AP Science Placement Test Important Terms: Biology, Chemistry, Physics, Environmental Science

Cell

The basic unit of life.

Organelle

A structure inside a cell that performs a specific job.

Nucleus

Controls cell activities and contains DNA.

DNA

Genetic material that carries instructions for traits.

Chromosome

A structure made of DNA containing genes.

Gene

A section of DNA that determines a trait.

Mitosis

Cell division that creates identical cells.

Meiosis

Cell division that creates sex cells.

Photosynthesis

Process plants use to make food from sunlight.

Cellular Respiration

Process cells use to release energy from glucose.

Homeostasis

Maintaining stable internal conditions.

Osmosis

Movement of water through a membrane.

Diffusion

Movement of particles from high to low concentration.

Ecosystem

Living and nonliving things interacting in an area.

Producer

Organism that makes its own food.

Consumer

Organism that eats other organisms.

Decomposer

Organism that breaks down dead material.

Habitat

Place where an organism lives.

Species

Group of organisms that can reproduce together.

Evolution

Change in species over time.

Natural Selection

Organisms with helpful traits survive and reproduce more.

Biodiversity

Variety of living organisms in an area.

Enzyme

Protein that speeds up chemical reactions.

Protein

Molecule used for structure and functions in the body.

ATP

Main energy source for cells.

Membrane

Thin layer controlling what enters and leaves the cell.

Mutation

Change in DNA sequence.

Atom

Smallest unit of an element.

Element

Pure substance made of one type of atom.

Compound

Substance made of two or more elements chemically combined.

Molecule

Two or more atoms bonded together.

Proton

Positively charged particle in the nucleus.

Neutron

Neutral particle in the nucleus.

Electron

Negatively charged particle outside the nucleus.

Atomic Number

Number of protons in an atom.

Mass Number

Total number of protons and neutrons.

Periodic Table

Chart organizing elements by atomic number.

Ion

Charged atom formed by gaining or losing electrons.

Ionic Bond

Bond formed by transfer of electrons.

Covalent Bond

Bond formed by sharing electrons.

Chemical Reaction

Process where substances change into new substances.

Reactant

Starting substance in a chemical reaction.

Product

Substance formed in a chemical reaction.

Acid

Substance with pH below 7.

Base

Substance with pH above 7.

pH Scale

Measures how acidic or basic a substance is.

Catalyst

Substance that speeds up a reaction without being used up.

Solution

Mixture where one substance dissolves in another.

Solute

Substance being dissolved.

Solvent

Substance doing the dissolving.

Density

Mass per unit volume.

Matter

Anything with mass and volume.

Law of Conservation of Mass

Matter cannot be created or destroyed.

Mole

Unit used to count particles in chemistry.

Mixture

Combination of substances not chemically bonded.

Physical Change

Change in appearance without forming a new substance.

Chemical Change

Change that forms a new substance.

Boiling Point

Temperature where a liquid becomes a gas.

Melting Point

Temperature where a solid becomes a liquid.

Force

A push or pull on an object.

Mass

Amount of matter in an object.

Weight

Force of gravity acting on an object.

Gravity

Force pulling objects toward Earth.

Motion

Change in position over time.

Speed

Distance traveled per unit of time.

Velocity

Speed in a specific direction.

Acceleration

Change in velocity over time.

Momentum

Quantity of motion an object has.

Inertia

Tendency of an object to resist changes in motion.

Friction

Force that opposes motion between surfaces.

Work

Force applied over a distance.

Energy

Ability to do work.

Kinetic Energy

Energy of motion.

Potential Energy

Stored energy.

Power

Rate of doing work.

Newton’s First Law

Objects stay at rest or in motion unless acted on.

Newton’s Second Law

Force depends on mass and acceleration.

Newton’s Third Law

Every action has an equal and opposite reaction.

Wave

Disturbance that transfers energy.

Frequency

Number of waves passing a point per second.

Wavelength

Distance between wave peaks.

Wave Speed

Speed a wave travels.

Electric Current

Flow of electric charge.

Voltage

Electrical potential difference.

Resistance

Opposition to electric current.

Circuit

Path through which electricity flows.

Magnetism

Force caused by magnetic fields.

Light Year

Distance light travels in one year.

Environment

All living and nonliving things around us.

Ecosystem

Organisms interacting with each other and their environment.

Biome

Large region with a specific climate and organisms.

Habitat

Natural home of an organism.

Population

Group of the same species in one area.

Community

Different populations living together.

Renewable Resource

Resource naturally replaced over time.

Nonrenewable Resource

Resource that cannot quickly be replaced.

Conservation

Protection and careful use of resources.

Sustainability

Using resources without harming future generations.

Pollution

Harmful substances entering the environment.

Air Pollution

Contamination of the atmosphere.