| A | B | 
|---|
| atom | basic unit of matter | 
| element | pure substance made of only one atom | 
| ion | an atom with an unequal number of protons and electrons | 
| isotope | an atom with an unequal number protons and neutrons | 
| neutron | a subatomic particle found in the nucleus; no charge | 
| proton | a positively charged subatomic particle located in the nucleus | 
| electron | orbits the nucleus of an atom; negative charge | 
| covalent bond | a bond that results from sharing electrons | 
| ionic bond | a bond that results from the transfer of electrons | 
| polar molecule | a molecule with a slight charge on each pole | 
| atomic number | the number of protons in an atom | 
| atomic mass | mass of the protons and neutrons of an atom | 
| solute | in a solution, the substance that is dissolved | 
| solvent | in a solution, the substance that dissolves the other substance | 
| solution | a combination of solute + solvent | 
| acid | releases H+ ions; pH of 1 to 6 | 
| base | releases OH- ions in water; pH of 8 to 14 | 
| homeostasis | maintaining stable internal conditions | 
| multicellular | 2 or more cells | 
| unicellular | one cell | 
| sexual reproduction | requires the union of two cells | 
| asexual reproduction | binary fission or cloning | 
| hypothesis | an educated guess; it must be testable | 
| independent variable | the variable that is manipulated | 
| control variable | the variable that is left alone; used for comparison. | 
| theory | a concept or idea that has been repeatedly tested; it is widely accepted because there is a lot of evidence to support it | 
| dependent variable | the variable that is being measured; what you are trying to figure out | 
| hydrophilic | a substance that interacts with water | 
| hydrophobic | a substance that does not interact with water. | 
| evolution | change over time | 
| organelle | a structure within a cell that carries out a specific function | 
| tissue | a group of similar cells that perform a similar function. | 
| organ | a group of tissues that work together to perform one or more complex functions | 
| population | same species, same place, same time | 
| community | different species, same place, same time | 
| ecosystem | a community of living things and the physical environment with which they interact | 
| electronegativity | the measure of the strength of attraction an atom has for electrons that are being shared in a covalent bond | 
| polar covalent bond | a covalent bond in which electrons are being shared unequally; results in a slightly negative charge on one end and a slightly positive charge on the other | 
| nonpolar covalent bond | a covalent bond in which electrons are shared equally | 
| hydrogen bond | a chemical bond that links an already covalently bonded hydrogen atom with a second electronegative atom | 
| specific heat | the amount of energy needed to raise the temperature of 1gm of a substance by 1 degree C. | 
| cohesion | water's ability to stick to itself | 
| adhesion | water's ability to stick to other substances | 
| surface tension | an increased attraction of water molecules at the surface to the water molecules below the surface. | 
| buffering system | a physiological system that functions to keep pH within normal limits of an organism |