All the members of one species in a particular area

Population A Population B Both areas have a population of 9.

The number of individuals in an area of a specific size.

Area AArea B Population A has a population density of 9/ yard 2. Population B has a population of 9/ foot 2. The areas have the same population but different population densities. One yard 2 One foot 2

 Population ◦ tells how many organisms there are ◦ is written as a number  328 burch trees  250,000 people  Population Density ◦ Tells how many organisms are in a certain ◦ is written as a number over an area ◦ shows how dense, or “smushed together”, the organisms are.  18 burch trees/ acre  2 people/ meter 2

Counting all the members of the population.

Counting signs of an organism instead of counting the actual organism.

Counting the organism in a small area and then multiplying to find the larger area.

Scientists capture animals and mark them. They go back later and recapture the animals. Scientists see how many are unmarked and then apply a formula to estimate the total population.

An environmental factor that prevents a population from increasing.

The largest population that an area can support.

An organism’s job or role in the ecosystem. Includes: what an organism eats, how it obtains food, and any predators.

The specific environment that provides the things an organism needs to live, grow, and reproduce; an organism’s home. A habitat provides food, water, shelter, living space. Examples: For fungus=moist earth of the forest floor. For an earthworm=tunnels in garden soil.

All the organisms of the same species living in the same area at the same time. Examples: All the prairie dogs in a prairie. All the red oaks of a forest.

All the different populations living in the same area at the same time. Example: All the living things (bacteria, protists, fungus, plants, and animals) in a forest.

A community of living things in an area and their nonliving environment. All the living things in a forest, plus the soil, rocks, water, air temperature, and weather.

An environmental factor that prevents a population from increasing. Examples: Food Water Shelter Living space Weather conditions Number of predators Number of competitors

The largest population that an area can support. Limiting factors often determine the carrying capacity of an area. Populations usually stay around the carrying capacity.

The struggle between organisms to survive as they attempt to use the same limited resources. Two or more predators that feed on the same prey. Snakes and hawks compete for mice.

Often animals can live in the same area and not compete, because they have different niches. They may eat different foods.

A relationship between two organisms in which one organism kills another for food. Also called predation. Examples: A coyote and a rabbit A bird and blueberry bush

A close, ongoing relationship between two organisms of different species that benefits at least one of the organisms. Note: Predation is not symbiotic, because predator-prey relationships are quick, not ongoing.

A symbiotic relationship between two organisms in which both organisms benefit. Example: A sea anemone and a clown fish.

A symbiotic relationship between two organisms in which one organism benefits and the other organism is neither helped nor harmed. Example: A bird builds a nest in a tree.

A symbiotic relationship between two organisms in which one organism benefits and the other organism is harmed. Example: Fleas on a dog

 The organism that a parasite (or virus) lives on or in and is harmed in a parasitic relationship.  The organism that benefits by living on or in a host in a parasitic relationship.

 A behavior or physical characteristic that allows an organism to survive in its environment.