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1. Interdependence among living organisms
2. Interaction between living organisms
3. Food webs
4. Photosynthesis
5. Conservation and preservation of organisms
6. Role of human beings in maintaining the balance of nature
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Species
a group of similar organisms with common
characteristics
species can interbreed to produce fertileoffspring
Population
a group of organisms of the same species
living in the same habitat. For example, a
population of zebras.
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Community
different populations of organisms living together in
the same habitat.for example, a community in the savannah consists
of populations of zebras, giraffes and bisons.
Ecosystem
the various communities that interact with one
another and with the non-living environment
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In an ecosystem, various organisms live
together and are interdependent on one
another for their survival.
Examples:(a) plants make their own food by
photosynthesis. Plants are dependent on
abiotic factors such as sunlight and water.
(b) animals like deer depend on plants forfood
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(c) Other animals like tigers depend on deer for food
(d) Organisms depend on one another for food,
shelter and protection.(e) Microorganisms like bacteria and fungi are
decomposers. They decompose dead organisms.
Decomposition releases minerals into the soil which
become nutrients for plants. The interdependence among living organisms and
the environment creates a balanced ecosystem
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A balanced ecosystem is an ecosystem
(a) That is stable
(b) Does not change very much over a period of time
(c) In which there is a continuous supply of basic
needs like oxygen, food, shelter and breeding
partners.
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Organisms interact in many ways in an
ecosystem to obtain food, shelter and
protection
Competitionorganisms compete with each other for the
same basic needs like food, water, shelter
and mates. Competition becomes intense
when basic needs become limited
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(a) intraspecific competition; competition between
organisms of the same species. For example, a
Bryophyllum leaf with new seedlings growing on theparent leaf
(b) Interspecific competition; competition between
organisms of different species. For example, an owl
and a snake compete for rats.
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Symbiosis is the close relationship between
two organisms of different species which live
together and interact with each other. There
are 3 types of symbiosis: commensalism,mutualism and parasitism
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A relationship in which one organism the
commensal benefits while the other organism
the host does not receive any benefit or
harm. A remora fish, often found attached under a
shark, gets free transport and free left by
the shark without harming the shark.
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A relationship between two different species
of organisms in which both organisms benefit
Lichen is made up of an alga and a fungus.
The green alga produces food and the fungusprovides shelter.
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A relationship in which one organism benefits
parasite while the other the host is harmed.
Ticks,fleas and lice parasites live on the skin
of mammals hosts and suck the blood of thehost
Round worms and tapeworms live inside the
intestines of human hosts and obtain food
and shelter from the host
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The predator kills and eats smaller animals
called the prey
Predators have long canine teeth, sharp
vision, sharp claws and teeth to hold and killprey. Predators are carnivores.
Prey relies on speed or camouflage to avoid
being caught by predators. Prey can be
either carnivores, omnivores or herbivores Examples are;
(a) Owl and rat
(b) Snake and chicken
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