(a) Define ecosystem. (b) Identify, with examples, two main components of the ecosystem. (c) Describe the interdependence between the two main components id...

(a) Definition of ecosystem

An ecosystem is a natural unit in which living organisms (plants, animals and micro-organisms) interact with one another and with their non-living physical environment (soil, water, air, sunlight and climate) as a functioning whole through the flow of energy and the cycling of nutrients.

(b) Two main components of the ecosystem (with examples)

• Biotic (living) component - all living things in the ecosystem. Examples: green plants (producers), animals such as goats and lions (consumers), and bacteria and fungi (decomposers).
• Abiotic (non-living) component - the physical and chemical surroundings. Examples: sunlight, water, air, soil, temperature and mineral nutrients.

(c) Interdependence between the two components

• Green plants use sunlight, carbon dioxide from the air, and water and minerals from the soil to manufacture food by photosynthesis, so the biotic depends on the abiotic.
• Animals depend on plants and on other animals for food and on the air for oxygen.
• When plants and animals die, decomposers break down their remains and return nutrients to the soil and gases to the air, enriching the abiotic environment.
• Living organisms release carbon dioxide, water vapour and wastes that become part of the physical environment, while the physical environment supplies the energy, gases and nutrients that sustain life. Thus the two components depend on and influence each other continuously.

(d) Two ways environmental balance can be achieved

• Afforestation and reforestation - planting trees to replace those cut down maintains the natural vegetation, protects the soil and keeps the carbon and oxygen balance stable.
• Control of pollution and conservation of wildlife - reducing the discharge of harmful wastes into air, water and soil, and protecting animal species (for example through game reserves), keeps the food chains and nutrient cycles undisturbed.