PSLE Science key terms

An organism that carries out all life processes such as taking in food, breathing, growing and reproducing. Examples include plants, animals, fungi and bacteria.

A basic activity that all living things perform to stay alive, such as nutrition, respiration, movement, growth, reproduction and getting rid of waste.

The smallest unit of a living thing that can carry out life processes. Some organisms have one cell; larger ones are built from many cells.

Sorting living things into groups that share similar features, so that they are easier to study and identify. Groups may be based on body coverings, how they move or how they reproduce.

An animal with a backbone inside its body. Fish, amphibians, reptiles, birds and mammals are the five vertebrate groups, each with distinctive features.

An animal without a backbone, such as an insect, worm, snail or crab. Many invertebrates have a hard outer covering that protects and supports the body.

A warm-blooded vertebrate covered in hair or fur that feeds its young with milk. Mammals breathe with lungs and most give birth to live young.

The process in which green plants use sunlight, water and carbon dioxide to make food, releasing oxygen. It happens mainly in the leaves and needs the green pigment chlorophyll.

The green pigment found in leaves and other green parts of plants. It absorbs light energy needed for photosynthesis, which is why most leaves look green.

Tiny openings, mostly on the underside of leaves, that let carbon dioxide in and oxygen and water vapour out. Each opening is controlled by two guard cells.

The loss of water vapour from a plant through its leaves. It helps pull water up from the roots and cools the plant on hot days.

The plant part that usually grows underground. Roots anchor the plant and absorb water and dissolved minerals from the soil.

The organs that break food into simpler substances the body can absorb. It includes the mouth, gullet, stomach, small intestine and large intestine.

The breaking down of large food molecules into smaller ones that can dissolve and pass into the blood. It begins in the mouth and continues along the digestive tract.

The movement of digested food and water through the walls of the small and large intestines into the blood. It allows nutrients to reach every body cell.

The heart, blood vessels and blood working together to carry oxygen, digested food and waste around the body. It transports substances to and from every cell.

A muscular organ that pumps blood around the body. It beats faster during exercise so that more oxygen and food reach the muscles.

A tube that carries blood through the body. Arteries carry blood away from the heart, veins carry it back, and capillaries link the two and exchange materials with cells.

The organs used for breathing, mainly the nose, windpipe and lungs. They take in oxygen and remove carbon dioxide and water vapour from the body.

The process in cells that releases energy from food, usually using oxygen and producing carbon dioxide and water. It is not the same as breathing, which moves air in and out.

The bones and joints that support the body, protect organs and work with muscles to allow movement. Bones also store minerals and make blood cells.

The muscles that pull on bones to produce movement. Muscles work in pairs, with one contracting while the other relaxes, and they need energy from food.

A place where two or more bones meet so that movement can happen. Different joints allow different movements, such as bending, turning or swinging.

The stages a living thing passes through from the start of its life to the time it produces offspring of its own. Examples include egg, young and adult stages.

The process by which living things produce new individuals of the same kind, so that the species continues to exist. It may involve seeds, eggs or live young.

The sprouting of a seed into a young plant when conditions such as water, warmth and air are right. The seed absorbs water, swells and the young root appears first.

A change in body form during an animal's life cycle, such as a tadpole becoming a frog or a caterpillar becoming a butterfly. The young often looks very different from the adult.

A feature or behaviour that helps a living thing survive in its habitat. Examples include thick fur in cold places and fins for swimming.

The place where a living thing normally lives and finds what it needs, such as food, water and shelter. Different habitats support different communities of organisms.

Colouring or body shape that lets an animal blend with its surroundings, helping it hide from predators or sneak up on prey. It is a common adaptation.

A series of living things in which each is eaten by the next, showing how energy passes from one organism to another. It usually starts with a green plant.

An organism, usually a green plant, that makes its own food using sunlight. Producers are the starting point of most food chains.

A living thing that cannot make its own food and must eat other organisms. Animals are consumers, and they may eat plants or other animals.

Anything that has mass and takes up space. Solids, liquids and gases are all matter, and matter can change state when heated or cooled.

A state of matter with a fixed shape and volume because its particles are packed closely and held in place. Solids keep their shape unless a force changes it.

A state of matter with a fixed volume but no fixed shape, because its particles are close but can slide past one another. Liquids flow and take the shape of their container.

A state of matter with no fixed shape or volume, because its particles are far apart and move freely. Gases spread out to fill whatever space is available.

The change of a liquid into a gas at its surface, happening at any temperature. It speeds up when the liquid is warmer or exposed to moving air.

The change of a gas into a liquid when it is cooled. Water vapour in warm air turns into droplets on cold surfaces such as a glass of cold drink.

The rapid change of a liquid into a gas throughout the liquid when it reaches a certain temperature. Bubbles form and rise to the surface.

The change of a solid into a liquid when it is heated enough. The temperature at which this happens is the same temperature at which the liquid freezes.

The change of a liquid into a solid when it is cooled to a low enough temperature. The particles slow down and settle into fixed positions.

Two or more substances combined without a chemical reaction, so each keeps its own properties. Mixtures can often be separated by filtering, sieving or evaporating.

A mixture in which a substance dissolves evenly in a liquid to form a clear liquid. The dissolved substance does not settle and cannot be seen.

Separating an insoluble solid from a liquid by pouring the mixture through a filter that traps the solid particles. The clear liquid that passes through is called the filtrate.

A push or a pull that can change an object's speed, direction or shape. Forces are measured in newtons and can act when objects touch or at a distance.

A force between two surfaces that resists sliding and slows moving objects down. It produces heat and can be reduced with oil or rollers.

The force that pulls objects towards the Earth and keeps them on the ground. It acts at a distance and gives objects their weight.

The ability to do work or cause change. Energy comes in forms such as light, heat, sound, electrical and kinetic, and can be transferred or stored.

A form of energy that flows from a hotter object to a cooler one. It can change an object's temperature or make it change state.

A form of energy that lets us see and travels in straight lines. It can be reflected by shiny surfaces and bent when it passes into a different material.

A dark area formed when an object blocks light travelling in straight lines. Its size and position change as the light source or object moves.

A complete loop through which electric current can flow, containing a source such as a battery, wires and a component such as a bulb. A break in the loop stops the current.

A material that lets electricity or heat pass through it easily, such as copper or steel. Metals are usually good conductors.

A material that does not let electricity or heat pass through easily, such as rubber, plastic or wood. Insulators are used to protect people from electricity and heat.