CCSLC Integrated Science key terms

Information gathered directly through the senses or with instruments, such as noting colour, mass or temperature. It describes what actually happens rather than explaining why it happens.

A reasoned explanation or conclusion drawn from observations and prior knowledge. Unlike an observation, it goes beyond what was directly sensed and may later be shown wrong.

A testable, provisional statement predicting what will happen in a given situation. It must be worded so that evidence gathered in an investigation could support or reject it.

Any factor in an investigation that can change or be changed, such as temperature, time or amount of light. Investigators identify variables so they can control or measure them deliberately.

An investigation in which only the factor being tested is allowed to differ, while all other conditions are kept the same so results can be compared meaningfully.

A standard setup, or a kept-constant condition, used for comparison so that the effect of the tested factor can be judged. It shows what would happen without the treatment.

A quantity expressed as a number together with a unit, obtained using a suitable instrument. Repeating measurements and averaging them improves trust in the value.

One of the agreed international units used in science, such as metre, kilogram, second, kelvin, mole and ampere. Using them lets results from different places be compared directly.

How close a measured or calculated value is to the true value. It is improved by using well-calibrated instruments and careful technique, not simply by repeating readings.

How close repeated measurements are to one another, regardless of whether they are correct. Precise readings can still be inaccurate if the instrument is wrongly calibrated.

The extent to which an investigation, if repeated, would give similar results. It is increased by repeating trials, taking larger samples and controlling variables carefully.

A judgement about what the evidence shows, stating whether the hypothesis was supported and explaining the pattern found. It should be limited to what the data can justify.

The smallest unit of a living thing that can carry out all life processes. Some organisms consist of one cell; others, like humans, are built from many specialised cells.

The process in which green plants use light energy to combine carbon dioxide and water into glucose, releasing oxygen. It stores energy in food and forms the base of most food chains.

The green pigment in chloroplasts that absorbs light for photosynthesis. It gives leaves their colour and is why most food chains ultimately depend on light captured in plants.

The chemical release of energy from glucose inside living cells, using oxygen in aerobic respiration and producing carbon dioxide and water. It happens day and night in plants and animals.

The net movement of particles from a region of higher concentration to one of lower concentration, caused by random motion. It explains gas exchange and the spread of smells.

A sequence showing how energy passes from one organism to the next through feeding, beginning with a producer. Arrows point in the direction the energy travels.

An organism, usually a green plant or alga, that makes its own food by photosynthesis. Producers supply the energy that enters the rest of a food chain.

An organism such as a bacterium or fungus that breaks down dead material and waste, releasing nutrients back into the soil. Decomposers recycle matter so producers can reuse it.

The particular place where an organism normally lives, such as a pond, a leaf or the soil. A habitat supplies the food, water, shelter and space an organism needs.

A community of living organisms together with the non-living surroundings they interact with, such as soil, water and air. Energy flows through it while matter is recycled.

A feature or behaviour of an organism that improves its chance of surviving and reproducing in its habitat. Adaptations develop over many generations through natural selection.

All the individuals of one species living in the same area at the same time. Its size changes with births, deaths, immigration and emigration, and with resources available.

A living thing too small to be seen clearly without a microscope, including bacteria, some fungi and protists. Some cause disease, while others are useful in food production and decomposition.

A microorganism or other agent that causes disease, such as certain bacteria, viruses or fungi. Pathogens spread by various routes and can often be limited by hygiene and immunisation.

The process of making a person resistant to a disease, usually by vaccination, which prompts the body to produce antibodies and memory cells in advance of infection.

A preparation containing weakened, inactivated or partial parts of a pathogen that stimulates a protective immune response without causing the full disease.

A protein made by certain white blood cells that binds specifically to a foreign substance, helping to destroy or neutralise it. Antibodies give the body targeted defence against infection.

The breakdown of large food molecules into smaller, soluble ones that can be absorbed into the blood. It involves both mechanical action, such as chewing, and chemical action by enzymes.

A protein that speeds up a particular chemical reaction without being used up, for example a digestive enzyme breaking down starch or protein. Each enzyme works best at a certain temperature and pH.

The movement of digested food molecules, water or minerals through the wall of the intestine into the blood or lymph. It is helped by a large surface area.

Tiny finger-like projections lining the small intestine that greatly increase the surface area for absorbing digested food. Each villus contains blood vessels close to its thin surface.

The smallest particle of an element that can take part in a chemical reaction. It consists of a nucleus containing protons and neutrons, surrounded by electrons.

A pure substance made of only one kind of atom, which cannot be split into simpler substances by chemical means. Examples include oxygen, iron and carbon.

A pure substance formed when two or more different elements are chemically combined in fixed proportions, such as water or carbon dioxide. Its properties differ from those of its elements.

Two or more substances blended together without chemical bonding, in no fixed proportion, such as air or salt water. The substances keep their own properties and can often be separated physically.

The smallest particle of a substance that can exist on its own and still keep the substance's properties, made of atoms joined together. Water molecules contain two hydrogen atoms and one oxygen atom.

A separation method that passes a mixture through a filter, trapping insoluble solid particles while the liquid passes through. It separates an insoluble solid from a liquid or solution.

A separation method in which a liquid is boiled, the vapour is cooled and condensed, and the liquid is collected. It can separate a solvent from dissolved substances or liquids with different boiling points.

The change of a liquid into a gas at its surface, occurring at any temperature. It is used to recover a dissolved solid from a solution by boiling off the solvent.

The capacity to do work or cause change, existing in forms such as kinetic, potential, thermal, chemical, light and sound. Energy is conserved overall but can be transferred and transformed.

The energy an object has because of its movement. It increases with the object's mass and rises sharply as its speed increases.

The principle that energy cannot be created or destroyed, only transferred or changed from one form to another. The total energy of a closed system stays the same.

The transfer of thermal energy through a material by particles passing on vibrations or, in metals, by free electrons. Solids, especially metals, conduct best.

The transfer of thermal energy in fluids by the movement of warmer, less dense regions rising and cooler, denser regions sinking. It sets up circulating currents.

A push or pull that can change an object's speed, direction or shape. It is measured in newtons and has both size and direction.

A force that opposes motion when two surfaces move or try to move against each other, converting kinetic energy to heat. It can be reduced with lubricants or smooth surfaces.

The attractive force between objects that have mass, which on Earth pulls objects towards the centre of the planet. Its strength decreases with distance.

The amount of matter in an object, measured in kilograms and unchanged by location. It affects how strongly gravity pulls on the object.

The force of gravity acting on an object's mass, measured in newtons. It changes with location, so an object weighs less on the Moon than on Earth.

The force acting normally on each unit of area of a surface, measured in pascals. It increases when force increases or area decreases.

The mass of a substance per unit volume, usually in grams per cubic centimetre or kilograms per cubic metre. Less dense materials float in denser fluids.