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Science Glossary A

Acceleration The Change in Speed divided by the time taken for the change
Acid A substance that turns blue Litmus red and has a pH of less than 7. Acids have sour tastes and a sharp feel
Acid Rain Rainwater with a pH of less than 5.5
Activity Series A list of metals placed in order of how reactive they are
Adaptation A structure or habit that helps an organism to survive in its habitat
Aerobic Respiration In this type of respiration Oxygen is used to release energy from food
Alkali A substance which reacts with an acid to form a salt and water. Alkalis are bases dissolved in water
Alkali Metals The elements of Group I of the periodic table, e.g. Sodium
Alkaline Earth Metals The elements of Group II of the periodic table, e.g. Calcium
Alloy A mixture of metals
Alternating Current (A.C.) An electrical current that constantly changes direction
Altimeter An instrument that measures changes in pressure and translates it into height above sea level
Amp The Unit of Current
Anaerobic Respiration In this type of respiration Oxygen is not used to release energy from food
Area The amount of surface that covers an object
Asexual Reproduction New Individuals are formed from one parent only
Atom The smallest part of an element that still has the properties of that element
Atomic Number The number of protons in an atom of that element
Absolute Zero The lowest theoretical temperature (0K = -273°C) where all molecular activity ceases
Acceleration Rate of change of velocity
Acid A compound that yields hydrogen ions (H+) when in aqueous solution  Acids have a sour taste and turn blue litmus red
Alkali A base that is soluble in water
Alloy A substance formed by the combination of two or more elements, at least one of which must be a metal
Anion A negative ion
Atomic number The number of protons in an atom
Atomic symbol The letters representing each of the elements
Atomic Mass The average mass of an atom
Atoms Composite particles of protons, neutrons and electrons  The smallest part of a substance that can take part in a chemical reaction
Base A compound that yields hydroxide (OH- ) ions when in aqueous solution  Bases have a bitter taste, feel soapy and turn red litmus blue
Boiling point The temperature at which a liquid turns to a vapour
Bond A chemical link between atoms
Capacitance The ability to store an electric charge
Carbohydrates The major energy source within plants and animals: sugars, starches and glucose polymers
Carbon The basic element in all organic compounds
Catalyst A substance that speeds up a chemical reaction but is not used up in it
Cation A positive ion eg Ca++
Cell The smallest independent part of an organism
Charge Either positive or negative
Chemical Formula The ratio of elements in a substance example: the chemical formula of common salt is NaCl, sodium and chlorine in a ratio of 1:1
Chemical Reaction The transformation of substances by the rearrangement of their atoms
Chromosomes DNA molecules that contain the set of instructions required to build and maintain cells
Compound A substance containing more than one element
Conduction Heat or electricity transfer from molecular or atom to atom, eg: heat passing along a metal bar
Convection Heat transfer through the movement of a fluid, eg: warm air rising
Covalent bond A bond formed between atoms that share pairs of electrons
Crystal Solid substance with a regular geometirc arrangement of atoms
Density The mass per unit volume in a substance
Diffraction The bending of light when it passes from one transparent medium to another example from water to glass or air
Diffusion The random movement of molecules within a fluid
DNA Deoxyribonucleic Acid - Genetic material located inside the nucleus
Elasticity The ability of a body to regain its original shape after deformation
Electric Current A flow of electrons through a conductor, the size of the current is proportional to the rate of electron flow
Electrons Negatively charged atomic particles
Electromagnetic waves Waves with both an electric and magnetic component They are: radio, micro, infra-red, visible light, ultraviolet, X and gamma rays
Electrolyte An ionic solution that is an electrical conductor
Element A substance composed of atoms all with the same atomic number or A substance that cannot be split chemically into smaller substances
Endothermic reaction A reaction in which heat is absorbed ie: melting or boiling
Energy The ability to do work Work is done by transferring energy from one form to another For example the chemical energy in a fuel is converted to thermal energy as it burns
Enzymes Biological catalysts, proteins that control specific processes within the body
Equilibrium A stable situation in which products and reactants are balanced
Evaporation The change of state of a substance from a liquid to a gas below its boiling point
Evolution Natural selection, the survival of the fittest, is the driving force behind it Fitness is the ability to survive and reproduce, not necessarily a measure of physical fitness
Exothermic reaction A reaction from which heat is lost eg: combustion
Fats Molecules of fatty acids or glycerol
Fission Splitting the nucleus of an atom into smaller units
Fluid A liquid or gas
Force A push or a pull An action (transfer of energy) that will accelerate a body in the direction of the applied force
Frequency The rate as which periodic motion repeats itself
Friction A measure of the resistance felt when sliding one body over another
Fusion 1 - Change of state of a substance from a solid to a liquid  2 - The joining together of two atomic nuclei
Gametes Sex cells (Spermatozoa or Ova) that carry the genes donated by each parent
Gene A unit of inheritance - A section of DNA
Gravity The attraction that all bodies have for one another
Halogen Highly reactive gases forming group 7 of the periodic table example Chlorine
Heat A form of energy or The internal energy of a body (substance)
Hydrocarbon Compounds containing only hydrogen and carbon atoms
Inertia Tendency of a body to remain at rest or move in straight line
Inheritance Determined by a set of chromosomes  These originate in the parents and are passed on to an offspring during fertilisation It follows then that since chromosomes are inherited, all the features of an organism must be inherited
Ion Atom with an unbalanced electrical charge caused by the loss or gain of one or more electrons
Ionic bond An bond formed by the electro-magnetic attraction between ions of opposite charge
Isotope An element that has more or less neutrons than normal  Many isotopes are radioactive
Kinetic energy The energy possessed by a body in motion
Latent heat The amount of energy required to change a solid to a liquid or liquid to a gas
1st Law of Thermodynamics The amount of energy in the universe is fixed  It cannot be created or destroyed only changed from one state to another
2nd Law of Thermodynamics Heat cannot pass from a cold to a hot body The opposite condition where heat always flows from a hot to a cold body is valid for the whole universe
Lens Light modifier  Convex lenses focus and concave lens diffuse light waves
Light The visible part of the electromagnetic spectrum: red, orange, yellow, green, blue, indigo and violet - White light is a combination of all the above colours- A form of Energy
Magnet A body which produces a magnetic field All magnets are di-poles and follow the rule that like poles repel and unlike poles attract
Mass The quantity of matter in a body
Metals Elements characterised by their opacity, malleability and thermal and electrical conductivity
Molecular formula The number and types of atom in a molecule  For example the molecular formula of methane is CH4, one atom of carbon and four atoms of hydrogen
Molecule A group of atoms bonded together  It is the smallest part of a substance that retains the chemical properties of the whole
Moment A rotating effect  See torque
Momentum The product of mass x velocity  Momentum is conserved in any system of particles
Monomers Small molecules that link together to form a polymer
Neutralisation A reaction in which the characteristics of an acid or base disappear
Neutrons Particles with zero charge forming part of an atomic nuclei
Newtons Laws of Motion Classical laws which enable the prediction of the path of any object from a grain of sand to entire galaxies:
Newtons 1st Law of Motion A body will remain at rest or move with a constant velocity unless acted upon by an outside force
Newtons 2nd Law of Motion The acceleration of a body is proportional to the applied force  This is expressed by the universal formula:  Force = mass × acceleration
Newtons 3rd Law of Motion For every action there is an equal and opposite reaction
Noble gases Elements with zero valency  They form group 0 or 8 in the periodic table and are non-reactive
Nucleus Organelle containing the chromosomes or that part of an atom containing the protons and neutrons
Organelles Specialized organs within cells
Organic Compounds Substances that contain Carbon
Ozone An isotope of oxygen that blocks ultra-violet radiation Normally found in the stratosphere
pH Scale The strength of acids and bases  Pure water has a pH value of 7, acids have a lower value and bases higher
Phase Changes Freezing, Melting, Boiling, Condensing, Subliming, Evaporation
Photosynthesis The conversion of water and carbon-dioxide by plants into glucose and oxygen  Light is used as an energy source
Polymerisation The repetitive bonding of small molecules (monomers) to produce large molecules (polymers)
Polymers Long chain molecules such as PVC, nylon or DNA produced by the polymerisation of monomers
Potential Difference The voltage difference between two points  Electricity flows from a high to low level of potential
Potential Energy Amount of useable energy within a body at rest
Power Amount of work done per second
Products The substances produced in a chemical reaction
Proteins Amino acid polymers with specific biological functions, especially the growth, regeneration and repair of cells
Protons Positively charged particles forming part of atomic nuclei - 3 quarkhadrons
Radiation Transfer of heat between bodies without a change in the temperature of the intervening medium or Any release of energy from its source
Radioactivity The spontaneous release of energy from atomic nuclei
Reactants The substances that take part in a chemical reaction
Refraction The bending of a light wave as it passes from one medium to another, eg from air to water
Relative Atomic Mass (Mr) The mass of an atom relative to one atom of carbon  Carbon has a Mr of 12
Reproduction Reproduction is the process by which a new organism is produced
Resistance Opposition to current flow in a conductor
Resonance A state where the natural frequency of a body equals an applied frequency
Respiration The production of energy by the oxidisation of glucose
Specific Heat The heat capacity of a body
Strain The deformation of a body under an applied load
Stress The measure of the force acting on a body
Temperature How hot one body is when compared to another
Torque The tendency of a body to rotate under an applied force
Valency A measure of the reactivity of an element
Velocity The rate of change of distance with respect to time
Viability The ability to survive to adulthood
Viscosity The internal friction of a fluid, thick fluids have a high viscosity and thin fluids low
Weight The gravitational force exerted on a mass
Work The amount of energy transferred to a system
Zygote A fertilised egg, the fusion of a male and female gamete
Seven Characteristics of Life Nutrition, Respiration, Excretion, Growth, Reproduction, Movement and Response
Excretion The removal of waste matter from the body
Respiration The release of energy from food in a cell
Reproduction The formation of new organisms
Nutrition The way an organism gets its food
Response Reacting to changes in the surroundings
Vertabrate An animal with a backbone
Invertabrate An animal without a backbone.
Plant cells consists of .. Cell wall, Cell Membrane. Nucleus, Chloroplasts, Cytoplasm (and Large Vacuoles)
Animal Cells consist of three main parts Cell membrane, Nucleus, Cytoplasm (and Small Vacuoles).
What do you use to identify Plants and Animals? A Key
Cytoplasm A watery fluid found between the nucleus and cell membrane.
Tissues Tissues are a group of similar cells which carry oyut the same function, e.g. red blood cells carry oxygen
An Organ An Organ is a structure that contains two or more tissues working together,e.g. the heart.
A System A number of Organs working together, e.g. The digestive system
Eyepiece The Lens on a microscope closest to the eye.
Focus knobs Allow the image in a microscope to be seen clearly. Two types - Coarse and Fine. Use Coarse first then fine.
Stage Holds the microscope slide using clips.
Mirror or Light Used to illuminate (light up) the slide.
Coverslip A thin square piece of glass used when making up a slide.
Iodine Solution Used to test for starch and stain onion cells
Total magnification in a microscope is calculated by .. Multiplying the power of the eyepiece lens by the power of the objective lens being used. e.g. 10 x 40 = 400 times.
Objective lens Lenses located on the nosepiece of a microscope. Each gives a different magnification, e.g. x 4, x 10, x 40.
Epidermis The outer layer of cells covering an organism.
Six Constituents of a Balanced Diet Carbohydrates, Fats, Proteins, Vitamins, Minerals and Water
Anaemia Lack of Iron leading to a poor red blood cell count.
Food Pyramid Guideline Diagram of the types and amounts of food that should be eaten to maintain a balanced diet.
Five Food Groups Cereals, Bread and Potatoes. Fruit and Vegetables. Dairy Products. Meat and Fish. Other types of food.
The Amount of Food a Person Needs Varies due to .. Age. Gender. Activity Levels. Health.
Test for Starch Iodine turns blue/black (positive test) with starch. It remains a red/brown colour if no starch is present (negative test).
Test for a reducing sugar Benedict's solution (Blue in colour) plus dissolved food sample in a heated water bath. A brick/red colour indicates a positive test
Created by: p-furl1