PDF- -Mary Jones, Diane Fellowes-Freeman and David Sang Cambridge - Cambridge Checkpoint Science Workbook 2 Answers


Answers to Cambridge Checkpoint Science Workbook 2 You may award one mark for each answer or part of an answer

4 b) Green

c) The ethanol takes the green-coloured chlorophyll out of the leaf

Test the leaves to make sure they do not contain any starch

Investigating the effect of carbon dioxide on starch production 4 a) (i) It is transparent to let light through for photosynthesis

(ii) It keeps the gases around the plant from mixing with air gases

It releases carbon dioxide gas into the air in the bag

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Investigating oxygen production in plants 5 a)

100 90 80

Bubbles per minute

c) 90 d) He could have repeated the procedure a few times and found an average

e) He could collect a tube full of gas and test it with a glowing splint

If it relights,

f) Oxygen is produced in photosynthesis,

so this shows that as light intensity increases,

the rate of photosynthesis increases

g) (i) The distance between the lamp and the test tube

(ii) The number of bubbles produced

Plants and light 6 Cover one leaf with aluminium foil and another leaf with transparent plastic then leave the plant in the light for over 4 hours

Take each leaf from the plant and test it for starch

Biomass 7 a) Wet biomass is the mass of a living thing when it is alive

Dry biomass is the mass of a living thing after it has been killed and dried out

B 3000 kg,

C 6000 kg,

D 4500 kg

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6500 6000

Biomass of species/kg

B Time periods

d) The numbers are going up and the animals might be breeding

e) The average biomass is going down because there are lots of small young ones

f) The smaller ones have been eaten by predators

Minerals 8 Minerals are needed by plants for growth and development

The transport of water through a plant 9 a) Root hairs

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The cell structure of a leaf 10 a) A – epidermal cell

B – guard cell

C – chloroplast

D'– nucleus

(ii) It prevents water escaping from the plant

2 Starch

3 Protein

A (Note the last two could also be A,

D) 5 a) Iodine solution

6 a) Food

White cloud formed in water

carrot peanut lentil butter cheese lamb orange

Water remained clear ✔

b) Make sure all Bunsen burners and spirit burners are turned off

How the body uses nutrients 7 Protein – building tissues and organs

Fat – making cell membranes

Carbohydrate – quickly released energy store

Fibre – helps food pass along the intestines

Vitamin A – helps us to see in the dark

Vitamin C – prevents scurvy

Calcium – strong bones and teeth

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10 Days

b) The average weight rises up to 51 g on day 9 then falls again after day 12

c) The average weight rises steadily to 71 g by day 15

d) It made them increase in weight

e) It showed that the four nutrients did not provide all that was needed for growth

f) Mammals produce milk for the healthy growth of their young

g) (i) They increased in weight

(ii) Their rate of growth slowed down

(in fact they eventually began to lose weight

The amounts of nutrients in food 10 a) Fat,

d) He must eat vegetables and fruit,

cereals or pulses because they all contain fibre,

which forms soft faeces that are easier to release from the body

A healthy diet 11 At the top should be chocolate,

at the bottom should be pasta,

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e) It breaks it up into smaller pieces

 2 Large food molecules do not dissolve in water and cannot pass through the lining of the digestive system into the body

Small food molecules do dissolve and can pass through the wall of the digestive system into the body

b) Because they speed up reactions but are not changed or used up in them

Along the alimentary canal 4 a) Water,

6 a) H,

F b) Bile duct

Enzymes 8 a)


Time for enzyme to work/min

the breakdown of starch increased

c) The starch broke down in 1 minute

d) It took much longer than she predicted

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11 10 9

Time for starch destruction/minutes

f) The enzyme worked best at 40 °C

A high temperature slowed down the working of the enzyme

The heart 2 a) A – right atrium,

B – left atrium,

C – right ventricle,

D – left ventricle

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blood vessels 3 a) A – artery,

B – vein

140 130

Pulse rate/bpm

d) From 60 seconds until 120 seconds

Su Lin,


c) Spread throughout the organs

What is in the blood

?  6 Red blood cell – transports oxygen

White blood cell – fights disease

Platelets – help blood to clot

Plasma – transports digested food

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Moving oxygen to the cells and Moving carbon dioxide to the lungs and Moving glucose to the cells  7 Large

A healthy heart 10 a) Fatty foods

b) It can make a fatty layer in them

d) It causes the pressure to rise

b) It has to push the blood round a much bigger body

d) By eating a balanced diet and cutting down on fatty foods

The parts of the respiratory system 3 a) Ciliated epithelial cells

X – cytoplasm,

Y – cell membrane,

Z – nucleus

d) They beat backwards and forwards to move the mucus up to the top of the windpipe

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Breathing movement


External intercostal muscles relax Ribs move up Diaphragm muscles contract Chest volume decreases Ribs move down Air moves out Air moves in Diaphragm muscles relax Chest volume increases External intercostal muscles contract

Expiration ✔

✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔

Gaseous exchange 6 At the end of the bronchioles

d) The oxygen combines with haemoglobin to make oxyhaemoglobin

 8 a) To test for carbon dioxide in inhaled and exhaled breath

c) Make sure the limewater in both tubes is clear

gently breathe in and out of the central tube for 30 seconds

note the appearance of the limewater in both tubes

d) (i) tube A will remain clear and tube B will become cloudy

(ii) The air drawn into tube A does not have enough carbon dioxide in it to turn the limewater cloudy

the air from Paul’s breath has enough carbon dioxide in it to turn the limewater in tube B cloudy

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Respiration  9 glucose + oxygen ➔ carbon dioxide + water

c) It breathes in large quantities of air quickly to supply the oxygen that is needed to break down the substances made during anaerobic respiration

Smoking and health 11 a) Nicotine

b) (i) They stop the cilia beating

The male and female reproductive organs  2 Male reproductive organs

Female reproductive organs

testes scrotum penis sperm duct

The menstrual cycle  3 a) Female

c) (in any order) 1 – pregnancy,

Fertilisation  4 Oviduct

The development of the baby  6 Uterus

b) Carbon dioxide (but accept waste products)

d) Stop the ovaries producing more eggs

stop the wall of the uterus breaking down

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10 Foetus

Gestation periods (weeks approx



the longer the gestation period

(ii) Adult humans are larger than most goats but smaller than most cows

e) It does not fit in because the guinea pig is smaller than the cat yet has a longer gestation period

f) In the longer gestation period of the guinea pig,

the pups have developed much more than the kittens

Birth 12 D,

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7 Diet,

7 Diet,


Developing country 10


b) The children from developed country have 1 kg more mass than those from developing countries

d) The children from the developed country put on greater mass from age 4 to 5 than the children from the developing country

2 Marasmus


pizzas and crisps or other high-fat,

high-carbohydrate food as appropriate

nerve and blood vessel damage in the feet (leading to amputation),

kidney damage that could be fatal

taking part in an exercise programme

b) To help the body build up again

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7 Diet,

Drugs  5 If more than one line is drawn from any drug,

Non-medical drug – reduces ability to fight disease

Alcohol – causes nerve damage

Tobacco – slows down growth

 6 a) Because they are cheaper

Appearance – they become thinner

e) Vomit blocking the windpipe

A b) Any of the following: A – danger of suffocating on vomit

B – leads to having more alcohol to keep state of relaxation but leads to other changes

C – falling over can cause injuries

D'– behaviour can lead to fights or dangerous activities,

for example balancing on a bridge

E – slow responses may lead to accidents

Increase activity then sadness

heart and brain damage Hallucinations,

mental illness Speeds up reactions and causes confusion Carelessness,

sleeplessness Slows down body to point of death

amphetamines cannabis ecstasy cocaine heroin

c) Seeing and hearing something that is not there

Disease 10 STD – sexually transmitted disease,

STI – sexually transmitted infection,

AIDS – acquired immune deficiency syndrome,

TB – tuberculosis,

HIV – human immunodeficiency virus,

PID – pelvic inflammatory disease

12 Malaria

c) It can cause blindness and deafness

14 Egypt,


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c) Strong forces of attraction

d) The particles stay in one position but can move to and fro about that position

which means that they can be squashed together

Particles in liquids are already very close so must be squashed much harder to get them closer

When states of matter change 5 a) He puts the petri dish over the graph paper and the ice cube in the middle of the petri dish

c) He checked that no water had spread out from the cube then set the clock running

He observed the position of the melted water regularly by measuring its edge against the squares of the graph paper and recorded how many squares the water had covered

d) He could set up three sets of apparatus – one in a fridge,

d) The line is not a straight line – it bends to the left and then bends to the right as you come down it


f) The higher the temperature the faster the evaporation

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which rises to the surface and bursts,

releasing the gas particles into the air

(ii) Because the steam is cooled down by the cold water in the jacket and condenses to form water

come together and slide over each other

Gas pressure 8 a) (i) It is smaller

(ii) The temperature is lower so the particles travel more slowly and push with less force on the wall of the balloon

(ii) The temperature is higher so the particles travel more quickly and push with greater force on the wall of the balloon

Diffusion 9 a) Use the same amount of water and ink in all parts of the test

c) (i) B (ii) The particles at a higher temperature have more energy and spread out faster than the particles at a lower temperature

d) The liquid is completely shaded in

b) A battery to produce a current of electricity

c) Humphrey Davy reasoned that as an electric current is produced when some new substances are made then perhaps an electric current could be used to break down a substance into its elements

e) He predicted that potash contained an unknown element

f) 1 – He continued his investigation by heating some solid potash on a platinum spoon

The link between elements and atoms 3 An element is made from one type of atom

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The properties of elements 5 Element

Copper – green

Magnesium – white

Sodium – golden yellow

Chemical symbols  8 Collect gold,

Mix in a crucible for an hour

Heat in a bath for a day

Leave for a month

Then put in a bottle

 9 a) Jons Jakob Berzelius in 1813

b) Each element is identified by the first letter of its name

If two or more elements begin with the same letter another letter in the name is also used

The first twenty elements of the periodic table 10 a) and b) Name

  1 hydrogen   2 helium   3 lithium   4 beryllium   5 boron   6 carbon   7 nitrogen   8 oxygen   9 fluorine 10 neon

H He Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar K Ca

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compounds and mixtures Mixing elements and From elements to a compound 1 a) Property

Colour Test with a magnet Mixing with water

yellow not magnetic tends to float

b) The iron springs to the magnet but the sulfur does not

c) The iron sinks and the sulfur tends to float

d) Bunsen burner provides heat

pipe clay triangle holds the crucible

tripod supports the pipe clay triangle

non-magnetic solid that sinks in water

Chemical reactions and equations 2 Reactant A + reactant B ➔ product C + product D

Chemical names of compounds 4 a) Copper carbonate – blue-green solid

Sodium hydroxide – colourless solid

Sodium chloride – white crystalline solid

Carbon dioxide – colourless gas

Copper sulfate – bright blue crystals

(iii) Snail shells and birds’ eggs

Mixtures 5 Tiny particles of insoluble solid mixed with a liquid – suspension

Liquid droplets in a gas – aerosol

Tiny water droplets mixed with air – mist

Gas bubbles trapped in a liquid – foam

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Separating mixtures  8 a) Decant it

b) The liquid is carefully poured out of the beaker without disturbing the sediment

B – filter paper,

C – support,

D – beaker

c) The filter paper has holes in it,

which let the water through but are too small to let the solid particles through

conical flask with side arm and rubber tube,

b) Make sure they all have the same amount of liquid in them

c) (i) They are spun round very fast

(ii) They are forced to the bottom of the test tubes

c) (in any order) 1 – It is more soluble than the other pigment

d) By putting a cold water jacket around it as in the Liebig condenser

e) Antibumping granules and salt crystals

b) It forms two layers with the oil being the top layer

opens the tap and draws off the vinegar into a beaker and then closes the tap

She then opens the tap again and lets the oil flow into a second beaker

Metals and non-metals in the periodic table  2 a) Helium,

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The uses and properties of metals and The uses and properties of non-metals 3 Aircraft – aluminium,

liquid mirror telescope – mercury,

making cells to generate electricity – zinc,

wires in electrical circuits – copper,

Potassium – explodes in water

Iron – rusts

Sulfur – burns with a blue flame

Bromine – makes red-brown toxic fumes

b) Iron sulfide did not conduct electricity

(ii) Iron is a metal so it is a conductor of electricity

(ii) Sulfur is a non-metal and so does not conduct electricity

Chemical properties of metals and non-metals 6 Make it take part in a chemical reaction

c) Sodium + chlorine ➔ sodium chloride

b) Sodium + oxygen ➔ sodium oxide

c) Sulfur + oxygen ➔ sulfur dioxide

(ii) One sulfur atom and two oxygen atoms



Explosions caused by dust 1 a) Respiration

c) Respiration and photosynthesis

d) The Sun’s energy is trapped in food by photosynthesis

We use the energy in food to live

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b) Fuel + oxygen ➔ carbon dioxide + water

Reactions with oxygen 5 A chemical reaction where oxygen is added to a substance

(ii) The mouse needs oxygen for respiration and without it the mouse would die

c) The fats and oils in them have oxidised and made the food rancid

open the hand warmer and wrap it round the bulb of the thermometer and observe the rise in temperature

Number of spots

Number of spots

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13 Speed

c) As the number of spots increases and then decreases,

rusting develops early in the experiment and then slows down

d) (i) It is not a good method

(ii) Some of the larger spots join together,

which reduces the spot count while the amount of rusting increases

e) Measure the area of the spots either using a ruler to measure distance across or use tissue paper/ transparent plastic with squares on it and measure the number of squares converted to rust each day

c) Zinc is more reactive with oxygen than iron and forms an oxide layer over the bucket,

which keeps oxygen away from the iron and so it does not flake off

Bronze – patina

Copper – verdigris

Speed records  4 Distance per minute is 100 × 6 = 600 m,

distance per hour is 600 × 60 = 36 000 m = 36 km/hr

 5 a) 80 000 metres divided by 60 = 1333 metres

b) 15 seconds is ¼ of a minute

c) (i) 1067 divided by 4 = 266

75 metres

75 = 33

d) The lion will catch the zebra

Measuring speed  6 B,

D  7 a) Radio waves

b) The radio waves are reflected off the vehicle back to the radar gun

c) It compares the time difference between sending the beam and receiving it back

 8 a) They have all got different reaction times

They have all got different views of the start and finish line

c) (i) 60 × 60 = 3600 metres/hr = 3

6 km/hr

(ii) 90 × 60 = 5400 metres/hr = 5

4 km/hr

(iii) 120 × 60 = 7200 metres/hr = 7

2 km/hr

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14 Sound

B 5 m,

C 1 m

Dabir – A

Harum – B

f) They could use one person to go down each zip wire

the person keeps the same shape on each one

all trolleys are oiled to the same degree

the same person operates the stopwatch

Distance/time graphs 10 a)

10 9 8 7


b) In the 30 to 40 second period

c) In the 60 to 90 second period

The sound goes higher as the vibrating length decreases

From vibration to sound wave  2 It is a to-and-fro or backwards-and-forwards movement about a fixed point

but must have a variety from: people,

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14 Sound

c) The particles move apart and the air pressure falls

d) Regions of low and high pressure

Describing a wave  8 a) A – wavelength,

B – amplitude

b) 1 – the distance from one crest top to the next,

Detecting sound waves  9 C,

Oscilloscopes 10 a) It allows you to see waves produced by sounds

(ii) A picture of the sound wave

d) It can store the displays made on the screen and build up a data bank of sound waves for further study

The loudness of a sound 11 The loudness increases

Road drill – a) – 110

Normal speech – c) – 55

The pitch of a sound 13 The frequency decreases

b) It will be lower than the others

B – quieter,

C – loud,

D – very quiet,

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15 Light

TV screen,

b) Anything from things like clothes,

furniture and furnishings to desk items and food and drink

Light rays 2 Some of the light is reflected from dust in the atmosphere

3 Long,

straight lines of light with straight edges

Classifying non-luminous objects 4 Transparent – can see clearly through – light is not scattered as it passes through

Translucent – cannot see clearly through – light is scattered as it passes through

Opaque – cannot see through it – light does not pass through

Shadows 5 a) When light shines on an opaque object

b) On the side away from the light source

d) The position of the light source and where the shadow falls

b) The shadow centre is dark but the edges are lighter

Reflecting light 7

(ii) A mirror or smooth shiny surface

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15 Light

Passing light through transparent materials 10 a)

b) A change in the speed of light

Colour 12 a) C,

B b) With your back to the Sun

13 Red,

(ii) The green colour is filtered out so no light comes from the chloroplasts

Filters needed

White light Blue light Yellow light Cyan light

blue and green filters Blue filter Green and red filters Blue and green filters

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The behaviour of magnets 3 a)

5 4 3 2 1

South pole

b) The power of the magnet decreases with distance from its poles

c) The north pole is stronger than the south pole

d) (i) The south pole with cards 4 and 5

(ii) They both have the same result,

which goes against the pattern set up in the rest of both graphs

Inside a magnet 4 Domains

The magnetic field 5 a) and c) line of force

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The Earth’s magnetic field 6 The two parts of the iron and nickel core moving at different speeds

The link between magnetism and electricity 7 A magnetic field is generated around it

b) The magnetic field of the current induces magnetism in the piece of iron and turns it into a magnet

c) The wire loses its magnetic field and the iron loses its magnetism

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