Cambridge IGCSE Combined Science 0653 Vocabulary Flashcards

Movement

An action by an organism or part of an organism causing a change of position or place.

Respiration

The chemical reactions in cells that break down nutrient molecules and release energy for metabolism.

Sensitivity

The ability to detect and respond to changes in the internal or external environment.

Growth

A permanent increase in size and dry mass.

Reproduction

The processes that make more of the same kind of organism.

Excretion

The removal of waste products of metabolism and substances in excess of requirements.

Nutrition

The taking in of materials for energy, growth and development.

Diffusion

The net movement of particles from a region of their higher concentration to a region of their lower concentration (i.e. down a concentration gradient), as a result of their random movement.

Osmosis

The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane.

Active Transport

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration.

Catalyst

A substance that increases the rate of a chemical reaction and is unchanged at the end of the reaction.

Enzymes

Proteins that are involved in all metabolic reactions, where they function as biological catalysts.

Photosynthesis

The process by which plants synthesise carbohydrates from raw materials using energy from light.

Ingestion

The taking of substances, e.g. food and drink, into the body.

Digestion

The breakdown of food into smaller pieces or soluble molecules.

Absorption

The movement of nutrients from the intestines into the blood.

Assimilation

Uptake and use of nutrients by cells.

Egestion

The removal of undigested food from the body as faeces.

Transpiration

The loss of water vapour from leaves.

Pathogen

A disease-causing organism.

Transmissible Disease

A disease in which the pathogen can be passed from one host to another.

Active Immunity

Defence against a pathogen by antibody production in the body.

Drug

Any substance taken into the body that modifies or affects chemical reactions in the body.

Ecosystem

A unit containing the community of organisms and their environment, interacting together.

Biodiversity

The number of different species that live in an area.

Proton Number (Atomic Number)

The number of protons in the nucleus of an atom.

Mass Number (Nucleon Number)

The total number of protons and neutrons in the nucleus of an atom.

Ionic Bond

A strong electrostatic attraction between oppositely charged ions.

Covalent Bond

Formed when a pair of electrons is shared between two atoms leading to noble gas electronic configurations.

Electrolysis

The decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current.

Exothermic Reaction

A reaction that transfers thermal energy to the surroundings leading to an increase in the temperature of the surroundings.

Endothermic Reaction

A reaction that takes in thermal energy from the surroundings leading to a decrease in the temperature of the surroundings.

Activation Energy ($E_a$)

The minimum energy that colliding particles must have to react.

Redox Reactions

Reactions involving simultaneous oxidation and reduction.

Solute

A substance that is dissolved in a solvent.

Solvent

A substance that dissolves a solute.

Saturated Solution

A solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature.

Hydrocarbon

A compound that contains hydrogen and carbon only.

Polymers

Large molecules built up from many smaller molecules called monomers.

Speed

Distance travelled per unit time ($v = \frac{s}{t}$).

Acceleration

Change in speed per unit time ($a = \frac{\Delta v}{\Delta t}$) for an object moving in a straight line.

Mass

A measure of the quantity of matter in an object.

Weight

The gravitational force on an object that has mass.

Gravitational Field Strength ($g$)

The gravitational force per unit mass ($g = \frac{W}{m}$). Near the surface of the Earth, $g$ is approximately $9.8\,\text{N/kg}$.

Density

Mass per unit volume ($\rho = \frac{m}{V}$).

Power

Work done per unit time ($P = \frac{W}{t}$) or energy transferred per unit time ($P = \frac{\Delta E}{t}$).

Pressure

Force per unit area ($p = \frac{F}{A}$).

Refraction

The change in direction of a light ray passing from one medium to another.

Ultrasound

Sound with a frequency higher than $20\,\text{kHz}$.

Electric Current

The charge passing a point per unit time ($I = \frac{Q}{t}$).

Electromotive Force (e.m.f.)

The electrical work done by a source in moving a unit charge around a complete circuit.