OceanofPDF.

com
 OceanofPDF.com

Mammhot

enSci

th
(wi
ttle
a li he
lp from some le
ephan
t shrews)
 OceanofPDF.com

Senior Editor eJ nnySich

Senior Art Editor StefanPodhorodecki

Editors K
,elsie
V
i ckyBesaw
Richards

Designer Kit Lane

ak
cJet Design Development Manager

Sophia MTT

ak
cJet Designers Stefan
odhorodecki,
P

Priyanka Bansal

Senior DTP Designer Harish Aggarwal

Production Editor R
ob Dunn

Production Contr
oller Sian Cheung

Managing Editor r
F ancesca Baines

Managing Art Editor Philip Letsu

Publisher Andrew Macintyre

Art Director Karen Self

Associate Publishing Dir

ector Liz Wheeler

Publishing Director o
J nathan Metcalf

Contributors ack
J Challoner
,

Andrea Mills, Georgia Mills

Consultants e
,PDerek
ohnson
nnyJHarve
y

W
h
ti thanks to Helen
eters
P for the index and

V
t
cioria Pyke for proofreading

First published in Grea

t Britain in 2020y b

Dorling Kindersle
y Limited

One Embassy Gardens,8

V iaduct Gardens, London Y
SW11 7A

Artwork cyright
op © 2020 David Macaulay

e T xt and design copyright © 2020 Dorling Kindersle

y Limited

A
P
e nguin Random House Company
 OceanofPDF.com

Csoent

Matter Light

States of matter 8

eflection
R

Changing states 10

efraction
R

Density 12

White light

Materials 14

Seeing colour

Separating mixtures 16

Electromagnetic radiation

Elements 18

Static electricity

Atoms 20

Electric current

Molecules 22

Magnetism

Chemical reactions 24

Rapid reactions 26

Forces

Combustion 28

What are for

ces?

The pH scale 30

D e f o r ming forces

Acceleration

32

Life Momentum

What is life? 34

Action and reaction

Bacteria 36

Gra
vity

Cells 38

riction
F

ypesTof cell 40

Drag

Plants 42

Pressure

F l o we r s 44

Hydraulics

Seeds 46

F l o ating

o F od chains 48

F light

Digestion 50

Simple machines

Breathing 52

Circulation 54

Earth and space

OceanofPDF.com
 OceanofPDF.com

Matter
 OceanofPDF.com

States of matter

Everything aroundoyu is made of .rom

matter
Ftrees

to compu t e r s to t h e air oy u’re breathing – i f i t ta k e s

up space,sit’ m
. Ma tter
a tter exi s t s in three m a i n states:

solid, liquid, an d g as. Wh e n a substance changes from

o n e s tate to a ,n iother
t is still m a d e u p of exac t l y the

same tiny particles. Bu t t h e p a r t ic l e s behaev in ver y

different ways in each state, as demonstrated yb

the mammoth s i n these three beaker s.

Solid

In this
, thebeaker
mammoth matter is

f o r ming a solid. The particles are locked

together in a strong
, dense structure and

tdon’want to let go of . each

Thisother

swi hy solidshav
e a fixed shape.
OceanofPDF.com
OceanofPDF.com

Thawing

Drip by drip, the

mammo
th emerges

as the e
ic.smel
t
 OceanofPDF.com

Statetostate

WATERVAPOUR

t a W er can change back and forth

between its .states

Ice melts
endlessly

, whiintochevawater
porates into steam,

and steam condenses, whi

intochwater

freezes, aintosubstance
.iceUsually n

i
t
i
has to go through the liquid statebut in

s
o
p
certain circumstances it can skip this step

t
D

a
and turn straight from a solid into a gas.

m
i
l
b
This is called sublimation. When the

u
S
reverse happens, and a gas tur ns directly

into a solid, it is known as deposition.

ICE

Waetr

The temperature atwhich a solid

t u r n s to a liquid is called its melting

orpoint.
water this
F is 0°C (32°F).

Heating the ice bey

ond this

temperature means its particles gain

enough energy to break awayfrom

each other and become a liquid.

Drying off

The warmth of the

fire dries the mammo

th’s

tew fur by turning the

owat
er
vapour
t. in
 OceanofPDF.com

Density

Matter makes up evr y o bject on the planet, ubt

Weighing it up

some things have more than others. Density is a Three very diffe

standing on th

measure of how much mass (amount of matter)

look similar in

an object h a s for its ov lume (how much space

show that each m

it takes u p ) . M o s t solid objects are more d e n s e

mass. This is b

becausetheir parctiels aer packed. colseyl together

ha
ving the same

three mammoth

Liquids an d g ases tend t o b e less dense because

different densitie

their particles ar e more spread out.

Wyol mammoth

stoL of air is

trappedbetween

the dual
viindi

strands of wool in

this soft struc

ture,

making
t much
i less

dense sthan
t i

flesh-and-bone

double.
 OceanofPDF.com

Grani
e tmammo
th

The strong stone of this sculpture is

made up of part
ciel s that are very

sjec
tare
close
ense
. ther
D
ogetob

heavier for their size – this one has

smashed the scales!

 OceanofPDF.com

A transparent glass window blocks

out wind and rain

thout
wi obscuring

Materials

the view. Glass si made by heating

All the objects around us are made of materials.

Some materials, such as wood, metals, and

ceramics, are made from substances found in

nature. O t h e r s are m a d e yb c h emical reactions.

T h e s e ar e known as synthetic materials. Objects

are often made from many d i f ferent materials,

each wi t h i ts o wn u s e ful properties.

biF reglass fshing

i rods

b i F reglasstis a ligh but strong

composi
e tmat
eri
al made

of glass and plasti

c.

Gone fishing

An elephant shrew fishing trip is a mammoth Rubber hose

Bendy rubber is a

undertaking
. The shrews ha
vecarefully selected

natural material that

the right materials to construct their handcrafted

makes good tubing –

holiday home. Each material has properties that

t, twei
ixfle
ble,
gh ghli

can make it very good at some things and totally

and .wat
erproof

useless at others.
oodWis hard and
, so sturd
it y

makes a good material for the cara

svanbarrel-
’
 OceanofPDF.com

a F bric shad
e

t andLgihsoft, thisabri
fc

sheet can provide shade

from the Sun bu

t tnoblock

out
.t cothe
eymlpeltghli
 OceanofPDF.com

Sandyture
mix

The sludgy mix is a

combinati
on of sal
ty sea

, sand,
wat
er sand
tof rock.
bi

The biggest

lumps are ftle

in the ve
sie

Magne
sitm

Amagnet would

ceDtnaing the

remove any iron

mixture leaves

eltcrianstihpesand.

the sand lying

at theomttbo

e t l i F r paper

n i T y holes in the

ret l i f paper allow

idlqui through bu
t

notsolidlcipar
t es.
 OceanofPDF.com

Types of mixture

Solution

Salt water is a solution – a mixture

A beam of light will pass straight

where one substance (salt) is dissolv

ed

through a salt-water solution because

in another (water). The salt is so ev

enly

there are no particles to er flect the light.

mixed with the water thatthere are no

visible particles: the salt seems to vanish

into. Mixtures
the waterwith visible

particles, such as,sandy

are called
water

suspensions. A mixture that looks

evenlycombined to the naked

uteyb actually contains tin

y

particles is called a colloid.

ool
tC i

As the water vapour travels

through the condensing

t t iuni

cools and turns back

ot ild.qinui

Water

vapour

Distillation

Pure wat
er

o T separate substances

Thewater colleedct
dissolv
ed in a liquid,ouy can

heat the liquid to boiling

at the end is pure –

point so that it evaporates,

notmidextiw h any

elaving the substances

other substances.

obehind.
collect Tthe liquid

itself,ouy need to capture

the vapour and condense it.

This is called distillation.

Bubble, bubble

When all the water

 OceanofPDF.com

Hforhdyrogen

Hydrogen si tnothat
H

common on Earth, but

Organizing the elements

t’s the
i most abundan
t

The elements are arranged into a chart

leemen
t in theverse.
Uni

called the periodic tab

. lElements
e with

similar properties are positioned together in

vertical columnscalled groups.Each element

Li

has its own chemical symbol made up of one

or two letters – O representsoxygen,uAis

Be

gold, and He stands for helium.

Many
lats me

The elemen
st in the middle

of the periodi
act ble, shown

Na

here in blue, are the transi

noit

M
g

als.t me
These include
e), iron (F

silver (Ag), and copper (Cu).

aC

Sc

Ti

Cr

Mn

Rb
e F

oC

Sr

Zr

Nb

Mo

c T

Ru

Rh

s C

Ba

La-

uL
Hf

a T

Re

Os

Ir

rF

Ra Ac-

f R

Lr
Db

Sg

Bh

Hs

tM
 OceanofPDF.com

Examining the elements

Elements
Each element is made from just one type of atom

(see pages 20–21). This gives every element its own

Everything i n the Univer s e is m a d e of

properties
. Most of the elements are solids at oom
r

. matter
If oy u c o u l d break d o wn m a tt e r i n t o

temperature
, and many of these are metals, such

as iron and gold. Solid non-metals include carbon

i t s s i mp l e s t substances,oyu wo u l d be l e f t

and. Some
sulfur elements are gases at oom
r

w i t h t h e e l e m e nts. T h e s e ar e the building

temperature – among these areoxygen,

blocks of evr y t h i n g in t h e world, from

hydrogen, and helium.

mountains to mammoths. M o s t elements,

such as oxygen and carbon, a r e f o u nd

naturally on E a r t h, w hi l e o t he r s haev been

createdyb scientists in l a boratories.

What makes a mammoth?

Lik
e all animals, mammo
ths are

made up mostly of oxygen,

carbon, and hydrogen. These

three elemen
st are the main

ingredi
s tinenall
vingli things.

Chlorine (Cl)

This pale green gas

isvery react
ev i (quiock t

join
thther
wi
o s)leemen
t

andextremely poisonous.
 OceanofPDF.com

A t o m s

Under construction

Atoms are t h e minuscule building blocks

This mammoth-built model shows the structure

that make up all . Everything

matter you

of an atom. The nucleus in the centre is made

know is made rfom atom s – stars, books,

up of protons and neutrons, while the excitable

mammoths, evenoyu r own

. Atoms
body

electrons whizz around outside in areas called

are so tiny that seven b i l li o n o f them could

shells. The attraction between the positively

chargedprotons and negatively charged

fit insi d e t hi s f u ll stop.
o buiTl d a n a tom you

electrons is what holds the atom together

.

would need three even smaller types o f

particle: protons, neutrons, an d e l ectrons.

 OceanofPDF.com

Whizzing eletrons
c

Electrons zoom around

the nucleus,talik
ebi

sing
plane
ttorbi

the Sun.

eO
tur shell

The more elec

trons an

ota m has, the more

she
t llsneeds
io t

hold them.

Nucleus

tlyThe
packed
ghti

onsprot and neutrons

orm
f the nucleus

in thetre
en
c

oftheatom.
 OceanofPDF.com

Construction complete

Molecules

At this chemical construction site

, two colourl

gases have come together to of r m one of

o wT o r more atoms joined together make

important compounds on planet Earth:. w

a molecule. Molecules c a n b e en o r mous,

Vati l for life as we know it, and great

containing thousands of atoms, or they c a n

for quenching a thirst, all it takes

to make a water molecule is

be simple, ma d e o f just two o r three. S o m e

anoxygen atom and two

have only one type of atom: these a r e called

hydrogen atoms looking

elemental molecules. Ot h e r s combine atoms

to form a bond.

of different elements to f or m compounds.

T h e t h ing all molecules have in common i s

that they ar e held together by ch emical bonds.

How chemical bonds work

Each
ydrog
h

The atoms in a molecule are bonded together because the

y

s toff
ar
thstwi
just one

share electrons. Atoms of each element (see pages 18–19)veha

eelctron, but has spac

e

a certain number of electrons

. The electr
o n s f o r m shells around

orf two. B onding

th wi
an

thenucleus. Each shell can hold a specific number of electrons

.

oxygenatomcompl
eset

If the outer shell is not full, the atom can fill it upy bsharing

each
ydrogen
h om’s
at

electrons with another atom. This creates a chemical bond

between the two atoms.

Hydrogen

Oxygen

Eachhydrogen

The ygen
ox omatneeds

mota needs one

two more elec

trons
o t

moreelectronto

settuo rfilishell.

settuo rfilishell.
OceanofPDF.com
 OceanofPDF.com

Getting a reaction

Themammothsinthealb,trying

togetareactionbetweentwostarting

chemcias,orl reactants.Thereactants

canbeelements,madeom
fr justonetype

of atom,orcompoundscontainingmore

thanonetypeof atom.Whenthebonds

holdingthemtogetherstarttobreak,a

chemicalreactionistakingplace.

1. Mixing it up

The mammoth carefully pours the

green liquid into the red

, powder

and then stands well back. Often

youneed to apply heat to get a

reaction going
,utb sometimes

simply mixing the reactants

together will do the trick.

Reactions around us

Chemical
t ha
’ enpconiesyoinC
ltacedrohnm
ealci

nm
golieghn.rabusyhldater–lat
 OceanofPDF.com

Heat t
andg
ihl

These are signs that

a chemical reac
onti

sait king place.

2. Whizz, pop, bang!

As soon as the two substances

mix, they start to eract with

. each
Theother
chemical bonds

between their atoms and

molecules break and refo r m.

 OceanofPDF.com

Rapid reactions

Some chemical reactions happen ver ,y wshl iowly

le o t h e r s

t a k e p la c e i n t h e blin k o f a n .eye Explosi o n s are ver y

quick reactions th a t re lease a l o t of heat, l i gh t , and

sound. T hey re lease g a s e s so q u i c kly that they c a n blow

things ap a r t . Fireworks u s e controlled explosions and

colourful chemical reactions to c r ea t e a d a z z l ing

l i g h t sh o w in t h e night
. sky

Rapidtrock
e

The gunpowder propels

the
o the
trock
ine

air in ant.inst
an
OceanofPDF.com
 OceanofPDF.com

Combustion

The flamefrom a cosy camprveifpidreos

lightandheat – morethanenough to

toasta marshmaloworw
t o.When a

reifburns, a hemi
c calearctioncaled

combusotinsitaking .eacplCombustion

,and,reeloduces
arpsesenergyweart

carbondoixdiea,ndsometm
i esother

chem
t,oscalio.It is one of the most

usefulreactionsforhumanut
s,b ti can

easilygetout of con
ortl.Goodjob these

mammothfirewardensa.restandingy b

r iF etblank
e

Smo
thering the flame
th wi

a blank
tops
st
e ygen
ox

reaching the fire.

Fires need oxygen to keepub. rThe

ning
air around us

is 20 per cent oxy

gen – more than enough to sustain a

roaring fire.Thereisoxygen in our breath, too

, so

whenyou gently blow air into embers

,they glow

bright orange as the fire gets

. stronger

The fire triangle

Fire always needs three things to get going and

stay burning: oxy

gen, fuel, and heat. This is known

as the fire triangle

e can
. W use this knowledge to

build aoaring
r fireb
u
, t also to put it out again:

taking away an
y of the three sides of the

triangle extinguishes the fire

.
 OceanofPDF.com

Sprayingthwiwat
er

Do
uth
sing
wa
t
ew
ar
t
i k
es

away the heat so the

fire goes out.

T
N
E
G
Y
X
O

F U E L
 OceanofPDF.com

Low numbers

Numbers lower

than 7 are

acc.
idi

‹
›

3
—

—
—

—
2

—
—
1

—
d
i
c
0

a
 OceanofPDF.com

Oesophagus

o F od travels from

The pH the mou

oththe
t

ots mach through a

tube called the

oesophagus.

scale

Animportantpropertyof ynasubstance

eakaci
. dW
sarefou
isitsndain
cdityi mn
ay

foodsa,wh
ndiltas
etsterosou
ngacids
r caneat

throughmetalor damage skni. The opposite

of an acidis a .ebsaBasesthatcan dsiovel

inwaterarecalledalkaislTh
. eyusuallytaste

bitterandmaybe used as cleaningproducst

becausetheyttack
a aftsandoils.Strongaklails

canbe ujst as dangerousastrongaci

.sd

motS ach lining

The aci
d si creat
ed

bylelsc in the lining

Acid or alkali?

ofthestomach.

royT
em
teheoih
sneotcntb
aevdn
rteolsgiet

fi .sikd
saltyh
eaosu
S
ilcren
tsicaptHeocatsl Stomach acid

.shim
teT
ursaehepH
eocarm
lgsofesw
o0h
t1w
4lt,i
There are some powerful acids inside the human

. The stomach
bodyproducesd
hy
rochloric acid,

numbncse,d
grih
acin,aunm
dnbeniskergail

which helps digestood

f and kills off any h a r mfulbugs
.

7n
bgefiIn
.aeu
rlt oum
xan
idyaw
h
,citain
kail

The pH of stomach acid is usually between 1.5 and

hh
oyetarcnu
lentdbecomen
.aeu
rlt

3.5, so the stomach walls are pr

otected om
fr the acid

byalayerof sticky mucus (which also stops stomach

acid digesting the stomach itself).

Washing powder

Washing powder is a

base – a solid subst

ance

that forms an alkali when

Water

t i dissolves .inrwat
e

Water is usually

neu
.tral, at pH 7
OceanofPDF.com
 OceanofPDF.com

Life
 OceanofPDF.com

Kingdoms of life

Whatislife?
Scientists hav
e disco
vered almost two million different

species of living things

, ranging
so far
om
fr tin
y bacteria

LifeonEarthcomesin al shapesand zeis,

to whales and giant trees
. All these of r ms of life are

placed into seven major divisions, called kingdoms

.

fromplantsandtoadstoolsandseaweed,to

you
eadi
r ngthisbook
.Althoug
right
h now

livingthingsmayol okdiferent,theyshare

Animals

somespecifccharacteristicsthatsetthem

T
nkgsihdiom
n
u,cid
lm
esdrab
,immsal

apartrfomnon-livingthnigs.

reptiles, frogs and toads

, fish, insects
,

spiders, and wo r ms. Animals eat other

eseu
ascnlsedom
vgn
ram
en
svriasndha

p
hm
aetnh
tld
esrp
m
onovd.

Sensing surroundings

B eing able
o respond
t o t

Plants

There are more than 390,000 different your surroundings means

types of plant, om
fr tin
y weeds to

l etdeyfvaiini
you are l e.

gigantic forest trees.Mostheavlea

ves

Sping
ott the sabre-

and manyvha
eflowers or cones
. The
y

thed
oo t cat in the grass

use sunlight to make their own food.

wil he
lp this mammoth

yats that way!

Fungi

Neither plants nor animals, fungi

include mushr
ooms and toadstools
.

Most of them grow in damp

places, such as woodland

floors or on rotten wood.

Algae

Often found
, algae
in water
include

seaweeds. Many look similar to plants

and, in the same way as plants, make

their own foody busing sunlight.

Protozoans

, single-celled
These tiny organisms live
 OceanofPDF.com

Checklist for life

These munching mammoths show the

sevencharacteristics shared byall living

things. They gow

r and change,move

Animals breathe in ygen

ox

around, get rid of waste

, and can

o power
t respirat
oni

reproduce themselves. They can sense

and respond to their surroundings.

They take in nutrients from food

and use them to release energy

inside their cells in a process

called respiration.

On the move

A galumphing mammoth is hard

ot missbut someefilorms

move more subtly

s. Plan
t

can turn
owards
t.
t ghli
 OceanofPDF.com

Bacteria

Bacteria ar e th e s m allest living things on E a r th.

They can multiply ver y , qa nuickly

d there a r e s o

many trillions of them i n the world it w ould be

impossible to count them. They a r e f o und just

about everywhere: i n so i l,, awater

n d the air

aroundoyu , inside your body a n d on

its surface, too. Each b a c t er i u m is

made of just one cell, with a evry

simple structure.

Pilus

Many small hairs,

or pili, on the

cel’ls surfacehelp

t i citsotk things.

l eC l membrane

This thin inner lay

er

separates the inside

of the erium
bac
t from

theerou
tlelcwall.

tIcontrols which

substances can pass

in and out.
 OceanofPDF.com

Good or bad?

Most bacteria are useful because they break

down dead or decaying plant and animal

matter and put the released nutrients back

into the soil. Bacteria inside the human body

help us digest, food.

someHow
bacteria
evr

entering the body can be harmfulandeven

,byreleasing
deadly
poisons into body tissues

or causing infectious disease.

Larg
est
eine
n
it

Sm
est
aline
n
it

Gut bacteria

There are trillions of bacteria in the

human digestive system, mostly inside

the large intestine

. They help to break

down food and produce some nutrients.

 OceanofPDF.com

Cells

Every living th i n g on E a r th i s made u p of tiny u n i t s

called cells, which ar e so s m a ll that they c a n only b e seen

with a microscope. S o m e living things, such a s bacteria,

only have on e c e ll . O t hers, such as p l a nt s a n d big, bulky

woolly mammoths, haev trillio n s a nd t r i llions of cells.

Animal cell

Each cell in a mammoth’

s trunk is a tiny powerhouse
.

The nucleus is the control centre of the cell and contains

all of the instructions for how the cell should work.

Mitochondria power the cell by releasing. Cells

energy

are surroundedby a thin, oily cell membrane, and are

filled with a jelly-like fluid called the cytoplasm.

l eC l membrane

Thisforms a

v i tceprote barrier

around the cell.

Nucleus

The nucleus
OceanofPDF.com
 OceanofPDF.com

Cells on par

Quick march! T

features just a f

Types

human
. There
bodyis a

shapes and size

here aren
’tshown t

of cell

cell is about 1

Although they share th e s a m e b a s i c parts, t h e

cells on parad

nerve cells can

trillions of cells that m a k e u p a l i v i ng o r g anism

a r e no t a l l the same. C e l l s come i n many

different sh a p e s and sizes, wi t h s pe c i a l features

to allow t h e m t o do s p e c i fic jobs. T h e human

body contains mo r e th a n 2 0 0 different types

of cell, each w i t h its own s p e c ia l f u nction.

S o m ethe
a
e
il p
lc
ells
i

have a brush-like

surfa
o
e
tc absorb

fluids and
s nu
t
trien

gE
g cel

The largest human body

c
es
lli the femalesex c
el.
l

W
zh
iel ni t
feed
r by a sperm

t grows
ce,
l i ot a
in.baby

Sperm cell

The male sex c

ell is

the smallest human body

ll.
e
c It has a long
lai t

othe
t
lp
swim
i

ot the egg.
 OceanofPDF.com

lat muscle
Skel cell

Muscle cellscontract

(shor
en)
ot move
t

s par
tof the .body

Neurons have
Neuron

a long thread

These lelsc are par

t

called the axon

of the nervous syst

em

and carry messages

around the .body

Cac
ardi

muscle cell

A large drople
t ofqui
dliatf

sistored in each fatcell,

whichis used as a source of

energy for the .body

Branching structures called

dendri
set pass the nerve

etsO ocltas etsO ocyte

signal from one neuron

These bone cels help keep This type of bone celhelps

o the
t xt
ne
 OceanofPDF.com

Plants

m
orF tower i n g t r ee s to minusc u l e m o sses,

p l a n t s co
r
v
e about a th i r d of land o n Earth.

P
a
ln
s
a
r
t
ve
in
ilg
h
t
nig
u
s
jk
is
t
le
m
an
i,sa
d
l

n e e d f oo d t.o B ugro
t w unlike mammoths

andelephants
hre
w p
s
,lantsma
ketheirown

foodu
singin
gre
de
int
s h
y
e
t gat
her
f
romtheir

env
oir n m e n t . T he oxygen they r
e l e a s e in

the proc e s s is v i ta l to life o n Earth.

Leaves

The plant’s broad, fla

tle
es
av act like

solar panels, soaking up the sunlight.

The lea
es
v also take in carbon dio
xide

,from
through
the air
tin
y holes on

their surface called stomata.

 OceanofPDF.com

(see panel below). There is

chlorophyll throughout the

n v
o i e
i
t w
c
o
e
f
s

- t

s h

s e

r s

C
b u T es
e

m
called phloem

transport

sugar

l y X em

transport

water

Strongemst

The support
ev i stem

holds the plant up and

transport
s water

and nutri
ts.ne

Waetr

Thewater that travels

around the plant keeps

 OceanofPDF.com

Inside a flower

This inquisitive elephant shrew’

s fur

has a dusting of pollen from visiting other

flowers. When the shrew brushes against

the, this
flowerpollen sticks to a pad called

the stigma. The pollen grows a tube down

to,the
where
ovarythe female eggs are

stored, and fertilizes the eggs to produce

the seeds that will make new plants.

 OceanofPDF.com

Types of fruit

Anther

When a flower is fertilized,theovary swells

l o P len is produced in the

up to become a fruit. The fruit contains the

male par
t of the flower
,

seeds that will grow into new plants.

in sac
s calledthers.
an
 OceanofPDF.com

Going travelling

Some seeds are light enough to be blown

on the wind or tough enough to float on

. Others
water rely on animals for a ride
.

Many ha
vepods that explode
, flinging their

contents away from the parent plant.

Coconut

Sailng away

S ome large seeds have

awaterproof coating and

Dandiloen

are carried on
. rwat
e

seed

oCconu
s tcanven
e float

on ocean curren
.st

Airborne

t Small,
seeds
twei
gh ghli

are carried away on the

e t stslighbreeze.

tiH ching a rid

e
 OceanofPDF.com

a T yts treat
s

o T tempt animals

ton ieating them and

spreading their seeds,

stfrui
areoften

tly coloured.
bri
gh

Seeds

o F rnew ,seeds
palnts toumgstwobe
r pserad

faoroand
clowsedie.toTthe paerntplant,they

wouldcompeteforfood,li.gSeeds
ht,andwat
ear er

spreadnimanydifferentwayB
s.eingswaolwyedb

ananimalto pop out the other end, undgiested,

in a peli of poo si ujst one of them.

saP sed out in poo

Seeds intfrui
eat
en by

an animal can pass

t gh ri

through the digest

ev i

etysm and out the

Seed leaves

other end.
 OceanofPDF.com

Food chains

Lefoin Ehtar niskledbecausepalnsatndanm

i asl

iIn.vosrhitpdeh
eorfpctidrsiofreachother

,enecsgrassi umyncheadm
bammoht who is

wnchgaoituofrthungryeprdeaodtrsyot

.ecnuopThiis anxaempelof aofdchani.

Grasia ifenuptlsoucreof ofd

ahteboom
t of het ahcnwi,heli

htesaobther-dactsiyoam
bltorf

ahettopfanicgnoht.realstal

tSunilgh

The Sun is the original

source of energy in almost

all food chains.

Green grass

At the bottom of the food chain

aretheproducers. Usually these

 OceanofPDF.com

Hungryhunter

If the mammoth gets m

unc
hed, then

energy will pass to the sabre-toothed

cat. Animals that eat other animals are

called secondary consumers. Ca

ts eat

only meat, but some secondary

consumers eat plants as well, making

them primary and secondary consumer. s

Foodwebs

Most creatures play a part in more than one ood

f chain.

Interlinkingood
f chains for m a complex networ
k called a

o
fodweb, whichshows how energy flo
ws between animals

in a particular habitat. In this Arctic food,web

the producers

aretiny photosynthesizing algae known as ytoplankton.

ph

o T p predat
or

The ller
ki whale si at the

op tof theood
f web,
th wi

no natural predators.

Dungtlebee

This decomposer

Kiler whale
feeds on poo
 OceanofPDF.com

a T kee ta bi viaSl

The chopper Asquirt of this wat

ery liqduihelps

comes down and ot mositen the foodorf swallowing,

digest
oin begins. andains
cont enzymes that start

o break
t t down.
i

Keeping it moving

Themammothsarehardtwaokrinthis

our
b,usnitbyoofdyod’ti digestoinafctory

muecshtlatkeeptheofodvimo
nginthe

Molars

rgihtdirectoin.Thewalslof theoesophagus,

These big, flat

stomachand
, nitesntiesrpipleike
nivlewa
grinders mince up

M
O
U
T
H

food, just elik your

me
emvontsopush.theofodaolng

molar
theedo.
t

w o P erfulstomach juies
c are

full of enzymes – chemicals

that break down food

ot in

Oesophagus

A pipe called

the oesophagus

connec
s tthe

throat
o t

thestomach.

Stomach

Inthestomach, foodsi

churned
o at thi
ck,
in

gloopyqudili .

T
 OceanofPDF.com

Slowprocess

It takes at least 24 hours for the food

ouy eat to

be digested. Exactly how long depends on wha

t

itisv
you
’e eaten.
ruit and
F vegetab
les are easier

for the body to digest than mea

t, so they pass

through u
mch
. mor
e quickly

SMALL

INTESTINE

Smaltine
sleint

As the soupy

mixture passes

through the small

test
n iine, nu
strien
t

pass out through

st i

walls oand
the
t in

bloodstream.

t s eSmal
inelint

o F od can spend up

ot 5 hours in the

small
set t
 OceanofPDF.com

Breathing

Body cells need oxygen to work. Getting

oxygen from t h e air into the bloodstream, so

i t c a n b e delivered to body c e l ls, is t h e j o b of

the lungs. T h e s e bi g s p on g y ba g s s uc k i n air to

absorb oxygen and push a i r back out t o release

waste carbon dioxide.

Breathe in...

The diaphragm is a sheet of musclethat sits underneath

the lungs. When it contracts (gets shorter), it makes the

space inside the chest

. Thebigger
intercostal m
uscles

between the ribs help too,bypulling the ribcage

outwards. The lungs expand and air rushes in.

Ribs and

ercost
tal
in

Lungs

muscles
expand

Hollow tubes

The air passes

o two
t in

pipes calle
d bronchi, whi
ch

branch
o smaller
t in

bronchioles.

Diaphragm
 OceanofPDF.com

stoL of

Tinyair sacs

surro

Tluhnlefaogrs

e.oildelcvsaoplimcsri

These are surroundedby tiny

bloodvessels called capillaries.

In the alveoli,xygen
o from the

air passes into the capillaries

ohbte,wdaksn)erih(

C
around the body in the blood.

l
o

s
s a W edbiactrodnex(i

-
in capillaries shown in blue)

p
passes from the blood into

i A sin

, to bethebreathed
air out.
w

called

i
d
g
e
n
t l u
h e

... and out

ve
iPtcerotmembrane

When the diaphragm relaxes it springs

A thin membrane surrounds each

back into a dome shape, shrinking the

lung and sti

ocks t the diaphragm

amount of space in. the hc estvity

ca

and
ercost
talinmuscles. B tween
e

The lungs are squeezed smaller and

the membrane and the lung

airisforced out.

is a laery of d.flui

Air pushed ou
t

When the muscles relax,

the lungs shrink and

air rushes out.

B r o nchus

(plural bronchi)
 OceanofPDF.com

Circulation

Inside you are m i l l io n s o f blood vessels carrying

oxygen a n d nutrients to cells throughout your

. T hbody
i s incredible network is c a l le d t h e

circulato r y system. If all the blood vessels

in your body w er e la i d o ut , t h ei r t o tal

lengthcouldcricelplanetEarthtwce.i

s u J t imagine how many more blood

vesseslareinsidea mveaismammoth.

etan
ct
Irtwork
i ne

ver
yE par
t of the body

has
erites
ar and veins

for
v i de
l ering and

removing blood.

Strong vessels called

Capillaries

etra riescarryoxygen-rich

Arteries and veins are connectedy btinyvessels called

blood away from the hear

t.

capillaries. These micr

oscopic tubes make up 98 per cent

Their walls are thicker

of all the body’

s bloodvessels,for m ing a branching networ
k

because they carry blood

around body cells and tissues. The walls of capillaries are

at higher pressure than

only one cell thick, allowing oxygen and nutrients in the

the blood in the veins.

bloodstream to pass into bodycells, where the

y are used to

release energy and power the

astecells
from
. W this pr
ocess,

such as carbon dioxide, seeps back into the capillaries

and is. carried away

Thin-walled veins carry

oxygen-poor blood from

 OceanofPDF.com

Muscle layer

etrA ries have

a thick la
yerof

muscle that helps

tnoc rol the flow of

blood coming from

the heart.

eW
tbl
ihoodcell

These cells are

part of the immune

etsy m. They help

t eetalPl

ot destroy bact
eri
a
 OceanofPDF.com

Waste disposal

Humans and mammoths alike chur n o ut some

pretty unpleasant products. T has’t b e c a us e c e ll s i n

the body are constantly producing waste, which must

be released so you c a n stay.aste

healthy
Wproducts

are f lushed out of the body a s urine and sweat, a n d

breathed out when you exhale. Another typ e o f

waste is poo, w h ich is u n d igested food that p a s s es

out of the digestive system.

Slippery sweat

Urinary system If the body gets too hot, sweat is

secretedby pores in the skin. Sweat

The kidneys and bladder are part of the

contains some waste products

, such as

urinary system, which gets rid of waste from

excess salt, that the body doesn

t’need.

the bloodstream. Bloodessels

v carry blood

to the kidneys
,where h a r mful chemicals and

excesswater are remo

veda n d t u r ned into urine.

This liquid trav

els thr
ough two tubes called

ureters to the
. Asbladder
this storage chamber

filsup, sensors alert the brain that it is time to

go to the toilet. The urine leav

es the body

through a tube called the urethra.

sy Kidne

Skin

owT kidteney
rsfli

waste from the

blood and turn

o urine.
tt in i
 OceanofPDF.com

Factorywaste

In this busy
, different
factory waste products are being

producedybthe body and cleaned away bysome

helpful mammoth workers. Getting rid of waste from

body cells is called excretion. The body does thisyb

producing urine in the kidne

ys,secreting sweat from

skin pores, and exhaling carbon dioxide from the

lungs. Unlike waste pr

oducts madeybcells, poo is just

passing through. The expulsion of poo from the body

is called egestion.

Large

test
n iine

Kidney

What’s in wee
?

s a W te chemicals and excess water vlea

ethe

body via urine

, orwe. Urine is produced

bythe kidneys
,which filter unwanted

waste productsom
fr the bloodstream.

Stale exhale

Carbon dioxide is a waste

product thatlees
av the body

through
our
y lungs when

youberathe out (see pages

52–53).
ater alsoW
leav
es

the body as water vapour

 OceanofPDF.com

Bones

Masses of mighty bones lie beneath a

mammoth’s skin. Bones are made of tough

living tissue, a n d join togethe r t o for m a

skeleton. A mammoth’s bones might be

a l o t bigger than a h uma

s, n’ubt they

do the same ojb, protecting squishy

inner organs li k e t he h e a rt a n d lungs,

and working with the muscles and

tendons to moev the body around.

Theskeleton

A mammoth’s massive skeleton is made

up of more than 300 bones. This giant X-ray

machine reveals the bones in a ghostly

. glow

X-rays pass through soft tissues such as skin

and muscle but are stopped by dense bones,

so the bones show up as white shadows.

What’s in a bone
?

Bones need to be strongand hard,utbthey must

be light, too, or we wouldn

tbe
’ abletomov
earound.

Inside a bone, criss-crossing bone struts with spaces

suT sk

in between form a structure that is light and

. str
ong

Amammoth’s tusks

are oversized

frontet e h,

notbones.
 OceanofPDF.com

Joints

Abodys’ bones are not just jumbled up an

y old

they lock together carefully

howat– places called

joints. Therearesev
eral different types of joint,

allowing pairs of bonestomov

e either up and

down,from side to side, or around in cir

cles.

l eP vis

The bowl-shaped pelvis

connec
osthbo
t the

backbone and the legs.

Ribs

Rows of curved bones

make up the ribcage,

whichctesthe
tpro

hear
t andther
o

organs.
 OceanofPDF.com

Muscles

Astrongskeletonwtd
on’ulbemuchusewithout
Muscle pairs

Muscles work byc

muscelstomeovtiaround.Thesebundlesof

their fibres to g

tissuecontracts(horten)topullon bon,esmaking

can only pull,

h
temmeThe
.ov humanbody has morethan

movein two differ

650musclesandmany of these kw
rotogether

workin pairs. O

pull the bone, ot

inpairs.Thesemammothsaregettinga kw
ro

contracts to mov
e

outdemonstratingthepair of umsclesfoundin

thehuman upper a r m – thebicepsandtricep

.s

Lower arm

Squeeze!

Thebiceps mammoth

squeezes
, se
ther
oge
lft t i

sening
shor
tbodyi and

pulling on the lower arm.

 OceanofPDF.com

Arm straightens

The biceps cannot mov

e the bone

back again to straighten the ar m

because it can only pull, not push.

Instead the triceps muscle takes

the strain.

Elbow joint

The bones of the upper and

lower arm meet at a hinge

join
t, allowing the arm
o t

bend ande tstraigh

n.

At ease

The bieps
c

mammo
th has

a rest.
 OceanofPDF.com

Sensing and reacting

Nervous The nervous system controls

manyprocesses, such as breathing

and digestion, without the body

even being aware of it. But some

system

responses are consciously controlled:

Animals can sense a n d respon d t o things

when this mammoth spots a hungry

around them as quick a s a f l ash because

predator lurking in the undergrowth,

the nervous system is fired into action.

their bodies ar e controlledyb th e i r nervous

system. Billions of interconnecting nerve

cells, called neurons, ma k e u p t h i s super-

speedy communications network, carrying

messages as e l e ctrical nerve impulses

around the body quicker t h a n the

blink of an e.ye

Control and communication

:lam
serhentocprausTvwm
hyersntha

m
etsuoC
vy,N
rens(m
fpuoS)eda nlaheipanbtdrs

larsehm
po,itdvehrsyodrnaceptuwshi

fokswrtluoahntguoneayrehidobts sev.ren

yoserdnfovrsniSersnolagm
ihoeastbr

,esvrolreptm
ocesnm
wirdhteorsft

.snosinsaetgsculrclnadruosgtmsnrioehasrbm
tafi

Brain

The brain is made up of

ons
llibi of neurons and

tnoc rols almost all the

body’s
eiti s.
vact
i

Spinal cord

Connec
tnig the brain
 OceanofPDF.com

1. Sensory ner
v
e
s

Inf
ormat
oni from

the ey
es travels

ot the brain along

sensory nerves.

eyE

3. M
or
ot nerves

The brain sends a signal

Nerve cells

along the
or tnerves
mo

Neurons carry messages as electrical

o muscles
t in the legs

impulses at speeds of up to 400 km/h

o ensure
t the mammo
th

(250 mph). The signal trav

els along

makes a qui
.ck
waty ge
a

thecell’solng, thread-like axon until

it reaches the nextneuron. Where the

two cells meet is a tiny gap called a

synapse. The signal jumps across this

gap, and carries on its jour ney along

the next sneuron

’ axon.
 OceanofPDF.com

The eye

The ey
e is a n amazing o r g a n . It captures

Inside the eye

This cross-section view shows how the yedetects

light from o u r surroundings to give t h e

an image. Light enters the ey

e and passes through

brain a c l e a r p i c t ur e of what’s around us.

a clear disc called the lens. The lens bends the

morF tiny e l e p hant shrew s t o humans to

light (see page 91) to focus a sharp

, upside-down

huge, ha i r y mammoths, all mammals heav

image on the retina at the back of the ey

e.Light-

eyes that work t h e same

. Light
way enter s
sensitive cells on the retina convert the image to

nerve impulses and send them to the brain, which

through a h o l e called t h e pupil and is

processes the image

, f lipping it the right way up
.

focused on t o t he l i g ht-sensitive retina.

 OceanofPDF.com

Cornea

Thefront of the eye

is covered by a thin,

dome-shaped lay
er

of clear tissue,

which helps

focus the

t. ghli

Flipped

An upside-down

image isctedt de

C
ayirli muscles

bytheret
ina.

Thesecontrol the

shape of the lens.

Lens

A transparent disc

oocuses
f tt on ghli

therina.
et

ylJel

Thetre
en
c of the

ey
eball si lled
fith wi
a

jelly-leik flui
d.

rsIi

The coloured part of

the ey
e trols
con the

amoun
tt that
ofghli

ters
ne the pupil.
 OceanofPDF.com

The ear

Mammoth ear s a re much larger than

ours, ub t they work in t h e same way –

converting sound wav

e s into infor m ation

that th e b r a in c a n under stand. Large, f u r r y

fla ps on the sides o f the head are j u s t t h e

entrance to t h .e T ear
he hard work i s all

happening inside
.

How we hear

Sound waves enter the ear canal and are picked

upby the eardrum. The vibrations are then

amplified by the three tiny ossicle bones in the

middle ear before theymove into the inner ear

and through the cochlea. The cochlea translates

the vibrations into nerve impulses, which are

carried to the brain by the auditory nerve

.

Pinna

Theer
ou
t par
t of

Sensing movement

the ear collect

s

ralucrsircem
nlhaenraiT
etsceh

sound waves and

, s ede.dlviulhelitehrdW
fw
aiem
htneho

channels them
ot in

,sdegnseivm
euhoise
elrdunpeitnlhvfm
to

the ear canal.

s .nspi’ehasykldtureow
bhtT
ioh

. r negonivtslpm
oiltradsonsapyouf

Spinning
 OceanofPDF.com

Semicircul
ar canals

These fluid-fi
lled

tubes he
th
lp wi

balance.

Ossicles

Vibrat
oins from the ear drum

pass through these three

tiny bones. They mak

e the

vibrati
ons stronger and pass

them
o the
t inner
. ear

Hammer

Stirrup

Anlvi

Middle ear
Eardrum

The eardrum si

a highly tsensi ev i

membrane, which

etarbivswhensound

waves
t. t i hi

Inside the cochlea

 OceanofPDF.com

Body defences

T h e b o dy i s constantly under attack from g e r ms – h ar m ful

microbes such as b a c te r i a an d v i ruses., there

Luckilya r e

lots of barrie r s to preve n t an enemy invasion. Sk i n i s t h e

body’s f i r s t l in e o f defence, of r mi n g a wall stoppin g g e r ms

from entering
. Inside the
, saliva,
body t e a r s, and mucus

help to wash away any invaders. I f these f l u id defences

fail, the body’simmune system sends ar mies o f

soldier-like ce l l s to targe t a nd k i ll t h,e enemy

restoring the body t o full health.

repaired, just like this wall.

The immune system

n i T ycels in the blood called

The body’
s barriers are very effectiveutb the
y

tn’ac keep out all invaders. The immune system

f i g h t s g e r msthathav
e entered
, and the body

builds imm
unity against future infection. It does

ngisyfihanytdevbdiinggermsandopgruic

chemicals called antibodies that target them.

Phagocyte

1. First response

White blood cells called

phagocytes surround and

swallowupinvading

bacteria, destro
ying them.
 OceanofPDF.com

Window wipers

Mammoth fortress

Saltears
y t wash away

The body of a mighty mammoth is like

tdirfrom the ey
eballs.

a giant fortress designed to stop in

vader s
e T arsain
conta chemical

that helps llkibac

reta.i

from entering
. The attackers here are

elephant shrews, but the body is fighting

muchsmaller foes – microscopic bacteria

and viruses.

acking
att thetress
orf are

Slippy v
a
sali

Thetress
for moat is like

the slimyvasalithat keeps

the mouth moist and clean.

va
ains
Sialcontbact
eri
a-

lling
ki chemi
cals.
 OceanofPDF.com

Growing up

All living thing s g orw a n d change. An animal

s’

progre s s from bi r t h to a d ulthood is c a ll e d it s l ife

oung
cycl. e anim
Y a l s of t e n lo o k a lot like miniature

versions of their parents, ub t th e i r bodies undergo

important changes as they g e t . older

Baby body

B a b y m ammals have bigger

heads and er
shor
t legs, in

propooo
irntt their body

ze,
si than adul
s tdo.

Infancy

A newly born mammal depends on its

u o Y th

parents for food and protection. Its body

Growthslowsdownbuttheyoung animal

, grows
but theoung
rapidly
y animal is also

is still de
.eloping
vIt lear ns to become
 OceanofPDF.com

Primeeof
f li

This adult mammoth has

reached
s tfullzesii

and strength.

Winding down

As the body loses

muscle tissue, the

mammo
th shrink
s

t.in hei
gh
 OceanofPDF.com

Making mammals

Mammoths, elephant shrews, and humans

are all placental mammals. Their babies

grow inside the, supported

mother’s body
by

an organ called the placenta, until they are

ready to be born.
 OceanofPDF.com

Layingeggs

All birds and most insects, reptiles, and fish

lay eggs. The embryo develops inside until it is

Reproduction

readytohatch. Then the bab

y animal breaks

Whatdoyouget fi o y ucross a mael mammoth

through the shell or membrane and flops

,

wriggles, or swims into the world.

witha efmael mammoth? A minimammoth! All

fullygwor nlivingthingeshavawayto orepdruce

themsevles–withoutthis,specieswoulddie out

andlifecould not esxti.Mostanimalscreatenew

efilbycombiningcellsrfomtwop,sen
artin a

procescalledsexuarleproduocitn.

Newlife

Sexual repr
oduction needs two parents: a male and a female
.

Each parent pr
oduces special cells called sex cells, which

havehalf the usual number of chromosomes (see page 74).

These sex cells can combine and grow into a new organism,

which will ha
vea mixture of chromosomes inherited from

both parents. This means that in sexual reproduction each

new organism is unique

.

How an embryo develops

Male sex cells are called sperm and female sex cells are called eggs.

When two sex cells join the

y make a new cell, which gr
ows into an

embryo
. In mammals
, this happens inside, and
the female’
thes body

developingembryo is supported by an organ called the placenta.

i v iding
D

csell

Sperm

Producing clones
 OceanofPDF.com

DNA

A l l t h e i n s t ructions ne e d e d to m a k e a living

organism ar e stored in a big molecule w i t h a

v e r y lo n g n a m e: deoxyribonucleic ac i d , o r

DNA o
f r sh o r t . DNA is f ou n d i n si d e t h e c e l l s

of all living t h i n gs, pa c k e d into bundles

Chromosome

Chromosomes

called chromosomes
. If oy u c o u l d unraev l a

are found insi

de

chromosome you
d’ s e e the distinctive twisted

thecell nucleus.

Humans have 46

l a d d e r sh a p e o f the DNA m o l e c ul e i t s elf,

chromosomes.

known as t h e double h e l i x .

ots iH ne

DNA coils around a simple

ball-shapedein
pro
t called

otsih neto help elf

pack
st i

up inside the chromosome.

Base pairs

Just four chemi

calsorm
f

the <rungs= of the ladder

.

Each base can only pair

th wi
one
. ther
o

The long sides

 OceanofPDF.com

Chemical code

The instructions an organism needs to live

and grow are encodedybjust four chemicals

called <bases=. The specific order in which

the bases appear tells the body cells what to

do. A stretch of DNAthat contains a single

instruction is a gene – humans have 23,000

genes in total. When the body makes new

cells, to grow or reproduce, DNAunzips and

replicates (copies) itself.

i aP ring up

B a s e s a reattachedto

each unzipped de
sioorm
ft

two new strands of DNA.

Unzipped

The DNA

unziopsint

two strands.
 OceanofPDF.com

Evolution

Life on Earth has not always looked t h e way

it does
. Over
todaym i l li o n s of ey ars, species

change as they adapt t o their environment –

new species come into being, a n d other ones

die out. T h is l o n g proc e s s of chan g e

over time i s called evolution.

Gomphotherium

Paleomastodon

Gomphotherium had

This early elephant

bigger tusks – two pointy

relative lived about

ones in its upper jaw and

28 million years ago.

,shel-shaped
ovtwo flatter

It had a short trunk,

ones in. Itits lower jaw

short tusks, and ears set

walked the Earth about

 OceanofPDF.com

Large ears

Africanleephan
st

have much larger

ears than Asian

ele.stphan

Shaggy coat

W
oolly mammo
ths

had thick, coarse

haritoecptrot

them in their icy

environmen
t.

Asian elephant

The ancestors of the Asian

African elephant

tnyahpelehdlneatm
w
oham
to

sh
etieub
rgaetT
rciaestnhid

y lnboatibiol7lrpls.ea
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ivaehanletsdan
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Asian elephants are smaller than

tw
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eolbi dod
lyw
trao

African elephants and their heads

psiotn
htendof su
trntik,

are a different shape

. T heir

ketw
iin
h
csan
iehtfu
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numbershav
e declined so m
uch

ev haoen
trsu
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tta

Woyoll mammoth
recently that the
y are now in

ban
rchearh
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dyfetofli

400,000
about
Appearing

danger of extinction.

i6i
lb
7lt
OceanofPDF.com
 OceanofPDF.com

Energy
 OceanofPDF.com

What is energy?

Everything that happens in t h e Universe, from t h e

Sun shining to oy u r eading this book right

, u sneos w

. Energ
energy y i s what makes evry t hi n g go, an d i t is

all arou n d u s a l l the time. Energ y c an

t’ b e created or

destreoyd , ub t it c a n b e stored an d t r ansferred in

different ways.

1. At the top

Energy stored so it can be used

later is called potential

. energy

Sitting on the high platform, the

mammoth has stored gra

vitational

potential
. Thisenergy
is energy

that can be transferred when

gravity pulls the mammoth

back to Earth.

Loud landing
 OceanofPDF.com

Energy transfers

s ’ t Io
e
y
a
th
so
wk
w
u
e
sn
g
e
o
h
ry
n
e
w
a
itc
k
y
ig
o
rlh
ifa
tl

switchorrideab.cle
iBut
cy therearelotsof lessobvious

waysinwhichenergyisstoredandtransfer red.This

daringstuntmammothhasclimbedahighplatform.

o
A
u
n
ed
sh
d
y
g
fa
tio
r
e
g
h
fr
la
o
te
lsp
tfa
o
e
ln
itt

b
a
c
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wn
o
h
n
w
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g
te
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e
sa
mmh
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r
ta
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o
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hte
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tk
a
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s p
e
n
a
o
e
ln
g
itry
t

,paelh
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a
n
le
o
n
sa
g
irtn
y
ftiso
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e
d
trm
io
n
i.o
t

Energy around us
 OceanofPDF.com

Heat

How hot o r cold something i s depends o n Heattransfer

By holding a metal bar to a flame, the

how fa s t i ts p a r ticles ar e movni g – the faster

mammoth is making the elephant shrews hot

they mo
, ev t h e hotter they a r. e Heat is energ y

under the. Heat

collaris transferred along the

that ma k e s th e p a rticles move, rfaster

a i s ing

barby conduction. The particles in the solid bar

an object’stemperature
. Heat ca n b e

are not free to mo

vearound, but they vibrate

more,bumping into one another and passing

transferred from one thing t o another

on their. There
energyare two other ways in

and always treav l s from hot areas

which heat can be transfe

to colde r o n es, as t h e se e l e phant

shrews ar e finding out.

High energy

Theendofthe

taebladrsihbmeyat

thsetfalme,maknigi

elcti.rasveptarbairydlpi

Gaining energy

Asethlceipasrtofthe

oteach
alkenocnkmti

,energypasses
rehto

fromthehottt
se

tarpofthebarto

Redhot

The
al tbar
thome
vesgi off
 OceanofPDF.com

Convection currents

F l u id.sIf(liquidsandgases)canflowfreely uoyheatone

partof auflditi,spartcielsm
efaostverandthehea
tedfluid

expand,tsakingupmorespaceandbecomingless.dense

Theheat,denser
edfluidfstluaidrt,and
storiscool
e er

sevm
onitotaketsipalce.Thsciycleof rising warmfluid

andsni kni gcodlfuldisicaeldacecti

onvoncurr
ent.It

continuesuntilalof thefluidisthesametemp.erature

Sinking

Colder flduiis

more dense, so

t i sinks.

Rising

Heated fluidsi

less dense, so

t i rises.

Nottho

Evenat the cool end of

the
, the
bar
cles
ipar
t

are vibrat
ing, just tno

t i w h as much energy
.
 OceanofPDF.com

Sound waves

Mammoth mus
morF a whisper to a bang, a l l sounds are made

by objects that vibrate rapidly to a n d rf.o When This mammoth m

through its trunk,

you pl u c k a g u i t ar s t r in,g t h e string vibrate s a n d

making the skin o

udtsribhtsearoiunds,qtiuashniganchdgretis

This disturbs the

hteari ym
nitaes asecondnI.tur n,htesquashed

waveof sou

anchdetrasitdiustrbhsteairnexto,ti os that
waveshave lots of

sound – loud eno

htsveudtsrbiaenelbcenvrisltawiaspreadnig

off any
one in the way

o u t i n a l l directions li k e ripples on a pond.

 OceanofPDF.com

Seeing sound waves

Low-tched
pi sound
Soundwav
es are usually representedy vy
bwalines. The shape

Agreater wavelength

of the line tells you what the sound is like – whether it is loud

stadi( nce
tween
be each

or quiet, a high-pitched squeak or a low-pitched boom.

peak) means a lower

frequency and

a lower
tch.pi

aeP k

r T ough

Soundwave
Pitch

When we draw a sound,evwathe peak

The pitch of a sound depends on the

of thewav
e shows where the air is
l e vycneuaskqpyhew
othrgdnm
(efana

comT
edpsoe.rt,nopehsurw
teligh,
dehct.si)pdnso-hcyanguceobpaeA
sihd

is where the air is more spread out.

. hycntgenuqehgrdlniehaf v trohsaw
hsa
 OceanofPDF.com

Letting light

through

Most solid objects are

opaque – they block all

light – but some

materials allow light

sweva to pass through.

a r T nslucent materials let

some light through,utb

scatter it in all directions.

Opaque Tranuslcent

a r T nsparent materials

The elephant shrew Behind a sheet of

allow light to pass

is not visible behind a tracing

, thepaper

straight through.

sheet of white card. elephant shrew is

All the light is blocked. visib.lebut blurry

Light

T h i s s uper-sized shadow m a y l o o k like a w oolly

mammoth, but i t i s ju s t a trick of the light. L i g h t

i s a for m of energ y t hat we c a n see. I t only traevls

i n s t raight lines, or rays, so s o li d o bjects cast

shadows where they bl o c k light’s p a th. Light

bouncing of f objects i s what makes them

visible to o u r ey
es.

Shadowplay

A group of elephant shrews are playing

shadow puppets, casting a mammoth

silhouette on the wall behind. Shadows

 OceanofPDF.com

Big and blurr

y Small and sharp

The leephan
t shrew
regwroasndhcheutlmisTh

fur
ther fromt theghli
.sevleswsemershitTshi

source cast
s a smaller
,
esuoayeceolhrtcabeh

sharper shadow.
rehomrftecrudonfats hg i l

t ,gliedhlnaltwh syar

.dealevyaertrhpustoa
 OceanofPDF.com

Reflection

Most things reflect light – we see an object

Misshapen mammoths

when light bounces of f i t and enter s o ur ,geTihbsoemrakywngutli

onsitcelfe–rybuhtweroatf onisectlheftr

ey.s T h e smooth, shiny surface of a

hetm,masmh’to eda?otrlhosndIetfmiorir

mirror ref lects light in a p articular way

oniectlsefctiarmpemrolireaobglufcs

that creates a r eflection, o r mirror image.

edctghnlameitsfhayeotlrcidn.

This mystified mammoth has encountered

tfeohgBtalmniueosdvrtci,

nghcoientrl.ftnsahrqgdeutmiasammh’ot

some odd reflections i n a hall of mirrors.

Conceva

Where the mirror

curves inwards, the

mammoth looks

stretched.

Howmirrorswork

Mirrors,metals,and other shinysurfaces create reflections

because light bounces off them in a very

. This
ergular way

is known as specular reflection. When light bounces off a

rough surface
, it is scattered in different directions.This is

called diffuse reflection.

Rough surfac
e Smooth surfac
e

Bouncing off

yherat,relfcetd Wghitena,rhloycsiufghrsuchapsper

no.smitceShianrydiuns,gceihloatsnyuotarfcl,teshni
 OceanofPDF.com

Mirror image

Incoming

Whenyou look into

,youwill
a mirror

ray

see a mirror image of yourself.But

the image appears to be standing

behind. This
the mirror
is because the

light rays enteringouryseye appear

to come from behind. The

the mirror

image of an object in a mirror is

called a virtual image, and it is always

the same distance behind the mirror

as the object is in ont

fr of it.

edRectfl

ray

Where the mirror

bulges, the mammoth

looks squashed.
 OceanofPDF.com

Twisted trunk

The mammoth’s trunk is

straight, but to the elephant

shrew it looks bent. This is

because light is refracted as it

passes om
fr the water. to the air

The shrew’
s brain interprets light

r
d
e
ottsiD

aselling
vtra in a straight line
, so it

The trunk appears

sees the trunk as much closer to

the surface than it really.is o be

t in a
ff
eren
t di

t
o
in
is
o
pbecause of the

ref
n
oria
tcoft.
the ligh

Speed of light

yw
soou
llrhem
vaesthorghwatLnierat

om
sSeotw
rs.nhfpiesa ortuhgiadtsoe
 OceanofPDF.com

Refraction

Light no r mally treav ls in straight lines, ub t Tcri ks of the light

When light is refracted, it can trick our

it can sometimes bend, or refract.efraction

R

brains into seeing things in the wrong pla.ce

happens because rays of light traev l at different

If ouy put a pencil in a g lass of , it wiwalter

speeds through different substances. T hey pass

lookcrookedeventhoughit’s not. Lenses

quickly through air but slow down when they

are specialy shaped pieces of glass or

transparent plastic that put these tricks

move through water or glass.Refraction can

of the light to good use.

play tricks, distorting our, butviewit can

also be useful.

Magni
fying glass

Amagnfi ying glass has

a con
xvelens –

one that bulges

in the middle.

Colossal critter

The elephant shrew standing behind

the magnifying glass looks supersized

because of the way the light is

refracted as it passes through the lens.

 OceanofPDF.com

White light

T h e s unlight sneaking in through this

Making a rain

doorway may look white, but it’s actuall y When white lig

prism, the ligh

a combination of many d i f ferent colours of

as it passes from

light mixed together

. When white light travels

to air again. E

through a g l a ss prism, the colour s s e parate into

a different amo

a rainbow pattern, called the visible spectrum.

out. Raindrops

thats’ how rainbow

There is an infinite number of colour s in the

spectrum, but our eyes are able to identify

seven: re d, orange,
, gyelr leen,
ow blue,

indigo, and violet.

t etiWhligh
 OceanofPDF.com

Wavelngths of light

. s eenhgtoelfv T
w
vehasew
alsvathgrtLi ghitel

Project
or screen

(the distance between two peaks) determines the

The mammoth is wearing

enlght,ionshgedlhtw
sava R
. ourocw
lese

eat shewhi
tot refletc

while violet has the shortest. The shorter the

each colour
t. ofghli

lw
evaength, the more the light bends as it passes

through the prism, causing the colours to separate

.

t eloiV

Indigo

Blue

Green

l e Y owl

Orange

Red

t eVoli
 OceanofPDF.com

Seeing

colour

Our world is bur s t i n g with .colour

romF

the rich brow n o f a m ammoth’s f u r

to the glossy g re e n of a w at e r melon,

objects only look colourful because

tSunilgh

of the way they r eflect the light.

t Sunl
looks
etighwhi

butisutcaally made

Pigments in their

up of all the colours

of the rainbow.

Mouthwatering melon

The mammoth can see the

melon because light bounces off

it, and some of that light enters the

mammoth’seys. The light hitting

the melon is a mixture of all the

colours of the .rainbow

But pigments

in the melon
s skin
’ absorb light of all

the colours except for green – so

only the green light is reflected.

Absorbed

Pistgmen
in the melon’s

skin absorb all the

colours
tpecexgreen.
OceanofPDF.com

Black and white

A surface that reflects all colours will appear white

when white light shines on it. A surface that absorbs

all the colours looks black. Some surfaces absorb and

reflect a little bit of light across the whole spectrum –

these look grey in white light.

Under differentlights

Objects can look very different under different

coloured lights. In white light, a red surface erflects

only red light, and a green surface reflects only green

light. But a red light source contains only red light, so

the green object looks black, because it absorbs the

 OceanofPDF.com

Electromagnetic

radiation

o
T
te
sw
a
h
h
e
tg
rite
lau
sn
id
u
sp
a
y
eto
f

rr
e
a
c-y
g
v
rn
e
en
g
w
y
ia
o
derltlc
ac
elce
im
tn
e
g
a

.n
oitaid
o
u
a
fro
lh
E
rc
a th
gi l sa
h
n
tereffadi

l e vaw
h
e
d
h
ra
n
e
–
sg
te
h
ttseg
n
otla
e
n
dloiv h
te

.tseth
r
o
T
sh
y
o
p
re
fste
o
rr
h
a
e ortcelce
im
tn
e
g
a

radiation that we c a n n o t see, w h ic h ha

e
v

wavele n g t h s sh o r t e r or l o n g er t h a n those

of visible light.

Infrared imag
e

Infrared is a type of electromagnetic radiation with

wavelengths longer than visible light. All objects produce

infrared: our ey
es cannot see it, but we feel it as heat.

T h i s t h e r mal imaging camera detects heat and shows

the infrared wa
velengths on screen as different colours
.

T h e w a r m-blooded mammoth shows up bright red,

while the cold ice cream looks black.

Electromagnetic spectrum

Ho
t body
, cold snack

o e
n
rtfy
h
p
fe
sto
d
fiT
, h
g
e
tr o
r
m
te
ce
la
ig
n
e
t

The mammo
th’s body
vesgi

w
e
v
af o r m the electromagnetic spectrum.

off
s toflo infrared;

Alltrel
avat the speed of light, but the
yveha

the chi
llyec icream

differentwa
elengths
v (the distance betw
een

s ttle.
tver
yemili

two peaks), giving them different pr

operties
.

The shorter the wav

elength, the mor
e

energy the v
wa
etransfers.
 OceanofPDF.com

Seeing infrared

The camerastcdet
e infrared

wavelengths and represen

st them

asff
eren
t dicolours on screen, from

red est)
(ho
tto black
t (coldest).
 OceanofPDF.com

Static

electricity

T, hn ee gt atinyively charged particles inside

atoms ar e called electrons. Electrons can move

around and even transfer from o n e object to

another
. W h e n electrons build up i n one place,

objects ca n g a i n a <stati c = e lectric charge.

Fairground fun

The elephant shrews are using science to set up

their fairground attraction.

ubbingRa balloon

against the mammoth’s bristly hair

transfers electrons om
fr the hair to the

balloon. This creates a negative

chargethat allows the balloon to

stick to a wall as if y bmagic.

r eP fect for a game of

balloon darts!
 OceanofPDF.com

s ot P i ev i charge

Static charges

When electrons movefrom one object to

another they create static charges.

Objects that gain electrons become

negatively charged, while objects that

lose electrons become positively charged.

The attraction between positive and

negative static charges explains whya

charged balloon sticks to a wall and

thunderclouds release bolts of lightning

.

Negat
ve charge
i

-
 OceanofPDF.com

Wire loop game

The aim of this electrifying game is to move

the wire loop all the way around the wire

mammoth without letting the two wires touch.

When the wires aren

’ttouching
, the circuit

is not complete and current

. can
’tflow

But it needs a steady

hand – as soon as this

elephant shrew slips

Making con
cat

up and makes

When the loop touches

contact, the current

the wire, the circui

t si

flows and the bulb comple

edt andt theghli

bulb comes on.

lightsup.

Insulorat

Most mat
erials, such

as the plast
c icoating

on this wire, do tno

conduct
. tyel ctrici
 OceanofPDF.com

Electric current

Electricity po w e r s our lives – r

fom l i g ht bul b s t o m o b i le

phones, an d h o u se h o l d ap p l i a n c e s to e l e c tric vehicles. T he

e l e c t r i c cu r r e n t th a t ru n s t hrough al l t h es e d e vi c e s is a flow

of negatively charged pa r t i c l e s ca l l e d electrons

. A c u r rent

can only flow when there i s a c omplete, unbrok e n p a th

or circu i t f or i t to mo
v
e arou n d , a nd a power s u p p ly

No current

s u c h as a batte r y to g e t the electrons moving

.

Thispart of the wire –

beyond where the loop

uot ches the mammoth – is

tnopar
t of the circui
t and

no curren
t flows through
t. i

Inside the wire

In a metal wire
, some electrons ar
e free to mo
v
e

around. If the wire is connected to a battery in a

complete, unbroken cir

cuit, these electr
ons will

alme
ovin the same dir
ection – from the

negative side of a battery to the positiveside.

This flow of electrons is called electric curr

ent.

+
 OceanofPDF.com

Magnetism

T h e s e mighty mammoths are straining hard,

Forcesin actio

but they catn’ overcome the ofrce between two Horseshoemagnetsarecurvedintoa

Uhs-apebut, kilealmagne
l etwhyavtsoe

giant hor seshoe magnets. Magnetism is a n

endsor, <poles=The
. northpolesiusualyl

invisible force that can pull together or push

shownniredandthesouthpoleniue.lb

apart objects without actually touching them.

Magnetswiatltractandrepelothermag

dependingonhowthetwopole.nsileup

Magnetic materials
 OceanofPDF.com

How magnets work

A magnet is surroundedy ban nivsiible field, which is the area

where the magnet exerts its.forec An object made of magnetic

materials placed inside the field will be pulled towards the magnet.

Magnetic fields are representedby field lines – the lines are drawn

closest together near the poles where the field is strongest.

Stuck together

When the opposite poles of two

magnets are placed close, together

theyattract.each
Theother
magnets

Horseshoe magnet

stick together and try as they might,

T he poles of a

the mammoths cannot pull them apart.

horseshoe magnet

are close. together

The magnetic field

is strongest between

the poles.

Bar magnet

The magnetic force

from a bar magnet is

strongest at either end.

OceanofPDF.com
 OceanofPDF.com

Forces
 OceanofPDF.com

Tugof war

Whenwt oormoroercfwastrokr,

theycombinetoactas.aecsnirgloef

If hotecfrsarequalandacntig

niopposetidirecoitnsht,ey

balanceachotherand

nothnighappens.

Themammoths

takingpartnithsi

tugof warare

bothpulinlg

hadrbuthe

arevolcrfeis

,orezuntilsome

teammates

picthni.

What are

forces?

A force is a push or a pull.

o Y u can’t see a ofrce but you

can see w hat it does: forces can

 OceanofPDF.com

Typesofforce

Strong muscles

Scientists divide forces into two main kinds: contact

The mammoth’s muscles

forcesand non-contact forces. Contactofrcesare only

atireng
ex a strong

applied when two or more things are toucnhgi, while

pulling force.

non-contact forces act at a distance

.

Forcesatwork

Whenyou kick a ball youareexertingaforce that makes

theballmovTe. he gravity that brings the ball back down

to the ground is also a,ecorf and so is the upwardsforce

of the ground that stops the ball sinking in.

Measuring forces

Scientists use a unit called

the newton (N) to measure

.ecorf One newton is roughly

theforce needed to lift a small

apple. A device called a newton

meter can be used to measure

some types of .ecorf

 OceanofPDF.com

Moulding a mammoth

When you mould modelling

t , i clay doesn’t spring back

s toriginal
o i tshape.

ne T sion Compression

When a material is Pushing an object from

pulled from both ends

, both ends results in

it is said to be in tension. a d e f o r mingforce

A tension force stretches called compression.

anymaterial,even This squashes the

things that feel object, making it

solid. When a . The

shorter
legs

dog pulls on of a hc air become

its lead, for slightly shorter

example, whenyou sit

the lead on
. the hc air

stretches

. slightly

Squashed

The compressed

mammoth is squashed

smaller and bulges

out at thedes.
si

tched
Stre

Pulling from

bothends

makes the
 OceanofPDF.com

tsed
iwT

Thefront of the model turns

in one direct
oin while the

back turns in .ano

ther

r oT sion

orces can Ftur n an object. If the tur ning

forcesare all in one direction, the object

simply rotates.But if theyare pushing or

pulling in opposite directions, theycreate

torsion, which twists the

ou object. Y

use torsion whenouy wring out a cloth.

Howmaterials deform

Bending

Modelling clay is a plastic material: it retains

o w T or more forces applied in different

its new shape even after the deformingforces no

places and in different directions can make

longer act. Many materials are elastic, er t u r ning to

an object bend. Even things wedon’tthink

their original size and shape

. Metals are elastic up
of as bendy will bend slightly – such as a

tall building on a windy day or a bridge

to a certain point – but if youpull them very hard or

whenyou stand on it.

squash,them
they strongly
will permanently deform,

andeventually they will break.

Elasticity

A metal spring will stretch

 OceanofPDF.com

Wrong way round?

t i wSancgpeshlio,that
Veo
lcity

ehatvymmoth

o T a scientist, the word accelerationdoesn’

t

pusnhey,thesirw

mean <getting faster=, it means a change in an

t dwpordulceal

elocity is the. Vspeed

object’s at
velocity
which

oin.tleacroame

something is going in a particular direction. A

mo
ving object is accelerating if it speeds up or

slows down, or if it stays at a constant speedutb

changes direction.
orexample, objects
F moving

in a circle canveha
a constant speed, but because

theyare constantly changing direction, their

velocity is hcanging and they are accelerating

.

C E
O R
F

Swingball

The ball si ached

atto at

ensi
onstring.
in the Tstring

pulls the ball inwards, which

mak
t es
move
i in a circle.

Forceandmass

The push pro

vided byanelephant shrew

increases the speed of a cart with a mammoth

sitting on it. Compare its acceleration with

the other two carts in the race

.

Changitnigcovel y

The ball si moving at

a tconst
an
speed,

but because
t sniot i

moving in ta strai
gh

sline,
ttyvelisocii

awlays changing.
 OceanofPDF.com

A c c e l e r a t i o n

If oy u want t o make something go , faster

you need to

push it o r pull it. How q u i c kl y t h e o b j e sct’ s p e e d

changes – i t s acceleration – d e p en d s o n t h e size o f the

ofrce. I n this race, mammoth-carrying carts are being

pushed along by energetic ele phant shrews. T h e c a rts

accelerate as long a s the shrew s k e e p p u .shing

The

cart wit h t h e g r eatest acceleration will reach

the highest speed and win the race. B u t look

carefully – it’s n o t a level playing field.

Mammothmovers

There was only ever going to be one

winner in this mammoth-cart race.

This is because an object’s acceleration

depends not just on the force applied,

but also on the object’

s mass.If ou
y use

the same force to push two objects of

different masses, the lighter one will

accelerate more. But

quickly
if both

objects have the same mass,then more

force means more acceleration.

 OceanofPDF.com

Go, go, go!

The mammoth at

the back crashes

t ton i s nei.ghbour
 OceanofPDF.com

Chocks away!

Momen
tum si transf
erred

o the
t mammo
th in fron
t,

who swings out. When this

mammo
th swings back,

the process llwihappen

again in reverse.

ass
t on
Pi

The three middle

mammoths don’t move,

but they transf

er

momen
tum
o the
t

mammo
th in fron
t.
 OceanofPDF.com

Action and

r e a c t i o n

Every ofrce, everywhere i n the Universe, i s

matched wi t h a twin of the same strength that

works in t h e opposite direction. Another wa y of

saying th i s is that f or e ev r y action, there is a n

equal and opposite reaction. T he two forces are

equal in strength but are working on different

objects, in o p p os i t e directions.

Rocketreaction

Blasntignitotheairfomastandingstart,

thsiky-boundmammothsiusnigactoin-reactoin

to defy. The
gravity
rocket engine strapped to

the mammoth’s back produces an upward force

called thrust by sending out high-pressure gas

in the opposite direction. The thrust is enough

toovercome the pull of gravity that normally

keeps the mammoth fir mly on the ground.

traE hbound mammoth

Thismammoth’s
t weigh

eeps
kt firmly
i on the

groundunt
lia force
 OceanofPDF.com

..must come down

When the rocke

t runs out

of fue
l, the mammo
th’s

t wi
ll wei
bring
gh
t back
i

down
o Ear
th.
t

What goes up...

The thrust is

greater than the

mammo
th’s
t, wei
gh

so the mammoth

sshoo
tupwards.

T
H
G
I
E
W
 OceanofPDF.com

Howgravity works

Gravityisaforce that acts between two

objects. The pull of gravity is stronger the

Gravity

more mass the objectsveha

and the closer

Gravit y i s the ofrce that k e e ps t h e Moon i n orbit

the
y ar
. e together

around Earth, and stops u s rfom f loating of f

Earth’s s u r f ac e i n to s p a ce. It a c t s between any

two objects, pulling them towards each. other

, However
g r vity
a i s a weak for,ec s o its effects

Equalforce

There is an equal for

ce on each of the two

are only noticeable near objects with e n o r mous

objects,ev
en if theyvehadifferent masses. The

smaller object pulls on the massive object with

masses, such as Earth. T h e more mass something

exactly the same for

ce that the massive one pulls

has the g r eater the force of . g rvity

a

on the smaller one.

One giant leap

Greater mass, moregravity

The Moon has much less mass than Earth, so the force

The size of theforce depends on how much

of gravity is much weaker there

. A mammoth on the

mass each object has. Doubling the mass of just

one of the objects would double the gratviy

Moon would be able to jump much higher than on

between them.

Earth, because the force pulling it back to the surface

is not as strong
. It really would be one giant leap

for mammoth-kind.

Greaterdistance,lessgravity

The pull of gravity weakens the further away

the objects are om

fr .eac
Ifh other the distance

doubles, theforce is only a quarter of thesize.

Jumping up

The mammoth jumps

t i w h enough force

ot overcome the pull

of. gravi
ty
 OceanofPDF.com

Massandweight Wegtihon the Moon

t nseushomsf aoMti gn i hrtemto stam On the Moon, the mammoth weighs

teh,cgcrswriseuaoh–aemhfaiwewh one-sixth of what it does on Earth,

’ hstgomenhaTmi. hsvtlayemlrtonugpiso because gravity on the Moon is one-sixth

hsrtyerhanesawm,Eotshal astmi as strong as it is on Earth. A set of scales

s etghngs,aenthi oruceowbiMt shows this different weight,even though

gn ildenlehfnuedpot. y t i vga r themammoth’s mass has not changed.

a F lling down traE h

The mammo
sthtarst Gravi
ty pulling

oallftback down, Earth and the Moon

pulled by. gravi

ty ther
oget eeps
k

the Moon intorbi

around Earth.
 OceanofPDF.com

Friction

If oy u p u s h o r pull a n object al o n g a s u r f ac e t h ere

will always be a ofrce that a c t s i n th e o p posite

direction. T hat of rce is c a ll e d friction, an d i t i s

created whenever two surfaces rub together

. When

the mammoth whizzes down a slipper y s l i de, the force

of friction i s weak, s o the mammoth keeps speeding

up. But when the mammoth hits the ground, friction

increases, a n d the mammoth i s i n of r a rough ride

.

Slippery slide

Thereistn’much friction

between the smooth surface

 OceanofPDF.com

Everyday friction

Whenevertwo surfaces move

past one
, friction
another
is always

atwork. Sometimes this is very

useful – allowing tyres to grip the

road or a bicy
scle’
brakes

towork, for exampl. Ine other

situations, friction gets in the way

byslowing things down.

rictionF

can also make machines less

efficient and wear down their

movni g parts. Putting a layer

of liquid between mo
ving parts

reduces friction and stops

components wearing down.

This is called lubrication.

Get a grip

The soles of shoes are often made of rubber

to increase friction and stop us. slippingvero

It is friction that allows us to push ourselves

along as we walk.

Sticking surfaces

o T kepanobjecmov
t,gniveoyuahtopushorpulwil th

enoughofecrometverfciotn.Atthetopof dhtiel,s

garvtiyspulnilgthemammothdown.Butoncethe

mammothreaches thebottomof hdtiel,stheresino

opeocrfeprnilorgtwfi ardysamo,nowhere nrfciton

nicreasesthemammoth

soonoslwsdown.

Close-up view

ynietscafurlsAhval

.rsmpubF oicntsi

hytesdetaerbc

ngubimrpsand

. nghciotearcn
 OceanofPDF.com

ruT bulence

An irregularlyjecshaped
t ob

disturbs the
, creating
air a

swirlingnoitmo
, called turbulence,

whi
ch creat
es more drag.
 OceanofPDF.com

These two mammoths are sliding down the same

slope on identical sledges, but one is going faster than

Flowing air

the. The
otherfirst is sitting upright, pro
viding a big
Air flows easily over

the streamlined mammoth,

surface for the air to push against, so drag slows this

creating less turbulence.

mammoth down. But the other

Smooth surface

The smoo
th mat
eri
al

of this aerodynami
tc sui

allows air
o move
t over

,t reducing
easi
ly
i drag

and turbulence.
 OceanofPDF.com

Painfulpoint

If the mammoth were to sit on a single

nail, all of the mammoth’

s weight

would be pushing on a very small

area – the shar p point of the nail.

The nail would easily break the

skin and become embedded in

themammoth’s bottom.

High pressure

All the mammoth’s

t isweipushing
gh

on a tiny area.

Spkiy surface

The bed of nails look

s

uncomfor
bat le, but the

more nails there are

suppor
ing
t the mammo
th’s
OceanofPDF.com
 OceanofPDF.com

Pressing down

The lephan
e t shrews

h
avet
o push the small

o
t
sip n down a long way

f
oti l t the bigon
pist

up just
ttle.
a li

Piston power

There is no way a group of elephant shrews

could lift a mammoth using their muscles

alone – but they can do it usingydraul

h ics.

The combined weight of severalshrews pushes

down on the small piston and the pressure in

the fluid pushes up the other piston with

enough force to expose the mammoth’

s

underside for some routine cleaning

.

Liquid

pressure

As theon
pi
st

Hydraulics

pushes down,

Many powerful machines use hydraulics – a system

t i increases the

pressure in

of pipes and cylind e r s filled with liquid. T his is a

the fluid.

way of transferring of rces from place to place.

 OceanofPDF.com

ttl
t
fAeliil

The gbionpistmoves

a much short
er

atsdince than the

smallon.
pist

Hitthebrakes!

A car braking system uses hy

draulics to con
vert the

smallforce of the driver’

s oot
f pushing down into a

forcebig enough to stop .aPressing

heavy carthe

brake pedal transmits pressure thr

ough aydrahulic

fluid to pistons that push on the brake pads. These

 OceanofPDF.com

Up, up, and away!

sjec
t
can float
Ob in gases as

well as inqud
ili s. This balloon

ef iL ring

isfloating in air because

t is i

The mammoth’s ring is filled

lled
fith wi
he
lium, a gas that

th
, whi
ch
wi
airsi much less

si less dense than

. air

dense than
. wat
er

Ship’s hull
ains
, tcon
air

lowering
s ty
densi
t i

Forcesin fluids

o w T forces act on an object in water:

the weight of the object and a force

called upthrust. When you put an

 OceanofPDF.com

Floating

u oW ld a mammoth sink o r swim? That Changing density

Mammoths are mammals, and mammals float.

depends on whether it has taken swimming

That’s because their bodies are slightly less

lessons. But whether or not the mammoth

dense than. Awater

mammoth in water would

floats depends on its density – the amount

probably bob with its head above and its body

of matter packed into it. Objects that are

submerged in the. Bywater
donning a rubber

ring or a weight belt, the mammoth can rise

less dense than water will f loat, while those

above the surface or sink to the bottom.

that are more dense will sink.

 OceanofPDF.com

a T il fin

Along
th thwi
etailplane,

avert
cial piece called the

i atl fin he
lps
o keep
t

the aeroplane stable.

D
R
A
G

a T ilplane

w o P er

On this aeroplane, a

twsited rubber band

turns the propeller

.

Shrewair

ust like
J a paper aer
oplane
, this

shrew-packed plane would need a

helping hand to get off the ground.

But once in the air the spinning

propeller pr
o
des
vi the thrust needed

to keep it moving forwards

. Thi s

forward motion makes the wing slice

through the air in suc

h a way (see

panel) that keeps the craft airbor .e

n
 OceanofPDF.com

Wing shape

The cross onsec

i tof

How a wing works

the wing is a shape

The wing of an aeroplane is tilted at an angle

.

called an aerofoi.l

As the wingesmo
v thr
ough
, some
theairairis

forced
verothe top and some
. The
trav
els below

air,abov
while
emesov faster
the air that is pushed

belowamov
.Fes more
ster-mo
ving
slowly
air has a

lowerpressure than slow-mo

. This
vingdifference
air

in pressure abo
veand below the wing is whatcreates

lift. The curved shape of thewing, called an aerofoil,

allows the air to flow ound

ar the wing
. smoothly

Air flowing over

the wing is forced

downwards

Propeller

The propeller spins

, rapi
pushing
dly air

backwards to propel

the aeroplane forwards.

Air flowing under

the wing is forced

downwards

T
H
R
U
S
T
 OceanofPDF.com

Mighty machine

This machine uses several simple machines

to magnify the effort the elephant shrews are

putting in, to pluck tasty fruit from a tall

tree. See if youcan follow the sequence

,

and spot all the simple machines,

to find out how it works.

tretCou
w
negih

When the shrews re

lease

the rope, the

terwei
coun
t gh

fas
l , sending the scoop flying

upwards and launching an

orange
o the
t. inair
 OceanofPDF.com

Gears

Gears are simply wheels

t i w h cogs orttee h. This

onefiltsth
oetalit

Simple machines

release an orange.

A machi n e i s a to o l t ha t do e s a useful job.romFbicycl e s t o c a r

engines, most complicated machines are mad e u p of simpler

ones. T h e s i x m o s t basic machines all work by c h anging a

force in s o m e w a y – either changing its direction or

making it stronger or . weaker

M o s t pvide
ro

<mechanical advantage= – t h i s means they

increase the force to m a k e a jo b . e a sier

Types of simple machine

xTiehm
sarndsokifa hE.acmeism
plnehaci

B.ut ntoedm
csitapyleworheahonsctfeg

t u’oon
dy ceom
ngsrtoeh–fm
tioeorakef

.ecnartesveriagdtr otreavpyoiglaoyibhu

a F llingtrui
f

An orange drops out

andalls
owards
f t the

wedge below.
OceanofPDF.com
 OceanofPDF.com

Earth

space
 OceanofPDF.com

psoxE here

600 km (400 miles)

Thermosphere

80 km (50 miles)

Mesosphere

50 km (30 miles)

otarStsphere

16 km (10 miles)

o r T posphere

Earth’s atmosphere

The atmosphere is mainlyxygen

o and

nitr
ogen, with small amounts of carbon

dioxide and other gases

. About 75 per cent

of it is concentrated in, the lowesterlay

troposphere
,which is also where all weather

happens. The higherouy go

, the less gas

eacherlaycontains, until eventually the

atmosphere merges with space.

s absorb
t
Plan
 OceanofPDF.com

Inside Earth

sEh’taroutermayeotlsrithethnir,ocky

s’tcIur.atnsiyparotf thepalnetasaw,hoel

onyl64km4(0melisd)eepatishcikest

pI.farts oucyoudltakeascileoutof the

panlyetouwoudlseehtreseyralbeneath

thet,hcrueiqlsth:uehidugemaenretlay

ouecrtoera,ndthesodilnine.rTh
coree

dsitancerfomthesurafcetothecenetrisa

masvie64,00km4(0,00melis.)

Crust

The crust is very thin

Atmosphere

in re
on
olat
i the
t plane
t

This blatnke
of gases traps

as a whole,talik
ebi

enough heat to make the

the skin on an apple.

able
plane
tthabi
(see pages

148–149) and sprot

tce

against harmful solar ray

s.

tnoCsnient

Earth’s land masses

are the thick

est par
st

of the crust.

Oceans

The crust beneath the

oceans is thinner than

thelcont
ainen
t crust,

but made of a denser

rock called basalt.

Solid inner core

 OceanofPDF.com

caPcifi epalt

The largesto tec

t nci

palte lies under the

c i a Pf i c Ocean.

Under the crus

t

B leow the thin

crust is thetho

t.namel al yer
 OceanofPDF.com

Theplates move in

Movingmantle

the same direct

oin

The tectonic plates mo

vebecause

as the moving mantle

the
y sit on top of Earth’
s mantle
,

which is madeom
fr rock so hot

Here, two plates are

forcedoteg her

that it is semi-molten and can.emo

v

The rock mo
vesin currents that

circulate the heat (see page 83) – the

hottest rock rises

, then cools
, and

sinks. As the mantleock

r nearest

the surfacees
mo
v in thiscle
cy it

carries the crust along with it.

ltneMa
Curst

Plate tectonics

sh’E
tarsurfaceerlaysialwaysonthe .evm
o It simade

up of olts of rfagmentscalledtectonicplatesthatift

togetherilkehugepuzzlepiecesand f olat on top of

th
.The
emanteer
l laapteylsm
boew
lovnicredbiyl

,aboutas afosltwyl asour

y if,b
ngern
ut ailsgwor

wheretheymeethugeofrcescan be unelashed,

causingdramactichangestothe alndscap.e

l o V cano

l o V canoes are common

atplate boundaries.
 OceanofPDF.com

Making rock

cRoks are form

overthousands u

The movement o

heats and squee

while wind and

rocks and carr

mammoths are

conditions in th

The rock cycle

s tncah’fbiEtura, crevoerRotasekulftsm
eihysekm
tl

ovensim
orledflociskyecwoylrcaesr sE.rahcey

ypeotf orckanbuonetrdoineof ,yhpserto

m
,dentisEelhsta,rywisngawoyrnibarhewtae

.ortanosfrmdyuberssnathedpr
 OceanofPDF.com

The rocks that f o r m Earth’s crust are made rfom

naturally occurring substances called minerals. T hese

are chemical compounds that for m solid crystals and come

together in d i f ferent combinations to make or c k . T here are

three main types o f or ck: igneous, metamorphic, and

sedimentary
. Each i s for med i n a d ifferent
, giving
way

each ty p e its own d i stinctive characteristics.

Pressure cooker

Sadlyor
f the mammo
th,

this pressure cooker wil

never reach the kind

of pressure needed to

make
mat me
orphic rock.
 OceanofPDF.com

Howfossils form

Fossils
Thefor mationof afosiltakesmanymilionsof . years

Mostfosilswe
vnow
e haareskeletonsorshellsthta

evahbeen turnedtostone.Thisprocesshappenswhen

When a living t h i n g d i e s i t usually

ananimal,diandesisnquiorcklnear
yercovedwater

decomposes and vanishes

. I for
n ever ev r y

ybmudorsandbeforeitcancompletelydecomposeor

iseaten.Becausewaterisessentialtothisproces
,s special circumstances,
, iho
t wevecan
r elaev

manyofssilsareformedfromseaue.acrstr

arecordof tsiefl htatlastsfor bilionsof

ecall. yesarthW
ese ecrordsfosliThey
. are

Waterydeath

very,era ubtheyhelp us tounderstand

yrannosaurus
A T rex

drownsin a lake or

the fantastic creatures that used

swamp. Its body sinks

to roam Earth.

to the bottom and the

soft parts begin to

decompose
, lea
ving

behind only the

hard skeleton.

Sedimentlayers

Ov
er time
, the skeleton is

ocrved in elayr s of soft

sediment (mud and sand).

These build up andvero

millions and millions of

years are compressed

t o f o r m solid rock.

Astoneskeleton

As the skeleton is buried,

minerals dissolved in the

water enter pores in

the bones. and solidify

 OceanofPDF.com

Uncoveringafossil

Water can be used to

loosen the sediment

around a fossi
l.
 OceanofPDF.com

Water cycle

The wate r o n Earth i s constantly moving between

the sea, t h, ea nair

d the land i n a never-ending

cycl. e T h e a mo u n t of water stays t h e same, i t just

moves from place t o place and changes for m . T h i s

constant recyclin g o f water means that when oy u

t a k e a d r i nk from t h e t a p s’ti t h e same stuf f thir sty

mammoths were drinking thousands of ey a r s a go.

Transpiration

Most of the water vapour in the atmosphere comesom

fr

evaporated
, butseasome
wateralso comesom
fr plants
.

Plants take up water from the ground thr

ough theiroots
r

and release it through their leav

es in a pr
ocess called

transpiration. Rainforests give off so much water vapour

thatthey createlow-hanging clouds.

Water vapour

Heat
ed by the

Coluds

Sun, water turns

Thewater in the clouds

otvapour and

tually
ven
llwie allf as rain.

rises
ot the
in

atmosphere.
 OceanofPDF.com

Clouds look darker as

they become more and

more full of water

Changing states

The Sun drives the watercycleby heating the

water on Earth’
s surface so some evaporates

a n d t u r ns to water vapour (see pages 10–11).

When the water vapour rises and then cools

,

it condenses (turns back into liquid) and forms

clouds, which release water as rain back to the

ground. It can take a water droplet anything

from a few days to tens of thousands of years

to get back to the ocean.

Backto the sea

Water joins streams and

vers
ri and flows back

ot the ocean.
 OceanofPDF.com

Seasons

In many p a r t s o f the world , t h e yea r i s split into

distinct seasons: spring, summer

, autumn, a n d

. winter
I n summer the days are longer and w a, r mer

while winter days ar e short and cold. T h e reason

for th i s is that E a r th s p in s o n a tilted a x is. T h e a xis

i s a n imaginar y l ine running through the planet

from po l e t o pole. T h e tilt of the axis means that

different pa r t s of the globe t i l t towards or a way

from th e S u n a t different ti m e s of the. ey ar

Direct light

When a hemisphere is tilted towards the Sun it receiv

es

more direct sunlight. The Sun is shining directlyerhead

ov

so its light is more concentra

outedcanand feels
. Y hotter

demonstrate this with a torch and a ball. If youshine the

torchdirectly onto the ball, the light is concentrated

in one place
. If ouy use the same tor
hc to

illuminate a larger area of the ball, the light

spreads out and

. is weaker

t Dregicti l h

t The
is ligh
 OceanofPDF.com

September

hNedsrm
topswhneitroia

hteSusntaiIu.tmnhitenohtren

hempsheiarndhpgsiter

emseurapte sout.hererehpsnmehiT

hetdm
arenhsldm
taryise

hnegthbil.om
etpshrei

Axsi

Ear
th spins around

Sun

this line onceve ery

24 hours.

Long summer days

More of the northern

hemisphere islluminat
i ed,

l i Tdet axis

so the da
syare

longer there.

Equat
or
 OceanofPDF.com

Climate

T h e w eather is w ha
s’t going o n in t h e air around us –

whether it i s rainy o, rwindy

d r y o r still, s u nny or overcast.

T h e w eather changes from day t o day ubt t h e typical

weather of a p articular area is known a s its climate.

Lots of things c a n affect a n area

s’ climate, including

its heig h t a bove sea elvel , d i stance from th e s e a,

and whether it i s flat o r mountainous. But the

main fac t o r is i t s distance from t h e .equator

Climate zones

The equator is an imaginary line around

the centre of Earth. This part of the globe

receives the most direct sunlight, so it has a hot,

, tropical
sunnyclimate.The polar regions,

far from the ,equator

receive the least direct

sunlight and have cold frosty climates. Next

to the polar regions are the temperate zones,

and between the temperate and tropical

zones lie the subtropics.

C
OceanofPDF.com
 OceanofPDF.com

Greenhouse

effect

s u J t a s a g la s s g reenhouse keeps plants w a r m yb

trapping heat inside, g a s es i n Earth’s a t mosphere

stop war mth from t h e Sun escaping b a c k into space.

Whti out this g re enhouse ef f e c t , our planet wou l d

be too cold t o support li f e a s w e know i t .

Some energy

isrefltedcback

ton ispace by

the atmosphere

tSunilgh

Energy from

the Sun
ers
t en

the atmosphere,

provi
tdinggh
li

and warmth.
 OceanofPDF.com

Climate change

The greenhouse effect is a natural

process and vital to life on Earth.

Infrared escapes

But burning fossil fuels, such as coal

Some heat passes

and gas, increases the amounts of

through the

greenhouse g ases in the atmosphere

.

atmosphere and

This is leading to an increased

escapes
o inspace.
t

greenhouse effect, where the

atmosphere is trapping more heat

than before and thesworlclimate

d’

is getting
. T hehotter
knock-on effects

ontheplanet’s naturalenvironment

could be catastrophic.

r t x E eme weather

The world warms up

The warm gases themselves

radi
eatheat, so Ear
th and

the atmosphere

t ge
warmer
.

Infrared

absorbed

Greenhouse gases

in the atmosphere Industry

absorb infrared Greenhouse gases

radiotaintime ted are released

by the warm Earth. byrofac

t ies and

The air warms up. powerstat

noi s.
 OceanofPDF.com

Moon

T h e M o on i s Earth’s constant companion in

space. I t i s cl o s e en o u g h th a t many of its

features ca n b e seen with the naked e.ye It

s h i n e s brightly in t h e n i ,g but
ht s ikty doesn’
t

have any l i g ht o f its own – the light w e s e e is

actually reflected rfom t h e Sun. Unlike Earth,

the Moon i s a dead world b e c a u se i t has no

Formation of the Moon

water or a i r t o suppor t l ife.

The Moon for med about 4.5 billion years ago. No

one knows for sure

,but the most common theory

suggests that a Mars-sized asteroid collided with the

n e w l y f o r med Earth. Debris from the collision was

Moonsuit
flung into Earth’s orbit, where it eventually clumped

A real spac
tesui
would

together into one large rocky mass.

ectprotall part
s of

an astronaut’s .body

On the surface

This four-legged space explorer has a close-up

view of the Moon’

, cratered
s ocky
r surface
.

Most of the craters were f o r med billions of

years ago,when asteroids smashed into the

young Moon. The biggest impacts made

e n o r mous craters that flooded with va

la fr
om

inside the Moon. The va

la cooled and solidified,

f o r minglarge, dark plains called maria, or seas

.

Lunarmovements

TheM
.ootn
osp
uaiotsrb
lu
n
tinaisxdiEb
hat,r
 OceanofPDF.com

Regol
th i

A thick lyaerof loose

dust and brok

en rock

called regoli
th covers

theeire
nt surf
ace

of the Moon.

In shadow

From the Moon,

only the part of

tEar
thupli by the

Sun is visible.

Scorching surface

The Moon has no atmosphere

t ofrom
ec
tpro
ti the

Sun’s ra
syor
o hold
t in

heatt.atAsnigha result,

temperatures can reach

127°C (260°F) in the day

anddropto -173°C

(-280°F)t.at gh
ni
 OceanofPDF.com

Solar System

T h e S o lar System i s Earth’s g i g a ntic neighbourhood in

space. A t the centre i s the Sun, the star whose e n o r mous

gravitational pull kee p s t he w hole system together

. Eight

planets are held in orbit, along with billions of smaller

objects, including asteroids, d warf planets, an d c o mets.

T h i s m a mmoth model shows t h e main member s, ubt

s’ti n o t to scale, o r it would neve r fi t o n t h e page!

Sun

The planets

Thistly
bri
an
llitho

The four planets closest to the

ball of gas is so gbi

Sun
enus,–Earth,
,Mercury
V and
that more than

1 on
lli
mi Ear
ths could

Mars – are small, rockyworlds.

t insi
t.fi
de i

The four outer most planets are

gas giants, made mainly of

hydrogen and helium.

Saturn
 OceanofPDF.com

Minor members

The planets are the biggest member s of the Solar

System but millions and millions of smaller objects

also orbit the Sun. Many of these are found in the

outer Solar System,ond

be
y the orbit of the most

distant planet, Neptune.

Ice gitan

e T mperatures on

Uranus, the coldest

plane
t, plumme
ot t

Uranus
otulP

an icy -224°C

(-371°F).

Dwarf planets

These large
,oughly
r spherical bodies are not big enough

to be classified as fully fledged planets. Eris, the largest,

is only half the size of . There

Mercury
are currently five

dwarf planets that we know about, but there could be

manymore waiting to be discov

ered.

Gasltai

Cosmicvoyager

Comets are visitors from the outer reaches of the

Solar System that veltrain very elongated orbits

 OceanofPDF.com

Galaxies

A galaxy is a collection of stars, gas, and dust held

together
. Galaxies
y bg vity
come
ra in a variety of

Milky Way

shapes and sizes, butthe

y can be gr
ouped into our
f

Our Solar System can b e of u n d in a galaxy

main types: spiral, barred spiral, elliptical, and

. Scientists
irregularthink there are hundreds of

called th e. M
A lillk yayof W the star s w e

billions of galaxies in the Universe

.

can see i n Earth’s n i g h t s k y are i n the Milky

Gaalxytnec re has

.romFyo auWr view inside the , wgalaxy

e

a long, flat shape

can never s e e i t s voe r a l l shape. B u t if

w e c ou l d s e e i t rfom t h e same view

a s t h is f u r r y s pa c e, i trteavller

would lo o k l ik e a giant,

glowing whirlpool.

Spiral Barred spiral

Arms spiral out

from thetre
en
c

Elcilaplt Irregular

Black hole

Scientists think most galaxies hav

e a s u p e r massive

black hole at their centrA

e. black hole is the result

of vast quantities of matter crushed into a point

OceanofPDF.com
 OceanofPDF.com

Glossary

ANCESTOR COMPOUND DRAG

An animal or plant from which A chemical substance made

Aforce that acts to slow

a more recent animal or plant fromatoms of two or more

downobjectsmoving through

is descended. different elements.

liquids or gases.

ANTIBODIES CONCAVE

EGG CELL

Chemicals pr
oducedy bthe Describes an object that

m e F ale sex cell.

immune system that locate and curves inwards

.

mark bacteria and viruses of r

ELECTRICITY

destruction.
CONDENSATION

A way in which energy is

When a gas turns into a liquid.

transferredy ba flow of

ASTEROID

charged particles
.

A space rock.
CONDUCTION

The transfer of heat or

ELECTROMAGNETIC

M
SO
TA PHERE

electricity between solid objects.

SPECTRUM

Thelayers of gas around

The range of evwalengths and

a planet.
CONDUCTOR

frequencies of electromagnetic

A material such as metal

radiation.

M
OTA

throughwhich heat or

T he smallest unit of an electricity can

. easily flow

ELECTRON

element, containing protons

,

, negativelyAcharged
tiny

neutrons
, and electr
ons.
CONSUMER

particle found in an atom.

An animal that eats plants or

AXIS

other animals.

ELEMENT

eblneviisToheraliundwhchi

.nshpisEtar
CONVECTION A pure substance that can
t’be

brokendown. any further

Tharetnorfs ou
rhtaeht gha

BACTERIA

dqui.golars

ELEPHANT SHREW
Microscopic organisms with a

simple, single-celled for m. Some

CONVEX

A small, rodent-like mammal

can cause disease.

Describes an object that bulges with a long snout. Also known

in the centre
.
as a sengi.

CAPILLARIES

The smallest blood vessels in the

DECOMPOSER

ENERGY

. Capillaries
bodycarry blood to

An organism that breaks down

Energy is transfer redevery time

and from the cells

.

decaying matter into nutrients.

something happens. It can be

 OceanofPDF.com

GREENHOUSE GASES MOLECULE PRODUCER

Gases in the atmosphere

, such
o w T or more atoms that are
Anm
ogsarnhiam
toodafkes

as carbon dioxide and methane

,

bonded. together

hortughapsnhydoiset

that absorb heatom

fr the Sun.

netayebm
h.reaosntial

UN
TARAL SELECTION

IMMUNITY

PROTEIN

The processbywhich organisms

The body’
s ability to prev
ent

with less successful traits die out,

A substance that a living thing

illness from certain bacteria

while organisms with more

uses to form its tissues.

or viruses.

successful traits survive and are

able to pass on their genes.

PROTON

INFRARED

y l evlicditetgirasphocpA

Radiation with wav

elengths

NACTER

suednluenochfutinof m
.onta

longer than visible light, which

A sugary solution producedy b

we feel as heat.

flowers to attract pollinating

RADAITION

animals.

N
I SULATOR

Energy that veltra

s through

A material such as plastic spaceinwave.s

NEURON

throughwhich heat or

A nerve cell.

electricity cannot
. easily flow

REFLECTION

When light bounces off an

NEUTRON

LIGHT

object and trav

els in a

A particle with no chargeof und

ytrlnfaTopeh hte

different direction.

within the nucleus of an atom.

ci tengmoamurrttcceaethpltse

v asfeo . eneaewcsW tnereff id

REFRACTION

NUCLEUS

dethrugoeihlopelm
tcuka

T he bending of light as it

emu.lbritcsepivs

eTofhorecnlt a,cle

elsarvt om
fr one substance

sDNiAhde’l.lhweltchre

to. another

serhoAfetcrsnl
LIQUID

aonmtm,adeof onsptr

A state of matter in which the

RESPIRATION

. onsradnuet

particles are loosely packed and

The processy which

b living

easily slide past. each other

, Liquids
and takeflothe
w shape cells use oxy
gen to erlease

NUTRIENT

of their. container

energy from food.

Chemical substances that cells

need to grow and

. repair

MAGMA

SABRE-TOOTHEDT CA

MenotrckdelpnhwEit.air
ORBIT

A large extinct cat species with

onlg, curved upper canine teeth.

The path that one object

MAMMAL

makes around another

object .due to g vity

ra
A w a r m-blooded animal that

SEDIMENT

produces milk to feed. itsoung

y

Small bits of weathered rock,

ORGANISM

minerals, and organic

. matter

MAMMOTH

A living. thing

A prehistoric mammal species

SEED
 OceanofPDF.com

I n d e x

bold

bloodvessels 53, 54, 55, 56 conductors 100

Pagenumbers in type

refer to main entries body temperature 56 conservation of momentum

bone cells 40, 41 consumers 48–9

A
bone marrow 58 contact forces 107

58–9

bones , 60 continents 135

a b s o r ption, light 94, 95

110–11

brain 62, 63, 64, 66, 67, 90, 91 contraction 60

acceleration , 115

125

braking systems ocnvection currents 82,

acids 30–1

114–15

breaking point 109 ocnvergent boundaries 137

action and reaction

52–3

breathing , 62, 134 ocnvex lenses 91

adaptation 76–7

brittle materials 109 ocnvex mirrors 89

adulthood 71

bronchi52 core,Earth’s 135

aerodynamics 121

129
bronchioles 52 c o r n e a 64, 65

aerofoils

buoyancy 126–7 corrosion 27

aeroplanes 128–9

butterflies 70 counterweights 130

air 16, 52, 53, 90, 126, 150

craters 150, 151

air pressure 129

120–1 crust, Earth’s 135, 136, 137, 139

air resistance , 128

C

crystals 138, 139

algae 34

capillaries 53, 54, 57

cytoplasm 37, 38

alkalis 30–1

carbon 18, 19

aluminium 15

carbon dioxide 28, 43, 52, 53, 56,

D
alveoli 53, 57

134, 148

amplitude 85

decanting 16, 17
carbon fibre 14

animals

decay 49
carbon monoxide 28

cells 38, 40

decomposers 49
cardiacmuscles 40, 41, 61

food chains 48–9

defences, body

c a t e r pillars 70

habitats 146

d e f o r mingforces

cell membranes 36, 38, 39

12–13

life on Earth 34, 134

density

cell walls 36, 39

38–41

seed dispersal 46, 47

deposition 11

cells 35, , 51, 52, 56

anthers 45
diamonds 18

central nervous system (CNS) 62

antibodies 68
diaphragm 52, 53

ceramics 14, 109

anus 57
diffuse reflection 88

Ceres 153

22–3

archaea34
diffused light 144

chemical bonds

Arctic 49 digestion 24, 31, 37, 47,

chemical energy 81

24–5

a r m s 60–1 62

chemical reactions 14, , 28,

arteries 54 dinosaurs 141

43

26–7

direction 106, 110

asexual repr
oduction 73

speed of

displacement 13, 126

asteroid belt 152

chemical symbols 18

distance 116
asteroids 150, 152

chlorine 19

134

distillation 17
atmosphere
, Eart
sh’ , 135,

chloroph
yll 43

distorted view 90, 91

148, 149

chloroplasts 39, 41, 43

20–1

divergent boundaries 137

atoms 19, , 22

chromosomes 73, 74

74–5

DNA37,

attraction

chrysalises 70

dominant genes 75

electrostatic 98, 99

ciliary muscles 65
 OceanofPDF.com

freezing 10, 11 intestines 51, 57 melting 10, 11, 24

frequency 85 iris 65
mercury (element) 19

118–19

friction iron 27, 102

Mercury (planet) 152

fruit 45, 47 irregular galaxies 154

metals 14, 19, 102

fuel 28, 29, 114

m e t a m o r p hic rock 138, 139

70

fungi 34
m e t a m o r p h osis

mcirowes
av 96

joints 59, 61

mid-ocean ridges 137

G
p u J iter 152

154–5

Milky
ay W

154

galaxies

minerals 41, 42, 139, 140

gamma rays 97

mirror images 88,

gases 9, 10–11, 12, 16, 17, 19, 25,

kidneys 56

mitochondria 38

26, 82, 83

kinetic energy 80, 81

mixtures, separating

fluid pressure 123

22–3

molecules

greenhouse 148–9

112–13

L
momentum

gears 130, 131

150–1

large intestine 51, 57

Moon 17, 116,

genes 74, 75

larvae 73

motor impulses 63

g e r mination 47

alva150, 151

mountains 137, 151

g e r ms 40, 68, 69

law of reflection 88

movement

glands 56

110–11

es
ealv 41, 42, 43, 47, 142

acceleration

glass 14, 109

lens 64, 65

energy 81

g l o b a l w a r ming 149

levers 130, 131

life 35

glucose 43

34–5

112–13

life , 134, 148, 149, 150

momentum

gold 18

70–1

lifecycle

sensing 66

graphite 18

lift 128, 129

mucus 68, 69

grass 48

86–7

116–17

light 42, 64, 65, 81, , 99

muscle cells 40, 41

gravity 107, 114, , 118,

60–1

chemical reactions 25, 26, 28

muscles 53, 55,

119, 128, 154

144

148–9

direct
music 84

greenhouse effect

96–7

electromagnetic radiation

grip 119

88–9

reflection

ground 99, 107, 115

90–1

refraction
g r o u n d water 143

76

natural selection

94–5
70–1

seeing colour
growth 35,

Neptune 152, 153

92–3

gunpowder 26 white

nerve impulses 62, 64, 66, 67

light bulbs 100, 101

nervous system 41,

light rays 86–93

neurons 41, 62

lightning 99

neutrons 20, 21
hair cells 67

liquids 8, 10–11, 12, 16, 17, 82, 83

newtons 107
hatching 73

fluid pressure 123

nitrogen 134, 148

Haumea 153

124–5

hyd
arulics

non-contact forces 107

healing 68

load, spreading 122–3

66–7

non-metals 19
hearing 63,

loudness 85

nuclear energy 81
heart 40, 54, 61

lubrication 119

nucleus
heat 24, 25, 26, 28, 29, 80, 81,
 OceanofPDF.com

88–9

reflection , 94, 95
smell 63

90–1

refraction , 92
smooth muscles 61

tail fins 128

152–3

regolith 151
Solar System , 154, 155

tears 68

72–3

reproduction 35, 44–5, 71, ,

solids 8, 10–11, 12, 19

teeth 50, 58

75

and light 86

temperate climates 147

reptiles 73

separating mixtures 16

temperature 10, 82

repulsion 98, 102–3

solutions 17

Earth 144, 145, 146, 147, 149

respiration 35, 56, 57

sound 26, 80, 81

Moon 151

84–5

retina 64

soundwav
es 66, 67,

tendons 60

ribosomes 37

space

tensions 108

134–49

ribs 59

Earth
thrust 114, 115, 128

rift valleys 137

gravity 116, 117 tilt,Earth’s 144

154–5

rivers 143

torsion 109
Milky
ay W

138

150–1

ock
r cle
cy

touch 63
Moon

152–3

rockets 26, 114

t r a n s f o r m boundaries 137

Solar System

138–9

rocks 134, 135, 137, ,

translucent materials 86

species 76, 77

140–1, 152 transparent materials 86

specular reflection 88

142

transpiration
roots 41, 42, 43, 47

speed 106, 110–11, 118–21

90 transport 149
rope15

speed of light , 96

triceps 60, 61

rotors 129

s p e r m 40, 73

tropical climate 146, 147

rubber 14, 15

spinal cord 62

troposphere 134

rusting 27

spiral galaxies 154

trunk 58

spongy bone 48

turbulence 120–1

S springs 80, 81, 109

tusks 58

squashing 108

saliva 50, 68, 69

74

twins, identical

stars 154, 155

S a t u r n 152

twisting 109

98–9

static electricity

scabs 68

steam 11

screws 130, 131

steel 14, 102

sealevels 149

ultraviolet 97
144–5
stems 43

seasons

unbalanced forces 107, 116

stigma 44

sedimentary rock 138, 139

universal indicator 30

stirrup 67

sedimentation 138, 140

Universe 18, 80, 114, 134, 154

46–7

stomach 50, 51

seeds 45,

uplift 138

stomach acid 31

sensing 34, 35, 62, 63

126

upthrust

s t o r ms 99

sex cells 40, 44, 45, 73

Uranus 153

streamlining 121

sexual maturity 71

ureter 56

stretching 108, 109

sexual repr
oduction 73

56

urinary system

sublimation 11

shadows 86–7

urine 57

subtropical climates 147

shape 106, 108–9

sugars 42, 43, 51

shells, electr
on 21, 22

Sun 143, 148, 150, 151 V

shoots 47

Earth’s orbit 144, 145

sieving 16, 17

vacuoles 39, 41

152–3

64–5

Solar System

sight 63,

valves55

130–1

sunlight 43, 47, 48, 92, 94, 146,

simple machines

vapour 10, 11, 17, 142, 143

148
sinking 126, 127

veins 54

110
s u p e r massiveblack holes 154
skeletal muscles 61

velocity

suspensions 17
skeleton 58, 140

e V nus 152

sweat 56
skin 40, 56, 57, 68–9

vibrations 66, 67, 81, 82, 84–5,