8th Grade Vocabulary

FCAT Science Glossary Grade 8

(Knowledge of the terms in the Grade 5 glossary is assumed.) 

abiotic an environmental factor not associated with the activities of living organisms

acceleration rate of change in velocity, usually expressed in meters per second; involves an increase or decrease in speed and/or a change in direction

air resistance force of air on moving objects

allele any of two or more alternate forms of a gene that an organism may have for a particular trait

amplitude in any periodic function (e.g., a wave) the maximum absolute variation of the function

asexual reproduction a form of reproduction in which new individuals are formed without the involvement of gametes

biodiversity the existence of a wide range of different species in a given area or specific period of time

biotic factors in an environment relating to, caused by, or produced by living organisms

calorie unit of energy; the amount of heat needed to raise one gram of water one degree Celsius at standard atmospheric pressure

chemical weathering the breakdown and alteration of rocks at or near Earth’s surface as a result of chemical processes

circuit an interconnection of electrical elements forming a complete path for the flow of current

conduction the transmission of heat through a medium and without the motion of the medium

conservation of energy a fundamental principle stating energy cannot be created nor destroyed but only changed from one form to another

convection heat transfer in a gas or liquid by the circulation of currents from one region to another

crest the peak or highest point on a wave

crust outermost layer of Earth covering the mantle

dependent variable factor being measured or observed in an experiment

deposition the process by which sediment is carried by forces (e.g., wind, rain, or water currents) and left in a certain area

diffraction the change in direction of a wave caused by passing by an obstacle or traveling through an opening

dominance tendency of certain (dominant) alleles to mask the expression of their corresponding (recessive) alleles

ecosystem an ecological community, together with its environment, functioning as a unit

efficiency the relative effectiveness of a system or device determined by comparing input and output

electromagnetic radiation the emission and propagation of the entire range of electromagnetic spectrum including: gamma rays, x-rays, ultraviolet radiation, visible light, microwaves, and radio waves

electron a stable elementary particle that is negatively charged and orbits the nucleus of an atom

entropy a measure of randomness or disorder of a closed system

erosion a combination of natural processes in which materials from Earth’s surface are loosened, dissolved, or worn away and transported from one place to another

fossil fuels the remains of animal or plant life from past geologic ages that are now in a form suitable for use as a fuel (e.g., oil, coal, or  natural gas)

frequency the number of cycles or waves per unit time

gene a specific part of a chromosome or sequence of DNA that determines a particular feature or characteristic in an organism

heterozygous cell or organism that has two different alleles for a particular trait

homozygous cell or organism that has identical rather than different alleles for a particular trait

independent variable the factor that is changed in an experiment in order to study changes in the dependent variable

inertia the property of an object, due to its mass, by which it resists any change in its position unless overcome by force

magnetic field the region where magnetic force exists around magnets or electric currents

mass the amount of matter an object contains

meiosis the process of nuclear division in cells during which the number of chromosomes is reduced by half

mitosis a process of nuclear division in eukaryotic cells during which the nucleus of a cell divides into two nuclei, each with the same number of chromosomes

neap tide a twice-monthly tide of minimal range that occurs when the Sun, Moon, and Earth are at right angles to each other, thus decreasing the total tidal force exerted on Earth

neutral a particle, object, or system that lacks a net charge

neutron a subatomic particle having zero charge, found in the nucleus of an atom

nucleus the center region of an atom where protons and neutrons are located; also a cell structure that contains the cell’s genetic material

ocean basin a depression on the surface of Earth occupied by water plate tectonics theory of global dynamics in which Earth’s crust is divided into a smaller number of large, rigid plates whose movements cause seismic activity along their borders

potential energy energy stored in an object due to the object’s configuration and position

pressure the force exerted per unit area

prism a piece of glass with polished plane surfaces that disperses a beam of white light into its component colors

proton a subatomic particle having a positive charge and which is found in the nucleus of an atom

Punnett square a graphic checkboard used to determine results from a particular genetic cross

radiation emission of energy in the form of rays or waves

recessive an allele for a trait that will be masked unless the organism is homozygous for this trait

screw a type of simple machine that consists of an inclined plane wrapped around a cylinder

sexual reproduction reproduction involving the union of gametes producing an offspring with traits from both parents

spectroscope an instrument that uses a prism to separate and catalog light wavelengths

speed amount of distance traveled divided by time taken; the time-rate at which any physical process takes place

spring tide the tide of increased range that occurs twice monthly at the new and full phases of the Moon

thermal energy internal energy found by adding the kinetic energy of particles making up a substance

tropism the motion of an organism or part of an organism toward or away from an external stimulus

trough the lowest point on a wave

variable an event, condition, or factor that can be changed or controlled in order to study or test a hypothesis in a scientific experiment

velocity defined as the time-rate at which a body changes its position

displacement divided by the time of travel

vibration a repetitive movement around an equilibrium point

virus a noncellular, disease-causing particle that uses the genetic material from its host to reproduce

wavelength the distance between crests of a wave

wedge a type of simple machine that consists of an inclined plane used to separate two objects

wheel and axle a type of simple machine that consists of a rod driven through the center of a cylinder that is allowed to rotate freely, yielding a mechanical advantage equal to the cylinder’s diameter