An organized way of gathering and analyzing evidence about the natural world

A process of noticing and describing events or processes in a careful, orderly way

A possible explanation for a set of observations or a possible answer to a scientific question

An experiment in which only one variable is changed

The group in an experiment that is exposed to the same conditions as the experimental group except for one independent variable

Evidence; information gathered from observations

A well-tested explanation that unifies a broad range of observations and hypotheses, and enables scientists to make accurate predictions about new situations

A particular preference or point of view that is personal, rather than scientific

The scientific study of life

The genetic material that organisms inherit from their parents

A signal to which an organism responds

The relatively constant internal physical and chemical conditions that organisms maintain

The combination of chemical reactions through which an organism builds up or breaks down materials

The part of Earth in which life exists, including land, water, and air or atmosphere

The basic unit of matter

The center of an atom, which contains the protons and neutrons

A negatively charged particle; located in the space surrounding the nucleus

A pure substance that consists of one type of atom

One of several forms of a single element, each of which contains the same number of protons but different numbers of neutrons

A substance formed by the chemical combination of two or more elements in definite proportions

A chemical bond formed when one or more electrons are transferred from one atom to another

A type of bond between atoms in which the electrons are shared

The smallest unit of most compounds that displays all the properties of that compound

The attraction between molecules of the same substance

The force of attraction between different kinds of molecules

A type of mixture in which all the components are evenly distributed

A mixture of water and nondissolved material

A compound that releases hydrogen ions (H+) in solution; a solution with a pH of less than 7

A compound that releases hydroxide ions (OH-) in solution; a solution with pH of more than 7

A compound that prevents sharp, sudden changes in pH

A compound made up of carbon, hydrogen, and oxygen atoms; a type of nutrient that is the main source of energy for the body

A macromolecule made mostly from carbon and hydrogen atoms; includes fats, oils, and waxes

A macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

A macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair

The monomer for proteins

The monomer for carbohdyrates

The monomer for nucleic acids

The process that changes, or transforms, one set of chemicals into another set of chemicals

The energy that is needed to get a reaction started

A substance that speeds up the rate of a chemical reaction

A protein catalyst that speeds up the rate of specific biological reactions

The study of how organisms interact with each other and with their environment

Any living part of the environment

Group of individuals that belong to the same species and live in the same area

An assemblage of different populations that live together in a defined area

All the organisms that live in a place, together with their physical environment

A group of ecosystems that share similar climates and typical organisms

A physical, or nonliving, factor that shapes an ecosystem

Used to test hypotheses

Used to help understand events that are difficult to study directly; often based on data collected through observation and experimentation

An organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer

First to produce energy-rich compounds that are later used by other organisms

An organism that obtains food by consuming other living things; also called a consumer

An organism that relies on other organisms for its energy and food supply; also called a heterotroph

Kill and eat other animals

Obtain energy and nutrients by eating plant leaves, roots, seeds, or fruits

Eat both plants and animals

Chew or grind detritus particles into smaller pieces

Feed by chemically breaking down organic matter

Consume the carcasses of other animals that have been killed by predators or have died of other causes

A series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

A network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem.

Each step in a food chain or food web

An illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or food web

The total amount of living tissue within a given trophic level

A process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another

The process of converting nitrogen gas into nitrogen compounds that plants can absorb and use

The process by which soil bacteria convert nitrates into nitrogen gas

Day-to-day condition of the Earth's atmosphere

Occurs when organisms attempt to use the same limited resources

Average conditions over long periods of time; year-to-year patterns of temperature and precipitation

Environmental conditions that vary over small distances, for example: south side of a tree or building

When carbon dioxide, methane, and water vapor allow visible light into the atmosphere, but trap heat energy

The horizontal lines used to mark regions of the Earth, like a ladder

Located between 23.5 degrees S and 23.5 degrees N and receives nearly direct sunlight all year

Located between 23.5 degrees and 66.5 degrees North/South. Receives less direct sunlight and varying amounts of sunlight throughout the year.

Located North of 66.5 degrees N and south of 66.5 degrees S. Receives very indirect sunlight and experiences darkness certain times of the year.

Movement of warm and cool water caused by unequal heating of the Earth's surface at different latitudes.

Unequal heating and cooling of Earth's atmosphere causing movement of air masses

The ability to survive and reproduce under a range of environmental circumstances

The general place where an organism lives

Describes what an organism does and how it interacts with biotic and abiotic factors in its environment

Any necessity of life- water, nutrients, light, food, or space

Competition between individuals of the same species

Competition between individuals of different species

No two species can occupy exactly the same niche in exactly the same habitat at exactly the same time

The interaction when one animal captures, kills, and eats another animal

The interaction in which an herbivore feeds on producers

A single species that is vital to ecosystem stability

Relationship when two species live closely together

Relationship when both species benefit

Relationship when one species benefits and the other is harmed

Relationship when one species benefits and the other species is neither harmed nor benefited

More or less predictable step-by-step process in a community following a disturbance

Occurs in an area in which no trace of a previous community is present

First species to populate an area during succession

Occurs in an area that was only partially destroyed by disturbances

a dense covering formed by the leafy tops of tall rain forest trees

the layer in a rain forest found underneath the canopy formed by shorter trees and vines

material formed from decaying leaves and other organic matter

a biome with long cold winters and a few months of warm weather; dominated by coniferous evergreens; also called boreal forest

a layer of permanently frozen subsoil found in the tundra

organisms that live attached to or near the bottom of lakes, streams, or oceans

typically small organisms that drift in, and may swim through, aquatic environments; includes both phytoplankton and zooplankton

an ecosystem in which water either covers the soil or is present at or near the surface for at least part of the year

a kind of wetland formed where a river meets the ocean

the numbers of males and females in different age groups of a population

the movement of individuals into an area occupied by an existing population

the movement of individuals out of an area

a growth pattern in which the individuals in a population reproduce at a constant rate

a growth pattern in which a population's growth rate slows or stops, following a period of exponential growth

the largest number of individuals of a population that a given environment can support

a factor that causes the growth of a population to decrease

a limiting factor that depends on population size

a limiting factor that affects all populations in similar ways, regardless of population size

the scientific study of human populations

a change in a population from high birthrates and death rates to low birthrates and death rates