| A | B |
|---|
| acceleration | the amount of change in speed per unit of time |
| amplitude | the height of a wave from its trough or crest to its midpoint |
| atomic mass | the combined mass of protons in and neutrons in an atom |
| atomic number | the number of proton in an atoms nuleus |
| atoms | smallest unit of matter; extremely small particles that make up matter |
| adaption | the ability of an organism to survie and reproduce in its environment becasue of certain special charachteristics |
| altitude | the vertical distance above or below sea level |
| angiosperm | a plant in which fruit forms around the seeds, covered seeds |
| anther | part of a flower where pollen is made |
| apparent motion | the illusion created by the Earth's rotation and revolution that makes it appear as thought the sun and other stars are moving around the Earth |
| asexual reproduction | reproduction in which the offspring has only one parent |
| axial tilt | the incline in the Earth's axis that causes the poles to lean toward and away from the Sun |
| axis | imaginary line that connects the North and South poles, in which the Earth rotates on |
