Year 8 Science Revision: Physics, Biology & Chemistry

Year 8 Science Revision

Light & Space · Respiration · Unicellular Organisms · Combustion · Metals · Rocks

Year 8 · Science Department

What We'll Cover

Year 8 · Science Department

Light & Space

Earth & Space

Respiration & Breathing

Unicellular Organisms

Combustion & Metals

Rocks

01

Light on the Move

How light travels, what it is, and how it interacts with matter

Light on the Move

Key Terms

Vacuum

Completely empty space, no particles.

○

Matter

All things made of matter; 3 states: solid, liquid, gas.

◈

Transverse Wave

Vibrations at right angles to wave direction.

∽

Longitudinal Wave

Particles vibrate same direction as wave.

≣

Transparent

Light passes through without scattering.

◻

Translucent

Lets light through but scatters it.

▨

Opaque

Does not let light through.

◼

Reflect

Bounce off a surface.

↶

Absorb

Soak up / take in.

◉

Transmit

Pass through a substance.

➔

Year 8 Science

Rays, Images & Shadows

Ray

A narrow beam of light, represented by a straight line with an arrow showing its direction.

Image

A picture formed when light rays intersect or appear to intersect in a mirror, on a screen, or behind a lens.

Shadow

A dark area where light cannot reach because an opaque object is blocking the light path.

Pinhole Camera

A simple device without a lens that forms an inverted image when light travels through a tiny hole.

Source

The original point or object where a wave or light beam begins its journey.

Scattered

Light deflected from a straight path as it reflects off a rough surface or travels through an imperfect medium.

Reflection

Laws of reflection, ray diagrams, and types of reflection

02

Reflection — Key Terms & Law of Reflection

The Law of Reflection

Angle of Incidence = Angle of Reflection

Plane Mirror

Smooth flat mirror.

Ray Box

Equipment producing narrow light beam.

Normal

Imaginary line at right angles to surface where light hits.

Incident Ray

Ray going towards mirror.

Reflected Ray

Ray bouncing off mirror.

Angle of Incidence

Angle between incoming ray and normal.

Angle of Reflection

Angle between normal and leaving ray.

Ray Tracing

Method marking path of light ray.

SPECULAR REFLECTION

All reflected light goes same direction, smooth mirror.

DIFFUSE REFLECTION

Scattered in all directions, rough surface.

Year 8 Science

Refraction & Lenses

Refraction

Change in direction when light goes from one transparent material to another

Interface

Boundary between two materials

Lens

Curved transparent material that changes direction of light rays

Converging Lens

Lens that makes rays come together

Angle of Refraction

Angle between normal and refracted ray

Focal Point

Where parallel rays are brought together by converging lens

Focal Length

Distance between centre of lens and focal point

Cameras & the Human Eye

Year 8 Science

Digital Camera

uses electronics to record image

Sensor

detects light, converts to electrical signals

Retina

changes light energy into nerve impulses

Aperture

hole controlling how much light reaches sensor

Pupil

hole in front of eye that light passes through

Shutter

protects sensor, opens when photo is taken

Memory Card

stores images

03

Earth & Space

Astronomers, seasons, gravity, and the universe

Gathering the Evidence

History of Astronomy

Year 8 Science

Ptolemy

90–168 AD

Earth at the centre; Moon, Sun, and planets orbit around Earth.

Nicolaus Copernicus

1473–1543

Earth and planets orbit the Sun in circles.

Galileo Galilei

1564–1642

Used the telescope to observe the heavens, providing solid evidence for Copernicus' model.

Johannes Kepler

1571–1630

Sun at the centre; planets travel in <span style="color: #F4B41A; font-weight: 700;">elliptical</span> orbits, and moons orbit planets.

Seasons & Gravity

Year 8 Science

Beyond the Solar System

Year 8 Science

Constellation

Pattern of stars

Stars

Huge balls of gas giving out energy; Sun is a star

Galaxy

Large group of stars

Milky Way

Our galaxy containing our Sun

Universe

All millions of galaxies combined

Light Year

Distance light travels in 1 year ≈ 10 million million km

Proxima Centauri

Nearest star to Sun, 4.22 light years away

Phases of the Moon

Moon appears different shapes due to its position relative to Earth and Sun

Spacecraft

Allow scientists to investigate space by collecting samples and readings

04

Respiration

& Breathing

Aerobic & anaerobic respiration, gas exchange, and the circulatory system

Aerobic Respiration

Conducted the candle in a jar experiment.

Identified the active part of the air.

Proved oxygen is needed; showed it makes up 21% of air.

glucose <span style="color:#F4B41A">+</span> oxygen <span style="color:#F4B41A">&rarr;</span> carbon dioxide <span style="color:#F4B41A">+</span> water

Starting substances,<br>found on the left side of the equation.

New substances made,<br>found on the right side of the equation.

<strong style="color: #F4B41A; font-weight: 700;">Combustion vs. Respiration</strong> &mdash; same word equation, but an entirely different mechanism!

Using oxygen to release energy from glucose.

Same word equation as respiration but a different process.

Year 8 Science

Gas Exchange System

Gas Exchange & Getting Oxygen

Year 8 Science

Breathing

Muscle movement allowing lungs to expand/contract

Ventilation

Movement of air in/out of lungs

Diaphragm

Organ below lungs, contracts/relaxes

Alveoli

Little pockets in lungs — increase surface area, walls one cell thick for fast diffusion

Diffusion

Movement of particles from high to low concentration

Mucus

Sticky liquid trapping dirt/microorganisms

Cilia

Tiny hairs sweeping mucus from lungs

Red Blood Cells

Haemoglobin

Oxygen binds here

Arteries

Capillaries

Veins

Plasma

Tissue Fluid

Anaerobic Respiration

Glucose

Lactic Acid

Anaerobic Process

Occurs in the cytoplasm when no oxygen is available, primarily during strenuous exercise.

Energy Yield

Anaerobic respiration releases significantly LESS energy compared to aerobic respiration.

Advantages

Provides a quick, sudden burst of energy exactly when the body forcefully demands it.

After Exercise

Lactic acid diffuses into the blood, is carried to the liver, and is converted back to glucose.

EPOC / Oxygen Debt

Extra oxygen needed after exercise to replace lost oxygen and convert lactic acid back to glucose.

Feature

Aerobic

Anaerobic

Oxygen

Required

Not required

Products

CO₂ + Water

Lactic Acid

Energy Yield

High

Low

Year 8 Science

05

Unicellular Organisms

Cells, microorganisms, fungi, bacteria, protoctists, and the carbon cycle

The Five Kingdoms of Life

UNICELLULAR

One cell (e.g. bacteria, amoeba)

MULTICELLULAR

Many cells (e.g. humans, plants)

PROKARYOTES

<div style='display: flex; flex-direction: column; gap: 12px; font-size: 19px;'><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #F4B41A; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Unicellular</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #F4B41A; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>No nucleus</span></div></div>

PROTOCTISTS

<div style='display: flex; flex-direction: column; gap: 12px; font-size: 19px;'><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #AEE2D0; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Mainly unicellular</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #AEE2D0; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Have nucleus</span></div></div>

FUNGI

<div style='display: flex; flex-direction: column; gap: 12px; font-size: 19px;'><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #FF8C00; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Mainly multicellular</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #FF8C00; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Nucleus</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #FF8C00; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>No own food</span></div></div>

PLANTS

<div style='display: flex; flex-direction: column; gap: 12px; font-size: 19px;'><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #32CD32; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Multicellular</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #32CD32; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Nucleus</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #32CD32; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Make own food</span></div></div>

ANIMALS

<div style='display: flex; flex-direction: column; gap: 12px; font-size: 19px;'><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #DC143C; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Multicellular</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #DC143C; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>Nucleus</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #DC143C; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>No own food</span></div><div style='display: flex; align-items: flex-start; gap: 12px;'><span style='color: #DC143C; font-weight: bold;'>•</span> <span style='opacity: 0.9;'>No cell wall</span></div></div>

Microorganisms

Too small to see without a microscope.

Diffusion

Particles spread out to fill the available space.

Viruses

Not living — cannot survive without a host cell.

Year 8 Science

Microorganisms in Detail

FUNGI

Budding

(asexual reproduction — small new cell grows from parent)

Fermentation

(anaerobic respiration: glucose → CO2 + water)

Population

Limiting Factor

BACTERIA

Binary Fission

(cell splits into two)

Chromosome

(instructions for organism)

Flagella

(tail for movement)

Lactic Acid

(glucose → lactic acid)

PROTOCTISTS

Algae

(uses photosynthesis)

Chloroplast

(site of photosynthesis)

Chlorophyll

(green substance absorbing light)

Producers

(make own food, start of food chain)

Year 8 Science

CO2 + water → glucose + oxygen

Decomposers & the Carbon Cycle

Photosynthesis

Respiration

Feeding

Decomposition

Combustion

Ecosystem

All environmental factors + organisms in a habitat

Decomposers

Feed on dead organisms/waste, recycle substances

Decay

Breakdown of dead organisms

Carbon Cycle

Shows how carbon compounds are recycled

Combustion

Burning fuels releasing CO₂

Feeding

Transfers carbon from plants to animals

Essential Nutrients

Carbohydrates

Energy source

Proteins

Growth and repair

Fats

Energy storage, insulator

Year 8 Science

Combustion

06

Fuels, burning, fire safety, air pollution, and global warming

Fuels & Oxidation

Year 8 Science

Fuel

Substance from which stored energy can be usefully transferred.

Fossil Fuels

Formed from living organisms millions of years ago — e.g., petrol, diesel.

Hydrocarbons

Compounds that contain only carbon and hydrogen atoms.

Combustion

Burning in air, gives out energy as heat and light.

Fuel Cell

Special cells that release energy directly from hydrogen.

Hydrogen

Oxygen

Water

Oxidation

The chemical process of reacting with oxygen.

Oxide

A chemical compound formed by the process of oxidation.

Reactants

The starting substances in a reaction.

Products

The new substances formed as a result.

Metal

Oxygen

Metal Oxide

Conservation of Mass

Mass is never gained or lost — atoms just rearrange.

Forms white zinc oxide. Mass appears to increase as oxygen from the air is added.

Fire Safety & Air Pollution

Year 8 Science

Global Warming & Climate Change

More CO₂ = Warmer Earth = Climate Change

Year 8 Science

Greenhouse Gases

Gases that trap energy from the Sun in the atmosphere (e.g., CO₂, Methane).

Greenhouse Effect

Energy trapped by greenhouse gases is transferred back to Earth's surface, causing warming.

Global Warming

The long-term increase in global temperatures due to a higher concentration of greenhouse gases.

Climate Change

Significant changes to global weather patterns, leading to more extreme storms, floods, and droughts.

Evidence

Average global temperatures are increasing, and polar ice caps are melting at a rapid rate.

07

Metals & Their Uses

Properties, corrosion, reactivity series, acids, and alloys

Year 8 · Science Department

Metal Properties & Corrosion

Physical Properties

Observable characteristics like melting point, density, and conductivity.

Chemical Properties

Describes how a substance acts and reacts with other substances.

Properties of Metals

Specific Metal Uses

Copper

Good conductor, used in circuits & water pipes. Unreactive, non-poisonous, malleable.

Aluminium

Strong and light, used in window frames.

Catalytic Converter

Platinum, palladium & rhodium — converts dangerous gases.

Corrosion

Any reaction with oxygen at the metal surface.

Rusting (Corrosion of Iron)

Requires both water AND oxygen.

iron + oxygen + water → iron hydroxide

Ti + O₂ → TiO₂

Preventing Rust (Barriers)

Year 8 Science

The Reactivity Series

Increasing Reactivity

Potassium

Sodium

Lithium

Calcium

Magnesium

Aluminium

Zinc

Iron

Tin

Lead

Copper

Mercury

Silver

Gold

Platinum

Reactivity

How quickly/vigorously something reacts.

Reactivity Series

List of metals in order of reactivity.

Metals & Water

Produce metal hydroxide + hydrogen;

sodium + water &rarr; sodium hydroxide + hydrogen

Effervescence

Production of gas when metals react with acid.

Reaction Key

Catches fire

Reacts very quickly

Reacts

Slow/partial

No reaction

Year 8 Science

Metals, Acids & Alloys

metal + acid → salt + hydrogen

magnesium + sulfuric acid → magnesium sulfate + hydrogen

Year 8 Science

Rocks

Rock types, weathering, erosion, the rock cycle, and materials in the Earth

08

Section 08 · Geological Sciences

Rocks & Their Properties

Geologist

Scientist studying rocks and Earth

Rocks

Naturally occurring substances made of different grains

Minerals

Chemical compounds found in rocks

Texture

Combination of sizes and shapes of grains

Interlocking Crystals

Grains fit together closely — firm, don't wear away easily

Rounded Grains

Gaps fall between grains — not strong, wear away easily

Porous

Rounded grain rocks that absorb and hold water

Permeable

Water is capable of running straight through

Uses of Rocks

Cement

Key building material made from limestone

Concrete

Composite mixture of cement + sand + gravel

Year 8 Science

Igneous & Metamorphic Rocks

Igneous Rocks

Metamorphic Rocks

Year 8 Science

Weathering & Erosion

CHEMICAL WEATHERING

Acidic rainwater reacts with minerals, wearing rocks away.

BIOLOGICAL WEATHERING

Plant roots splitting rocks apart.

PHYSICAL WEATHERING

Freeze-thaw action

(water in cracks → freezes → expands → crack gets bigger)

Temperature changes causing expansion and contraction.

Erosion

Movement of loose/weathered rock

Abrasion

Rock fragments bumping into each other

Sediment

Bits of rock/sand in streams

Glacier

Rivers of ice transporting large rocks

Year 8 Science

Sedimentary Rocks & The Rock Cycle

Sedimentary Rocks

Formed from layers of sediment experiencing compaction and cementation (e.g. sandstone, mudstone).

Compaction

Heavy overlaying layers create pressure that forces water out and squashes grains tightly together.

Cementation

Dissolved minerals crystallize in the gaps between sediments, acting as a natural glue.

Texture

Always composed of rounded grains that have been worn down by physical weathering and erosion.

Year 8 Science

Magma

Igneous Rock

Sediment

Sedimentary Rock

Metamorphic Rock

Materials in the Earth

Year 8 Science

Native State

Metals found as pure elements in rocks, requiring no chemical extraction.

Ores

Rocks containing enough metal or valuable compound worth mining commercially.

Extracting Ores

A multi-step process: Mining → Crushing → Chemical Reactions to purify.

Mining Problems

Destroys natural habitats on a massive scale and causes severe pollution.

Rare Metals

Excessively hard to obtain in high concentrations, making them very expensive.

Recycling

Using a material again rather than extracting raw ones or trashing them.

Recycling Advantages

Cuts down on mining pollution and landfill waste; allows raw material supplies to last longer; requires significantly less energy than extracting new ores.

Recycling: Better for the Planet!

Environment

Supply Lasts Longer

Less Energy

Revision Tips & Resources

Flash Cards

Write the term on one side, definition on the other

Word Banks

Create a glossary with all key definitions

Q Cards

Write questions and test yourself

Diagrams

Label diagrams: eye, lungs, rock cycle, etc.

BBC Bitesize • Seneca Learning

You've got this! Highlight each definition once you know it ✓

Year 8 · Science Department