ICSE Class 8 Biology, Unit 3: Ecosystems

What this unit aims at

A community of organisms (plants and animals) in a given area, live in harmony with the environment. There is a close interaction between the living (called biotic) and non-living (called abiotic) components of the environment. The study of interaction between biotic and abiotic components is known as ecology and the ecosystem is the basic unit of study. There are many types of ecosystems, namely aquatic (fresh water/ marine), terrestrial (forest/ grassland/ desert), etc. The composition of biotic community and the abiotic components (environment) varies in different ecosystems. Organisms develop adaptations suited to live in a particular environment. Living organisms, which may be producers (plants), consumers (animals) or decomposers (micro-organisms), are linked to each other through food chains. Ecosystems exhibit two important functional attributes (a) A unidirectional flow of energ

Your child should be able to

• define the terms ecosystem, producer, consumer, decomposer, food chain, food web and pyramid of numbers, with examples (technical terms)
• explain and analyze the biotic and abiotic components of an ecosystem
• interpret the relationship between different biotic components in terms of food chain, food web and pyramid of numbers
• evaluate the abiotic factors and their influence on biotic factors
• describe and provide examples for inter dependence relationships between organisms (symbiosis, parasitism and predation)
• draw relationship between the flora and fauna of a particular forest ecosystem
• make a flow chart of a food chain and food web

Key concepts in this unit

• Understanding ecosystems: definition, interaction between biotic and abiotic factors;
• Biotic components consisting of producers, consumers, decomposers. Meaning of food chain. Food web, and pyramid of numbers.
• Interdependence between organisms: symbiosis, parasitism and predation.
• Brief account of abiotic or non-living components such as air, soil, water and climatic factors such as sunlight, temperature, humidity and wind;
• Only, forest ecosystem with its flora and fauna to be taught.