Environment means “surroundings.”  A living thing's environment is made up of all of the living and non living materials around it, including plants, animals, air, soil, heat, light, food, water, and anything else that plays any role in its life.

The natural development of a living thing over time is its natural history.

Ecology is the study of the relationship among organisms (living things) and their environments.

Scientific methods are problem solving methods scientists use.  The steps include defining the problem, making a hypothesis (a question or statement that can be tested), testing the hypothesis, analyzing results, and making conclusions.

An organism is a living thing—an individual capable of carrying on the activities of life.

The biosphere is all parts of Earth where life exists, either on land, in water, or in the air.

In photosynthesis, green plants, algae, and some other organisms capture the energy of sunlight and change it into a form of energy that they can use or store.  Most of the energy that power life in Earth's biosphere is made available through the process or photosynthesis.

Factors such as rainfall, sunlight, temperature, the nearness of large bodies of water (oceans), and elevation determine the climate (the general weather pattern) in an area.

A population is all of the individuals of the same species that live and interact with one another in the same place at the same time.

A community is made up of all of the interacting populations in n environment.

An ecosystem is a community of organisms and their environment, all working together as a natural unit.

A niche is the way in which a particular species or individual organism fits in a community, including the way it feels, the space it takes up, how it reproduces, and how it interacts with non living factors.

A habitat is the physical place where an organism lives out its life.

Producers are organisms such as green plants that make food from carbon dioxide and water, using the Sun's energy.  Through photosynthesis, they make the Sun's energy available to other organisms.

Consumers are organisms that cannot make their own food; they must eat other organisms to get energy.

Symbiosis is the close association between two or more organisms of different species.

A limiting factor is anything that limits the survival, reproduction, distribution, or number of organisms in an environment.

A food chain is a simple model that shows how energy from producers is passed from one consumer to another within an ecosystem.

A food web is a model that shows all of the feeding relationships in an ecosystem.  It usually appears as a network of connected food chains.

Transpiration is the loss of water vapor through pores in the leaves of plants.

Excretion is when an organism releases the waste products of its life processes to the outside environment.

Respiration is the process in which the cells of an organism break down food to release energy.

Soil erosion occurs when soil is worn away by water, wind, or glaciers.

Petroleum, natural gas, peat, and coal are fossil fuels, which formed from organisms that decayed in the absence of oxygen.

Renewable resources are replenished by natural processes.  Renewable resources include fresh water, fresh air, soil fertility, organisms, and elements like carbon and nitrogen.  Renewable resources also include inexhaustible resources, such as the Sun's energy.

Nonrenewable resources exist in limited amounts and are not replaced through natural processes.  They include oil, coal, natural gas, copper, aluminum, and the products made from these resources.

A pollutant is any material that can harm the health, survival, or well-being of an organism.

The greenhouse effect warms Earth when gases in the troposphere trap heat near Earth's surface.  Sunlight travels through the atmosphere and reflects off the surface; then some of the heat is absorbed by water vapor and greenhouse gases and radiated back toward Earth's surface.

Physical or chemical pollutants such as particulates and weak acids contaminate the air create air pollution.

Particulates are tiny, solid particles of dust, ash, soot, pollen, and other visible pollutants in the air.

Acid rain has a pH lower than that of ‘normal’ rainfall.  Acid rain leaches nutrients from soil, makes standing water acidic, and damages plants and buildings.

Conservation is the careful, planned management of a natural resource to preserve and protect it.

A solid waste is any unwanted material that is not a gas or a liquid.  Solid wastes may include such solids as metals, plastics, paper, and spoiled food.

Hazardous wastes are any solid wastes that contain toxic compounds are unstable, catch fire easily, or corrode metals.

Bioremediation is using organisms such as plants and bacteria to destroy hazardous wastes or make them harmless.

An extinct species no longer exists.  All the individuals have died and the species has disappeared from Earth.

An endangered species has so few individual survivors left that it could become extinct.

Threatened species are declining in numbers in the wild and are likely to become endangered.