Definitions

A habitat is the physical place where a plant or animal (population) lives. It must supply the needs of organisms, such as food, water, temperature, oxygen, and minerals.
A population is a group of living organisms of the same kind living in the same place at the same time.
All of the populations in the same habitat interact and form a community.
A niche is the role and position of an organism (species) in the community. No two species can occupy exactly the same niche.
The community of living things interacts with the non-living world around it to form the ecosystem.
Ecosystem is a complex interaction of living and non-living processes e.g. as small as a puddle or as huge as the Earth.
Habitats that have similar climate and plants are called biomes.



More Definitions

• A population consists of all individuals of a species that occur together at a given place and time. All populations living together and the physical factors with which they interact compose an ecosystem.
• Populations of organisms can be categorized by the function they serve in an ecosystem. Plants and some microorganisms are producers—they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem.
• For ecosystems, the major source of energy is sunlight. Producers use photosynthesis to transform energy entering ecosystems as sunlight into chemical energy. That energy then passes from organism to organism in food webs.
• The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystems.