ABSORPTION  
When light hits an object and does not get reflected back 
(eg when light hits a piece of black paper it is absorbed, this is why the paper looks black) 

ACID    more
A liquid with a pH value less than pH 7
 Acids:      i. usually sour to taste (do NOT taste anything in the lab.)
                ii. will neutralise an alkali.
                iii. turn BLUE litmus indicator RED

Examples of some acids: lemon juice (citric acid), vinegar (acetic acid), hydrochloric acid (found in your stomach) and sulphuric acid (found in car batteries).

Acids are often corrosive which means they will attack and eat into substances such as acid and skin.

ACID RAIN    
Rain water which has dissolved gases from the air and become acid is called ACID RAIN. Gases which cause acid rain include sulphur dioxide (formed when fossil fuels like coal and oil are burnt) and nitrogen dioxide (comes from car exhausts).

NOTE: all rain water is slightly acid due to carbon dioxide which is naturally present in the air.

AIR PRESSURE  
It is the moving particles continuously colliding against the edge of a container that causes the pressure in a gas. 
How to increase the pressure
:i) By squashing the particles closer together (eg pumping up a tyre or blowing up a balloon)
ii) By warming the gas. This makes the particles vibrate faster (this is why a balloon expands when heated)  more

For evidence of the fact that particles are moving see diffusion and Brownian Motion. 
(See also Atmospheric pressure).   more

ALGAE  
Single celled plants. Reproduce asexually by binary fission. Live in wet places. Have no leaves or roots. more

ALIMENTARY CANAL
The tube that links the mouth to the anus down which food travels. more

ALKALI   more
A liquid with a pH value greater than 7
Alkalis:
i. feel soapy to touch
ii. will neutralise an alkali
iii. turn RED litmus indicator BLUE

examples: washing soda (sodium carbonate), caustic soda (sodium hydroxide), ammonia soln., garden lime (calcium hydroxide), indigestion mixture (eg magnesium hydroxide).

Alkalis are caustic and can burn your skin. Alkali in your eyes is particularly dangerous.

AMMETER  
An instrument used for measuring current. It is placed in series with the conductor being tested and has a very LOW resistance.   more

AMNION  
A water filled sac (containing AMNIOTIC FLUID) that helps support and protect the developing embryo.     more

AMPHIBIANS  
One of the VERTEBRATES. An animal that lays soft jelly covered eggs in water. Have smooth moist skin. Adults live on land or in water. Young live in water and go through metamorphosis. eg frog. more

AMPLITUDE  
The size of a wave. The amplitude of a sound wave determines what its VOLUME will be.

ANNELIDS  
Segmented worms with bristles on each segment eg earthworm or leach.

ANTHER  
Male part of a flower. Where pollen is made.   more

ARACHNIDS  
Animals that have 4 pairs of legs, 2 parts to the body eg spider, scorpion.

ARTERIES Carry blood away from the heart.

ARTHROPODS  
Animals that have many pairs of jointed legs and an exoskeleton. The arthropods are divided into several smaller groups eg insects, arachnids and crustaceans.
Examples: woodlouse, spider, fly.

ASEXUAL REPRODUCTION   more
In asexual reproduction NO fertilization required. (ie no sperm or pollen is needed)
i) Production of spores in non-flowering plants eg moss, and fungi.
ii) Budding eg in cactus 
iii) runners eg in the strawberry)
iv) Tubers eg in potato).
v) Binary fission in single cells eg in amoeba (a single-celled animal) or in algae (single-celled plants).

The way all individual cells multiply. Disadvantage: daughter cells identical to parent cells. Advantage: A quick process. Rapid colonisation.

ATMOSPHERIC PRESSURE  more
Atmospheric pressure is caused by the air around us pushing against all surfaces it touches. Normal air pressure , at sea level, is about 10n/cm2.

Atmospheric pressure increases with depth. It acts in all directions. Atmospheric pressure is responsible for many things we observe around us: eg sucking milk up a straw, holding a rubber sucker to the wall or the working of a vacuum cleaner.

ATOM  
The smallest possible part of an element. Elements consist of only a single kind of atom
Compounds consist of at least two different kinds of atom.

BIRD  
One of the VERTEBRATES. A warm blooded animal that lays hard-shelled eggs on land. Bodies covered in feathers eg thrush.

BLADDER  
Organ in a human that stores urine. Urine leaves the bladder through a tube called the URETHRA. In males the urethra leaves the body through the penis. Other organs

BLOOD  
A fluid in our body that consists of a clear watery liquid known as plasma and a variety of other larger particles eg
red blood cells: these carry oxygen around the body and give the blood its red colour.
white blood cells: these help fight disease
platelets: very small cells that help the blood clot

Uses for blood:  
i) Transports food and oxygen to the cells.
ii) Transports waste away from the cells.
iii)Helps protect the body from infection.
iv) Helps regulate the body temperature (37EC)

BRAIN  
Controls and coordinates all the major functions of the body. Where all the nerves meet.

BROWNIAN MOTION   more
The vibrating motion of smoke particles seen when brightly lit smoke in a smoke cell is viewed through a microscope. It is caused by the tiny, fast moving air particles hitting against the smoke particles and knocking them about.

If the air in the smoke cell is warmed then the smoke particles will vibrate quicker because the air particles will be moving faster.

If larger smoke particles are used the motion will slow down.

BUNSEN BURNER  more
A piece of apparatus that burns gas and is used to heat apparatus. It has an air hole that controls the flame temperature by regulating the flow of air into the burner.

When the air-hole is open: A hot, blue, roaring flame.

When the air-hole is closed: A cooler, smoky, luminous yellow flame. Not used to heat apparatus as it is very sooty.

CAPILLARIES
Tiny blood vessels that carry blood to the individual cells.

CAPILLARY ATTRACTION  
A force which drags liquids up fine holes or cracks. It is what causes porous objects soaking up water and allows blotting paper and towels to absorb water.

CARNIVORE   more
An animal that eats only meat. (Carnivorous)
eg thrush, pike, ladybird

CELL more
The basic unit of all life. All cells contain a nucleus, cytoplasm and a cell membrane. Plant cells also have a cell wall, a large vacuole and sometimes chloroplasts.

CELL MEMBRANE The living outer boundary of the cell. The membrane is selective in allowing what passes through it (into or out of the cell). more

Cells build up into tissues, tissues into organs and organs into organisms. Found in ALL cells.

CELL WALL
The dead, outer edge to the cell. gives the cell strength. Made of cellulose. Found ONLY in plant cells . more

CHEMICAL CHANGE  more
When a new substance is formed and a chemical reaction has taken place.
Examples of a chemical reaction are: decomposition, combination, combustion, rusting, photosynthesis, oxidation and neutralisation

Signs that a chemical change is taking place are:
i. Heat given out ii. Colour change

A chemical change will usually be permanent.
eg Burning magnesium (to form magnesium oxide)

CHEMICAL REACTION  
Any process where a new substance is formed (see above)

CHLOROPLASTS  
The part of a PLANT CELL that is green. Found only in certain plant cells above ground. Chloroplasts contain chlorophyll which makes them look green. They are where photosynthesis is carried out.  more

CHORDATES
Animals with a backbone. Have an internal skeleton. eg Lion, snake, frog.

COELENTERATES
Jelly-fish/sea anemones. Have central mouth surrounded by stinging tentacles eg Portuguese Man of War

COLD-BLOODED
Animals whose body temperature alters with the temperature of the surroundings eg fish. All animals except for birds and mammals are cold blooded.  more

COMBUSTION Another name for BURNING. A combustible material is one that burns easily.  more

Products of combustion: the chemicals produced when something is burnt. eg. The products of combustion when wax is burnt are carbon dioxide and water.

COMMUNITY A collection of all the animals and plants that live in a particular area.  more

COMPOUND The substance formed when two or more elements are chemically combined together.

eg HYDROGEN (element) + OXYGEN (element) = WATER (compound).

Other compounds: Copper sulphate, magnesium oxide, calcium carbonate
Note: the elements in a compound cannot be separated without a chemical reaction taking place.

CONSUMER All the animals in a food chain are consumers (plants are producers). Animals rely on other animals or plants for their food as they cannot produce their own.
The PRIMARY consumer is the first animal in a food chain. Always a HERBIVORE.
The SECONDARY consumer is the second animal in a food chain and is always a carnivore.    more

CONTRACEPTIVE A device used to prevent sperm from reaching the egg during sexual intercourse. Examples are a contraceptive pill (used by a woman) or a condom (worn by the man). The use of contraceptives helps stop over-population A condom also helps stop the spread of AIDS.

CRUSTACEANS Animals that usually have 5 pairs of legs, eg crab, woodlouse. Belong to the phylum of Arthropods.

CRYSTALLISATION The process for obtaining the solute from a solution by warming the solution until crystals start to appear and then letting the solution cool.

eg obtaining copper sulphate from copper sulphate solution.

CRYSTALS A crystal is a solid in which the particles are arranged in a REGULAR pattern. Crystals will often have flat sides and straight edges.

CURRENT The rate at which electricity moves along a conductor. Measured in amperes (amps) using an instrument called an ammeter. more

CYTOPLASM The living contents of a cell (excluding the nucleus). Found in ALL cells. more