HiSET Science: Hierarchical Structure of the Biosphere

Biosphere

Components
The biosphere is the region of the earth inhabited by living things. The components of the biosphere from smallest to largest are organisms, populations, communities, ecosystems, and biomes. Organisms of the same species make up a population. All of the populations in an area make up the community. The community combined with the physical environment for a region forms an ecosystem. Several ecosystems are grouped together to form large geographic regions called biomes.
A population is a group of all the individuals of one species in a specific area or region at a certain time. A species is a group of organisms that can breed and produce fertile offspring. There may be many populations of a specific species in a large geographic region. Ecologists
study the size, density, and growth rate of populations to determine their stability. Population size continuously changes with births, deaths, and migrations. The population density is the number of individuals per unit of area. Growth rates for a population may be exponential or logistic. Ecologists also study how the individuals are dispersed within a population. Some species form clusters, while others are evenly or randomly spaced. However, every population has limiting factors. Changes in the environment or geography can reduce or limit population size. The individuals of a population interact with each other and with other organisms in the community in various ways, including competition and predation, which have direct impacts population size.

Community Interactions
A community is all of the populations of different species that live in an area and interact with each other. Community interaction can be intraspecific or interspecific. Intraspecific interactions occur between members of the same species. Interspecific interactions occur between members of different species. Different types of interactions include competition, predation, and symbiosis. Communities with high diversity are more complex and more stable than communities with low diversity. The level of diversity can be seen in a food web of the community, which shows all the feeding relationships within the community.

Ecosystems
An ecosystem is the basic unit of ecology. An ecosystem is the sum of all the biotic and abiotic factors in an area. Biotic factors are all living things such as plants, animals, fungi, and microorganisms. Abiotic factors include the light, water, air, temperature, and soil in an area. Ecosystems obtain the energy they need from sunlight. Ecosystems also contain biogeochemical cycles such as the hydrologic cycle and the nitrogen cycle. Ecosystems are generally classified as either terrestrial or aquatic. All of the living things within an ecosystem are called its community. The number and variety of living things within a community describes the ecosystem's biodiversity. However, each ecosystem can only support a limited number of organisms known as the carrying capacity.