Lion Science Scientia non habet inimicum nisp ignorantem		Northwest High School Jefferson County, MO

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Abduction - A muscle movement that takes an appendage laterally from the midline.
Abiotic - Nonliving.
Absolute zero - The lowest possible temperature.
Abyssal zone - The floor of the deep-ocean plane from about 4000 meters down to about 6000 meters.
Acaulescent - Plants with basal leaves and a leafless flower stalk.
Acceleration - The rate of change in velocity.
Acccelerators - Large, complicated machines used to shoot high energy particles into atoms for atomic research.
Accessory fruit - A fruit composed of the plant ovary wall plus other flower parts.
Accuracy - Refers to how close a measurement is to the true value of the quantity.
Achene - A dry fruit with more than one carpel, a single seed, and the fruit coat free from the seed coat.
Acid - A substance that produces the hydronium ion, H₃O ⁺ in solution.
Acid anhydride - An oxide that produces an acid when dissolved in water.
Acid rain - Rain containing sulfuric acid (H₂SO₄) produced by the burning of fossil fuels with a high sulfur content.
Acoustics - The science of sound.
Activated complex - Formed when molecules collide with enough kinetic energy to cause changes in the electron clouds of both molecules, allowing a reaction to proceed.
Activation energy - The energy needed to start a chemical reaction.
Adaptation - Any trait giving an organism an advantage in a certain environment.
Adaptive radiation - Many species appear to be related to a single ancestral species.
Addiction - A dependence on a substance.
Adduction - Moves an appendage toward the midline.
Adenine - One of two double carbon ring nitrogen bases in DNA.
Adipose - Fleshy or fatty.
Adventitious root - A root that grow from a plant's stem or leaves.
Aerobic - Refers to the use of molecular oxygen.
Aggregate fruit - Derived from more than one pistil on one flower.
Agonists - Muscles primarily responsible for an action due to their contraction.
AIDS - Acquired immunodeficiency syndrome.
Alcohols - Organic compounds containing the hydroxyl group.
Algae - Plant-like protists that carry on photosynthesis.
Alimentary canal - The tube containing food as it passes through the body.
Alkali Metals - Elements in Group 1 on the periodic table.
Alkaline Earth Metals - Elements in Group 2 on the periodic table.
Alkanes - Saturated hydrocarbons with only single bonds.
Alkenes - Unsaturated hydrocarbons with at least one double bond.
Alkynes - Unsaturated hydrocarbons with at least one triple bond.
Allantosis - The amniote egg membrane that stores embryonic wastes.
Allele - Any of the several alternative forms of a gene.
Allele frequency - The percentage of a specific allele of a gene in the gene pool.
Alloy - Any mixture of two or more substances, as long as at least one is a metal.
Alpha particle - A helium nucleus given off by the nucleus of a larger atom.
Altair 8800 - The first personal computer, produced in kit form in 1975.
Alternating current - AC electricity whose current flow changes direction periodically.
Alternation of generations - The alternation between diploid and haploid cells or organisms.
Altricial - Birds that lay few eggs and incubate them for a short period.
ALU - The arithmetic logic unit that performs calculations in computers and calculators.
Alveoli - Small sacs that increase the surface area of the lungs.
AMA - Actual Mechanical Advantage, the factor by which a mechanism multiplies the force put into it.
Amino acids - The 20 nitrogen-containing organic compounds used to build proteins.
Ammocoete - The filter-feeding larval stage of a lamprey.
Ammonification - Bacteria decomposers breaking down amino acids from dead animals and animal wastes into NH₄OH.
Amnion - The membrane enclosing the fluid in which an embryo developes.
Amorphous - A substance whose particles have no regular pattern.
Ampere - A measure of the amount of electric current flowing past a given point per second.
Amphetamine - A type of stimulant.
Amphoteric - A substance that acts as either acid or base, depending on what it reacts with.
Amplitude - The maximum distance molecules are displaced from their rest position in a wave.
Anaerobic - Refers to the absence of molecular oxygen.
Anaphase - The stage of mitosis in which the chromosomes move to opposite ends of the cell.
Androecium - A term for all the stamens of a flower together.
Angiosperms - The flowering plants.
Anhydrous - Without water.
Animal - A multicellular, eukaryotic, heterotrophic organism.
Anions - Ions with a negative charge.
Annuals - Herbaceous plants that live for only one year.
Antagonists - Muscles that relax to smooth the action of the agonists.
Antenna pigments - The bulk chlorophyll molecules that collect and channel energy to the reaction centers..
Anterior - Refers to the front end of an organism.
Anther - The part of the plant stamen that produces pollen grains
Antibiotics - Natural chemicals that inhibit the growth of some bacteria.
Anticoagulin - A chemical in snake venom that thins the blood.
Antimatter - Matter composed of antiparticles.
Anti-oncogene - A gene that suppresses tumor growth.
Antiparticles - Particles that have exactly the same mass but opposite charges.
Antlers - Solid bone extensions from the skull of most species of deer.
Aorta - The body's major artery leading from the left ventricle of heart to the body.
Aphotic zone - A zone of deep, permanently dark ocean water.
Apical meristem - Located at the tips of stems and roots, this meristem produces growth in length known as primary growth.
Apomixis - The process by which plants form seeds without gamete formation or fertilization.
Appendicular skeleton - The part of a vertebrate skeleton containing the skull, spine, and ribs.
Applied science - The practicle use of scientific information; technology.
Aqueous - Having to do with water.
Aquifer - A layer of relatively porous and permeable underground rock, allowing water to move through it.
Arachnid - A term commonly used as a group name for spiders and their close relatives.
Arachnoid layer - The middle layer of the three protective tissues of the brain, consisting of a web-like elastic tissue.
Archaebacteria - A relatively small kingdom of bacteria.
Archimedes' Principle - The buoyant force of an object is equal to the weight of the fluid displaced by the object.
Aromatic hydrocarbons - Hydrocarbons containing benzene, C₆H₆.
Arrhenius Theory - One of the three common acid/base theories.
Arteries - Thick-walled blood vessels that carry blood under high pressure away from the heart.
Arthropod - An animal characterized by an exoskeleton and jointed appendages.
Asexual reproduction - Producing offspring without the use of gametes.
Asphyxiant - A gas or vapor that causes injury by reducing the amount of oxygen available for breathing.
Astronomy - The study of objects in the universe.
Asymmetrical - Having no definate shape and cannot be divided into equal parts.
Atom - The smallest particle of an element.
Atomic number - Represents the number of protons in an atom.
ATP - Adenosine triphosphate is the molecule most organisms can actually use for energy.
Atrium - The collecting chamber of the heart.
Autonomic nervous system - Nerves that control involuntary muscles.
Autotrophic - Organisms that are able to produce their own food.
Auxins - A group of plant hormones that promote cell elongation, apical dominance, and rooting.
Average Speed - The total distance divided by the total amount of time traveled.
Avogadro's Number - 6.02 X 10 ²³
Avogadro's Principle - At equal temperature and pressure, equal volumes of gases contain the same number of molecules.
Axial skeleton - The part of a vertebrate skeleton containing the arms, shoulders, legs, and pelvis.
Axon - An elongated extension of the neuron body that carries impulses away from the cell.
Azimuth - A direction from one place toward another expressed as degrees on a compass.

Bacilli - A term used to indicate rod-shaped bacterial cells.
Background radiation - Radiation found naturally in the environment.
Bacteria - Single-cell organisms with no nucleus.
Bacteriophage - A virus that commonly infects bacteria.
Balanced Force - When a number of forces act on a body simultaneously and the resultant of these forces is zero then the forces are said to be balanced.
Balanced equation - A chemical equation with the same number of each type of atom on both sides.
Barbiturate - A type of depressant.
Bark - The tissues outside the wood and the cambial layer of woody stems.
Barometer - A device used to measure atmospheric pressure.
Baryons - Regular subatomic particles composed of three quarks.
Base - A substance that produces the hydroxide ion, OH ^- in solution.
Base unit - physical units defined by an operational definition - i.e. gram, liter, meter, second. All other physical units can be derived from these base units.
Basic anhydride - An oxide that produces a base when dissolved in water.
Batesian mimicry - A harmless species mimicing the warning coloration of a dangerous species.
Bathyal zone - The ocean floor from the continental shelf down to about 4000 meters.
Battery - A series of connected electrochemical cells.
Beaker - The most versatile piece of glassware in the chemisty lab.
Becquerel - The unit for the measure of decay in radioactive nuclides.
Benign - Refers to a tumor whose cells remain attached to the parent tumor.
Benthic zone - The ocean floor.
Bernoulli's Principle - The pressure in a moving stream of fluid is less than the pressure in the surrounding fluid.
Berry - A fleshy fruit composed of more than one carpel with few to many seeds.
Beta particle - An electron given off by the nucleus of an atom.
Bicuspids - Teeth with two points for shearing and shredding.
Biennials - Short-lived herbaceous plants that produce only vegetative growth the first year, then bloom the second year.
Big Bang Theory - A theory explaining the formation and operation of the Universe.
Binary acid - An acid composed of hydrogen and one other element.
Binary compounds - Compounds composed of two elements.
Binary fission - DNA replicates and then the cell pinches inward and splits in two.
Binomial nomenclature - A two name system for writing scientific names.
Biochemistry - The study of the chemical reactions of life.
Biodegradable - Subject to decay by microorganisms.
Biogeochemical cycles - The process by which abiotic materials move from the atmosphere or soil into organisms and back again.
Biology - The study of living things.
Biomass - The weight of living matter in a particular area.
Biomaterials - Mechanical devices used as replacements for various parts of the human body.
Biome - A large geographical area described by its climate, soil, flora, and fauna.
Biosphere - The total of all ecosystems on Earth.
Biotic - Living.
Biotic potential - The maximum growth rate of which a population is physiologically capable.
Bit - A single electronic switch.
Bivalve - A filter-feeding mollusk with two shells.
Black hole - A concentration of matter which has a gravitational field strong enough to curve spacetime completely around upon itself so that nothing can escape, not even light.
Blastopore - The point where a blastula begins to fold inward.
Blastula - A hollow sphere of cells formed as zygote cells divide.
Blight - A quickly developing decay or discoloring of leaves, stems, or flowers caused by plant parasites.
Boiling point - The temperature at which the vapor pressure of a liquid is equal to standard atmospheric pressure; changing a liquid into a gas.
Boiling point elevation - The addition of a nonvolatile solute making a solution boil at a higher temperature.
Bones - The hard, mineral structures making up the skeleton of most vertebrates.
Bosons - The force carriers in atoms.
Boyle's Law - The volume of a fixed amount of gas varies inversely with the pressure of the gas.
Brain stem - Connects the cerebrum with the spinal cord.
Bronchi - The two branches of the trachea leading to the lungs.
Bronchioles - The smallest branches of the bronchial tubes.
Bronsted - Lowery Theory - One of the three common acid/base theories.
BTU - British Thermal Unit - One BTU is the amount of thermal energy necessary to raise the temperature of one pound of liquid water by one degree Fahrenheit
Buffer - A solution that can absorb moderate amounts of acid or base without a significant change in pH.
Bulb - Fleshy, upright, underground stems with fleshy leaves or scales.
Buoyancy - The force of a fluid that pushes up on an object in the fluid.
Buret - A graduated pipet with a dispensing device at one end.
Bursa - A fluid-filled sac in the knee and shoulder joints to cushion the bones.
Byte - A string of eight bits.