Year 9 Science Comprehensive Study Resource

Flashcards covering key terms and concepts across Year 9 Science, including scientific inquiry, energy transformations, disease and human body systems, materials, ecology, and chemical principles.

Independent variable

The variable that you deliberately change in an investigation.

Dependent variable

The variable that you measure in an investigation to determine the outcome.

Controlled variables

The variables that are kept the same throughout an investigation to ensure a fair test.

Reliability

The extent to which an experiment yields similar results when repeated.

Energy

The ability to cause change or do work.

Kinetic energy

The energy of movement.

Potential energy

Stored energy, such as that held in a raised object or a stretched spring.

Thermal energy

Energy linked to the movement of particles; often felt as heat.

Chemical energy

Energy stored in substances such as food, petrol, and batteries.

Electrical energy

Energy transferred by moving electric charges.

Renewable energy source

An energy source that is naturally replaced on a short timescale.

Non-renewable energy source

An energy source that is used faster than it is naturally replaced.

Energy efficiency

A measure of how much of the input energy is transferred into useful output energy.

Law of conservation of energy

A principle stating that energy cannot be created or destroyed, only transferred or transformed.

Sankey diagram

A specific type of flow diagram used to show the energy input and output of a device, where the thickness of the arrows is proportional to the amount of energy.

Disease

A condition that affects normal body function.

Pathogen

A microorganism or biological agent capable of causing infectious disease.

Bacteria

Single-celled organisms; some cause disease, while many are harmless or useful.

Virus

An infectious agent that reproduces strictly inside living host cells.

Parasite

An organism that lives on or in a host and benefits at the host's expense.

Transmission

The mechanism by which an infectious disease spreads from one host or place to another.

Vaccine

A biological preparation that trains the immune system to recognise and respond rapidly to a pathogen.

Antibiotic

A medicine used to treat bacterial infections, which is ineffective against viruses.

Antigen

A foreign particle that triggers an immune response when entering the body.

Acquired immunity

The targeted immune response developed against a specific antigen.

B-cells

White blood cells that make specific antibodies against antigens.

Synapse

The gap between two neurons across which nerve impulses are transmitted chemically.

Neurotransmitter

A chemical released at a synapse that diffuses to the adjacent cell to initiate an electrical impulse.

Effector

An organ or cell, such as a muscle or gland, that carries out the body's response to a stimulus.

Receptor

A specialized cell or nerve ending that detects internal or external environmental stimuli.

Reflex arc

The neural pathway that mediates a rapid, automatic reflex action from receptor to effector.

Endocrine glands

Ductless glands that release hormones directly into the bloodstream.

Homeostasis

The human body's tendency to resist change in order to maintain a stable, relatively constant internal environment.

Insulin

A hormone produced by the pancreas that signals the liver to take up glucose and store it as glycogen, lowering blood sugar levels.

Glucagon

A hormone secreted by the pancreas that signals the liver to break down stored glycogen into glucose, raising blood sugar levels.

Material

A substance used to make an object.

Physical property

A characteristic of a substance that can be observed or measured without producing a new substance.

Chemical property

A characteristic describing how a substance reacts chemically to form new substances.

Corrosion

Damage caused to a material through chemical reactions, such as the rusting of iron.

Polymer

A substance composed of long molecular chains of repeating structural units.

Biodegradable

Capable of being broken down and decomposed by living organisms under suitable environmental conditions.

Ecosystem

A community of living organisms interacting with each other and their physical, non-living environment.

Biodiversity

The variety of living things found in an area or on Earth.

Sustainability

Meeting present needs while managing and protecting resources and environments for the future.

Greenhouse gas

An atmospheric gas that absorbs and re-emits heat, contributing to the greenhouse effect.

Law of conservation of matter

The scientific principle stating that matter cannot be created or destroyed in a chemical reaction.

Mineral ores

Naturally occurring minerals that contain useful or valuable substances, such as metals, that can be extracted.

Atomic number $(Z)$

The number of protons found in the nucleus of an atom of a specific element.

Mass number $(A)$

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

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Reaction rate

A measure of how quickly reactants are converted into products in a chemical reaction.

Catalyst

A substance that increases the rate of a chemical reaction without being permanently altered or changing the products.