TASC Transdisciplinary Science key terms

A testable, tentative explanation for an observation that can be supported or rejected by evidence gathered in an investigation. It must be phrased so that observations could potentially contradict it.

The factor that an investigator deliberately changes or selects across trials in an experiment, so its effect on the measured outcome can be examined.

The outcome that is measured or observed in an experiment; its value is expected to respond to changes in the factor the investigator manipulates.

A test in which all factors except the one being studied are held constant, so any change in the measured outcome can reasonably be attributed to that single factor.

The comparison set in an experiment that does not receive the treatment being tested, providing a baseline against which the treated group's results are judged.

A broad, well-supported explanation for a body of related observations that has survived repeated testing and unifies many findings; it is not a guess.

A concise statement, often mathematical, describing a consistent pattern observed in nature, such as how force relates to mass and acceleration, without explaining why the pattern occurs.

Information obtained through direct observation, measurement, or experimentation rather than from reasoning alone, authority, or tradition. It is the basis for accepting or rejecting scientific claims.

The degree to which repeated measurements or repeated investigations produce consistent results under the same conditions, indicating that random error is small.

The extent to which a measurement or investigation actually measures or tests what it claims to, so conclusions drawn from the data are well founded.

A systematic error or slant in design, sampling, measurement, or interpretation that pushes results consistently in one direction away from the true value.

The number of individuals or trials included in a study. Larger samples generally reduce the influence of chance variation and make results more trustworthy.

The smallest unit of life that can carry out all basic life processes; all organisms are made of one or more of these membrane-bound units.

The thin, flexible barrier surrounding a cell that separates its interior from the environment and controls which substances enter and leave.

A membrane-bound organelle in eukaryotic cells where cellular respiration releases usable energy from food molecules and stores it in ATP.

The green organelle found in plant cells and some algae where photosynthesis captures light energy and uses it to build sugars from carbon dioxide and water.

The process by which organisms with chlorophyll use light energy to convert carbon dioxide and water into glucose and oxygen, storing energy in chemical bonds.

The set of chemical reactions in cells that break down glucose, releasing energy that is captured in ATP, with carbon dioxide and water as common waste products.

Adenosine triphosphate, the small molecule that cells use as a ready energy currency; releasing its terminal phosphate group powers many cellular reactions.

Deoxyribonucleic acid, the double-stranded molecule that stores genetic instructions in the sequence of its bases and is copied before cells divide.

A segment of DNA that carries instructions for making a functional product, usually a protein, and is passed from parents to offspring.

A long DNA molecule wrapped with proteins into a compact structure; humans carry 46 in most body cells, arranged in 23 pairs.

A change in the base sequence of DNA that may arise from copying errors or environmental damage and can alter the trait a gene influences.

The process by which individuals with inherited traits that improve survival and reproduction in a given environment leave more offspring, shifting trait frequencies in a population over generations.

An inherited feature or behavior that helps an organism function better in its environment, often shaped over many generations by natural selection.

The net movement of particles from an area of higher concentration to an area of lower concentration, driven by random molecular motion until the distribution is even.

The diffusion of water across a selectively permeable membrane from a region of lower dissolved-solute concentration to a region of higher solute concentration.

The smallest unit of an element that retains that element's chemical properties, consisting of a nucleus of protons and neutrons surrounded by electrons.

A pure substance made of only one kind of atom, defined by its atomic number and listed on the periodic table; it cannot be broken down chemically into simpler substances.

A substance formed when atoms of two or more different elements are chemically bonded in fixed proportions, giving properties unlike those of the starting elements.

An atom or group of atoms that has gained or lost one or more electrons, giving it a net positive or negative electric charge.

A chemical bond formed when two atoms share one or more pairs of electrons, typically between nonmetals, as in the bonds holding water molecules together.

An attraction between oppositely charged ions that holds them together in a compound, typically formed when a metal transfers electrons to a nonmetal.

A scale from 0 to 14 expressing the concentration of hydrogen ions in a solution; values below 7 are acidic, 7 is neutral, and above 7 is basic.

The principle that energy cannot be created or destroyed in ordinary processes, only transferred between objects or converted from one form to another.

The energy an object possesses because of its motion, calculated as one-half the mass times the square of the speed.

Stored energy an object has because of its position or condition, such as a raised mass in a gravitational field or a stretched spring.

The relationship stating that the net force on an object equals its mass multiplied by its acceleration, so acceleration grows with force and shrinks with mass.

The theory that Earth's rigid outer shell is broken into large plates that move slowly over the mantle, causing earthquakes, volcanoes, and mountain building at their boundaries.

Heat transfer by the circulation of a fluid in which warmer, less dense material rises and cooler, denser material sinks, driving plate motion and many weather patterns.

The ongoing set of processes by which igneous, sedimentary, and metamorphic rocks are formed, broken down, and transformed into one another over geologic time.

The transport of weathered rock and soil material from one place to another by agents such as flowing water, wind, ice, or gravity.

The continuous movement of water among the ocean, atmosphere, and land through evaporation, condensation, precipitation, and runoff, powered mainly by solar energy.

The warming of a planet's surface that occurs when certain atmospheric gases absorb and re-emit outgoing infrared radiation, slowing heat loss to space.

The Sun and all objects gravitationally bound to it, including eight planets, their moons, dwarf planets, asteroids, and comets orbiting in roughly the same plane.

The attractive force between any two objects with mass; its strength grows with the masses involved and weakens with the square of the distance between them.

A crosscutting idea that events have reasons and outcomes; scientists test proposed links by changing one factor and observing whether the measured result responds.

A crosscutting concept emphasizing that the size, time span, and amount of a system matter, and that phenomena look different at very small or very large scales.

A crosscutting idea that objects and processes can be studied as sets of interacting parts, with simplified models used to predict and explain behavior.

A simplified representation, such as a diagram, physical object, or set of equations, used to describe, explain, or predict how a real system behaves.