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Form 2 Form 2
Science Chapter 4Science Chapter 4
Interdependence among LivingInterdependence among Living
Organisms and the EnvironmentOrganisms and the Environment
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Content
1. Interdependence Among Living Organisms
2. Interaction Between Living Organisms
3. Food Webs
4. Photosynthesis
5. The Importance of The Conservation and Preservation Of Living Organisms
6. Role of Man in Maintaining the Balance in Nature
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4.1 4.1
Interdependence Among Interdependence Among
Living OrganismsLiving Organisms
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Habitat
• A habitat is the natural living place of natural living place of
plants and animals.plants and animals.
• A habitat provides an organism with air, space, food, shelter and a place in which to breed.
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Species
• A species is a group of organisms that have the same shape and structure.
• They can also breed together to produce can also breed together to produce
offspring that are fertile.offspring that are fertile.
• Penguins , rat, cat and elephant are examples of the different species of organisms.
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Population
• A population is a group of organisms comprising the same species that live together in a habitat.
• For example,
(a) a population of monkeys
in a tree
(b) a population of elephants
on a grassland
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Community
A community consists of
several speciesseveral species of animal and plant population that live together and interact with one another in a habitat.
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Ecosystem
• An ecosystem consists of several several
communitiescommunities that interact with one another and with the physical environment (non-living things such as water, air, soil, light and mineral salts).
• For example,
(a) a pond ecosystem
(b) a tropical rainforest ecosystem
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1. Prey-predator
• A predator is an organism that kills and eats another organism.
• A prey is the organism that is eaten.
predator
prey
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1. Prey-predator
• A predator usually has special physical characteristics such as sharp claws and fangs, or a sharp beak, with which to kill its prey.
• A prey usually has the ability to run away a from a predator.
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Symbiosis
• Symbiosis basically
means ‘living together’ .
• There are three types of
symbiotic relationships,
namely
i. Commensalism
ii. parasitism and
iii. mutualism.
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I .Commensalism (Symbiosis)
• In commensalismone species benefits from the interaction, as the other is unaffected.
• The unaffected species is the host.
Staghorn fern obtains sunlight,
Tree is not effected .
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I .Commensalism (Symbiosis)
remora and the shark
The anemonefish lives among the
forest of tentacles of an anemone
and is protected from potential
predators.
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ii. Parasitism (Symbiosis)
• Parasitism is another type of interaction between two organisms.
• Only one organism benefits.
• The other organism suffers some disadvantage.
Rafflesia absorb minerals from roots
of other plants.
Louse suck blood
from their
host
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ii. Parasitism (Symbiosis)
• A parasite is an organism that lives on or inside the other organism.
• The host is the organism on or in which the parasite lives.
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Two groups of parasites :
2. Parasites that live
inside the host
organism.
• For example,
tapeworms and
hookworms inside the
intestines of humans
and animals.
1. Parasites that live
out side the host
organism.
• For example
mosquitoes, lice and
fleas suck blood
from their host .
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iii. Mutualism (Symbiosis)
• In mutualism, the interaction is beneficial to both species.
• Mutualism is a form of cooperation.
• They obtain nutrition and shelter from each other.
The bird eats the fragments of food left
between the crocodile teeth.
So the crocodile gets its teeth cleaned.
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Competition
• Competition occurs when organisms compete for the same basic resources.
• Animals compete to obtain water, food, living space and mates for reproduction.
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Competition
• Plants compete to obtain water, sunlight, minerals and living space.
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Biological control
• Biological control is a method in which a predator, the natural enemy to a certain pest, is used to control the population of that pest in an area.
The aphid is a pest to the
gardeners, damaging his
plants.
The ladybirds helps the
gardener by ridding him of
these pests
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Biological control
• Biological control has many advantages as compared with using pesticides.
• Some of them are:
(a) it does not pollute the environment
(b) it does not kill other organisms except
the pests
(c) it is cheap and safe to use
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Biological control
Barn Owls (Tyto alba) a
proven natural predator
of rats in Oil Palm
When the eggs hatch,
the ichneumon larvae
feed on the body of the
host .
Biological weed
control involves the
release of
organisms that
attack plants to
control weeds.
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Food Chain
• A food chain is an energy flow showing how
energy in food is passed from plants (producers)
to animals (consumers).
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Food Webs
A food web consists of several food chains that
are interlinked to one another
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Pyramid of numbers
• A pyramid of numbers shows the number of organisms at each stage of the food chain.
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Pyramid of numbers
• From the base of the pyramid to its peak:
(a) the number of organisms decreases
(b) the size of the organisms increases
(c) more energy is lost
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• Photosynthesis is a process that occurs in green plants, in which food is madefrom water and carbon dioxide in the presence of chlorophyll and sunlight.
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Photosynthesis equation
Carbon dioxide
water
chlorophyll
sunlight
Glucose
(food)oxygen
The glucoseglucose produced is transported to
other parts of the plant to be:
(a) oxidised through the process of
respiration to provide energy
(b) stored as starch
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The role of photosynthesis
a) enable green plants to make their own
food.
b) regulate and maintain carbon dioxide
content in the atmosphere.
c) increase oxygen content in the
atmosphere.
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Experiment 1 break the
cells.
remove chlorophyll
soften the
leaf
Test for starch .
Turn blueblue--black.black.
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Experiment 2
Aim :
To show plant need carbon dioxidecarbon dioxide for photosynthesis .
Info :
Sodium hydroxide absorbs carbon dioxide
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The carbon cycle
• The carbon cycle is the circulation of the circulation of the
carbon element on the Earthcarbon element on the Earth..
• These processes take place continuously.
• The carbon cycle maintains the content of carbon dioxide in the air.
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The carbon cycle
• The processes that release carbon dioxiderelease carbon dioxideinto the air include:
(a) respiration and breathing
(b) combustion
(c) decomposition
• Photosynthesis, which takes place in green plants, removes carbon dioxideremoves carbon dioxide from the air.
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The oxygen cycle
• The oxygen cycle is the circulation of oxygen on
the Earth.
• These processes take place continuously.
• The oxygen cycle maintains the content of
oxygen in the air.
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4.54.5
The Importance of The The Importance of The
Conservation and Preservation Conservation and Preservation
Of Living OrganismsOf Living Organisms
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The greenhouse effect
• The greenhouse effect occurs because a layer
of carbon dioxidecarbon dioxide in the atmosphere prevents a
portion of heat from escaping to the outer space.
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The greenhouse effect
• The greenhouse effect raises the Earth's temperature.
• This is known as global warmingglobal warming.
• This phenomenon causes changes in the world's weather and climate.
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Result of global warming
The sea level increases and this results inthe flooding of low-Iyingcoastal areas.
The melting of icecaps at both of the Earth's poles.
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The depletion of the ozone layer
• The ozone layer absorbs most of the ultraviolet rays before it reaches the Earth's surface.
• Chemicals such as chlorofluorocarbonschlorofluorocarbons (CFCs), used in the manufacture of aerosol sprays, refrigerators and air conditioners, are pollutants that break down the ozone molecules in the ozone layer.
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Ozone depletion effects
• Ultraviolet rays that reach the Earth cause:
(a) skin cancer
(b) cataract of the eyes
(c) the human immune system to
malfunction
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Acid rain
• Gases such as sulphur dioxide and nitrogen dioxide dissolve in rainwater to form acid rain.
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Acid rain effects
Acid rain can:
a) destroy sculptures .
b) lower the soil pH value and make it unsuitable for plants.
c) River water that is polluted by acid rain is no longer suitable for aquatic organisms.
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4.64.6
The Importance of The The Importance of The
Conservation and Preservation Conservation and Preservation
Of Living OrganismsOf Living Organisms
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• Managing environmental pollution can save our Earth.
• The following are steps that can be taken to reduce environmental pollution:
(a) use unleaded petrol
(b) ban nuclear testing
(c) create special places to burn rubbish
(d) implement stricter law enforcement on the
disposal of toxic waste from factories
(e) hold campaigns to prevent pollution
(f) recycle, reuse and reduce materials
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