Oxford Science 9 Victorian Curriculum Second Edition Vocabulary Review

Vocabulary and key conceptual definitions from Chapters 1 through 8 of the Oxford Science 9 Victorian Curriculum textbook.

independent variable

A variable (factor) that is changed in an experiment.

dependent variable

A variable in an experiment that may change as a result of changes to the independent variable.

sample size

The number of subjects being tested or used in an experiment.

outlier

A data value that is outside the normal range of all the other results.

accuracy

How carefully, correctly and consistently data has been measured or processed; in science, how close a measured value is to the true value.

parallax error

An error, or inaccurate reading, that occurs as a result of reading a scale from an angle.

zero error

An error that occurs when an instrument has not been adjusted to zero before the measurement is taken.

SI system

An international system of measurement based on the metric system, with units such as kilogram, metre, and kilometre.

derived units

Units of measurement that are calculated using a combination of SI (international system) base units, e.g. $\text{cm}^3$ for volume ($\text{base unit is cm}$), $\text{m}^2$ for area ($\text{base unit is m}$).

biosphere

A layer around the Earth's surface that supports life; consists of the atmosphere, hydrosphere and lithosphere.

ecosystem

A community of living organisms (biotic) and non-living (abiotic) factors.

abiotic

All the non-living components of an ecosystem; for example, light, temperature, water.

biotic

Relating to the living organisms in an ecosystem.

decomposer

An organism that gains nutrients by breaking down dead organisms into simpler nutrients.

symbiosis

A close physical relationship between two organisms of different species.

mutualism

A type of relationship between two organisms of different species in which both organisms benefit.

commensalism

A type of relationship between two organisms of different species, in which one organism benefits and the other is not affected.

parasitism

A relationship in which one organism (parasite) lives in or on the body of the other organism (host) and benefits while the host is harmed.

photosynthesis

A chemical process used by plants to make glucose and oxygen from carbon dioxide, sunlight and water. The equation is: $6CO_2 + 12H_2O \rightarrow C_6 H_{12}O_6 + 6O_2 + 6H_2O$.

aerobic respiration

The second step in the breakdown of glucose to carbon dioxide and water; occurs in the mitochondria when oxygen is present and produces $34\,ATP$ molecules. The equation is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 36\,ATP$.

glycolysis

The first part of cell respiration in which glucose is broken down to produce energy; occurs in the cytoplasm and produces $2\,ATP$ molecules and pyruvate.

enhanced greenhouse effect

An increase in carbon dioxide and other heat-capturing gases in the atmosphere, resulting in increased warming of the Earth.

carrying capacity

The maximum number of organisms in a population that can be sustained by an ecosystem.

stimulus

Any information that the body receives that causes it to respond.

receptor

A structure that detects a stimulus or change in the normal functioning of the body.

neuron

A nerve cell.

axon

The part of a neuron (nerve cell) that carries an electrical message away from the cell body to the synapse.

myelin sheath

A fatty layer that covers the axon of a nerve cell, which helps to speed up a nerve impulse.

synapse

A small gap between two neurons that must be crossed by neurotransmitters.

neurotransmitter

A chemical messenger that crosses the synapse between the axon of one neuron and the dendrite of another neuron.

reflex

An involuntary and nearly instantaneous movement in response to a stimulus.

central nervous system

The control centre of the body, consisting of the brain and spinal cord.

peripheral nervous system

All the neurons (nerve cells) that function outside the brain and spinal cord.

autonomic nervous system

The part of the nervous system that controls involuntary actions such as heartbeat, breathing and digestion; maintains homeostasis.

homeostasis

The process by which the body detects and responds to stimuli to ensure a stable internal state is maintained.

endocrine system

A collection of glands that make and release chemical messengers called hormones directly into the bloodstream.

pathogen

A microbe that can cause disease, such as bacteria, fungi, protozoans and viruses.

phagocyte

An immune system cell that surrounds, absorbs and destroys pathogens in a process called phagocytosis.

antibody

A molecule produced by B cells that binds to a specific part of a pathogen, causing them to clump together.

vaccination

An injection of an inactive or artificial pathogen that results in the individual becoming immune to a particular disease by creating memory cells.

plate tectonics

A combination of two theories (continental drift and sea-floor spreading) that explains global patterns of geological activity and the movement of the continents.

subduction

The movement of one tectonic plate under another tectonic plate.

diverging boundary

A plate boundary where tectonic plates are moving apart, which can form rift valleys or mid-ocean ridges.

transforming boundary

The boundary between two tectonic plates that are sliding past each other along a single fault line.

atomic number

The total number of protons in the nucleus of an atom; used to identify the element.

mass number

A number that represents the total number of protons and neutrons in the centre of an atom.

isotope

An atom of a particular element that has more or fewer neutrons in its nucleus than another atom of the same element.

half-life

The time taken for half the radioactive nuclei in a sample to decay into stable atoms.

cation

A positively charged ion that results from an atom losing electrons.

anion

A negatively charged ion formed when an atom gains electrons.

exothermic reaction

A chemical reaction that releases extra energy as heat, light, or both, as atoms go from high-energy reactants to low-energy products.

endothermic reaction

A chemical reaction that absorbs energy from its surroundings to produce high-energy molecules from low-energy molecules.

pH scale

A scale representing acidity or alkalinity; acidic solutions have a $pH < 7$, alkaline solutions have a $pH > 7$, and neutral solutions like pure water have a $pH = 7$.

neutralisation

A reaction in which an acid and a base combine to produce a metal salt and water; general reaction: $\text{acid} + \text{base} \rightarrow \text{salt} + \text{water}$.

corrosion

The gradual destruction of materials, usually metals, by a chemical reaction with their environment.

combustion reaction

An exothermic reaction between a fuel and oxygen that produces heat, carbon dioxide and water.

voltage

Potential difference; the difference in the electrical potential energy carried by charged particles at different points in a circuit; measured in volts ($V$).

resistance

A measure of how difficult it is for charged particles in an electric circuit to move; measured in units called ohms ($\Omega$).

Ohm's law

The discovery that the voltage drop across a fixed-value resistor is always directly proportional to the current through it, written as: $V = IR$.

electromagnetic induction

The production of voltage (and hence a current) in a circuit by the magnetic field through the circuit or by the relative movement of the magnetic field and the circuit.

transformer

A device that changes the voltage at which energy is transmitted by an alternating current ($AC$).