1

1 Speed

» Calculating speedKnow 1 The distance it travels each second.

2 Total distance travelled and total time taken

3 Person B

4 a) Stay at the same speed

b) Speed up

c) Stay at the same speed

d) Slow down

5 (average) speed = (total) distance travelled/(total) time taken

6 a) distance = speed × time

b) time = distance/speed

7 E.g. metres per second, kilometres per hour, miles per hour, kilometres per second

8 a) metres per second

b) miles per hour

c) kilometres per second

9 12 m/s

10 25 km/h

11 4 km/s

12 Speed Distance Time5 m/s 100 m 20 s8 km/h 4 km 30 min

12 m/s 48 m 4 s5 m/s 125 m 25 s2 m/s 8 m 4 s

24 m/s 240 m 10 s40 km/h 120 km 3 h

4 km/h 20 km 5 h15 km/s 90 km 6 s

3 m/s 10 800 m 1 h

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Apply1 a) 5 m/s

b) 1500 m

c) 8 min 20 s

2 a) 3 h

b) 20 min

c) 22.5 miles

» Finding speed from a graphKnow1 diagonal, steeper, gradient, stationary/still, speeding, slowing, curve

2 a) A: slow steady speed, B: stationary, C: accelerating, D: fast steady speed

b) A: 0.3 m/s, D: 3 m/s

Apply1 a) 0–5 s, 20–30 s

b) 10–20 s

c) 5–10 s

d) 30 m

e) 3 m/s

f) 1 m/s

g) 1 m/s

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2 3 4 5 6 7 8 9 10Time (s)

2 Average speed:

• 0–3 s, average speed = 2 m/s

• 3–5 s, average speed = 0 m/s

• 5–10 s, average speed = 0.8 m/s

For the whole journey, average speed = 1 m/s

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1 Speed

3

» Relative speedKnow1 relative, difference, speed, opposite, add

2 a) 10 km/h

b) 70 km/h

Apply1 a) 0 m/s

b) 20 m/s

c) 0 m/s

d) 10 m/s

» AccelerationKnow1 How quickly an object’s speed increases or decreases.

2 a) Yes

b) No

c) Yes

d) No

3 F E D B C A

Apply1 A curve

2 Object B should have a steeper curve than object A.

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2 GravityKnow 1 Gravity

2 Kilograms

3 Newtons

4 weight = mass × gravitational fi eld strength

5 g

6 10 N/kg

7 The mass of the planet and how close you are to it

8 10 N

9 200 g; 2 N

10 Person A would weigh twice as much as person B.

Apply1 Weight is measured in newtons; mass is measured in kilograms. Either

‘I have a mass of 60 kg’ or ‘I weigh 600 N’ would be correct.

2 (Smallest to largest) Moon, Earth, Jupiter, Sun – because the Moon has the least mass and the Sun has the most.

3 80 N

4 5 kg

5 a) Increase

b) Decrease

6 23.1 N/kg

7 Mass Weight (on Earth)2 kg 20 N48.6 kg 486 N15 kg 150 N0.68 kg 6.8 N100 g 1 N38 g 0.38 N90 g 0.9 N

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Voltage and resistance

» VoltageKnow1

Cell

a)

Bulb

b)

Wire

c)

2 The amount of energy shifted from a cell to each moving charge, or from each moving charge to a component

3 Voltmeter (the symbol is a V in a circle)

4 A power supply gives charges energy and pushes them around the circuit – it does not make the charges.

5 A battery is more than one cell – it is the plural.

6 B – the circuit is incomplete.

D – the two cells are the opposite way around from each other.

E – there is no power supply.

F – there is no component (this is called a short circuit).

Apply1 a) 4.5 V

b) 0 V

c) 1.5 V

2 B – half the brightness of A, as the potential difference is shared.

C – double the brightness of A, as there are now two cells providing twice as much potential difference.

D – the same as A; two cells means twice the potential difference but two bulbs means that this is shared.

» ResistanceKnow1 A conductor allows electricity to pass through it and has a low resistance,

whilst an insulator does not let electricity pass through it and has a high resistance.

3

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2 Conductors – copper, nickel, iron, aluminium Insulators – wood, plastic, paper

3 How hard it is to push charges through the material

4 The fl ow or movement of charge

5 Ammeter

6 resistance = voltage/current

7

Apply1 2.5 Ω

2 30 V

Resistance (Ω) Voltage (V) Current (A) 2 10 5 3 9 3 7.5 15 2 8 24 3 3 12 4 2 14 710 80 8

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4 Current » Multiple loops

Know1 Switch, cell, battery, bulb, voltmeter, ammeter

2 How many charges are passing through a point each second

3 Increase the voltage (add batteries) or decrease the resistance

4 C A F D B E

5 Series – A, B, D; Parallel – C, E

6 a) The current in a series circuit is the same/shared everywhere but the potential difference is the same/shared across each component.

b) The current in a parallel circuit is the same/shared between branches but the potential difference is the same/shared across each branch.

7 Hot wires

Apply1 a) Brightness will halve – the voltage is shared between the two bulbs.

b) Brightness will stay the same – the voltage across each bulb stays the same as before.

2 a) 2 A each

b) 6 A

c) 10 V

d) 10 V

e) 5 V

» StaticsKnow1 A tiny, negatively charged particle that is part of an atom

2 a) Negative

b) Positive

3 Non-contact – the objects don’t need to be touching for the force to be there.

4 Like charges repel, opposite charges attract.

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5 a) Attract

b) Repel

c) Attract

d) Repel

e) Repel

f) Repel

Apply1 A potential difference

2 a) Negative

b) Positive

c) Positive

d) No charge

3 A C E D B

4 a) As you rub the balloon, electrons are transferred either to it or away from it. This leaves the balloon either negatively or positively charged.

b) Positive, otherwise they would not attract.

5 a) To you

b) Away from you

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5 Energy costs » Energy

Know1 1000

2 A B D C E

3 a) 800 kJ

b) 2800 kJ

Apply1 a) Jogging

b) i) 1400 kJ

ii) 1000 kJ

iii) 400 kJ

iv) 2800 kJ

» Energy resourcesKnow1 Something with stored energy that can be released in a useful way.

2 A substance that can be burned to release energy.

3 Coal, oil and gas

4 Non-renewable resources will run out whereas renewable sources will not.

5 a) Coal – non-renewable; advantage – reliable; disadvantage – produces carbon dioxide.

b) Solar – renewable; advantage – no carbon dioxide produced; disadvantage – only works when sunny.

c) Wind – renewable; advantage – no carbon dioxide produced; disadvantage – only works when windy and is noisy.

d) Nuclear fuel – non-renewable; advantage – reliable and no carbon dioxide produced; disadvantage – produces radioactive waste.

e) Oil – non-renewable; advantage – reliable; disadvantage – produces carbon dioxide.

f) Biomass – renewable; advantage – can grow more, carbon neutral; disadvantage – takes up space to grow plants for food

g) Waves – renewable; advantage – reliable; disadvantage – expensive.

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h) Gas – non-renewable; advantage – reliable; disadvantage – produces carbon dioxide.

i) Geothermal – renewable; advantage – reliable; disadvantage – expensive.

Apply1 Plants grew using energy from the Sun and were eaten by animals →

Plants and animals died and sank to the bottom of oceans/swamps → These were buried by many layers of sediment → Over millions of years the temperature and pressure turned them into fossil fuels

2 Most non-renewable sources are running out and produce carbon dioxide when burned, which leads to the enhanced greenhouse effect. Renewable resources will not run out and do not produce carbon dioxide.

3 a) B – uses 10% more

b) A – uses 5% more

c) B – uses more solar energy

d) A – uses more tidal energy

e) A – 80 MW of coal, 20 MW of wind

B – 150 MW of coal, 5 MW of wind

» Energy in the homeKnow1 Power is how fast energy is transferred by a device.

2 1000

3 cost (p) = power (kW) × time (hours) × price per kWh (p/kWh)

Apply1 Cost (p) Power (kW) Time (h) Cost per kWh (p)

110 5 2 11198 3 6 11112 2 4 14147 1.5 7 14 80 8 1 10100 2 5 10 40 2 4 5

2 Appliance Power in W Power in kWLight bulb 100 0.1Desktop computer 300 0.3Kettle 2000 2Fridge 200 0.2Hairdryer 1500 1.5Electric shower 8000 8Washing machine 500 0.5

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6 Energy transfers » Energy stores

Know1 Joule

2 a) When an object is raised.

b) When an object is speeding up.

c) When an object is stretched or compressed.

3 a) Elastic

b) Kinetic

4 a) Gravitational

b) Kinetic

Apply1 a) gravitational → kinetic

b) chemical → thermal

c) kinetic → gravitational (→ kinetic)

d) elastic (→ kinetic) → gravitational (→ kinetic)

e) chemical → kinetic

» Energy dissipationKnow1 The total amount of energy is the same at the start and the end of a

transfer.

2 Energy is wasted as heat, which cannot then be used usefully again.

3 a) Lubrication – oil

b) Insulation/double glazing/carpets and curtains

4 Light, sound, electricity

5 a) Light

b) Sound

c) Electricity

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Apply1

Energy put into system (J) Energy usefully transferred in the system (J)

Energy dissipated in the system (J)

Percentage of energy used usefully

50 30 20 60%100 80 20 80% 16 4 12 25%500 250 250 50% 75 25 50 33% 10 8 2 80%200 180 20 90% 20 6 14 30% 40 32 8 80% 20 17 3 85% 60 30 30 50%

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7 Sound » Describing sound

Know 1 A repeating back-and-forth motion

2 Decibels

3 a) Piccolo, scream, yapping dog, whistle, squeak etc.

b) Double bass, train horn, thunder etc.

4 Bell – source, air particles – medium, ear – detector

5 330 m/s

6 Gas, liquid, solid

7 a) Distance from the midpoint to the crest or trough of the wave

b) Time it takes for one complete wave to pass a point

c) The number of waves that pass a point in 1 second (cannot be labelled on diagram)

Period

Amplitude

8 Oscilloscope

9

10 A – amplitude is 4 m, period is 6 s

B – amplitude is 15 m, period is 16 s

B would be the loudest as it has the largest amplitude.

Apply 1 Particles vibrate in the same direction as the wave is travelling.

2 There are no particles to pass the vibration on.

a) B b) C c) A d) D e) C f) B g) D h) A i) B j) C

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3 The vibrating bell causes the air particles round it to vibrate. The vibrating air particles pass their vibration on until the vibrations reach your ear.

4 a) The amplitude marked is double what it should be.

b) The arrow should be labelled period, not wavelength.

c) The arrow should be double the length.

5 40 Hz

» Ranges Know1 The average hearing range of a human – the difference between the

lowest and highest frequency sounds the average person can hear.

2 20–20 000 Hz

3 Young girl – hearing range gets smaller as you get older.

4 Sound with frequency above 20 000 Hz (above human hearing range)

5 1000

6 An echo is a refl ected sound wave, for example when shouting in a tunnel or cave. Bats use refl ected sound waves to detect their prey.

Apply1 Medical imaging (e.g. looking at unborn babies), industrial uses

(e.g. checking equipment for cracks), SONAR

2 a)

Ear canal

Cochlea

Eardrum

Bones

b) Ear canal – channels sound, eardrum – vibrates when sound hits it, ossicles/bones – pass vibrations on, cochlea – converts sound to electrical signals for the brain

3 Hearing is usually damaged through loud noises – e.g. headphones with music playing too loudly, fi reworks close by, a loud concert, loud industrial noises (e.g. building site). It could also be damaged through infection.

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8 Light » Transmitted light

Know1 a) All the light energy is transferred to the object.

b) The light passes through the object.

c) The light bounces off the object.

d) The light bends as it passes through the object.

2 a) Transmitted

b) Absorbed

c) Refracted

d) Refl ected

3 The angle of incidence is equal to the angle of refl ection.

4 Normal

r

iMirror

Angle of incidenceAngle of reflection

Reflected ray

Incident ray

Ray box

5 30 degrees

6 45 degrees

7 Refraction is the bending of light. It happens when light travels between materials/media with different densities.

Apply1 a) Angles should be measured from the normal, not the mirror.

b) Both arrows are pointing at the mirror – one needs to point away.

c) The mirror is the wrong way around.

d) The angle of incidence is not equal to the angle of refl ection.

2 The light ray should travel from the apple to the mirror, then into the eye. Make sure arrows are included.

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Normal

Angleof incidence

Angle ofincidence

Angle ofrefraction

Glass block

Refracted ray

NormalIncident ray

Angle of refraction

4 a) When light travels from a less dense to a denser medium, it bends towards/away from the normal.

b) When light travels from a denser to a less dense medium, it bends towards/away from the normal.

c) Light doesn’t refract if it enters a new medium at 0/90 degrees.

» ColoursKnow1 Transparent materials allow all light to travel through them, e.g. glass.

Translucent materials allow some (but not all) light to pass through, e.g. frosted glass. Opaque materials do not let any light pass through, e.g. wood.

2 When light bounces off an object but not at the same angle as it hit it

3 An object that emits (gives off) light (e.g. a light bulb)

4 From top to bottom – red, orange, yellow, green, blue, indigo, violet For example:

White light

5 Green, red and blue

Apply1 Magenta – between red and blue

Yellow – between red and green

Cyan – between blue and green

White in centre

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8 Light

17

8 Light8 Light8 Light8 Light8 Light8 Light8 Light8 Light8 Light8 Light8 Light8 Light8 Light

1717

2 Filter colour Will this filter transmit……blue light? …red light? …green light?

Blue Yes No NoRed No Yes NoGreen No No YesYellow No Yes YesCyan Yes No YesMagenta Yes Yes No

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9 Particle model » Model of solids, liquids and gases

Know1 a) Solid – closely packed and in a regular pattern

b) Liquid – closely packed but not in a regular pattern

c) Gas – widely spaced apart and with no regular pattern

2 Ice – particles vibrate about fi xed positions.

Water – particles slide past one another in random motion, but move relatively slowly.

Water vapour – particles move in random motion at high speeds.

3 a)

Gas

b) A (They move randomly in the liquid state.)

c) D (melting)

Apply1 a) The particles are already closely packed together.

b) The particles are free to move anywhere within the confi nes of the container.

c) The particles in a solid are more closely packed together than in a liquid.

d) The particles of a solid are locked into fi xed positions, but the particles of a liquid are free to slide over each other.

» Changes of stateKnow1 D (sublimation)

2 a) D

b) B

c) D

d) A

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9 Particle model

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Apply1 a) Water particles leave the liquid and then move in between the air

particles.

b) Evaporation (not boiling)

2 a) The particles lose energy.

b) The particles move closer together.

c) The particles move more slowly.

3 The forces of attraction between the particles in ice are weaker than those between the particles in solid sulfur.

Sulfur has a higher melting point than ice, so more energy is required to overcome the forces of attraction between the sulfur particles than between ice particles.

4 The particles gain energy as the water is heated. The high-energy particles then leave the liquid at the surface. Once they have left the liquid they move around in random motion at high speeds. This process continues until all of the particles have left the liquid.

» Sublimation, diffusion and pressure

Know1 D (sublimation)

2 B (diffusion)

Apply1 Particles of potassium permanganate leave the solid and become

dissolved in the water. The potassium permanganate particles then move randomly in between the water particles and spread throughout the water.

2 The particles of a liquid are much closer together than the particles of a gas. Hence it is more diffi cult for diffusing particles to move in between the particles of a liquid.

3 Bromine particles leave the liquid from the surface.

Bromine particles in the gas are free to move randomly, so they move in between the air particles and eventually occupy the whole of the gas jar.

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Separating mixtures

» Pure substances and mixtures

Know1 B (dissolves)

2 a) Air is a mixture.

b) Iron is a pure substance.

c) Sodium chloride is a pure substance.

d) Mineral water is a mixture.

e) Sea water is a mixture.

3 a) The salt is the solute.

b) The water is the solvent.

c) The mixture of salt and water is a solution.

Apply1 a) Liquid salol is a pure substance. A solution of salol is a mixture of salol

in a solvent.

b) Leave the solution in a warm place until all of the solvent has evaporated. The solid left behind is salol.

c) Allow the liquid to cool to below the melting point of the solid.

2 a) The solvent is alcohol.

b) The solute is iodine.

» Purifying liquidsKnow1 a) Liquid

b) Solution

c) Liquid

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10 Separating mixtures

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2 a) Chalk

b) Sugar dissolved in water

c) Sugar

3 a) In Step 1, the mixture of salt and sand is put into a beaker containing water and the mixture is stirred with a glass rod.

b) In Step 2, the mixture is poured through a fi lter funnel into a conical fl ask.

c) In Step 3, the liquid from Step 2 is put into a basin to allow the water to evaporate.

Apply1 • Add water and stir (until all the salt has dissolved).

• Filter the mixture.

• Leave the fi ltrate in a warm place so that the water evaporates.

• The substance left behind is salt.

2 • Add water and stir (until all the sugar has dissolved).

• Filter the resulting mixture.

• The solid residue is rice.

3 a) Distillation

b) Evaporation

c) Filtration

d) Chromatography

4 a) Distillation

b) i) 100 °C

ii) Water

iii) The water boils and evaporates, leaving the dissolved solids behind in the fl ask.

The water vapour rises and then passes through the condenser.

As the water vapour passes through the condenser it cools down and condenses to form liquid water.

» ChromatographyKnow1 Chromatography is a method of separating different coloured substances

in a mixture.

Apply1 a) Dye R contains three colours since there are three spots on the

chromatogram.

b) The result for dye Q appears to be incorrect because neither of the spots lines up with the spots for blue, red or green.

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Metals and non-metals

» MetalsKnow1 a) Can be beaten into a new shape.

b) Can be drawn into a wire.

c) Shatters/breaks into pieces when hit with a hammer.

2 Metals: calcium, copper, mercury, iron and aluminium

Non-metals: carbon, sulfur and bromine

3 a) Bromine and mercury

b) Mercury is a metal. Bromine is a non-metal.

4 B (cobalt, iron and nickel)

Apply1 a) A is a non-metal. It is a gas and all gaseous elements are non-metals.

B is a metal. Oxides of metals are basic.

C is a metal. Metals are good conductors of heat.

D is a non-metal. Non-metals are poor conductors of heat and their oxides are acidic.

E is a metal. Metals are good conductors of electricity.

b) A could be hydrogen.

B could be copper or nickel.

C is mercury.

D is sulfur.

E could be gold, silver or platinum, or any other unreactive metal.

2 a) i) It is a non-metal because it does not conduct electricity.

ii) It has a high melting point.

iii) It is not very reactive because it does not burn in air.

iv) It is brittle.

b) No, it cannot be either sulfur or gold. It cannot be sulfur because sulfur has a low melting point and burns when heated in air. It cannot be gold because gold conducts electricity.

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11 Metals and non-metals

23

3 a) Calcium and magnesium

b) Iron or zinc

c) calcium > magnesium > zinc > iron > copper

» Metals, acids and the reactivity series

Know1 A (zinc + sulfuric acid → zinc sulfate + hydrogen)

Apply1 a) Y > X > W > Z

b) Mix the gas with air and put a fl ame next to the mouth of the test tube. A squeaky pop is produced.

2 a) Z

b) X

c) Z > Y > X

d) • Concentration of acid

• Temperature

• Size piece of metal

Note: the volume of acid used is not important as long as it completely covers the piece of metal and is in excess, i.e. is more than enough to completely react with the metal.

» How do metals and non-metals react with oxygen?

Know1 C (oxidation)

2 The magnesium burns with a bright, white fl ame, forming a white solid/powder.

Apply1 a) zinc > nickel > lead

b) i) No reaction, because lead is less reactive than nickel.

ii) Zinc is more reactive than nickel, so a reaction will take place producing zinc oxide and nickel.

2 a) i) Oxygen

ii) Aluminium oxide

b) Below copper

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» Displacement reactionsKnow1 A (displacement)

Apply1 a) Zinc is less reactive than magnesium and so will not displace

magnesium from a magnesium compound.

b) i) iron + copper sulfate → iron sulfate + copper

ii) Colour of solid changes from grey to pinky-brown (accept pink or brown).

Colour of solution changes from blue to (pale) green.

c) Hydrogen is more reactive than copper, but less reactive than iron.

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Acids and alkalis

» The pH scaleKnow1 Sulfuric acid – 0 to 3, citric acid – 4 to 6, sodium chloride – 7

2 a) HCl

b) NaOH

c) H2SO4

d) KOH

e) HNO3

f) Ca(OH)2

3 Add universal indicator, note the colour and compare with a colour chart.

4 B (they can neutralise acids)

Apply1 Volume of acidic

solution (cm3)Volume of alkaline solution (cm3)

pH of mixture

25 15 225 17 725 19 12

2 Test tube A contains hydrochloric acid.

Test tube B contains vinegar.

Test tube C contains sodium chloride.

Test tube D contains washing soda.

3 a) Lemon juice or lemonade

b) Oven cleaner

c) Milk

4 a) • Add the soil to water and stir.• Filter to remove the insoluble substances. • Use a pH meter or universal indicator to measure the pH of the

fi ltrate.

b) The results do support the statement because the petals have different colours at different pH values.

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» Acids reacting with alkalisKnow1 B (neutralisation)

2 An indicator is a substance that can be used to identity if a solution is acidic or alkaline. The indicator has different colours in acidic and alkaline solutions.

3 Methyl orange is red in acidic solutions and yellow in alkaline solutions.

Apply1 pH at start pH at end Experiment

5 14 B 7 6 A 7 7 D 7 1 E14 7 C

» Acids reacting with metal carbonates

Know1 Carbon dioxide

2 B (a salt, water and carbon dioxide)

3 D (it turns limewater milky)

Apply1 a) Any value between 0 and 3

b) The limewater turns milky.

c) 7

2 a) B (it is weakly acidic)

b) Neutralisation

c) Calcium carbonate

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13 Earth structure

» The structure of the EarthKnow1 a) The centre part of the Earth, made up of mainly iron and nickel.

b) The layer between the crust and the core, made up of semi-molten rock called magma.

c) The outer layer of the Earth, made up of solid rock.

2 Most rocks are a mixture of substances including minerals, although some rocks are made up of just one mineral. Most rocks are made from two or more minerals coming together.

A mineral is a pure substance.

3 Coal is a mixture, not a pure substance. It is composed of many compounds called hydrocarbons.

Apply1 E > B > A > C > D

» Types of rockKnow1 a) i) Rock formed from layers of sediment.

ii) Rock formed from cooled lava or cooled magma.

iii) Rock formed from existing rocks that have been exposed to heat and pressure over a long time.

b) Sedimentary – chalk, limestone or sandstone

Igneous – basalt, granite or obsidian

Metamorphic – marble, schist or slate

2 a) The remains of the plant are called fossils.

b) The remains of plants are found in sedimentary rocks.

c) Weathering can break down rocks to form soil.

Apply1 a) Fossils are formed when an animal dies in a watery environment and

then gets buried in mud and silt. Over time the sediment builds up and gets hardened into rock.

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b) Fossils are destroyed by the high temperatures and by the high pressures that are needed for igneous rocks or metamorphic rocks to form.

c) Fossils of soft-bodied animals are not often found because squishy body parts tend not to hold up as well as hard shells and bones over time, wearing away before they can leave an impression in the rock.

2 a) A river carries pieces of broken rock as it fl ows along. When the river reaches a lake or sea, the transported rocks settle to the bottom and form a layer called sediment. Other rocks get deposited on top of this layer and the rocks at the bottom become squashed and harden into sedimentary rock.

b) Over time, other rocks are deposited on top of this layer of rock and harden as they become squashed. This can continue for many years until several layers of sedimentary rock are built up.

c) In layer F. Fossil 3 is older than fossil 2. The rocks that make up layer F were deposited before those that make up layer E.

» The rock cycleKnow1 Weathering is the wearing down of rock by physical, chemical or biological

processes. Erosion is the movement of rock by water, ice or wind.

2 Physical weathering

Apply1 a) Any two from:

• Physical weathering caused by wind or rain or fl owing water. In physical weathering the chemical composition of the rock does not change.

• Chemical weathering caused by reaction between the rock and substances such as oxygen, carbon dioxide and acids. In chemical weathering the chemical composition of the rock changes.

• Biological weathering in which the rock is broken down by living organisms.

b) i) Erosion

ii) Wind or water (e.g. streams, rain, waves)

c) D (marble)

2 a) By the action of water on the rock wearing away the surface.

By the action of wind and rain on the rock, wearing away the surface.

By the rocks knocking into one another as they are transported in fl owing water and wearing away the surface.

b) In a river or stream or on the beach. The rocks are constantly being moved by fl owing water and have a lot of opportunity to knock into one another.

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3 a) Sedimentary

b) i) The granite was heated until it melted. The bottom layers of limestone were then heated and put under pressure to form the metamorphic rock called marble.

ii) Rock Y was formed by fast cooling of the molten magma. It cooled more quickly because it was close to the surface.

4 a) Wind and water have weathered rock A, breaking it into small pieces. The small pieces have then been transported away by water and wind. This is called erosion.

b) i) When molten lava or molten magma cools and solidifi es.

ii) It was formed by slow cooling of the molten magma.

c) Metamorphic

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14 Universe

» The Earth in spaceKnow1 a) The path taken by the Earth around the Sun.

b) The time it takes for the Earth to complete one orbit around the Sun.

c) The time it takes for the Earth to complete one rotation about its axis.

2 a) 8 minutes and 20 seconds

b) 4 years

c) Milky Way

Apply1 a) A (the Moon is closer to Earth than Mars)

b) C (the Moon)

» The solar systemKnow1 a) C (a planet)

b) Telescope

Apply1 a) Position A. Quaoar is closest to the Sun in this position.

b) Position C. Quaoar is furthest from the Sun in this position, so the effect of the Sun’s gravity is weakest at this point.

c) i) Accept any number between 2500 and 3500 million km.

ii) The further away the planet’s surface is from the Sun, the lower the temperature.

iii) The average surface temperature decreases with increasing distance from the Sun because planets that are further away from the Sun receive less of the Sun’s energy. This is because the Sun’s energy spreads out as you get further from the Sun.

2 a) X is the Sun and Y is Mercury.

b) Jupiter is further from the Sun and therefore has further to travel. It is also moving more slowly than Mars.

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14 Universe

31

c) i) The time differences between the sightings are very similar (76 and 75 years).

ii) 2061 or 2062

3 a) They had not been discovered.

b) In our solar system the Sun is at the centre, not the Earth. In our solar system the planets orbit the Sun, not the Earth.

4 a) i) A ‘year’ on Neptune is longer.

ii) Neptune takes longer to orbit the Sun.

b) i) Gravity

ii) Gravity gets weaker the further the planet is from the Sun.

» Phases of the moonKnow1 The Moon refl ects light from the Sun towards the Earth.

2 Ecliptic plane

Apply1 A – full moon, B – new moon

» Beyond the solar systemKnow1 a) A collection of stars held together by gravity.

b) The distance light travels in 1 year.

c) A body in the universe that gives out light.

2 a) D (stars)

b) D (universe)

Apply1 a) The image from a telescope on Earth would not be bright enough to see.

b) The planet takes 150 days to orbit the star.

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15 Movement

» The seven life processesKnow1 All living organisms share seven life processes. We can remember them

using ‘MRS NERG’. ‘M’ stands for movement, ‘R’ stands for respiration, ‘S’ stands for sensitivity, ‘N’ stands for nutrition, ‘E’ stands for excre-tion, ‘R’ stands for reproduction and ‘G’ stands for growth.

Apply1 a) Excretion

b) Respiration

c) Reproduction

d) Nutrition

e) Sensitivity

f) Movement

g) Growth

2 a) The stem of a plant moves upward as it grows, whilst the roots of a plant move downwards as they grow.

b) Flowers (anthers, petals, ovary, pollen, style) or seeds

c) Sunfl owers sense where the Sun is in the sky and rotate their fl owers to face the Sun as much as possible.

» SkeletonsKnow1 Movement, support, protection and blood cell production

2 A joint

3 Tendon

4 Bone marrow (found in the centre of the bone)

5 Calcium is a metal; phosphorus is a non-metal.

Apply1 Having a softer head allows a baby to be born more easily (as it can be

squashed a little as the baby is born). The head is the largest part of a baby so having a softer head makes childbirth easier.

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15 Movement

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2 a) Having hollow bones makes them lightweight, so it is easier for birds to fl y.

b) Having hollow bones might make them weaker, so more easily broken.

» JointsKnow1 The adult human skeleton is made up of 206 bones, and where any

two bones meet is called a joint. Pairs of muscles around a joint allow it to move because muscles are able to contract (shorten) and relax (lengthen). A joint has several different structures within it. For instance, tendons join muscle to bone, ligaments connect one bone to another across a joint and cartilage is a smooth tissue found at the end of bones, which reduces friction between them.

Apply1 Synovial fl uid acts as a lubricant in many of the joints in the human body.

2 Hinge joints, because at each joint in a fi nger the movement is like a hinge – only in two directions. This allows the fi nger to curl.

3 A shoulder joint can move in many directions, making the shoulder a very fl exible joint. The most fl exible joints are ball-and-socket joints, so it seems likely that this is the joint in the shoulder.

4 a) The mouth/jaw

b) The shape of the skull would change.

c) The skull contains the brain. If the skull were to change shape, it may cause brain damage.

» Antagonistic muscle pairsKnow1 Joints give fl exibility and movement to a skeleton. Joints are where bones

meet and many joints in the human body can move because of the action of antagonistic muscle pairs. These are pairs of muscles working in unison to create movement. When one of the muscles in the pair is contracting (shortening), the other muscle must relax (lengthen), and these changes cause the joint to move. For example, to move your lower arm up, your biceps contracts, and your triceps muscle relaxes. To move your lower arm down the opposite occurs. An example of an antagonistic muscle pair in the leg is the quadriceps muscle and hamstring muscle.

Apply1 a) The shin muscle contracts because it must be getting shorter. The calf

muscle relaxes because it must be getting longer.

b) On tiptoes your calf muscles contract and shorten whilst your shin muscles relax and lengthen.

2 The heart is made of muscle because it needs to pump blood around the body. Muscles can contract and relax, and the contractions of the heart muscle pump the blood around the body.

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16 Cells

» Comparing cellsKnow1 Movement, respiration, sensitivity, growth, reproduction, excretion and

nutrition

2 The nucleus

3 Cytoplasm is a jelly-like structure where important chemical reactions take place.

4 Many plant cells contain chloroplasts which absorb light energy so that the plant can make food, but animal cells do not. In plant cells the cell membrane is surrounded by a cell wall, but this is not present in animal cells. Inside a plant cell, but not in an animal cell, is an area that contains liquid, and can be used by plants to keep the cell rigid and store substances. It is called the vacuole.

Apply1 Any two from: water, nutrients, waste products, oxygen (for respiration)

2 Chloroplasts carry out photosynthesis. The leaves of a plant are most exposed to sunlight, and sunlight is necessary for photosynthesis to occur.

3 Cells are very small, but we can use microscopes to study them. When we prepare a microscope slide we often stain the cells we want to observe. This helps us to see the internal structures of the cells (like vacuoles and nuclei) more clearly. We then cover our sample with a cover slip before placing the slide on the microscope stage and looking at it through the eye piece. We have to focus the microscope carefully to ensure that we get a clear image of the cells we want to observe.

» Specialised animal cellsKnow1 Structural adaptations are special features to help a cell carry out its

functions.

2 a) Nerve cells (or neurones)

b) Red blood cells

c) Sperm cells

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Apply1 If substances can dissolve quickly from the red blood cells then there is a

greater chance that the oxygen they carry can be passed to the cells that need it.

2 a) A shorter tail might mean that the sperm cannot swim as far or as quickly as other sperm cells, so will reduce its ability to fertilise the egg.

b) A smaller tail base might mean fewer mitochondria in the sperm cell. Mitochondria release energy through respiration, so with fewer of them, the sperm cell may not be able to travel as far, so reducing its ability to fertilise the egg.

3 The cilia can be used to move the unicellular organism itself (rather than moving other things like dust and egg cells).

» Specialised plant cellsKnow1 Two plant cells that are specialised for a particular function are root hair

cells and phloem cells. Root hair cells have a large surface area that helps them to absorb water and nutrients from the soil. Phloem cells have holes in their ends to allow sugar solution to travel through them. Plants use phloem cells to transport the sugars made during photo-synthesis in the leaves to where they are needed elsewhere in the plant for growth or storage.

Apply1 a) Special features to help a cell carry out its functions.

b) They have no ends and they are strengthened by lignin.

c) Having no ends means the cells can join together to form straw-like structures. Being strengthened helps them to stay open, so that water can always fl ow through them.

2 a) They have a second cell wall that is strengthened by lignin.

b) Roots and/or stems (these parts of plants support the plant the most)

c) Xylem cells are also strengthened by lignin.

3 a) Photosynthesis (because they contain chloroplasts)

b) Stems, because stems are also exposed to sunlight (which is necessary for photosynthesis).

» Organising cellsKnow1 a) A living thing made up of one cell

b) A living thing made up of many types of cell

2 In multicellular organisms similar, specialised cells are organised into tissues, and these are organised into organs. For instance, muscle

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cells form muscle tissue, and muscle tissue makes up a lot of the heart in mammals. Different organs work together in organ systems that carry out vital life processes. For instance, the heart and blood vessels make up the circulatory system, which is responsible for transporting substances around the body.

3 a) Immune system

b) Reproductive system

c) Muscular–skeletal system

d) Respiratory system

Apply1 a) The fl agellum

b) The pili

2 Multicellular organisms need organ systems in order to carry out the seven life processes. In humans, movement is achieved by the muscular–skeletal and nervous systems; reproduction is achieved by the reproductive system; respiration is carried out by the respiratory and circulatory systems; and nutrition and excretion are carried out by the digestive system.

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17 Interdependence

» ClassificationKnow1 Classifi cation is a way in which we can group and name different

living things, or organisms. Carl Linnaeus was an early pioneer of classifi cation, and he came up with fi ve big groups, or kingdoms. These were animals, plants, fungi, bacteria and other single-celled organisms. Each of these groups is sub-divided further. For instance, the animal kingdom can be divided into two more groups: animals with a backbone (called vertebrates) and animals without a backbone (called invertebrates). For example, snails, worms, insects and crabs are all invertebrates, whilst mammals, birds, reptiles, amphibians and fi sh are all vertebrates.

Apply1 a) Mammals

b) Fish

c) Birds

d) Amphibians

2 a) Orcas do not have gills like fi sh do, so cannot breathe underwater. They have to surface for air.

b) Mammals feed their young with milk, and this is true for orcas.

c) Without hair, orcas are more streamlined so can move through water more easily.

» Feeding relationshipsKnow1 An ecosystem is made up of the living things in a given area and their

non-living environment, within which there are food chains and food webs. A food chain starts with a producer – a green plant or alga that makes its own food by photosynthesis. Any animal that eats this plant or alga is called a primary consumer. Other animals can eat these primary consumers and are called secondary consumers, and so on. The top of a food chain is occupied by the top predator – the animal that no other animal consumes. Each stage of a food chain is called a trophic level, and food chains can link up to form a food web.

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2 a) Decomposer

b) Consumer

c) Omnivore

d) Population

Apply1 Humans are consumers. Even though we grow food (so we might be

thought of as producers) and often compost our food (so we might be thought of as decomposers), our role in a food chain is as a consumer.

2 You could argue that humans are at the very top of their food chain because very few humans are consumed by other animals. But you could also argue that those humans that are consumed by other animals (like polar bears or sharks) are second from top of their food chain.

3 Food chains are often limited to no more than fi ve trophic levels because only about 10% of the energy from one trophic level is transferred to the next. If more energy was transferred between trophic levels then more organisms could survive in the next trophic level, and so more trophic levels would exist.

» Pyramids of number and biomass

Know1 Pyramids of number show the number of organisms in each trophic

level of a food chain. Each trophic level is drawn as a horizontal bar and the wider the bar, the greater the number of organisms. Usually, as we move up through the food chain, the number of organisms decreases quickly because only about 10% of the energy of each trophic level is transferred to the next one, and fewer organisms can survive. So we get a perfect triangle shape. Sometimes we get an imperfect triangle shape – this happens when one very large plant, like a tree, forms the fi rst trophic level. It can also happen when many parasitic organisms like fl eas feed off the top predator in a food chain, causing a very wide top bar.

Apply1 a) Biomass is the living mass or dry mass of an organism.

b) Pyramids of biomass take the size of the organisms in each trophic level into account, so are always perfect triangles.

c) Measuring biomass often requires killing and drying out an organism, whereas counting the number of organisms does not.

2 They will be perfect triangles, like pyramids of biomass. Only about 10% of the energy of each trophic level is transferred to the next, so each level will always be signifi cantly smaller than the previous one.

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» Changes in ecosystemsKnow1 Predators are animals that hunt and eat other animals, and prey are the

animals that are hunted. An example of a predator–prey relationship in the UK is barn owls and voles. In any ecosystem there are usually more prey than predators. This links to what we know about pyramids of num-ber and biomass – each new trophic level gets smaller as we go up the pyramid because only about 10% of the energy in each level is trans-ferred to the next. If a change in the ecosystem reduces the number of prey, then the number of predators will fall as they have less food. If the change causes the number of predators to fall, then the number of prey will rise as fewer of them are being hunted and killed.

Apply1 a) The seal population will get smaller because, with less plankton,

there is less food for the sardines to eat, so fewer sardines for the seals to hunt.

b) The sardine population will get smaller. With fewer polar bears, there will be more seals (as fewer of them are hunted by the polar bears), and with more seals to hunt the sardines, the sardine population will decrease.

c) The orca population will increase. With more polar bears, there will be fewer seals (as more of them are hunted), so the sardine population will increase (as fewer of them are hunted by seals). This means there will be more sardines for the orcas to hunt, so their population will rise.

d) Interdependence

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Plant reproduction

» The life cycle of a plantKnow1 a) The seed produces its fi rst shoot, which grows upwards towards the

light, and its fi rst root, which grows downwards following gravity.

b) By photosynthesis

c) Insects can carry pollen from the male part of one plant to the female part of another plant.

d) The nuclei of the sex cells fuse.

e) Any two from: by wind, by animals, by water

2 a) Ferns or mosses

b) i) Dandelions, daisies, daffodils (or any other plant that produces brightly coloured fl owers)

ii) Grasses or trees

Apply1 Brightly coloured fl owers are used to attract insects, and the plant uses

the insects to transfer pollen to other plants.

2 Either by wind (the plant relies on wind to blow the pollen from it to other plants) or by animals (animals can brush against the fl ower and then carry the pollen to another plant).

» Sexual reproductionKnow1 a) Fertilisation

b) Anther

c) Fruit

d) Stigma

e) Seed

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18 Plant reproduction

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Apply1

2 a) To provide protection for the seeds and to provide an incentive for animals to eat seeds and spread them around.

b) They can be brightly coloured, taste good, and are often large relative to the seeds they carry.

c) The stamens and stigmas hang outside the fl ower, so that it is easier for the pollen to be blown from the stamen by the wind, and for the pollen to land on the stigma.

» Asexual reproductionKnow1 The strawberry plant or spider plant

2 A clone is a plant that is genetically identical to its parent.

Apply1 In asexual reproduction only one parent is involved and the offspring are

clones of the parent. In sexual reproduction two parents are involved and the offspring are not genetically identical to either parent. Sexual reproduction produces greater variation in the population.

2

3 Runners encourage the clones to put down roots further from the parent plant. In this way the clones are less likely to compete for resources like water and light. Plantlets that fall from the leaves of the parent plant will compete with the parent for the same resources.

Reproduction stage Order

The fertilised egg develops into an embryo. 4The pollen grain forms a pollen tube, which grows down through the style towards the ovary. 2

The ovule grows into the seed. 5A pollen grain from a different plant lands on the stigma of a flower. 1The ovary forms the fruit that surrounds the seed. 6The nucleus of the pollen grain containing DNA passes down the tube to fertilise the egg inside the ovule. 3

Reproduction stage OrderSmall plantlets (or clones of the parent plant) develop on offshoots of the runner. 3

The plantlets develop roots that grow into the soil and the clone plant continues to grow. 4

A thin, flexible stem-like structure called a runner starts to grow at the base of the plant’s stem. 1

In this way, the clone plants do not share the same nutrients, sunlight and water that the parent plant needs. 5

The runner grows horizontally along the ground. 2

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4 Plants that reproduce sexually. This is because sexual reproduction causes greater variation in the population of the species, or a wider gene pool. With a wider gene pool it is easier to adapt to changes to the ecosystem.

» Seed dispersalKnow1 During sexual reproduction in plants, a plant is pollinated and fertilised –

pollen from one plant is transferred to the stigma of another, and the nucleus from the pollen grain fertilises the egg. The ovule then devel-ops into the seed, and how this seed is dispersed varies between plants. Some plants, like dandelions, make seeds that are lightweight and can be easily blown away from the parent by the wind. Other plants make seeds that can fl oat, and so can disperse from the parent plant on water. Other plants rely on animals to carry their seeds away. One way they do this is by making fruit that encourages animals to eat them and expel the seeds somewhere else by egestion.

Apply1 Because the seeds can travel a long way from the parent plant, the new

plants will not compete for the same resources that the parent plant needs, like water and nutrients.

2 The seeds have a protective coating that stops them from being digested.

3 Water dispersal, as the fl oating seed could reach an ocean and then be carried across the ocean to an entirely new continent.

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19 Variation

» Examples of variationKnow1 a) Wolf

b) Artifi cial selection

c) They have a gentle and caring nature.

d) Any two from: good sense of smell, intelligent (so it can be trained), small (so it can access all areas), obedient

2 Reducing the variation in a species means it has a narrower gene pool. This means that is less able to cope with changes to its ecosystem.

Apply1 Small bodies: so they can chase foxes through tight spaces or burrows.

Muscular: so they can run for long periods of time.

Intelligent: so they can be trained to hunt.

Vocal: so they can guide people to the fox.

» Causes of variationKnow1 A species is a group of living things that have more in common with

each other than with other groups. Different organisms of one species are able to interbreed and have fertile offspring. For instance, a golden retriever can breed with a cocker spaniel, and the puppies would be able to breed as well. Organisms from different species may be able to breed, but their offspring will be infertile. This means that the offspring cannot breed themselves. For example, a mule can never produce an offspring because it was made when a horse and donkey bred, and these animals are not in the same species.

2 a) Any one from: height, colour, size, tail length, type of coat, temperament (how it behaves)

b) Any one from: size, weight, coat length, coat markings, speed

3 Genetic variation and environmental variation

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Apply1 a) Both

b) Genetic

c) Environmental

d) Genetic

2 The twins must have had environmental factors that determined their skin colour. The twin with darker-coloured skin is likely to have lived in a sunnier climate when they were growing up, so they had skin that was tanned more of the time than the other twin.

» Types of dataKnow1 a) Continuous

b) Continuous

c) Discontinuous

d) Discontinuous

e) Continuous

Apply1 a) Continuous

b) A line graph

c)

1350

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140 145 150 155

Height of classmate (cm)

Nu

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t

160 165 170

×

×

×

×

×

×

×

×

×

The shape of the line is similar to the shape of a bell.

2 a) Genetic, because it is inherited

b) Discontinuous, because the values are groups

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19 Variation

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c) A bar graph

d)

O+05

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» Why is variation important?Know1 Variation is a measure of the differences within and between species.

A similar measure is biodiversity, which is the variety of living things. We know that species that show a lot of variation are more able to cope with change to their environment, and this is because with greater variation there is a wider gene pool. Species that can adapt to changes in their environment are less likely to become extinct than those that cannot. Animals, like dogs, that have been bred to have certain characteristics can often have a very narrow gene pool, and we say the animal is inbred.

Apply1 a) Any two from:

• thick white fur (insulation and camoufl age)

• thick layer of fat (insulation)

• strong legs (for swimming and running during hunting)

• small ears (to reduce heat loss)

• black skin (to reduce heat loss)

• large size (to reduce heat loss)

• large feet (for walking on snow)

• fur on soles of feet (insulation and grip)

• sharp claws and teeth (hunting)

b) A wide gene pool, or a lot of variation in the polar bear population

2 If there is a lot of variation in the population then the disease is not likely to affect each tortoise in the same way. Some of the tortoises might die, but others will survive, and so the population can survive.

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Human reproduction

» The life cycle of a humanKnow1 Once fertilisation occurs a human is just one cell, and this cell quickly

divides and copies itself many times. After 5 weeks of this, we call the developing human an embryo, and then from 11 weeks we call it a fetus. After 9 months, a baby is born and childhood begins. Adolescence starts when the child becomes a teenager, and during this stage of the human life cycle, puberty takes place. Puberty is a series of changes to teenagers’ bodies that result in them being able to sexually reproduce. Adulthood follows adolescence, and is the longest stage of the cycle. The human life cycle ends with old age. This stage is getting longer and longer as healthcare improves and people live for longer.

2 a) Any three from: pubic hair starts to grow on the body, hair starts to grow on the face, testicles start to produce sperm, a penis can become erect for the fi rst time, growth spurt, voice breaks (becomes deeper)

b) Any three from: pubic hair starts to grow on the body, breasts start to develop, hips widen, ovaries start to release eggs during the menstrual cycle (periods start), growth spurt

c) 8–14 years of age, and it lasts for about 4 years

Apply1 a) 1024 cells after 10 days

b) 0.06 cm/hr

There are 168 hours in 1 week, and speed is equal to distance divided by time. 10 cm/168 hours = 0.06 cm/hr

» The male and female reproductive systems

Know1 a) A group of organs working together to carry out one of the seven life

processes.

b) Any three from: circulatory system, muscular–skeletal system, respiratory system, digestive system, immune system

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2 a) G – Ovary

b) D – Vagina

c) A – Uterus (or womb)

d) F – Fallopian tube (or oviduct)

e) E – Cervix

3 a) E – Testicle(s)

b) D – Penis

Apply1 Statement Order

During ejaculation the semen enters the woman’s vagina near the cervix. 2Many sperm then enter the fallopian tubes (or oviducts). 4Many millions of sperm are released from testicles and mix with a nutrient-rich fluid, forming semen. 1

The fertilised egg is wafted into the uterus by ciliated cells that line the fallopian tubes. 6

Millions of sperm swim through the cervix and enter the uterus (or womb). 3The fertilised egg then settles into the lining of the uterus and develops into a baby. 7

One sperm finds and enters the egg and fertilises it. 5

» The menstrual cycleKnow1 The menstrual cycle prepares the female for pregnancy, and stops if the

egg is fertilised by a sperm. On average, it is a 28-day cycle that starts on day 1 with the loss of the lining of the uterus. We call this menstruation and it is often called having a period. After menstruation has occurred, the lining of the uterus begins to thicken again in preparation for a fertilised egg. On day 14 ovulation happens – an egg cell is released from one of the ovaries and this egg may be met by a sperm and fer-tilised. If fertilisation does not occur, then the uterus lining remains thick until the last day of the cycle, and is then lost during menstruation at the start of the next cycle. If fertilisation does occur, then the fertilised egg settles into the uterus lining and develops into an embryo. The lining is not lost, and the menstrual cycle stops.

Apply1 a) Ovulation happens: a female gamete, or egg cell, is released from one

of the ovaries.

b) Menstruation happens: the lining of the uterus is lost and passes through the cervix and out of the vagina. This is also called having a period.

c) The lining of the uterus remains thick but is lost at the end of this time.

d) The lining continues to thicken and the fertilised egg settles into it.

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2 a) An increase in the levels of oestrogen in the bloodstream causes ovulation to happen around day 14 of the menstrual cycle.

b) A fall in the levels of progesterone causes menstruation and the lining of the uterus is lost. But if the levels of progesterone remain high, then menstruation does not happen and the uterus lining can receive a fertilised egg.

» Gestation and birthKnow1 a) F – Fetus

b) B – Placenta

c) A – Umbilical cord

d) E – Amniotic fl uid

2 a) Oxygen and nutrients

b) Carbon dioxide and waste products

Apply1 Nicotine (from smoking) and alcohol can also diffuse through the

placenta, and these substances can harm the fetus and its development.

2 Statement OrderThe muscles of the uterus undergo a series of involuntary contractions. 2The placenta passes from the uterus through the vagina. 6The baby moves from the uterus, through the narrow opening of the cervix, to the vagina. 3

The amniotic sac surrounding the baby bursts and releases the amniotic fluid, which passes from the vagina. 1

The baby’s head is usually born first, followed by the rest of its body. 4The umbilical cord is cut and the baby takes its first breath. 5

3 Cravings are intense urges to eat unusual foods – often savoury or salty. Some people think this is the pregnant woman’s body telling her it needs specifi c nutrients.

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