Key Term

Organism

A living thing.

Habitat

An environment that provides a specific organism needs to live, grow, and reproduce.

Biotic Factor

A living or once living part of an organism's habitat.

Abiotic Factor

A nonliving part of an organism's habitat.

Population

All the members of one species living in the same area.

Community

All the different populations that live together in a certain area.

Ecosystem

The community of organisms that live in a particular area, along with their nonliving environment.

Density

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

Limiting Factor

An environmental factor that causes a population to decrease in size. Examples include food and water, climate and weather, and space and shelter.

Producer

An organism that makes its own food.

Consumer

An organism that obtains energy by feeding on other organisms.

Decomposer

An organism that gets energy by breaking down biotic wastes and dead organisms and returns raw materials to the soil and water.

Food Chain

A series of events in which one organism eats another to obtain energy and nutrients.

Food Web

Consists of many overlapping food chains in an ecosystem.

Energy Pyramid

A diagram that shows the amount of energy that moves from one feeding level to another in a food web.

The Law of Conservation of Mass

The principle that the total amount of matter is neither created nor destroyed during any chemical or physical change.

The Law of Conservation of Energy

The role that energy cannot be created or destroyed.

Evaporation

The process by which molecules at the surface of a liquid absorb enough energy to change to a gas.

Condensation

The change in state from a gas to a liquid.

Precipitation

Any form of water that falls from clouds and reaches Earth’s surface as rain, snow, sleet, or hail.