Science Terms A–C

Question 1

acceleration

Answer 1

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).

Question 2

acceleration due

to gravity

Answer 2

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.

Question 3

accuracy

Answer 3

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

Question 4

acid

Answer 4

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

Question 5

analysis

Answer 5

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

Question 6

aqueous solution

Answer 6

a solution in which the solvent is water

Question 7

arteries

Answer 7

the vascular tissues that carry blood away from the heart

Question 8

astronomy

Answer 8

the study of the planets, stars, and space

Question 9

atom

Answer 9

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.

Question 10

ATP

Answer 10

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

Question 11

atria

Answer 11

the chambers of the heart that receive blood

Question 12

base

Answer 12

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

Question 13

capillaries

Answer 13

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

Question 14

catalyst

Answer 14

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

Question 15

celestial equator

Answer 15

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

Question 16

celestial poles

Answer 16

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

Question 17

celestial sphere

Answer 17

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

Question 18

cell membrane

Answer 18

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.

Question 19

cell wall

Answer 19

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.

Question 20

centripetal force

Answer 20

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.

Question 21

chemical change

Answer 21

a process that involves the formation or breaking of chemical bonds

Question 22

chromosome

Answer 22

an organelle that contains the entire DNA of the organism

Question 23

component

Answer 23

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

Question 24

compound

Answer 24

a substance composed of more than one element that has a definite composition and distinct physical and chemical properties

Question 25

concentration

Answer 25

a measure of the amount of solute that is present in a solution. A solution that contains very little solute is called dilute. A solution that contains a relatively large amount of solute is said to be concentrated.

Question 26

conclusion

Answer 26

the last stage of the scientific method, where explanations are made about why the patterns identified in the analysis section occurred

Question 27

constellation

Answer 27

an apparent grouping of stars in the sky that is used for identification purposes. These stars are not necessarily near each other in space, since they are not necessarily the same distance from the Earth.

Question 28

continental rift

Answer 28

the region on a continent where new crust is being created, and the plates on either side of the rift are moving apart

Question 29

convergent boundary

Answer 29

a boundary between two of the Earth's plates that are moving toward each other

Question 30

cosmology

Answer 30

the study of the formation of the universe

Question 31

crystal

Answer 31

a solid in which atoms or molecules have a regular repeated arrangement

Question 32

current

Answer 32

the flow of charge past a point per unit time; current is measured in amperes (A)

Question 33

cuticle

Answer 33

the top layer on a leaf. It is a non-living layer consisting primarily of wax that is produced by the epithelium, a cell layer directly underneath.

Question 34

cytoplasm

Answer 34

a jelly-like substance located in the cell where all of the internal organelles can be found. The cytoplasm consists primarily of water and supports the cell and its organelles.

Question 35

cytoskeleton

Answer 35

organelles that are the internal "bones" of the cell. They exist in thick and thin tubules.

Question 36

calibration

Answer 36

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