Meanings of the Terms/Words which are used in General Science Grade VI, VII and VIII

Meanings of the Terms/Words which are used in General Science Grade VI, VII and VIII
Term/Word	Meaning
Glossary	A list of terms in a special subject, field, or area of usage.
Acid	A compound containing hydrogen which dissolves in water to produce hydrogen ions (H+) in the solution.
Acid rain	Rain water which is more acidic than usual. Rain water normally has a pH between 5 & 6 but acid rains have pH below 5
Acidic salts	Salt obtained as a result of reaction between strong acid & weak base (Na2 CO3)
Aerosol	A pressurized container used to spray liquids, like paint, in a fine mist
Alkali	A base which dissolves in water is an alkali
Alveolus	An air sac found in the ling which is adapted for gaseous exchange
Ammeter	An instrument for measuring electric current
Antibiotics	Chemicals used to treat many infectious diseases caused by microorganisms such as bacteria
Apparent brightness	How bright a star looks to observes on earth
A sexual reproduction	Reproduction that doesn’t involve the fusion of two gametes
Asteroids	Large lumps of rock and metal that orbit the sun in a region called the asteroid belt between mars and Jupiter
Astronomer	A scientist who studies the stars, planets, and other objects in space
Astronomy	The scientific study of the objects in space such as stars, asteroids and planets
Astrophysics	The science of the physical and chemical aspects of heavenly bodies
Atmosphere	The blanket of gases that surrounds the earth
Atmospheric pressure	The pressure caused by the weight of the air pressing down on the earth’s surface
Atom	This is a basic of matter which can’t be further divided
Basic salts	Salt obtained as a result of reaction between strong base and weak acid (NaHCO3)
Big bang	A tremendous explosion on the beginning of the universe
Big bang theory	The idea that all the matter in the universe came into being with a massive explosion known as the big bang
Biotechnology	The use of biological process from microorganisms to make substances (e.g. penicillin) or to provide services for human beings
Black hole	What is left when a very massive star collapses at the end of its life. A black hole’s gravity is so strong that nothing can escape, not even light
Breathing	The process that brings about an exchange of gases between the organisms and the environment
Bronchiole	One of the many tiny tubes which carries air to end from the alveoli in the lungs
Bronchitis	A lung disease in which the cells lining the bronchi and bronchioles are inflamed
Cancer	A disease in which body’s cell start to divide and multiply in an uncontrolled and disorderly fashion
Chemical Reaction	A change in which one or more chemical elements or compounds(reactants) form new compounds(the products)
Chemistry	The scientific study of all substances and how they react and combine
Chlorophyll	A green pigment found in most plants. It absorbs light energy during photosynthesis
Chromosome	A thread-like structure present in the nucleus of a cell. It contains hereditary materials called genes
Colloid	A mixture of extremely small particles of a substance dispersed in another in which it doesn’t dissolve. The particles are smaller than in a suspension
Comet	An icy jump of material that moves around the sun in a highly elliptical orbit, its ‘tail’ is a thin stream of gas and dust that reflects sunlight
Compound	It consists of two or more elements chemically combined together
Constellation	Stars that appear to form a group with a definite pattern or arrangement, when viewed from the earth
Current electricity	The type of electricity that can flow through wires
Decanting	Process of separating a liquid from a solid that has settled by pouring the liquid carefully out of the container
Deforestation	Destruction of forests due to human activities
Detergents	Substances which when added to water, enable it to remove dirt
Diaphragm	A muscular from the abdomen,’ sheet that separates the chest
Distillation	The process of separating a mixture of liquids, or a liquid from an impurity, by heating. The vapor of the liquid with the lowest boiling point comes off first and is condensed back to a liquid in the condenser
DNA	(Deoxyribonucleic acid)  Hereditary material of the cell
Dwarf star	A very small star that may be no larger than earth
Dynamo	A type of generator that produces direct current
Eclipse	The total or partial disappearance of a heavenly body when another one moves between it and the viewer
Effector	A muscle that respond to a message and reacts accordingly
Electric charge	Something that has an electric charge carries electricity. There are two types of electric charge, called positive and negative
Electric circuit	The path along which an electric current flows
Electric current	The flow of positive or negative electric charges
Electric field	The area in which an electric force has an effect
Electric motor	A device that changes electrical energy into movement
Electric shock	The effects on the human body caused by electric current from batteries
Electricity	The effect caused by the presence or movement of electrically charged particles
Electrolysis	Chemical reactions produced by passing electric current
Electrolytes	Electrolytes are chemical compounds, that help electric current to pass through them on ionization (e.g., Na CI, H2SO4)
Element	It is a pure substance which contains same type of elements
Endothermic reaction	A chemical reaction that takes heat from its surroundings
Evaporation	A change of state from liquid to gaseous (vapor), due to the escape of molecules from the surface. A liquid which readily evaporates is described as volatile
Evening star	Another name for the planet Venus, as it appears just after sunset
Exothermic reaction	A chemical reaction that releases heat into its surroundings
Filtering	The process of separating a liquid and a solid by pouring the mixture through a fine mesh (filter paper). The filter paper only lets liquid through PTO
Galaxy	A large group of stars, gas and dust
Galvanometer	An instrument for detecting or measuring very small electric currents
Gamete	A reproductive cell containing the haploid number of chromosomes
Genes	Units controlling inheritance and expression of characters
Genetic engineering	A technique used to transfer genes from one organism to another
Genotype	The genetic combination in an individual
Generator	A machine that turns the energy of movement, or kinetic energy into electrical energy
Guard cells	A pair of special cells present around opening (stomata) in the epidermis of a leaf that regulate the opening and closing of stomata
Hereditary characters	Characteristics which are inherited
Heredity	Transfer of characters from parents to their offspring
Indicators	A chemical compound that changes its color when an acid or an alkali is added into it
Insulation	A material that reduces heat transfer
Irregular galaxy	A galaxy with no definite shape or arrangement
Kilogram (kg)	Units of mass
Lens	A piece of transparent substance with curved surfaces, that makes light bend in a certain way
Light-year	The distance light travels in one year, or 9.5 trillion kilometers
Luminous	The term that describes any object that gives off light
Mass	The amount of matter that is in an object
Mesophyll	Cells found between upper and lower epidermis in a leaf. These cells contain chloroplasts
Meter (or shooting star)	A meteoroid that starts to burn up as it enters the atmosphere
Meteorite	Fragments of rocks striking the surface of the earth. The remains of a meteor that has survived the atmosphere and landed on earth
Meteoroid	A small piece of space debris
Meteoroids	Rocks or fragments of rocks and iron travelling in space
Meter (m)	Unit of length. 1000 meters equals 1 kilometer (km)
Milky way	A spiral galaxy to which out sun and the planets belong. The galaxy in which our solar system lies
Milky way galaxy	Such a galaxy containing solar system
Mineral acid	An acid which is produced chemically from a mineral e.g. hydrochloric acid is produced from sodium chloride and sulphuric acid is produced from sulpher
Mixture	It is formed by the combination of two substances in such a way that no new substance is formed
Model	A representation of something that can’t be seen easily or directly
molecule	It is formed by the combination of same or different atoms
Motor neurons	A nerve cell that transmits impulses to an effector
Nebula	Gigantic clouds of dust and gases in space
Nerve	A collection of nerve fibers
Nerve fiber	A long cytoplasmic extension of a cell body of a neuron. It serves to transmit impulses
Neuron	A nerve cell
Neutron star	A star whose core contains neutrons only
Non-luminous	Describes an object that doesn’t give out light of its own
Optical microscope	An instrument that uses lenses to make small objects look bigger
Optical telescope	An instrument that uses lenses and mirrors to make distant objects look closer
Orbit	The path in which one heavenly body moves around another
Organic acid	An organic compound that is acidic in nature. The most common ones are carboxylic acid (e.g., oxalic acid, formic acid, acetic acid)
Palisade tissues	Cylindrical cells arranged closely and vertically in the upper layer of mesophyll. These cells contain numerous chloroplasts which facilitate the absorption of sunlight
pH	Stands for power of hydrogen, a measure of hydrogen ion concentration in a solution
Pneumatic	Powered by the pressure of a gas, usually air
Pressure	A measure of the amount of force applied to a given area
Receptor	Sense organ, cell or nerve endings that detect stimulus
Recycling	Rendering used articles into useful ones
Reflex action	An immediate response to a specific stimulus without conscious control
Respiration	The process by which energy is released from food substances in living cells
Revolution	The movement of one object around another
Rotation	The spinning motion of an object
Salt	A compound formed by the neutralization reaction between acid & base
Satellite	Bodies that rotate in orbits around other bodies of greater mass under the influence of a gravitational field. For example, the moon is a natural satellite of the earth. Satellites which are used for relying radio, television and telephone signals around the earth are artificial earth satellites. They are called communication satellites.
Second (s)	Unit of time. A second is a duration in which the cesium -133 atom completes 9,192,631,770 vibrations under specified conditions
Selective breeding	Technology using breeding of selected organisms
Sexual reproduction	Reproduction that involves the fusion of two reproductive cells called gametes
SI units	An internationally agreed system of standard units used for scientific measurements
Soap	It is the sodium or potassium salt of a long-chain carboxylic acid. It is made by reacting animal fats or vegetable oils with Na OH or KOH. The process of making soap is called saponification
Solar system	The sun together with all of the planets and other objects orbiting it
Solar wind	A constant stream of invisible particles blow out into space from the sun
Space probe	Unmanned spacecraft sent to explore the solar system and beyond
Space shuttle	A reusable manned spacecraft that is launched like a rocket, but lands on reentry like plane
Space station	A large satellite orbiting the earth where astronauts can live and perform scientific research over fairly long period
Stars	Shinning objects of gases in nebula
Sun	This is a star
Supergiant	An extremely large star
Suspension	Fine particles of a solid suspended in a liquid in which the solid doesn’t dissolve
True brightness	The actual amount of energy in the form of light that is released by a star
Universe (for cosmos)	The collection of all matter, energy and space that exists
Universe theory	The idea that the universe expands and shrinks, in a repeating cycle of big bangs and big crunches
Vacuum	An empty space where there are no particles of air or other matter
Variable resister (or rheostat)	An electronic component that can be adjusted to give different amounts of resistance
Variable star	A star that changes gradually in brilliance
Variation	The differences that can be observed within a species
Voluntary action	An action that is controlled by the will
Volume	The amount of space something takes up. It is measured in cubic meters (m3). A smaller unit of volume is the cubic centimeter (cm3), o0 milliliter (ml). 1 cm3= 1 ml=1/1000000m3
Weather forecast	A prediction of what the weather will be for some time in the future
Weight	The measure of the force of gravity acting on an object
X-Rays	Wavelength, high-frequency electromagnetic waves that can pass through most soft substances but no hard, dense ones
zygote	A cell formed as a result of the fusion of the sperm and the ovum. It divides repeatedly and becomes the embryo