How to be Good at Science, Technology & Engineering

EARTH AND SPACE • RIVERS 299

Oxbow lakes REAL WORLD TECHNOLOGY

The meanders that develop in rivers are continually Hydroelectric power
changing shape as fast-flowing water in the outsides of
bends erodes the ground more quickly. Over time, a The energy of a flowing river can be harnessed
meander may get cut off to form an oxbow lake. to make electricity. To do this, a dam is built to
create a reservoir. Water is then allowed to flow
Here, erosion is gradually causing 2 through the dam via a channel, where it spins a
the neck of a meander to narrow (1), 1 machine called a turbine, which is connected to
while the loop itself is enlarging (2). an electricity generator. The electricity is then
carried away by power lines.

Eventually, the neck becomes so DAM POWER LINES
narrow (1) that at times of flood, RESERVOIR
some water crosses it.
1 GENERATOR
Finally, part of the loop becomes 1 TURBINE
cut off, leaving an oxbow lake (1), 2
while the river becomes temporarily RIVER
straightened out (2).

Oxbow lake

Salt marsh

DELTA

SEA

Tributary Meanders Mouth
A tributary is a smaller S-shaped loops, called The mouth of a river is where it
river that flows into a main river. meanders, form as a river meets the sea. Sediment deposited
Each tributary adds more water, nears the sea and the slope here may build up to form an area of
causing a river to swell in size on becomes more shallow. flat land and channels—a delta.
its journey toward the sea.

300 EARTH AND SPACE • GLACIERS

Glaciers EaArbthob’usytlga10lnadpcieiasrlccieconev.teoref d

Glaciers are masses of ice found in mountain ranges and
polar regions. As they flow slowly downhill, they wear away
the ground below and gradually change the landscape.

In the accumulation zone near the top of
a mountain, snow piles up. Deep layers
of snow are compressed to form ice. The ice
erodes (wears away) a bowl-shaped hollow in
the mountain, which may later become a lake.

The main body of the glacier flows Tributary
slowly downhill, typically moving by glacier
about 3 feet (1 metre) a day. Crevasses

Rocky debris from the valley Meltwater channel
becomes embedded in the glacier. It
gets dragged along by the ice, scraping
the ground and the sides of the valley
like a giant piece of sandpaper.

Giant cracks, known as crevasses, Ablation zone
and channels of meltwater crisscross
the upper surface of the glacier.

In an area called the ablation zone,
ice begins to melt as conditions get
warmer farther down the valley. The
glacier starts to break up.

At the foot of the glacier is a crescent- Terminal moraine Rocks
shaped mound of rocky debris (a deposited
terminal moraine), dumped by the melting by glacier
ice. Streams of meltwater flow away from
the glacier.

EARTH AND SPACE • GLACIERS 301
Main
Shaping the land Before a glacier Tributary valley
passes through, the valley
Over time, glaciers turn steep-sided main valley is V-shaped. Ice
river valleys into wide, U-shaped Tributary valleys descend
valleys (right). These are common in down to the floor of the Waterfall
Earth's northern hemisphere and main valley.
show that glaciers once covered far
more of the planet than they do today.

A glacier forms and
moves through the
main valley. The glacial ice
and rocky debris erode the
bottom and sides of the
valley, deepening and
widening it.

Thousands of years later,
the glacier has melted. The
main valley is now U-shaped
and its tributary valleys “hang,”
meaning they end high above
the main valley.

Accumulation Other glacial features
zone
As well as U-shaped valleys, glaciers leave behind a variety of
other geological (land) features after they melt. These become
visible once the glacial ice melts.

Drumlin Kettle lake
An egg-shaped hill made of A small, shallow, circular
loose rock debris deposited by a lake left by a large chunk of
glacier and then sculpted by melted glacier ice.
movement of the glacial ice.

The bowl-shaped
hollow will

become a lake if
the glacier melts.

Fallen rocks Erratic Esker
on surface A huge, isolated boulder that A winding ridge of gravel
has been transported a long way deposited by a stream running
and then dumped by a glacier. beneath a glacier.

302 EARTH AND SPACE • SEASONS AND CLIMATE ZONES

Seasons and
climate zones caSeutasoeshominbaaelnrncyhaaatennigomerasls
migrate.
Many parts of the world have four seasons: spring, summer,
fall, and winter. These seasons bring changes in day length,
sunlight intensity, and average temperatures.

Why we have seasons Earth’s path
around the Sun
The line, or axis, around which Earth
spins is tilted. Due to this tilt, Earth’s
northern and southern hemispheres lean
toward the Sun at different times of the
year. This results in the cycle of seasons.

Earth rotates around SUN
an imaginary line
called an axis.

June September December
The northern hemisphere tilts In September neither In December the southern
toward the Sun in June, giving hemisphere tilts toward the Sun, hemisphere tilts toward the Sun
northern lands the long days and so days and nights are the same and experiences summer. The
sunny weather of summer. The length everywhere. It’s fall in the northern hemisphere tilts away,
southern hemisphere tilts away northern hemisphere and spring giving it the long nights and cold
and has the opposite: winter. in the southern hemisphere. weather of winter.

EARTH AND SPACE • SEASONS AND CLIMATE ZONES 303

TRY IT OUT Polar zone

Beach ball climate model Equator

To see why Earth’s equator is much warmer than the
poles, try this experiment. Place a beach ball about
12 inches (30 cm) from a desk lamp and leave it for a
few minutes. Then feel the surface of the ball with your
hand. It will be warm around the equator but cooler at
the poles. This is because the equator faces the lamp
directly and feels the full force of its beam, while the light
at the poles hits the ground at a shallow angle and so is
spread out over a much wider area.

Climate zones

Earth’s shape and tilt cause different amounts of sunlight to reach different
parts of its surface. This causes climate zones—large areas of Earth’s
surface with distinct patterns of weather. There are three main climate
zones: polar, temperate, and tropical.

There are two polar zones: one around the North Northern
Pole and another around the South Pole. They temperate
are colder than the rest of the planet and have only zone
two seasons each year: summer and winter.

Earth’s two temperate zones both have
four seasons each year: spring, summer,
fall, and winter. Average temperatures are
mild, but summers can be very hot and
winters bitterly cold.

The zone near the equator is called EQUATOR
the tropical zone and is warm all year.
The northern and southern parts of the
tropical zone have rainy seasons and
dry seasons instead of summer and
winter, but the equator is rainy all year.

March Southern
In the northern hemisphere, temperate zone
the days are growing longer and
warmer, causing the season of
spring. Meanwhile, cooler fall
weather and shortening days
have arrived in the south.

304 EARTH AND SPACE • THE ATMOSPHERE incoEamArlelthtsh’sferaootmmxyopgsleapnnhtesr.e

The atmosphere Weather
balloons
Earth is surrounded by the atmosphere, a thin blanket of operate in
gases held in place by our planet’s gravity. The gases that this layer.
make up Earth’s atmosphere are vital to life on Earth.
Earth
The atmosphere’s layers

The atmosphere has five distinct layers. As you travel
from space through the atmosphere toward Earth, each
layer becomes thicker (denser) than the layer above.

Exosphere
The outer layer extends to
thousands of miles above Earth’s
surface. It merges with space.

Thermosphere
This layer is hundreds of
miles deep and is home to the
International Space Station.

Mesosphere
In the upper region of this 20-mile- (30-km)
thick layer, temperatures can be lower than
−225°F (−143°C), making it the coldest place on
Earth. Tiny space rocks burn up here, producing
streaks of light called meteors or shooting stars.

Stratosphere Shooting stars

About 22 miles (35 km) deep, this layer has

a protective band of ozone gas (a form of oxygen)

that absorbs harmful ultraviolet radiation from the

Sun, shielding the planet’s surface.

Troposphere Airplanes
fly here.

This layer is where all weather occurs.

It is 5 miles (8 km) thick above the poles, and

11 miles (18 km) thick above the equator.

EARTH AND SPACE • THE ATMOSPHERE 305

Gases in the atmosphere 21% oxygen
1% argon
Nitrogen and oxygen are the two main gases
found in the atmosphere, but there are tiny 0.05% carbon dioxide, neon,
amounts of other gases, too. In the lower methane, helium, ozone, and
layers, water vapor is present, making up other gases
about one percent of the air at sea level. 78% nitrogen

Global winds Polar cell

In the troposphere, air circulates up and down in patterns called atmospheric
cells. There are three groups of cells: polar, Ferrel, and Hadley cells. The air
movement in these cells, along with Earth’s spin (which makes the air veer east
or west) creates three global wind patterns that blow over Earth’s surface.

Winds called polar easterlies blow Ferrel cell
in polar regions. They blow away
from the pole, then Earth’s spin makes
them swerve from east to west.

Westerlies blow in temperate (mild Hadley cells
weather) regions. They blow away from
the equator, and then from west to east.

Trade winds blow in the tropics (near the
equator). In the northern hemisphere, they
blow from northeast to southwest (northeast trade
winds). In the southern hemisphere, they blow from
southeast to northwest (southeast trade winds).

REAL WORLD TECHNOLOGY Radio waves travel The ionosphere
in straight lines. reflects radio waves.
Bouncing radio waves A transmitter sends
out radio messages. A receiver picks
The atmosphere allows people to up messages.
communicate over long distances
by bouncing radio waves around the
world. Transmitters emit radio waves,
which travel toward a part of the
atmosphere known as the ionosphere.
The ionosphere reflects the radio waves
back to Earth, where they are picked up
by receivers elsewhere in the world.

306 EARTH AND SPACE • WEATHER

Weather pCoaalvtitmeperlraanacteoepfieeswrxitophedaeertothiyefepntriiccmteahseal .t

The air and water in Earth’s atmosphere are continually on the
move, driven by the Sun’s energy and Earth’s rotation. These
movements create wind, rain, and other types of weather.

Moving air

The changing weather can often be explained by the way large masses of air
move and collide in the atmosphere. Clear weather is associated with sinking air,
but rising air carries moisture high into the sky and produces clouds and rain.

SINKING DRY AIR RISING MOIST AIR

Clouds
form.

High pressure Low pressure
When air from high in the atmosphere sinks, it When air rises, it causes low pressure. The
presses on the air below, causing high pressure. air cools as it rises, and any moisture in the air
Air from high altitudes is usually dry, so high condenses to form clouds. Rising air usually brings
pressure brings clear, sunny weather. overcast or rainy weather.

COLD AIR Warm air rises WARM AIR Warm air rises
MASS steeply, forming MASS gently, forming
large clouds. thin clouds.

WARM AIR COLD
MASS AIR MASS

Cold front Warm front
When a mass of cold air pushes into warm air, If warm air pushes into cold air, it slides gently
it pushes the warm air up strongly. This is called a over it, forming a warm front. The moisture in the
cold front. The weather gets colder, and moisture warm air cools gradually as it rises, forming thin
in the warm air forms huge rain clouds. clouds and often bringing light rain.

EARTH AND SPACE • WEATHER 307

Extreme weather REAL WORLD TECHNOLOGY

The weather is often changeable, but sometimes it is far hotter, Weather charts
colder, or windier than normal. Extreme weather is unusual or
violent weather that can threaten lives and damage property. Weather forecasters use
charts to display the current
Hurricanes and typhoons are vast, A tornado is a rapidly spinning weather and their forecasts.
revolving storm systems that form column of air that produces The swirling lines on a chart
over tropical oceans. violent and destructive winds. are called isobars and
connect areas of equal
Electrical storms bring thunder Blizzards are severe storms in pressure. Warm fronts are
and lightning, strong winds, and freezing conditions, bringing shown by lines of red
heavy precipitation (rain or hail). heavy snowfall and very high winds. semicircles, and cold fronts
are shown by blue triangles.
These fronts often revolve
around areas of low
pressure, forming a weather
system called a cyclone.
Although a trained
meteorologist (weather
scientist) can predict the
weather using just a chart,
predictions are usually made
by supercomputers that
model Earth’s atmosphere.

LOW

During an ice storm, rain freezes Heat waves are spells of 1024
when it touches the ground, unusually hot weather that can 1032
coating everything in layers of ice. make people sick and destroy crops. 1040

Cloud types CIRROCUMULUS CIRRUS CUMULONIMBUS

The names of most clouds are based on ALTOSTRATUS
three basic shapes: wispy and feather-
like (cirrus); lumpy (cumulus); and flat NIMBOSTRATUS STRATUS CUMULUS
(stratus). Other Latin words are combined
with these. For instance, alto means the
cloud is medium-high, and nimbo or
nimbus means it’s likely to cause rain.

308 EARTH AND SPACE • OCEAN CURRENTS cuTrurerttonlettssraauvsseehl oliogcnhegwanays
distances.
Ocean currents

Driven by the wind and by Earth’s rotation, the water in the oceans
flows around the planet in huge streams called ocean currents.
These have a large influence on the climate of many countries.

Surface currents

Some currents flow along the sea surface. On the western sides of the oceans,
these surface currents carry warm water from the tropics toward colder regions.
On the eastern sides, currents carry cool water back toward the tropics. Many of
these currents combine to form huge circular flows called gyres.

The California Current carries The Gulf Stream carries The North Atlantic Drift
cold water down the eastern warm water up the western carries warm water from the
side of the North Pacific. This side of the North Atlantic. It flows Gulf Stream to Europe. It makes
makes the climate cooler on the very quickly and is one of the winters in the British Isles and
west coast of North America. world’s strongest ocean currents. Scandinavia warmer.

NORTH EUROPE ASIA
AMERICA AFRICA AUSTRALIA

SOUTH
AMERICA

ANTARCTICA

The Peru Current is a cold The Antarctic Circumpolar The Kuroshio Current
current off the west coast of Current is a cold current that carries warm water up the
South America. Cold air carries flows around Antarctica. It keeps western side of the North Pacific
less moisture than warm air, so it warm water away, which helps Ocean. It warms the southern
gives this coast a dry climate. stop Antarctic ice from melting. part of Japan.

EARTH AND SPACE • OCEAN CURRENTS 309
Pacific Ocean
Deep currents North Atlantic
Wind
Some currents flow along the seafloor. These are much Upwelling
slower than surface currents, but they play an important
role in the world’s climate, and they help sustain sea life.

Global conveyor Water sinks

In the North Atlantic, surface water cools

and becomes saltier as some of it turns to ice.

This makes the water heavier, so it sinks and

flows along the seafloor. Some of the deep

water can spend 1,000 years flowing slowly

over the seafloor before rising again in the

Pacific and returning. This giant current is

called the global conveyor and plays a key

role in the global climate. Some scientists think

melting Arctic ice could disrupt it, triggering Deep cold
an ice age in the northern hemisphere. current

Upwellings Nutrient-
In some parts of the world, winds push the rich water
sea away from the coast, causing water to rise
up from the deep. These rising currents are
called upwellings. They bring nutrients to the
surface, allowing many forms of sea life to
flourish. Many of the world’s most important
fishing sites are near upwellings.

REAL WORLD TECHNOLOGY Turbine
Current
Underwater turbines

Ocean currents carry vast amounts of energy.
If just 0.3 per cent of the energy in the Gulf
Stream could be harnessed, it would provide
enough power for the whole state of Florida.
Engineers are trying to develop technologies
that will one day be able to extract energy
from ocean currents. One idea is to build
turbines on the seafloor that work in the
same way as wind turbines on land.

310 EARTH AND SPACE • THE CARBON CYCLE Thiine2nc5ltrehepveaeeslarecotedmf ncbotayssrpbimnhocoenerreed19ithoh6axa0isdn. e

The carbon cycle

All living organisms contain carbon, and it’s found in many
nonliving materials too, such as fossil fuels and some rocks.
The movement of carbon between living organisms, the oceans,
the atmosphere, and Earth’s crust is called the carbon cycle.

Parts of the carbon cycle

Some parts of the cycle move carbon around in just a matter of days, while
other parts store carbon for millions of years. Human activities can speed up
the rate at which carbon dioxide is released into the atmosphere.

Factories Volcano
and power
stations

Respiration Burning fossil fuels Volcanic action Fossilization
Animals and other The burning of fossil Volcanoes and Some organisms don’t
organisms take in carbon fuels—whether in factories, hot springs slowly decay after dying. Instead,
through food and release it power stations, and homes return carbon from they become buried, trapping
as carbon dioxide. Carbon or by cars and planes— long-term underground carbon in the ground. Over
is also released when their releases carbon dioxide stores into the air as millions of years, their
dung or bodies decompose. into the atmosphere. carbon dioxide. remains form fossil fuels.

EARTH AND SPACE • THE CARBON CYCLE 311

REAL WORLD TECHNOLOGY Some heat escapes
back out into space.
Climate change
Trapped heat
The burning of fossil fuels has dramatically increased SUN
the rate at which carbon from underground stores AT

returns to the atmosphere. As a result, the level of Heat from
carbon dioxide in the atmosphere is rising. Carbon the Sun
dioxide traps heat in the atmosphere, in much the

same way as glass traps heat in a greenhouse, so MOSPHERE

our planet’s average temperature is rising too.

Many scientists think the warming climate is causing EARTH

glaciers to melt, droughts and floods to become more

frequent, and coral reefs to die.

CARBON RELEASED
CARBON ABSORBED

Deforested area

Photosynthesis Deforestation Ocean exchange Marine carbon capture
Plants take in Cutting down Carbon dioxide passes Some marine organisms
carbon dioxide from forests releases carbon between the oceans and use carbon dioxide to make
the air to make nutrients by back into the air if the air. The world’s oceans shells. When they die, their
photosynthesis. They also trees are burned or take in more carbon than remains sink to the seabed and
release carbon dioxide dead vegetation is left they release and are fossilize to form limestone, which
through respiration. to decompose. known as a “carbon sink.” acts as a long-term carbon store.

312 GLOSSARY

Glossary boiling point The temperature at chlorophyll A green substance
which a liquid turns to gas so quickly used by plants to absorb light
absolute zero The lowest possible anion A negatively charged ion. that bubbles form in it. energy for making food
temperature, defined as zero kelvin anode A positive electrode. (photosynthesis).
bond A force between atoms or
or –459.67°F (–273.15°C). molecules that holds them together. chloroplasts Tiny bodies in plant
cells that contain chlorophyll.
acceleration A change in the antibodies Proteins in the blood bone Hard tissue that is part of an
velocity of a moving object. that help the body attack germs animal’s skeleton. chromatography A way of
Speeding up, slowing down, and such as bacteria and viruses. separating colored chemicals in
changing direction are all forms of Brownian motion The random a mixture by letting them spread
acceleration. artery A thick-walled blood vessel motion of microscopic particles in through an absorbent material,
that carries blood away from the a liquid or a gas, caused by such as paper.
acid A compound that releases heart to other parts of the body. molecules colliding with them.
hydrogen ions when it dissolves in chromosome A structure in the
water. Vinegar and lemon juice are artificial selection The process by buoyancy The upward force on an nucleus of a cell, made from coiled
weak acids. which humans use animal breeding object in water. Buoyancy can make DNA strands, that carries genetic
or plant breeding to make changes objects float. information.
activation energy The energy to a species.
needed to start a chemical reaction. capillaries Tiny blood vessels that circuit A path that electricity flows
asexual reproduction carry blood to and from cells. around. All electrical devices have
aerobic respiration The process by Reproduction that involves only one circuits inside them.
which living cells use oxygen to parent. carbohydrate A biological
release energy from food. compound used as a source of climate The pattern of weather and
asteroid A large, irregularly shaped energy. Sweet and starchy foods seasons a place experiences in a
air pressure The force of air rock that orbits the Sun. are rich in carbohydrates. typical year.
molecules pushing against a
surface or container. atmosphere The layer of air that carnivore A meat-eating animal. climate change Long-term
surrounds a planet. changes in Earth’s weather patterns.
air resistance A force that slows catalyst A chemical that speeds up
down an object moving through atom A tiny particle of matter. An a chemical reaction without being clone An organism with exactly the
the air. atom is the smallest part of an changed itself. same genes as its parent.
element that can exist.
algae Simple, plantlike organisms catalytic converter A device in a colloid A mixture made up of tiny
that live in water and make food by atomic number The number of car that uses a catalyst to change particles of one substance
photosynthesis. protons in an atom. toxic exhaust gases into less dispersed in another in which it
harmful gases. does not dissolve.
alkali A compound that releases aurora Wavy patterns of colored
hydroxide ions when it dissolves in light in the night sky, caused by cathode A negative electrode. combustion (burning) A chemical
water. Alkalis neutralize acids. high-energy particles from space reaction in which a substance
hitting Earth’s atmosphere. cation A positively charged ion. combines with oxygen, releasing
alloy A material made by mixing a heat energy.
metal with another element. Alloys bacteria Microscopic, single-celled cell The basic unit from which all
tend to be stronger, harder, and organisms with no cell nuclei. living organisms are made. comet A large, icy body that orbits
more useful than the pure metal Bacteria are the most abundant the Sun. Comets develop long tails
they are based on. organisms on Earth. cell division The process by which when they are near the Sun.
one cell splits to produce two cells,
alternating current (AC) An electric base A compound that reacts with called daughter cells. compound A chemical consisting of
current whose direction reverses at an acid to make water and a salt. two or more elements whose atoms
regular intervals. cellulose A fibrous carbohydrate have bonded.
battery An energy-storing device that forms the walls of plant cells.
alveoli Tiny air pockets in the lungs that creates an electric current when concentration A measure of the
of mammals. connected to a circuit. Celsius A temperature scale based amount of solute dissolved in a
on the melting point of ice (0°C) and solution.
amp or ampere (A) A unit used to binary system A number system the boiling point of water (100°C),
measure electric current. with only two digits, 0 and 1. Digital with 100 equal divisions, called condensation The change of a gas
devices store and process data in degrees, in between them. into a liquid.
anaerobic respiration A type of binary form.
respiration that does not require chemical A pure element or conduction The movement of heat
oxygen. It releases less energy than biology The study of living things. compound. Water, iron, salt, and or electricity through a substance.
aerobic respiration. oxygen are all chemicals.
conductor A substance through
chemistry The study of matter. which heat or electric current
flows easily.

GLOSSARY 313

convection The spread of heat DNA Deoxyribonucleic acid, the embryo A very early stage in the fossil The remains or impression
through a liquid or gas, caused by chemical that stores genetic development of an animal or plant. of a prehistoric plant or animal,

warmer, less dense areas rising. information inside living cells. Animal embryos are microscopic. often preserved in rock.

core The innermost and hottest part drag The force that slows down an emulsion A mixture that consists of fossil fuel A fuel derived from the
of Earth, thought to be made of iron object as it travels through a liquid tiny droplets of one liquid dispersed fossilized remains of living things.
and nickel. or gas. in another. Coal, crude oil, and natural gas are
fossil fuels.
corona A layer of hot gas dynamo An electrical generator endothermic reaction A chemical
surrounding the Sun. that produces direct current. reaction that takes in energy from freezing point The temperature
the surroundings. at which a liquid turns into a solid.
covalent bond A type of chemical eclipse The shadow caused by a
bond between the atoms in a moon or planet blocking light from engine A machine that harnesses frequency The number of times
molecule. Covalent bonds form the Sun. the energy released by burning fuel something happens in a unit of
when atoms share electrons. to create motion. time. The frequency of a wave is
ecology The scientific study of the number of waves per second.
crust The rocky outer surface interactions between organisms enzyme A protein made by living cells
of Earth. and between organisms and their that speeds up a chemical reaction. friction A dragging force that slows
environment. a moving object down when it rubs
crystal A solid substance with a equator An imaginary circle around against something.
regular shape. Snowflakes and ecosystem A community of animals the middle of Earth, midway between
diamonds are crystals. and plants and the physical the North Pole and the South Pole. fulcrum (pivot) The fixed point
environment that they share. around which a lever rotates.
decibel (dB) A unit used to erosion The process by which
measure the loudness of sound. elasticity The ability of a material to Earth’s surface rock is worn down fuse A safety device used in
stretch or bend and then return to its and carried away by wind, water, electrical circuits. Most fuses consist
decomposition Breaking large original shape. and glaciers. of a thin wire that melts if too much
molecules into smaller ones. current passes through.
electric current The flow of electric evaporation The change of a liquid
density The mass (amount of charge—for instance, as electrons into a gas by escape of molecules fusion Joining together.
matter) of a substance per unit moving through a wire. from its surface.
of volume. galaxy A vast collection of stars,
electricity A form of energy carried evolution The gradual change of dust, and gas held together by
detergent A substance that makes by an electric current. species over generations as they gravity. Our solar system is part of
droplets of oil or grease disperse in adapt to the changing environment. a galaxy called the Milky Way.
water, making it easier to clean electrode A piece of metal or
things. Soap and dishwashing liquid carbon that collects or releases exothermic reaction A chemical galvanize To coat iron with zinc to
are detergents. electrons in an electric circuit. reaction that releases energy into protect it from rust.
the surroundings.
diffraction The spreading out of electrolyte A substance that gamete A reproductive cell, such
waves after they pass through a conducts electricity when dissolved fertilization The joining of male and as a sperm or egg.
narrow opening. in water. female sex cells.
gamma rays A type of
diffusion The gradual mixing of two electromagnet A coil of wire that fetus The unborn young of electromagnetic radiation with a
or more substances as a result of becomes magnetic when electricity an animal. very short wavelength.
the random movement of their flows through it.
molecules. filter A device that removes the gene A length of code on a DNA
electromagnetic spectrum The solid material from a liquid. molecule that performs a specific
digestion Breaking down food into whole range of different types of job. Genes are passed on from one
small molecules so that it can be electromagnetic radiation, from fluid A substance that can flow, generation to the next.
absorbed by cells. gamma rays to radio waves. such as a gas or liquid.
generator A machine that converts
direct current (DC) An electric electron A negatively charged food chain A series of organisms, movement energy into electricity.
current that flows in one direction particle that occupies the outer part each of which is eaten by the next.
only. See also alternating current. of an atom. Moving electrons carry germination The growth of a small
electricity and cause magnetism. food web The system of food plant from a seed.
displacement A chemical reaction chains in an ecosystem.
in which some of the atoms or ions electronics The use of electricity to glacier A moving mass of ice,
in a compound are replaced by process or transmit information, force A push or pull that can formed from accumulated snow.
different ones. such as computer data. change an object’s speed, direction
of movement, or shape. global warming A rise in the average
distillation A way of separating element A chemical made of only temperature of Earth’s atmosphere,
chemicals in a liquid by boiling the one kind of atom. formula A group of chemical caused by rising levels of carbon
liquid and collecting the different symbols and numbers that shows dioxide from burning fossil fuels.
parts as they condense. the atomic makeup of a chemical.

314 GLOSSARY

gravity A force that pulls all things ion An atom or group of atoms metamorphosis A dramatic neutralize Make an acid or alkali
with mass toward each other. that has lost or gained one or more change in the life cycle of an into a neutral solution (a solution
Earth’s gravity pulls objects to the electrons and so become positively animal. Caterpillars undergo that is neither acidic nor alkaline).
ground and gives them weight. or negatively charged. metamorphosis when they
develop into butterflies. neutron A particle in the
habitat The natural home of an ionic bond A chemical bond nucleus of an atom that has
animal or plant. caused by the attraction between meteor (shooting star) A small no electrical charge.
positive and negative ions. piece of rock or metal from space
hemisphere Half of a sphere. that burns up as it enters Earth’s newton (N) The standard unit
Earth is divided into the northern joule (J) The standard unit of energy. atmosphere, producing a streak of force.
and southern hemispheres by of light.
the equator. kinetic energy The energy stored in nucleus The central part of an
a moving object. meteorite A piece of rock or metal atom or the part of a cell that
hemoglobin A compound in from space that enters Earth’s stores genes.
red blood cells that carries oxygen laser A beam of intense light atmosphere and reaches the
around an animal’s body. consisting of waves that are in step ground without burning up. nutrients Chemical compounds
and of equal wavelength. that plants and animals need in
herbivore An animal that microorganism A tiny organism order to survive and grow.
eats plants. lens A curved, transparent piece that can be seen only with the aid
of plastic or glass that can bend of a microscope. ohm (Ω) A unit of electrical
hertz (Hz) The unit of frequency light rays. resistance.
used to measure waves. One microscope A scientific instrument
hertz is one wave per second. lever A rigid rod that swings around that uses lenses to make small omnivore An animal that eats both
a fixed point. Levers can multiply objects appear larger. plants and animals.
hurricane A violent tropical storm forces, making difficult jobs easier.
with torrential rain and high winds microwave A type of opaque Does not let light through.
that reach more than 74 mph lift The upward force produced by electromagnetic radiation.
(119 km/h). a wing as air flows past it. Microwaves are very short optical fibers Thin glass fibers
radio waves. through which light travels. They are
hydrocarbon A chemical light-year The distance light travels used to transmit digital signals at
compound made up of only in a year. One light-year is 5.9 trillion mineral A naturally occurring high speed.
hydrogen and carbon atoms. miles (9.5 trillion km). solid chemical. Rocks are made
of mineral grains stuck together. orbit The path of one body in space,
hydroelectricity The generation magma Hot, molten rock deep such as a moon, around another,
of electricity by using the energy underground. It forms igneous rock mixture A substance containing such as a planet.
in flowing water. when it cools and hardens. two or more chemicals that are not
chemically bonded to each other ore A naturally occurring rock from
igneous rock Rock formed when magnetic field The area around a as molecules. which metal can be extracted.
molten rock cools and solidifies. magnet in which its effects are felt.
molecule A group of two or more organ A major structure in an
indicator A chemical that shows magnetism The invisible force of atoms joined by covalent bonds. organism that has a specific
the acidity of a solution by attraction or repulsion between function. Organs in the human
changing color. some substances, especially iron. momentum The tendency of a body include the stomach, brain,
moving object to keep moving and heart.
induction The production of an mantle A thick, dense layer of until a force stops it. Momentum
electric current by a moving rock under Earth’s crust. The can be calculated by multiplying organic Derived from living
magnetic field. mantle makes up most of our mass by velocity. organisms or a compound based
planet’s mass. on carbon and hydrogen atoms.
infrared radiation A type of moraine A heap of rocky debris
electromagnetic radiation produced mass The amount of matter in dumped by a glacier. organic compound A chemical
by hot objects. an object. with molecules containing carbon
motor A machine that uses and hydrogen atoms.
insulator A material that reduces matter Anything that has mass electricity and magnetism to
or stops the flow of heat, electricity, and occupies space. produce motion. organism A living thing.
or sound.
melting point The temperature at nectar A sugary liquid found in osmosis The movement of water
integrated circuit A tiny electric which a solid turns into a liquid. the flowers of some plants. through a cell membrane (or other
circuit made of components printed semipermeable membrane) from a
on a silicon chip. metamorphic rock Rock that has nerve A bundle of nerve cells that weak solution to a strong one.
been changed by intense heat carry electrical signals through the
interference The combination of body of an animal. oxide A compound formed when
two or more sets of waves. and/or pressure underground but oxygen combines with other
neuron A nerve cell. elements.
without melting.

GLOSSARY 315

parasite An organism that lives reactive Likely to take part in skeleton A flexible frame that transformer A machine that
on and feeds off another organism, chemical reactions. Highly reactive supports an animal’s body. increases or decreases voltage.
called the host. chemicals react very easily.
solar system The Sun together translucent A term for a material
particle A tiny bit of matter. real image An image formed with its orbiting group of planets, that allows some light through but is
where light rays focus. Unlike a including Earth, and other smaller not transparent.
periodic table A table of all the virtual image, a real image can bodies such as asteroids.
elements arranged in order of be seen on a screen. transparent A term for a material
atomic number. solute A substance that dissolves that allows light through, making it
reflection The bouncing back of in a solvent to form a solution. possible to see through it.
pesticide A substance used to kill light, heat, or sound from a surface.
pests such as insects. solution A mixture in which the ultrasound Sound waves with a
refraction The change in direction molecules or ions of a solute are frequency too high for human ears
photon A particle of light. of light waves as they pass from one evenly spread out among the to detect. Ultrasound is used for
medium, such as air, to another, molecules of a solvent. medical scanning.
photosynthesis The process by such as water.
which plants use sunlight, water, solvent A substance (usually a ultraviolet (UV) A type of
and carbon dioxide from air to renewable energy A source of liquid) in which a solute dissolves electromagnetic radiation with a
make food molecules. energy that will not run out, such to form a solution. wavelength slightly shorter than
as sunlight, wave power, or wind visible light.
pH A scale used to measure how power. species A group of similar
acidic or alkaline a solution is. organisms that can breed with universe All of space and
resistance A measure of how much one another to produce offspring. everything it contains.
physics The scientific study of an electrical component opposes
forces, energy, and matter. the flow of an electric current. spectrum The range of different vapor Another word for gas,
colors in visible light, or the range especially a gas formed by
pitch How high or low a sound is. respiration The process by which of different types of electromagnetic evaporation from a liquid that is
Pitch is directly related to the living cells release energy from radiation. not hot enough to boil.
frequency of sound waves. food molecules.
stalactite A column of rock hanging vein A tube that carries blood from
plankton Tiny organisms that live retina A layer of light-sensitive cells from the roof of a cave. Stalactites body tissues to the heart.
in the water of oceans and lakes. lining the inside of the eye. grow slowly from calcium carbonate
deposited by dripping water. velocity The speed an object moves
polymer A carbon compound with salt An ionic compound formed in a specific direction.
long, chainlike molecules made of when an acid reacts with a base. stalagmite A column of rock on
repeating units. Plastics are The word salt is often used to refer the floor of a cave. Stalagmites grow vibration Rapid back-and-forth
examples of polymers. just to sodium chloride, the salt slowly from calcium carbonate movement.
used to flavor food. deposited by dripping water.
power The rate of transfer of volume The amount of space an
energy. The more powerful a satellite An object in space that stratosphere The layer of Earth’s object takes up.
machine is, the more quickly it travels around another in a path atmosphere above the clouds.
uses energy. called an orbit. The Moon is a watt (W) A unit of power. One watt
natural satellite. Artificial satellites sugar A carbohydrate with a small equals one joule per second.
pressure The amount of force around Earth transmit data and molecule. Sugars taste sweet.
pushing on a given area. help us navigate. wavelength The length of a wave,
surface tension A force in the measured from the crest of one
protein An organic substance that sedimentary rock Rock formed surface of water that creates a wave to the crest of the next.
contains nitrogen and is found in when sediment (particles of older delicate skin that can support very
foods such as meat, fish, cheese, rock) settles on the bed of a sea or small objects, such as insects. weight The force with which a mass
and beans. Organisms need lake and is slowly cemented is pulled toward Earth.
proteins for growth and repair. together over time. suspension A mixture made of
solid particles dispersed in a liquid. work The energy transferred when
proton A particle in the nucleus seismic wave A wave of energy a force moves an object. Work can
of an atom that has a positive that travels through the ground from tectonic plate One of the large, be calculated by multiplying force by
electric charge. an earthquake or explosion. slow-moving fragments into which distance.
Earth’s crust is divided.
radiation An electromagnetic sex cell A reproductive cell, such X-ray A type of electromagnetic
wave (or a stream of particles from as a sperm or egg. temperature A measure of how radiation used to create images of
a source of radioactivity). hot or cold something is. bones and teeth.
sexual reproduction Reproduction
radioactivity The breakdown of that involves the combination of sex tissue A group of similar cells,
atomic nuclei, causing radiation cells from two parents. such as muscle tissue or fat.
to be released.

316 INDEX

Index

A atmosphere C chlorophyll 88
Earth 280, 304–5, 311 chloroplasts 25, 89
acceleration 247, 256–7, 258 cameras 208–9 chromatography 129
acid rain 173 atmospheric pressure 306 canine teeth 32, 33 chromosomes 76–9
acids 148–9 atomic number 133, 154 capillaries 38, 39 circuits, electric 220, 222–3,
atomic structure 132–3 carbohydrates 28, 31
reactions with bases 150–1 atoms 15, 110–11, 218 carbon 104, 105, 132, 159, 224, 231
stomach 45, 148 atria 40 circulatory system 41, 60, 61
activation energy 144, 146 auroras 275 166–7 civil engineering 16
aerobic exercise 61 axis, Earth’s 302 carbon capture 167 climate 308
aerobic respiration 34 axles 253 carbon cycle 310–11 climate change 309, 311
air carbon dioxide 34, 35, 41, 43, climate zones 302–3
molecules 118–19, 137, 262 B clones 63, 98
pressure 262, 306 85, 88–9, 105, 136, 139, clouds 162, 219, 296–7, 307
air pressure 262, 306 backbone 58 167, 310–11 cnidarians 23
air resistance 238, 246 bacteria 45, 100, 101, 162, 170 cardiac muscles 57 coal 166
airfoil 260 bases 76, 77, 148 carnivores 102 cochlea 52, 53
algae 87, 101 teeth 33 collisions 248, 249
alkali metals 157 reactions with acids 150–1 carpels 92 colloids 122
alkaline earth metals 157 batteries 220, 222, 223, 224 casein 179 color blindness 81
alkalis 148, 149, 150 bees 92, 93, 107 catalysts 146–7 colors 212–13
alleles 81 Big Bang 269 catalytic converters 147, 176 comets 271
alloys 123, 160, 161 bile 31, 42 caterpillars 69 communities 102
alternating current 224 binary 230 cathodes 153, 220 compasses 226, 241
aluminum 121, 159, 161 biodiversity 107 cells 14, 24–5, 76, 77 competition 103
alveoli 36, 61 biology 14 atmospheric 305 composites 176
amino acids 31, 77, 170, 178 biomass energy 105, 187 division 74 compounds 111, 123, 152
ammonia 147 birds 23, 35, 83 osmosis 131
amoebas 101 respiration 34–5 carbon 166, 167
amphibians 23, 68 eggs 66–7 types of 26–7 ionic 135
amplitude 195 life cycle 65 cellulose 25 compression 236
amps 224 bladder 42 Celsius 189 concave lenses 207
anaerobic exercise 61 blast furnace 159 Cenozoic Era 292 condensation 115, 129
anaerobic respiration 35 blood 38–9 center of gravity 259 conduction/conductors 156,
analog devices 230 cells 26 ceramics 176–7
animals 14 heart 40–1 cerebral cortex 49 162, 190, 221, 225
animal kingdom 22–3 iron 160 charge, electric 132, 218, 219, conifers 87
cells 24 oxygen 34 220, 235, 240 contact lenses 51
classifying 23 bonds, covalent 136–7 chemical bonds 110, 134–7, continents 293
life cycles 64–9 bonds, ionic 134–5 144–5, 146, 178 convection 191
anodes 152, 220 bones 58–9, 60, 61, 172 chemical energy 182, 183 convex lenses 207, 210, 211
antibodies 44, 45 botany 14 chemical equations 140–1 copper 123, 159, 221
Archaeopteryx 83 brain chemical formulas 111 core
Archimedes’ principle 265 hearing 52–3 chemical reactions 15, 134,
argon 175 movement 56 138–9, 146–7, 158–9 Earth 280
arteries 38, 41 nervous system 46, 48–9 displacement reactions 143, Sun 274, 275
arthropods 23 vision 50–1 159 corrosion 148, 151
artificial selection 83 brakes 243, 261 energy and 144–5 covalent bonds 136–7
asexual reproduction 63, 98–9 Brand, Hennig 172 reversible 141 crude oil 168–9, 179
asteroid belt 270 breathing 36–7 types of 142–3 crumple zones 249
asthma 37, 44 bromine 174 chemical symbols 111 crust, Earth 280, 282
astronauts 163, 259 bronchioles 36, 37 chemicals, pure 123 crystals 135, 287
astronomy 15, 211, 268 Brownian motion 131 chemistry 15 current electricity 218, 220–5,
buoyancy 264–5 chlorine 174
butterflies 69 226
cuttings 99
cytoplasm 24, 26, 100

INDEX 317

D earthquakes 284–5 heat transfer 190–1 flight 55, 260–1
echinoderms 23 light 202–17 floating 263–4
Darwin, Charles 82 eclipses 279 living things 20 flowers 84, 86, 92–3
decanting 127 ecology 14, 102–3 measuring 184–5 fluorine 174
decibels 200–1 ecosystems 102 movement 54 foams 122
deciduous plants 87 effort 250–1 power stations 186–7 focal point 207, 210, 211
decomposers 104 egestion 43 and reactions 144–5 food
decomposition reactions 142 egg cells 26, 63, 80, 81 renewable 105, 187
deforestation 311 eggs 62, 65, 66–72 respiration 34 energy from 182
deformations 236 Einstein, Albert 131 sound 198–201 living things 20
deltas 299 elasticity 116, 236, 237 transfer 254 nutrition 28–9
density 118, 119, 120–1, 191, 265 electric charge 132, 218, 219, units 184 plants 85, 91
diamonds 166, 167 waves 194–7 supply 107
diaphragm (human body) 36, 220, 235, 240 engineering 16–17 food chains 104–5
electric motors 227 engines 192–3, 255 forces 15, 232–65
37 electricity 165, 218–31 environment balanced and unbalanced
diaphragms (speakers) 229 ecology 14, 102–3
diesel 169, 255 circuits 222–3 and evolution 79, 83 238–9
diffraction 197 current 220–1 humans and 106–7 drag 244–5
diffusion 39, 130–1 currents, voltage, and enzymes 31, 147 floating and sinking 264–5
digestive system 27, 30–1, 147 equations, chemical 140–1 friction 242–3
digital cameras 209 resistance 224–5 equator 303 gravity 258–9
digital devices 230, 231 electromagnetism 226–9 equilibrium 238 lift 260–1
dinosaurs 290, 292, 293 electronics 230–1 erosion 288, 289, 291, 294, magnetism 240–1
displacement reactions 143, generating 186–7, 227, 281, and motion 246–7
295, 298, 299 pressure 262–3
159 299 erratics 301 simple machines 250–3
dissolving 124–5, 128, 129, 131 and magnetism 226–9 eskers 301 speed and acceleration
distance–time graphs 257 measuring 185 esophagus 30
distillation 129 static 218–19 evaporation 90, 115, 128, 296, 256–7
DNA 76–7, 100, 178 electrodes 152 stretching and deforming
DNA fingerprinting 77 electrolysis 152–3, 159 297
drag 244–5, 261 electrolytes 152, 153, 165, 220 evergreen plants 87 236–7
dwarf planets 271, 273 electromagnetic spectrum evolution 82–3 work and power 254–5
excretion 42–3 fossil fuels 167, 173, 186, 187,
E 216–17 exercise 60–1
electromagnetism 133, 218, 310, 311
ears 52–3 and energy 185 fossils 83, 290–1, 292–3, 310
Earth 15, 268, 270, 272, 226–9 exhaust gases 147, 192, 193 fractional distillation 168
electronics 163, 221, 230–1 exoskeleton 59 freezing 114
278–311 electrons 132, 133, 134, 136, exosphere 304 frequency 195, 200, 230
atmosphere 304–5 exothermic reactions 144–5 friction 242–3, 244
carbon cycle 310–11 158, 165, 218, 219, 220, experiments 10, 11, 12–13 frogs 68
fossils 290–1 222, 223, 224, 225, 240 extinctions 293 fronts, weather 306, 307
glaciers 300–1 electroplating 153 eyes 50–1, 214 fruit 92, 93, 94
gravity 276 elements 110, 112, 133, 134 fuel cells, hydrogen 165
magnetic field 241 periodic table 154–5, 158 F fulcrums 250–1
and the Moon 278–9 ellipses 277 fullerenes 166
natural hazards 284–5 embryos 62, 66–7, 71, 72, 96 Fahrenheit 189 fungi 22, 170
ocean currents 308–9 emulsions 122 fats 28, 31 fuses 223
plate tectonics 282–3 enamel 32 feces 43
rivers 298–9 endoplasmic reticulum 24 ferns 87 G
rock cycle 288–9 endoscopes 215 fertilization 62, 71
rocks and minerals 286–7 endoskeleton 59 fetus 64, 73 galaxies 268, 276
seasons and climate zones endothermic reactions 145 fiber optics 215 gamma rays 217
energy 15, 180–231 filtering 126, 127 gas exchange 35
302–3 activation 144, 146 fire 171 gases 113, 114–15
structure 280–1 biomass 105 fish 23, 35
water cycle 296–7 electricity 218–31 flagella 100, 101 atmospheric 305
weather 306–7 engines 192–3 flame tests 157 density 121
weathering and erosion and exercise 185 flatworms 23 diffusion 130, 131
forms of 183 evaporation 128
294–5 food 29, 105 expanding 118–19
geothermal 281 noble 175
heat 188–9

318 INDEX

gasoline 169 human body 14 J logic gates 231
generators 186, 187, 227 blood 38–9 loudness 200–1
genes 76–83 cells, tissues and organs jet engines 193 loudspeakers 229
26–7 joints 59 lubricants 243
cell division 74 digestive system 30–1 joules 184, 254 lunar eclipse 279
mutations 79, 82 ears 52–3 Jupiter 271, 272, 273 lungs 34, 35, 36–7, 42, 61
genetic disorders 81 excretion 42–3
geology 15, 288–9 eyes 50–1 K M
geothermal energy 281 genetics 76–81
germination 96–7 gestation and birth 72–3 kerosene 169 machines, simple 250–3
germs 44–5 growth and development kettle lakes 301 maglev trains 228
gestation 72–3 74–5 kidneys 42 magma 285, 286, 289
giant planets 271, 273 health 60–1 kinetic energy 182, 183, 187, magnetic fields 160, 187, 226,
glaciers 295, 300–1, 311 heart 40–1
glasses 51 immune system 44–5 192 227, 241
global conveyor 309 lungs and breathing 36–7 magnetism 235, 240–1
global warming 167 muscles 56–7 L
glucose 88, 89 nervous system 48–9 and electricity 226–7
gold 121, 156, 159, 163, reproduction 70–1 larvae 69 magnets 187, 235, 240–1
respiration 34–5 lasers 214 malleability 116
221, 287 skeleton 58–9 lava 285, 289 mammals 23, 35, 64
Goldilocks zone 273 teeth 32 laws of motion 246–7, 260 mantle, Earth 280, 282
graphite 166 leaves 84, 87, 88–9, 90, 97 marine carbon capture 311
gravitational potential energy hurricanes 307 lenses 50, 51, 207, 208–9, 210 Mars 270, 272
hydraulic jacks 263 levers 250 mass
183 hydrocarbons 167, 168–9 life 14, 18–107
gravity 224, 234, 235, 238, hydroelectric power 187, 299 and acceleration 247
hydrofoils 245 cells 24–5 conservation of 139
246, 258–9 hydrogen 164–5 classification 22–3 and momentum 248
and orbits 276–7 hypotheses 10, 11 evolution 82–3 and weight 259
greenhouses 85 variation 78–9 mass extinctions 293
growth I what is life? 20–1 mass number 133
humans 74–5 life cycles 64–9 materials science 15, 176–7
living things 21 ice 294 lift 245, 260–1 matter 108–79
gunpowder 173 igneous rock 286, 288–9, 293 lifting magnets 229 states of 112–15
gyres 308 immune system 44–5 light 202–17 Maxwell, James Clerk 217
implantation 72 colors 212–13 meanders 299
H incisors 32, 33 electromagnetic spectrum measurements 12
induction, electromagnetic 227 mechanical advantage 251
Haber process 147 infections 44–5 216–17 melting 114
habitat loss 106 inflammation 45 fiber optics 195 membranes, cell 24, 26
hairs 45 infrared rays 191, 214, 216 plants 47, 85 Mendeleev, Dmitri 155
Halley’s Comet 277 inheritance 80–1 reflection 204–5 menstrual cycle 71
halogens 174 insects 35, 107 refraction 206–7 Mercury 270, 272
hardness 117 speed of 268, 269 mesosphere 304
health 60–1 life cycle 69 vision 50 Mesozoic Era 292
hearing 52–3 insulation/insulators 190, 221 waves 196, 197, 216–17 metal carbonates 150
heart 38, 40–1 integrated circuits 231 light bulbs 224, 225 metal oxides 150, 151
heartbeats 40 interference 197 light energy 183 metallic bonds 156
heat 183, 184, 188–9, 281 intermolecular forces 137 light microscopes 210 metalloids 155, 157
heat transfer 190–1 internal combustion engines light-years 268, 269 metals 115, 155, 156–63
heat waves 307 lightning 219 and acids 151
helium 118, 133, 175 192 limestone caverns 151 extracting 159
hematite 287 intestines 30, 31 lipids 28 reactivity series 158–9
hemispheres, Earth 302–3 invertebrates 22, 23 liquids 112, 114–15 metamorphic rock 286, 288–9
herbivores 102, 103 iodine 174 density 121 metamorphosis 68, 69
ionic bonds 134–5 diffusion 130–1 meteorology 307
teeth 33 ionosphere 305 solutions 124–5 microorganisms 22, 63
hips 58 ions 134–5, 138, 152–3 viscosity 117 microscopes 25, 210
iron 121, 156, 159, 160, 188 liver 31, 42 microwaves 216
artificial 59 IVF (in vitro fertilization) 71 load 250–1 mid-ocean ridges 282
Hooke, Robert 237
horsepower 255
hot-air balloons 118–19

INDEX 319

Milky Way 211, 268 nuclear energy 183 plants 14, 84–99 Q
minerals 29, 85, 91, 97, 286, nuclear fusion 275 asexual reproduction 98–9
nucleus cells 25 quartz 287
287 characteristics of 20–1 Quaternary Period 292
mirages 206 atoms 132, 218 excretion 43
mirrors 204–5, 210, 211 cells 24, 26, 76 flowers 92–3 R
mitochondria 24, 26 nutrition 20, 28–9 growth 85
mixtures 122–3 nitrogen cycle 170 radiation 191, 211
O oxygen supply 171 radio telescopes 211
separating 123, 126–9 photosynthesis 88–9, 145 radio waves 211, 216, 217, 305
Mohs scale 117 objective lenses 210 plant kingdom 22 radiometric dating 293
molars 32, 33 ocean currents 308–9 respiration 35 rainbows 213
molecules 110–11, 136 ohms 225 seed dispersal 94–5 rainfall 103, 162, 173, 294,
oil 288 seed growth 96–7
movement 130–1 transpiration 90–1 296–7, 298
states of matter 112–13 crude 168–9, 179 types of 86–7 ramps 251
mollusks 23 opaque 203 rare earth metals 157
momentum 248–9 optical fibers 195 plasma 39 reactions see chemical
Moon 202, 259 orbits 270, 276–7 plasticity 236
and Earth 276, 277, 278–9 organelles 24, 25, 26 plastics 177, 178, 179 reactions
phases 278 organisms 20–1, 76 plate tectonics 282–3, 284 reactivity series 158–9
moons, planetary 272, 273 platelets 39 recycling 104, 105, 161
mosses 87 single-celled 100–1 Pluto 271, 273 red blood cells 26, 39
motors, electric 227 organs 26, 27 polar zones 303 reflecting telescopes 211
mountains 283 osmosis 131 poles, magnetic 235, 240, 241 reflection 196, 204–5, 208
movement ovaries 62, 70, 72, 92, 93 pollination 86, 92–3, 107 refraction 196, 206–7
animals 54–5 overexploitation 106 pollution 106 renewable energy 105, 187
and forces 234, 242–3, ovules 93 polyethylene 178, 179 reproduction 62–71
oxbow lakes 299 polymerization 178
246–7 oxygen 34–5, 36, 41, 85, polymers 177, 178–9 asexual 63, 98–9
momentum and collisions polystyrene 121, 179 sexual 62, 64–71, 79, 80–1,
88–9, 97, 136, 165, 171, population
248–9 193, 305 86, 92–3
MRI scanner 241 ecology 102, 103 reptiles 23
muscles 56–7 P human 106 resistance 225
post-transition metals 157 respiration 20, 34–5, 60, 61,
cells 26 Paleozoic Era 292 potassium 158, 159
oxygen 34 Pangaea 293 potential energy 183, 224 105, 310
mutualism 103 parachutes 235 power 185, 254, 255 resultant forces 239
parallel circuits 223 power stations 167, 186–7, 225, retinas 50, 51
N parasitism 103 reversible reactions 141
particle accelerators 133 227 ribs 36, 37, 58
naphtha 169 particles, and heat 188 Precambrian Era 292 rivers 295, 297, 298–9
natural hazards 284–5 penis 70 precipitation 296 robots 231
natural selection 82 penumbra 203 predation 103 rock cycle 288–9
nectar 93 periodic table 154–5, 156, 157, pregnancy 65 rockets 193
neon 175 premolars 32 rocks 286–7
Neptune 268, 271, 272, 273 158 pressure 262–3
nerve cells 26, 48 pH 149 primary colors 213 weathering and erosion
nerves 48 phagocytes 44 producers 104, 105 294–5
nervous system 46–9 phloem vessels 91 prosthetic arms 49
nests 65 phosphorus 172 proteins 28, 31, 77, 105, 170 roots 84, 88, 90, 91, 96, 97
neurons 49 photons 209 protons 132, 133, 154, 165, rust 161, 171
neurotransmitters 49 photosphere 274
neutralization reactions 148, photosynthesis 88–9, 105, 145, 218 S
prototypes 17
150 171, 311 protozoa 101 salt 134–5, 297
neutrons 132, 133, 218 physics 15 PTFE 177 satellites 211, 277
Newton, Isaac 235, 246, 260, pinhole camera 208, 209 pulleys 253 saturated solutions 125
pitch 53, 200, 201 pupae 69 Saturn 271, 273
277 pixels 213 pupils 50, 51 scanning electron microscopes
newtons 235, 238, 239, 254 planes 260–1 pyrite 287
nitrogen 105, 137, 170, 305 planets 268, 270–1, 272–3, 210
science
cycle 170 276
noble gases 175 fields of 14–15
nonmetals 155 working scientifically 12–13

320 INDEX

scientific method 10 speed 256–7 thermoplastics 179 vitamins 29
screens 213 and forces 234, 246–7 thermoset plastics 179 volcanoes 285, 289, 293, 310
screws 252 of sound 260 thermosphere 304 voltage 222, 224–5, 230
sea 297 tidal power 187 volts 224
sea anemones 55, 63 spinal cord 48 tides 278 Voyager space probes 271
seasons 302–3 sponges 23 tissues 26, 27
sediment 290–1 spores 87 tornadoes 307 W
sedimentary rock 286, 288–9 stainless steel 160 touch 47
seeds 86, 87, 92, 93 stamens 92, 93 transformers 225 waste
stars 268–9, 276 transfusions, blood 39 decomposers 104
dispersal 94–5 states of matter 112–13 transistors 230 living things 20, 42–3
growth 96–7 transition metals 157 recycling 105, 170
seismic waves 284 changing 114–15 translucent 203
semiconductors 230, 231 static electricity 218–19 transparent 203 water
senses 20, 46–7 static friction 242 transpiration 90–1, 297 floating 264–5
series circuits 223 steel 160 tributaries 299 dissolving ionic compounds
sewage plants 101 stem cells 75 tropical zone 303 135
sex cells 62, 80, 86, 92, 93 stems 84, 91 troposphere 304, 305 molecules 136, 137
sex chromosomes 81 stents 41 tsunamis 285
sexual reproduction 62, 64–71, stigmas 92 turbines 186, 187, 193, 227, 299 water cycle 296–7
stimulus 46 turbulence 244 water pressure 263
79, 80–1, 86, 92–3 stomach 27, 30, 148 twisting 235, 236 water vapor 296, 297
shadows 202, 203 stomata 88, 89 watts 185, 255
shells stratosphere 304 U wave power 187
streamlining 244 wavelength 195
eggs 66, 67 stretching 236–7 ultrasound scans 72 waves 194–7
electrons 132, 134 subatomic particles 133 ultraviolet 217
sifting 126 submarines 263, 265 umbra 203 light 202–17
silicon chips 230, 231 sugar 91, 124 unbalanced forces 239, 246 seismic 284
silver 156, 159, 162, 221 sulfur 173 universe 258, 268–9 sound 198–201, 206
single-celled organisms 100–1 sulfuric acid 173 upthrust 264–5 tsunamis 285
skeletal muscles 57 Sun 202, 274–5 upwellings 309 weather 262, 306–7
skeletons 58–9, 290–1 Uranus 271, 272, 273 weathering 288, 294
skin 42, 45 eclipses 279 urine 20, 42, 43 weight 259, 264–5
skull 58 as energy source 102, 104, uterus 64, 70, 71, 72, 73 wheels 243, 253
sliding friction 242, 243 white blood cells 26, 39, 44, 45
smoking 61 182 V wind power 187
smooth muscles 57 solar system 268, 270–1 winds, global 305
sodium 134–5, 159 water cycle 296–7 vaccines 45 wings 55, 95, 260, 261
soil 85, 90, 105, 170 sundials 203 vacuoles 25 wires, electric 220, 222–3
solar eclipses 279 supernovas 154 valves 40 word equations 140
solar power 187 surface tension 137 variables 13 work 254–5
solar system 268, 270–5 suspension bridges 239 variation 78–9
solids 112, 114–15 suspensions 122 veins 38, 40 X
density 121 switches 222, 223, 230 velocity 248, 256–7
dissolving 124–5 synapses 49 ventricles 40 X-rays 162, 217
separating mixtures 126–9 synthesis reactions 142 Venus 268, 270, 272 xenon 175
solutes 124, 125 systems, organ 27 vertebrates 23 xylem vessels 90, 91
solutions 122, 124–5, 128, 129, vibrations 52, 188, 198, 229
T viscosity 117 Z
131
sound 183, 198–201 tadpoles 68 zoology 14
sound waves 52, 194, 197, tectonic plates 282–3, 284 zygotes 72
teeth 32–3, 172
198–9, 200–1, 206, 229 telescopes 210, 211 Acknowledgments
space 15, 211, 268–77 temperate zones 303
temperature Dorling Kindersley would like to thank Ben Ffrancon Davies,
gravity and orbits 276–7 Christine Heilman, and Rona Skene for editorial help; Louise
planets 272–3 ecosystems 103 Dick, Phil Gamble, Sean Ross, Mary Sandberg, and Jacqui
solar system 270–1 and heat 189 Swan for design help; Katie John for proofreading; and Helen
Sun 274–5 tendons 57 Peters for indexing.
universe 268–9 tension 236, 238, 239
species 20, 21, 22, 103 terminal velocity 245
invasive 106 testes 62, 70
variation 78–9 thermometers 189
spectroscopy 275