8. Dynamic Ecosystem
What is ecosystem? Biological community of interacting
organisms and their physical environment. Ecology – the scientific study of the
interaction of living organisms with other organisms and with the physical environment
8.1 The Abiotic and Biotic Component of the Environment
The abiotic component The non-living components such as1. pH value – soil and water2. Light intensity – as source of energy 3. Temperature 4. Humidity – amount of water vapour present in the
air5. Topography – physical features of land (altitude,
gradient and aspect of region)6. Microclimate – climate in a microhabitat
The biotic component The living organisms in the environment such as
1. Producers – synthesise organic substances (plants)
2. Consumers – eat other organisms (primary consumer, secondary consumer, tertiary consumer)
3. Decomposers – microorganisms that break down waste products and dead bodies (bacteria and fungi)
Identify the biotic and abiotic component in the pond ecosystem shown in the picture below.
Food chain, food web and trophic levels Food chain - sequence of organisms through which
energy is transferred. Each stage - trophic level
Food web – food chain interconnected. Energy flows through food web and lost when
it transferred from one level to another level of the trophic levels in the form of heat
Food chain, food web and trophic levels
The interaction between biotic component in relation to feeding Organisms interact with one another in
various ways such as
1. Symbiosis
2. Saprophytism
3. Prey-predator
1. Symbiosis Close relationship between two or more
different species which live closely together and interact with each other
Three categories:
a) Commensalism
b) Mutualism
c) Parasitism
a) Commensalism One species (the commensal) benefits, the
other (the host) don’t get benefits nor is harmed
E.g. epiphytes grows on branches of trees
b) Mutualism Relationship between two species of
organisms in which both benefit E.g. bacteria in the digestive system of human
c) Parasitism Relationship between two organisms in which
one organism (the parasites) benefits from the other organism (the host)
Two types: Ectoparasites – live on the surface of the host
(e.g. ticks and fleas) Endoparasites – live inside the body of the
host (e.g. tapeworms)
2. Saprophytism What is saprophytism and give examples.
3. Prey-predator Relationship where an organism which is
smaller, called the prey, is haunted and eaten by a stronger animal, the predator
E.g. an owl (predator) and a rat (prey) The interaction takes place in a cycle that
keeps the populations of both organisms in a dynamic equilibrium
The interaction between biotic component in relation to competition Competition – interaction between organisms
living together in a habitat and competing for the same resources that are limited supply
Two types:
1. Intraspecific – competition between the same species
2. Interspecific – competition between different species
Exercise Do Focus Practice 8.1 on page 181 in the
textbook