Science Terms A-C

the rate that velocity changes per unit of time and the direction it changes in, computed from the change in velocity divided by the change in time. Common units are meters per second squared (m/s2).

the acceleration of an object that is only acted on by the force of the Earth’s gravity. This value is given the symbol g, and near the surface of the Earth it has a value of approximately 9.8 m/s2. The direction of acceleration due to gravity is downward.

the closeness of an experimental measurement to the accepted or theoretical value

a substance that is a proton donor. The pH of an acid is less than 7.

a stage in the scientific method where patterns of the observations are made

a solution in which the solvent is water

the vascular tissues that carry blood away from the heart

the study of the planets, stars, and space

the smallest structure that has the properties of an element. Atoms contain positively charged protons and uncharged neutrons in the nucleus. Negatively charged electrons orbit around the nucleus.

(Adenosine Triphosphate) a chemical that is considered to be the “fuel” or energy source for an organism

the chambers of the heart that receive blood

a substance that is a proton acceptor. The pH of a base is greater than 7.

the examination of the performance of an instrument in an experiment whose outcomes are known, for the purpose of accounting for the inaccuracies inherent in the instrument in future experiments whose outcomes are not known

vascular tissues that receive blood from the arterioles and releases the blood to the venuoles

an agent that changes the rate of a reaction, without itself being altered by the reaction

the extension of the Earth’s equator out onto the celestial sphere

the extension of the Earth’s north and south poles onto the celestial sphere

the imaginary sphere which all the stars are viewed as being on for the purposes of locating them

an organelle found in all cells that acts as the passageway through which materials can pass in and out. This organelle is highly selectively permeable, only allowing materials to pass through that it “chooses” chemically.

an organelle found primarily in plant cells and fungi cells, and also some bacteria. The cell wall is a strong structure that provides protection, support, and allows materials to pass in and out without being selectively permeable.

the net force that acts to result in the centripetal acceleration. It is not an individual force, but the sum of the forces in the radial direction. It is directed toward the center of the circular motion.

a process that involves the formation or breaking of chemical bonds

an organelle that contains the entire DNA of the organism

the part of a vector that lies in the horizontal or vertical direction