Glossary

action potential The change in the electrical current in muscle or nerve cells to send nerve impulses

activation energy The minimum energy required for reactants to undergo a particular reaction

aerobic respiration Cellular respiration that occurs with oxygen

agonist The set of muscles that contracts during movement

amino acids The chemical building blocks of proteins

ammeter Device used for measuring quantity of electric current

amperes S.l. unit for electric current

anaerobic respiration Cellular respiration that occurs without oxygen

analogue Transmission of information as continuously varying signal

angle of incidence Angle formed between an incoming ray and a line normal (at right angles to) the boundary between two media

angle of reflection Angle formed between a reflected ray and a line normal (at right angles to) a reflective surface

angular speed Angle turned through by a rotating object each second

antagonistThe set of muscles that relaxes during movement

artery Blood vessels contract to conduct blood away from the heart

assimilate When cells take in, process, and utilize the products of digestion

ATP Adenosine triphosphate; used by cells as energy

autotrophs Organisms (i.e., plants) that produce their own food

base stations A unit which relays signals across a network

battery A collection of electrical cells; a source of current

biochemical Chemical processes that occur in cells of living organisms

biodiversity The variety of plants and animals living in a habitat

blood vessels The tube-like structures that carry blood to'and from the heart throughout the body

bone marrow Inner part of bones that produces blood

capillaries Smallest blood vessels that carry blood at the cellular level

carbohydrates Macronutrients, such as starches and sugars

cardiac muscle Muscle cells that make up the heart

cell phones A mobile telephone of relatively short range whose signals are relayed across a network of communications cells

cellular respiration Creation of ATP by breaking down glucose in cells

channel A range of frequencies designated for telecommunications

chemical digestion Chemical breakdown of foods through the action of enzymes and other substances produced by the body

chlorophyll Protein pigment in plant cells that contribute to the green colour of plants and allows photosynthesis to occur

chloroplasts Cell structures where photosynthesis occurs

circuit diagram A diagram showing the arrangement of an electric circuit

compact bone The dense portion of bone, mostly on ends and edges

complex carbohydrate Carbohydrates that are made up of many different monosaccharides or simple sugars

concave surface A surface with an inward curvature conservation The act of protecting or caring for the environment

continuous wave signal Continuously varying wave carrying information

converge When the distance between two things decreases with distance travelled, such as light rays

convex surface A surface with outward curvature

critical angle The angle of incidence after which rays passing across the boundary from a denser to a less dense medium are no longer refracted but reflected instead

diffusion The process of one substance spreading through another

digestion Breaking down food into its smaller chemical components

distance magnifier Increases the distance over which a force acts

diverge When the distance between two things increases with distance travelled, such as light rays

ecology The study of the interactions that occur in the natural world effector cells Cells that respond to signals from the nervous system

efficient The maximum output for the minimum possible input and waste

effort A force applied to produce a mechanical effect electric current The flow of electric charge

electrical signals Electrical impulses that are generated by and travel through cells

electromagnetic energy Energy carried by electrical and magnetic fields that travel in the form of a wave

endocrine system Body system responsible for producing and releasing hormones esophagus Tubular structure connecting the mouth to the stomach

estrogen Hormone associated with sexual development, and menstruation

exothermic Chemical change resulting in the release of heat

Fallopian tube Tube structure extending from the ovaries through which egg cells travel to the uterus

fast-twitch fibres Muscle cells responsible for fast bursts of activity

fatty acids One of the chemical building blocks of fats or lipids

fertilization When the genetic material of a sperm cell enters into an egg cell and combines with its genetic material

focal length Distance between optical axis and focal point of a lens

focal point A point at which waves or rays meet or originate

follicle stimulating hormone Contributes to the regulation of the reproductive processes in both males and females

force magnifier A machine that reduces the force required to move a load by increasing the distance over which the effort is applied

frequenciesThe number of wave cycles per second

gastric acid Acidic liquid produced by stomach cells

gears A wheel that is used with others to alter the relationship between the speed of a driving mechanism and other parts

glucose Simple sugar used by cells during respiration

glycolysis The stage of cellular respiration that occurs without oxygen when glucose is initially broken down

greenhouse gas An atmospheric gas that contributes to the greenhouse effect by absorbing infrared radiation

growth plates The portion of bones where elongation occurs

heterotrophs Organisms that must consume food

hydrocarbons Compound containing hydrogen and carbon

hypothalamus Portion of the brain that signals the release of certain hormones and coordinates aspects of the nervous system

incident ray A light ray incoming to any optical component

induces When an electrical or magnetic object produces an electrical or magnetic effect in another without touching

internet protocol Rules for transmission of data over the internet

isotope Different forms of elements that have the same number of protons but different numbers of neutrons in their nuclei

joule The 5! unit of work and energy kilocalories Unit of energy; used to indicate energy stored in foods lateral inversion The reversal of left and right in an image

lever A machine by which effort is applied to an object via a fulcrum

light-emitting diode An electronic device that allows electric current to flow in one direction only and produces light

load The force exerted by an object to which an effort is applied

local area network A telecommunications or computer network which links devices within a building or locally

lymph Clear liquid portion of blood

macronutrients Nutrients that are needed in large amounts to fulfil humans’ nutritional needs

mainframe A central computer used to deal with large quantities of data

menopause The time of life when menstruation no longer occurs

menstruation In females, the process during which blood and some tissue from the uterus exits the body through the vagina

metabolism Processes that occur within cells of living things to keep them alive

micronutrients Nutrients needed in small amounts to fulfil nutritional needs

moment In mechanics, the turning effect of a force around a pivot multimeter A device for measuring various electrical properties nervous system Network of nerves to send signals throughout the body network In telecommunications, a system of interlinked devices

neurotransmitter Chemicals released at the end of a nerve cell and that has an effect on the neighboring nerve or muscle cells

nodes A point through which numerous devices in a network are linked

non-renewable sources Natural resources that can be used up; there is no way to regenerate them

normal A line at right angles to an optical surface or boundary operating system Software supporting a computer’s key functions optical fibre A flexible glass fibre used to transmit signals using light organs A group of tissues that perform a bodily function

ovaries Organs in a female body where egg cells are produced, stored, and released

oviduct Small tubes that lead from the ovaries to the Fallopian tubes ovulation The process of an egg releasing from the ovary

parallel circuit An electrical circuit in which electric current divides into multiple circuit branches and then recombines

penis Male genital organ through which semen passes petrochemicals Substances made from petroleum or its by-products physical digestion Mechanically breaking down food into smaller pieces

pituitary gland An important gland in the brain that helps to control growth, development, and other bodily functions

plane mirror A mirror with a flat surface platelets Parts of blood that contribute to clotting pole End of a magnet or an electrically charged point

potential difference Difference in electric potential energy between two points in space or in a circuit; measured in Volts

potential energy Energy held inside a body due to bonds or other forces, or due to the position of a body within a force field

power The work done in a certain time, measured in Watts principal axis A line through the centre of an optical system probiotics Bacteria that are beneficial for human health

proteins Chemical substances made up of large chains of amino acids puberty The time of life when adolescents reach sexual maturity

ray diagram A schematic diagram showing the path of light rays

real image An image that exists in space

receptors Cells that receive an impulse or signal

red blood cells Cells that transport oxygen throughout the body redox reaction A reaction where electrons are gained and lost by

reactants renewable Resources that can be regenerated

resistance Effect on electrical current passing through a material by which energy is lost in the form of heat

resonators Objects that increase volume of sound through resonance router A device that relays data from one point in a network to another saliva Liquid formed in the mouth, containing digestive enzymes

sample rate the number of times that an analogue signal is ’sampled' or measured per second

saturated fats Fats that are formed by a high number of single bonds; usually considered to be less healthy in the diet

secondary digestive organs Organs that produce enzymes and other chemicals for digestion, but food does not pass through

semiconductor Materials which act like a conductor at high temperatures and an insulator at low temperatures

sensor A device for measuring a physical property electrically

series circuit A circuit in which there is only one current pathway

server A computer in a network that acts as a central resource

signaling molecules Chemical substances, such as hormones, that send signals throughout the body

simple sugars Monosaccharides

skeletal muscles Muscles that allow the skeleton to move

skeletal system System in the body that is composed of bones, joints, ligaments, and tendons

slow-twitch fibres Muscle cells responsible for slow, sustained activity

small intestine Part of the digestive system after the stomach, where the majority of nutrients are absorbed into the blood stream

spongy bone Part of the bone made up of lattice bone tissue

starches A type of complex carbohydrate

synapse The space between nerve cells through which neurotransmitters and signals pass

tendons Strong fibres in the body that attach muscles to bones

terminals Points by which an electric circuit is connected externally

testicles Organs in a male’s body where sperm is produced

testosterone Hormone associated with sexual development in males, but also produce in females

tipping point The moment when a number of small changes leads to a larger change that cannot be reversed

total internal reflection When light rays are reflected from a boundary between a more and a less dense medium

trans fat Produced when an unsaturated fat is converted to a saturated fat

transistor A component used as an electronic switch or as an amplifier

transmitter An antenna used to transmit signals as EM waves

unsaturated fatsFats formed by a high number of double bonds

vagina Female genital organ through which menstruation and child birth occur

virtual image An image formed by the eye from the light rays appearing to diverge from an optical component

voltmeter A device for measuring the potential difference in a circuit

watt The S! unit of mechanical and electrical power

weight-bearing activities Activities that require a person to work against gravity

white blood cells Cells that work to protect the body from diseases or infection

work The transfer or transformation of energy by a system

zygote Cell that forms after an egg cell has been fertilized by a sperm cell