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