Grade 8 CAPS Natural Science Flashcards

How do particles behave in a solid?

They vibrate in fixed positions, giving solids a definite shape.

How do particles behave in a liquid?

They are close together but can slide past each other, giving liquids fixed volume but no fixed shape.

How do particles behave in a gas?

They are far apart and move rapidly, allowing gases to fill any space.

What happens to particles during a change of state?

Their energy changes, but the particles themselves stay the same.

What effect does heating have on particles?

It increases their movement and energy.

What effect does cooling have on particles?

It slows their movement.

Why does diffusion happen?

Because particles are constantly moving from high to low concentration.

What is an atom?

The basic building block of matter.

What is an element?

A pure substance made of only one type of atom.

What is a molecule?

Two or more atoms chemically bonded together.

What is a compound?

A substance formed when atoms of different elements join chemically.

Why do compounds have different properties from the elements that form them?

Because chemical bonding creates new substances with new properties.

What does the periodic table show?

Elements arranged by atomic structure and chemical behaviour.

What are typical properties of metals?

Shiny, conductive and malleable.

What are typical properties of non-metals?

Dull, brittle when solid, and poor conductors.

What is a chemical reaction?

A process where substances interact to form new substances.

What is a reactant?

A starting substance in a chemical reaction.

What is a product?

A new substance formed during a chemical reaction.

What shows that a chemical reaction has occurred?

Colour change, heat change, gas formation or solid formation.

Why is mass conserved in a chemical reaction?

Because atoms rearrange but are not created or destroyed.

What is combustion?

A reaction with oxygen that releases heat and light.

What is rusting?

A reaction between iron, oxygen and water forming iron oxide.

What is decomposition?

A reaction where one compound breaks into simpler substances.

What is neutralisation?

A reaction between an acid and a base.

What is an exothermic reaction?

A reaction that releases energy.

What is an endothermic reaction?

A reaction that absorbs energy.

What determines a material's uses?

Its physical and chemical properties.

Why are metals used for pots and wiring?

Because they conduct heat and electricity well.

Why are plastics used for packaging?

They are durable, lightweight and corrosion-resistant.

Why are ceramics used for tiles and bricks?

They are heat-resistant and strong under compression.

What is density?

The mass per unit volume of a material.

What is the basic unit of life?

The cell.

What structures do plant and animal cells share?

Cell membrane, cytoplasm and nucleus.

What does the cell membrane do?

Controls entry and exit of substances.

What does the cytoplasm do?

Contains organelles and is where many reactions occur.

What does the nucleus do?

Controls cell activities.

What structures are unique to plant cells?

Cell wall, chloroplasts and a large vacuole.

What is the function of chloroplasts?

To carry out photosynthesis.

What is mitosis?

Cell division for growth and repair.

What is the role of the digestive system?

To break down food for absorption.

What is the role of the respiratory system?

To exchange oxygen and carbon dioxide.

What is the role of the circulatory system?

To transport nutrients, gases and wastes.

What is the role of the excretory system?

To remove waste products.

What is the role of the nervous system?

To detect stimuli and coordinate responses.

What is the function of the cornea?

To begin focusing light entering the eye.

What controls the size of the pupil?

The iris.

What does the lens do?

Changes shape to focus light onto the retina.

What is accommodation?

The lens changing shape to focus on near or far objects.

What do rods detect?

Dim light and movement.

What do cones detect?

Colour and fine detail.

What carries visual impulses to the brain?

The optic nerve.

What causes short-sightedness?

Light focusing in front of the retina.

What causes long-sightedness?

Light focusing behind the retina.

What is fertilisation?

The fusion of a sperm cell and an egg cell.

What is a zygote?

The cell formed when sperm and egg combine.

Where does the fetus develop?

Inside the uterus.

What is photosynthesis?

The process where plants make food using CO₂, water and sunlight.

Where does photosynthesis occur?

In the chloroplasts.

What does respiration release?

Energy from glucose.

How are photosynthesis and respiration connected?

Photosynthesis stores energy; respiration releases it.

What is an ecosystem?

A community of organisms interacting with their environment.

What are producers?

Organisms that make their own food.

What are consumers?

Organisms that eat other organisms.

What are decomposers?

Organisms that break down dead matter.

What is a food chain?

A sequence showing energy transfer between organisms.

What is a food web?

Interconnected food chains.

What happens to energy in a food chain?

It decreases at each level.

What is conduction?

Heat transfer through direct contact in solids.

What is convection?

Heat transfer in liquids and gases due to particle movement.

What is radiation?

Heat transfer through waves without needing matter.

What is the law of reflection?

Angle of incidence equals angle of reflection.

What is refraction?

Bending of light when it enters a new medium.

What does a converging lens do?

Focuses light rays together.

What does a diverging lens do?

Spreads light rays apart.

What causes static electricity?

A build-up of electric charge on material surfaces.

What happens when electrons transfer between materials?

One becomes negatively charged and one positively charged.

What causes a spark?

Sudden discharge of built-up charge.

What is lightning?

A massive discharge of static electricity in the atmosphere.

What is a force?

A push or pull that changes motion or shape.

What is gravity?

A force pulling objects toward Earth.

What is friction?

A force that opposes motion.

What are balanced forces?

Forces that produce no change in motion.

What are unbalanced forces?

Forces that change motion.

What is pressure?

Force applied per unit area.

Why do sharp objects cut better?

They apply force over a small area, increasing pressure.

Why does pressure increase with depth in fluids?

Because of the weight of the fluid above.

Why do hydraulics work?

Liquids cannot be compressed and transmit pressure evenly.

Why do some objects float?

Because they are less dense than the liquid they're in.

What causes day and night?

Earth's rotation.

What causes seasons?

Earth's tilt and revolution around the sun.

Why do we see moon phases?

Because of the moon's position relative to Earth and the sun.

What causes tides?

The gravitational pull of the moon on Earth.