Living Things and the Environment Habitats An organism

Living Things and the Environment

Habitats An organism obtains food, water, shelter, and other things it needs to live, grow, and reproduce from its environment. An organism is a living thing. A habitat is a place that an organism needs to live, grow, and reproduce.

Biotic Factors An organism interacts with the living parts of its habitat. Each organism affects all other organisms in its habitat. The living parts of a habitat include all the living things in it such as plants, animals, and microorganisms. The living parts of a habitat are called biotic.

Abiotic Factors An organism interacts with the nonliving parts of its habitat. Each organism affects all the non-living parts of its habitat. The non-living parts of a habitat are called abiotic. Abiotic factors include water, sunlight, air, soil, and temperature.

Level of Organization The smallest level of organization is a single organism, which belongs to a population that includes members of its species. The population belongs to a community of different species. The community and abiotic factors together form an Ecosystem. A species is a group of organisms that look alike and can mate and produce fertile offspring. A population includes all the members of the same species that live in an area. All the different populations in an area make up a community. An ecosystem is the community of organisms in an area and the non-living parts of the area. Ecology is the study of how living things affect one another and the environment.

Studying Populations Some methods of determining the size of a population are direct and indirect observations, sampling, and mark-andrecapture studies. Direct observation is finding the size of a population by counting exact numbers. Indirect observation is finding the size of a population by looking for signs of an organism such as nests. Sampling uses a small sample area and the number of organisms living in it, then estimating the number for the total population. Mark and Capture, first you capture then mark and track and then recapture to get an estimate of the total population.

Limiting Factors Some limiting factors for populations are food, water, space, and weather conditions. A limiting factor causes a population to get smaller. The amount of space can limit a population. The amount of food and water available can limit a population. The largest population that an area can support is called the carrying capacity.

Adapting to the Environment Every organism has a variety of adaptations that are suited to its specific living conditions. Natural Selection is the way characteristics become common in a species. Organisms survive to pass along characteristics that have helped them adapt. A niche is the role that an organism has in its environment. It is the way an organism “makes its living”.

Competition, Predation, and Symbiosis are three major types of interactions among organisms. Competition is the struggle between organisms to survive. Predation is when one organism kills another food. (Predator kills, Prey is attacked) Symbiosis occurs when two organisms live together mutually and can’t exist without each other.

Changes in Communities Primary Succession is the series of changes that occur in an area where no soil or organisms exist. The series of changes that occur in a community over time is called succession. Primary succession occurs when almost no organisms exist. (Pioneer organisms-first to appear, Climax Community-Fully developed ecosystem) After a volcano forms an island there is primary succession. Secondary succession occurs where an ecosystem has been changed, like after a forest fire destroys an ecosystem.

Energy Flow in an Ecosystem Each of the organisms in an ecosystem fills the energy role of producer, consumer, or decomposer. Energy enters most ecosystems as sunlight. An organism that can make its own food is a producer (autotroph- plant). Organisms that get their energy by eating other organisms are consumers (Heterotrophs-herbivores, carnivores, omnivores). Organisms that break down dead and decaying organisms are called decomposers.

Food Chains and Webs The movement of energy through an ecosystem can be shown in diagrams called food chains and food webs. A food chain shows how a series of organisms eat other organisms. A food web is made up of many food chains. Producer---->1 st Level Consumer---->2 nd Level Consumer