Osaka Public High School Entrance Examination - Science key terms

The distance an object travels per unit time, commonly expressed in metres per second or kilometres per hour; it describes how quickly position changes and is a scalar quantity.

Motion in which an object moves along a straight line at a constant speed, so it covers equal distances in equal time intervals and its velocity does not change.

The tendency of an object to resist changes in its state of motion; an object at rest stays at rest, and a moving object continues at constant velocity unless a net force acts.

The transfer of energy when a force moves an object through a distance in the direction of the force; measured in joules and calculated as force times distance.

The sum of an object's kinetic energy and gravitational potential energy in a mechanical system; it can change form but is conserved when only gravity does work.

The number of complete oscillations or waves passing a point each second, measured in hertz (Hz); it determines the pitch of a sound and the colour of light.

The relationship stating that the current through a metallic conductor is proportional to the potential difference across it, provided temperature stays constant; expressed as V = IR.

The production of an electric current in a conductor when the magnetic field around it changes, such as when a magnet moves near a coil; the basis of generators.

The conversion of electrical energy into thermal energy when current flows through a resistance; the heating effect increases with current, resistance, and time.

The smallest neutral particle of an element that retains the element's chemical properties; it consists of a nucleus containing protons and neutrons, surrounded by electrons.

A group of two or more atoms chemically bonded together, forming the smallest unit of a substance that can exist independently while keeping its chemical properties.

An atom or group of atoms that has gained or lost one or more electrons, giving it a positive or negative electric charge and allowing it to conduct electricity in solution.

A symbolic representation of a chemical reaction using element symbols and formulas, with reactants on the left and products on the right, balanced to show conservation of atoms.

The principle that the total mass of the reactants equals the total mass of the products in a closed chemical reaction, because atoms are rearranged but not created or destroyed.

A reaction in which two or more substances join chemically to form a single new substance, such as iron combining with sulfur when heated.

A chemical reaction in which a single compound breaks down into two or more simpler substances, often requiring heat, electricity, or light.

A reaction in which a substance gains oxygen or loses electrons; in everyday terms it includes burning, rusting, and the tarnishing of metals.

A chemical reaction in which a substance loses oxygen or gains electrons; it often occurs together with oxidation in processes such as extracting metals from ores.

The reaction between an acid and a base to produce water and a salt, resulting in a solution that is closer to neutral depending on the amounts used.

The maximum mass of a solute that can dissolve in a fixed amount of solvent at a given temperature, often expressed in grams per 100 grams of water.

A purification method in which a substance is dissolved in a hot solvent and then cooled so that pure crystals form while impurities remain dissolved or are filtered out.

The basic structural and functional unit of living things; it contains genetic material and is surrounded by a membrane that controls what enters and leaves.

The process by which a parent cell splits to form two or more daughter cells, allowing growth, repair, and reproduction in organisms.

A type of cell division that produces gametes with half the normal chromosome number, creating genetic variation through crossing over and independent assortment.

The passing of genetic information from parents to offspring through genes, which determines inherited traits such as eye colour or plant height.

The process by which green plants and some other organisms use sunlight, water, and carbon dioxide to produce glucose and oxygen inside chloroplasts.

The process in cells that releases energy from glucose by combining it with oxygen, producing carbon dioxide and water as waste products.

A sequence showing how energy and nutrients pass from one organism to another through feeding relationships, starting with a producer and ending with a top predator.

A community of living organisms interacting with each other and with their non-living environment, including factors such as sunlight, water, soil, and temperature.

A rapid automatic response to a stimulus that does not require conscious thought, mediated by a reflex arc through the spinal cord or brain.

A sudden shaking of the ground caused by the release of energy when rocks along a fault break and slip, producing seismic waves.

The point inside the Earth where an earthquake starts and energy is released; the point directly above it on the surface is the epicentre.

Molten rock beneath the Earth's surface, containing dissolved gases and minerals; it becomes lava when it erupts onto the surface.

Rock formed from layers of sediment that are compacted and cemented over time, often preserving fossils and showing stratification.

Layers of sedimentary rock or soil arranged one above another; younger layers are usually on top unless the ground has been disturbed.

The boundary between two air masses with different temperatures and densities; it often brings changes in weather such as rain or strong winds.

The orbiting of one celestial body around another, such as Earth's yearly journey around the Sun, which causes seasons and changes in visible constellations.

The spinning of a celestial body around its own axis, such as Earth's daily rotation, which causes day and night.