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