyramid

of

number

-Based on counting the numbers of organisms

at each trophic level.

-The number of organisms less than produces

because small proportion of energy taken in by

an organism.

-Parasitic food chains give inverted pyramids.

Pyramid

of

biomass

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MAIN IDEAS

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Pyramid

of energy

-Energy pyramid indicates total amount of

energy present in each trophic level.

-Also shows loss of energy from one trophic

level to the next.

-Shows clearly that energy transfer from one

trophic level to next accompanied by decrease

due to waste, respiration and death.

Calculation on energy

- Gross Primary Production(GPP) : the rate at which an

ecosystem's producers capture and store a given amount of

chemical energy as biomass.

-Net Primary Production (NPP) : referred to the remaining

fixed energy

-Ra : autotrophic respiration (respiration by plant)

NPP = GPP - Ra

Why food chain

consists less

than five trophic

level?

-When energy flows from one trophic level to another, energy

lost through respiration, excretion and heat to surroundings.

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BIOLOGY DIAGRAM

6. Food chain

7. Food web

8. Trophic level

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9. Ecological pyramid

10. Energy loss

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SUBTOPIC : 12.4 Biogeochemical cycle

LEARNING OUTCOMES: Describe biogeochemical cycle components (cycling pool and reservoir pool).

MAIN IDEAS

/KEY POINT EXPLANATION NOTES

What is

biogeochemical

cycle?

-Biogeochemical is the relation between biological and

geological/ earth components and chemical changes.

-Biogeochemical cycles is the second major function of

ecosystem (along with energy flow).

-Each cycle summaries the movement of chemical elements

through the living components of ecosystem

-Eg. : carbon cycle, nitrogen cycle, oxygen cycle, sulphur

cycle.

Component in

biogeochemical

cycle

1. Reservoir pool

2. Cycling pool

Carbon cycle -Carbon cycle: carbon dioxide fixation by plants and the

counterbalancing release of carbon dioxide in respiration.

-Reservoir pool :

-Cycling pool :

Photosynthesis -Carbon enters plants , algae, and

cynobacteria as CO2 which is

incorporated into organic molecules by

photosynthesis.

Cellular

respiration

Combustion

Burning of

fossil fuel

Decomposition

Erosion of

limestone

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BIOLOGY DIAGRAM

11. Carbon cycle

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SUBTOPIC : 12.5 Conservation and management

LEARNING OUTCOMES: a) Explain sustainable development.

b) Discuss threats to biodiversity in Malaysia

c) Discuss conservation of biodiversity in Malaysia

MAIN IDEAS

/KEY POINT EXPLANATION NOTES

Sustainable

development

-Sustainable development is development that meets the needs

of the present without compromising the ability of future

generations to meet their own needs.

Sustainable

forestry

Sustainable

algriculture

-crop rotations

-contour farming

-strip farming

-terracing

Sustainable fishery

Threats to

biodiversity in

Malaysia

-Habitat loss or conversion and economic exploitation of

natural resources have been the primary cause of biological

diversity loss in Malaysia to date.

-Now more likely to be industrial pollution rather than habitat

loss due to ongoing structural changes in the Malaysian

economy.

-Eg. leatherback turtle, milky stork, slipper orchid

Conservation

and preservation

Conservation

-Conservation is how humans impact organisms and of the

development of ways to protect biological diversity.

-Safeguarding populations of endangered species.

-Preserving entire ecosystems and landscapes.

Preservation

-Preservation implies complete protection, with little human

disturbance.

-Wilderness and certain unique habitats for wildlife must be

kept intact.

Ecosystem

management

-They are various techniques of conservation used in

ecosystem management, eg:-

i) Nature reserves and national parks.

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MAIN IDEAS

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ii) Planned land use

iii) Legal protection of endangered species

Eco-friendly

practices

-Practice of biological control such as using the owl as the

“guard” to kill or prevent mice and rats from destroying the

crop.

-Practice of crop planting rotation - growing a series of

dissimilar/different types of crops in the same area in

sequential seasons.

-Tagal System in Sabah – open and close seasons in fishing

activities.

Conservation of

biodiversity in

Malaysia

In-situ conservation

Ex-situ conservation