Answers to Revision questions Answers Unit 1 Biology€¦ · · 2015-10-22Answers 1 Answers to Revision questions ... environments / higher yields [2] [4] CCEA GCSE SCIENCE

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1 GCSE Science Single Award for CCEA

Answers to Revision questions

Unit 1 Biology1 Food and energy1 Add Benedict’s solution to the food (solution) [1]; and heat in a water

bath [1]; if sugar is present the solution will change from blue to brick-red [1] [3]

2 Carbon dioxide [1]; water [1] [2]

3 If the leaf had not been destarched all the leaf would be coloured blue-black after iodine was added [1]

It would not have been possible to show that light is necessary for photosynthesis [1] [2]

4 Count the number of oxygen bubbles given off with the lamp in one position [1]; for a set period of time [1]; move the lamp closer to or further away from the beaker and repeat [1] [3]

5 a) Sun [1]

b) grass/plants → seed-eating birds → bird of prey; or

grass/plants → cattle and sheep → man; or

grass/plants → rabbits → foxes

correct chain [1] arrows correct [1]

c) 4 [1]

d) Decrease [1]; as the numbers of insect-eating birds and frogs would increase [1] [6]

1827075_ANS_GCSE_Science_001-006.indd 1 13/08/14 6:09 PM


2 Chromosomes and genes1 base; gene; chromosome; nucleus; cell [1]

2 a) Organism Adenine Guanine Cytosine Thymine

A 20% 30% 30% 20%

B 36% 14% 14% 36%

All five correct [3]; three or four correct [2]; one or two correct [1]

b) Three bases on coding strand [1]; code for one amino acid [1]; sequence of amino acids determines protein structure [1] [6]

3 If homozygous both alleles (of a gene) are the same [1]; if heterozygous the two alleles are different [1] [2]

4 a)

T t

T TT Tt

t Tt tt

Gametes correct [1]; correct offspring [1]

b) Genotypes – TT : Tt : Tt : tt [1] Phenotypes – tall : tall : tall : short [1] [4]

5 a) Two [1]

b) Every generation has it / if rare, unlikely that 5 and 8 are carriers [1]

c) Both parents must be heterozygous (otherwise all children would have condition) [1] Each parent passes 50% normal alleles and 50% Huntington alleles [1]; 50% chance of child having condition as shown by pedigree diagram [1] [5]

6 a) Checking the DNA/genes of a foetus/individual for presence of genetic condition [1]

b) Down syndrome / cystic fibrosis [1] [2]

7 a) The transfer of DNA/gene [1]; from one species to another [1]

b) Any two from:

• can provide pesticide resistance / reduced expenditure on pesticides / less pollution from pesticides

• can provide high-quality foods (e.g. more nutritious, better flavour)

• can produce crops that can grow in a wider range of environments / higher yields [2] [4]

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3 Nervous system and hormones1 Reflexes are faster [1]; they do not involve thinking time [1] [2]

2 a) Phototropism [1]

b) Hormones / auxin [1]

c) Any two from: more light; more photosynthesis; more growth [2] [4]

3 a) X – ovary [1]; Y– vagina [1]

b) Oviduct [1]

c) Grows in size / develops a thick lining [1]

d) i) Both oviducts [1]; are cut [1]

ii) Is permanent/ very difficult or impossible to reverse [1] [7]

4 a) i) Peak in oestrogen is just before ovulation [1]

ii) Begins repair / build-up of uterine lining [1]

b) i) Progesterone [1]

ii) Completes build-up / maintains uterine lining [1] [4]

5 a)

Symptom Long-term effect

glucose in urine

thirst

eye damage

stroke

half mark each – round down [2]

b) Any three from: lifelong condition; many people have diabetes; cost of insulin; cost of treating long-term complications [3] [5]


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4 Adaptation and variation1 a) Discontinuous variation is variation in which individuals can be

easily placed in a particular group / there is no overlap [1]

b) Tongue rolling / blood group / presence or absence of ear lobes / any appropriate answer [1] [2]

2 a) Mutations are random changes in the structure or number of chromosomes/genes/DNA [1]

b) UV light / other appropriate answer (e.g. X-rays, gamma radiation) [1]

c) Down syndrome [1] [3]

3 Any three from:

• copper-resistant plants have a copper-resistant gene / are better adapted

• copper-resistant plants are more likely to survive

• and pass genes on to the next generation / have offspring with the beneficial gene

• therefore the percentage of the copper-resistant plants increases over time [3]

4 Any two from:

• plant more bamboo forests

• conserve existing forests

• special breeding programmes in captivity [2]


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5 Disease and body defences1 a) Tube C [1]

Microorganisms can enter through open tube in C / cannot get in Tubes A or B [1] Microorganisms get trapped by the swan neck in B [1]

b) Any two from:

• the tubes and broth must be sterilised at the start

• the same type of broth must be used

• the tubes must be kept at the same temperature

• the tubes must be kept for the same length of time [2] [5]

2 Similarity – both active immunity and passive immunity involve antibodies [1]

Difference – in active immunity the antibodies are produced by the body but are not in passive immunity / active immunity is relatively slow to take effect (passive immunity works quickly) [1] [2]

3 Antibiotic works quickly / vaccination takes time to be effective [1]; antibiotics work against a range of bacteria [1] [2]

4 a) i) Testing on cells in the laboratory [1]

ii) Trial and error nature of process / expensive equipment / highly-trained scientists involved [1]

b) Argument for – testing on whole body systems / checking for side effects / avoids testing on humans at this stage Argument against – humans are different to animals / may have different side-effects [2]

c) i) An effect (apart from the desired effect) that a medicine or drug has on someone [1]

ii) The side-effects may be minor / the benefits of the medicine outweigh the side-effects [1] [6]

5 a) Nicotine [1]

b) Carbon monoxide in cigarette smoke combines with red blood cells (rather than oxygen) [1]

Less oxygen can be transported in the blood [1]

Less oxygen available for respiration [1] [4]


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6 Human activity on Earth1 The countries affected by acid rain are not necessarily the ones

producing the pollution [1]

2 a) Photosynthesis [1]

b) Fossilisation [1]

c) Increased combustion of fossil fuels / deforestation [1]; causes build-up of carbon dioxide in the atmosphere [1]; carbon dioxide / greenhouse layer traps heat escaping from the atmosphere [1]

d) Climate change / polar ice caps melting / flooding / more land becoming desert [1] [6]

3 a) Number of lichens increase as distance from the town increases [1]; more lichens in 2010 than in 1960 [1]

b) There is less pollution further away from the town / pollution levels are lower in 2010 than in 1960 [1]

c) Any two from: only beech trees were used; 5 trees investigated at each distance; lichens counted only between 1–3 metres on each tree [2]

d) Count more trees at each distance / more area of tree / count greater number of distances [1] [6]

4 Slurry contains nitrate [1]; could run off into waterways [1]; and cause excess algal growth / eutrophication [1] [3]

5 a) The range of species in an area [1]

b) Rare or endangered habitat / rare or endangered species present [1]

c) Prevent light reaching woodland flood [1]; prevent other species from growing [1]; reduces biodiversity [1] [5]


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Unit 2 Chemistry7 Acids and bases1 a) Red [1]

b) Universal indicator will distinguish between different strengths of acids [1]; with universal indicator, hydrochloric acid is red and vinegar (ethanoic acid) is orange / both acids are red with red cabbage dye [1]

c) Add chopped red cabbage to water [1]; boil / grind it using a mortar and pestle [1]; filter / remove cabbage and use remaining solution [1] [6]

2 a) 14 [1]

b) Neutralisation [1]

c) Shows all values over time / provides continuous data / if using universal indicator you could miss the point of neutralisation [1]

d) Burette [1] [4]

3 a) 3 [1]

b) 7 [1] [2]

4 a) Excess stomach acid [1]

b) Sodium hydrogencarbonate is an alkali/base [1]; which neutralises the acid [1]; forming sodium chloride, water and carbon dioxide [1]

c) There is a build-up of carbon dioxide [1] [5]

5 a) Sodium hydrogencarbonate + citric acid → sodium citrate + carbon dioxide + water [3]

b) Carbon dioxide [1] [4]

6 a) Sodium sulfate [1]

b) 2NaOH + H2SO4 → Na2SO4 + 2H2O

(lhs: ‘2’ before NaOH; rhs: ‘2’ before H2O) [2] [3]


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8 The world about us1 a) Tectonic plates in the Earth’s crust float on the denser mantle

below [1]; the plates move due to convection currents in the mantle [1]

b) i) Volcano – Y [1] ii) Mountain building – X [1]

c) Tectonic plates moving alongside / past each other [1]

d) Richter scale [1] [6]

2 a) Any three from: originally the Earth was one large land mass; the continents separated; and moved apart; over millions of years [3]

b) Continents fit together like a jigsaw puzzle [1]; the rocks / living organisms / fossils in adjacent parts (if continents were joined back together) match closely [1] [5]

3 a) Formed by small rock particles / debris / remains of dead plants / animals forming layers of sediment on the Earth’s surface [1]; these layers were compressed by the weight of more sediment deposited [1]; over millions of years [1]

b) Any two from: sandstone; limestone; or any appropriate example, e.g. chalk, mudstone [2] [5]

4 Any three from: igneous rocks can have radioisotopes; a named example, e.g. potassium; these decay at a fixed rate over time; the age of the rock can be estimated by comparing the proportion of undecayed nuclei and daughter (decayed) nuclei [3]


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9 Elements and compounds1 a) A electron shell [1]; B electron [1]; C neutron [1]

b) 3 [1]

c) 7 [1]

d) 2, 1 [1] [6]

2 a) 3 [1]

b) 5 [1] [2]

3 2K + 2H2O → 2KOH + H2 [1] balancing [2] [3]

4 a) Magnesium [1]

b) magnesium > zinc > copper [1]

c) → magnesium sulfate [1] + copper [1]

d) Displacement [1]

e) Magnesium dissolves / disappears [1]; it forms magnesium sulfate [1]

or blue copper(II) sulfate loses its colour [1]; the copper is displaced [1]

or copper metal forms [1]; it is displaced from the copper(II) sulfate [1] [7]

5 a) Elements [1]

b) A alkali metals [1]; B alkaline earth metals [1]; C noble gases [1]

c) Period 4 [1]

d) 2 [1] [6]

6 Any five from: electron transferred; from sodium to chlorine; forms sodium ion (Na+) because there are more protons than electrons (after transfer); forms chloride ions (Cl-) because there are fewer protons than electrons (after transfer); sodium and chloride ions combine (attracted to each other); the sodium ions and chloride ions have full outer shells [5]


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10 Oil, polymers and materials1 Compounds containing carbon and hydrogen [1]; only [1] [2]

2 a) Heating crude oil [1]; fractions/hydrocarbons condense at their different boiling points [1]; and are separated as different products [1]

b) Any three of: petrol, diesel, refinery gas, naphtha, paraffin, fuel oil / lubricating oil, bitumen [3]

c) Any one from: refinery gas – fuel for gas ovens, LPG, chemicals; petrol – for vehicles, chemicals; naphtha – chemicals; paraffin – for heating, jet engines, chemicals; diesel – fuel for diesel engines, fuel oil/lubricating oil – fuel for ships, factories, central heating, lubricants and waxes; bitumen/tar – roofing, waterproofing, asphalt on roads [1] [7]

3 a)

H

HC

H

H

H C

H [1]

b) C2H6 + O2 → CO2 + H2O [1 for products]

2C2H6 + 7O2 → 4CO2 + 6H2O [1 for balancing] [3]

4 a) Any two from: hard; high melting point; unreactive [2]

b) Any two from: good conductor of heat; strong/hard; high melting point [2] [4]

5 a) The joining of many (similar) small molecules/monomers [1]; to make larger molecules/polymers [1]

b)

H H

n CC

H H

ethenemonomer

polythenepolymer

H n

C

H

C

H H

single bond [1]; brackets [1]; correct position of ‘n’ [1] [5]

6 a) Nanotechnology involves extremely small particles / 1–100 nm [1]; that have different properties compared with the ‘normal-sized’ materials [1]

b) Wound dressings / sterilising spray / sun cream [1] [3]

7 a) The use of electricity [1]; to break down compounds [1]

b) carbon/graphite [1]; negatively [1]; oxygen [1]

c) Al3+ + 3e- [1] → Al [1] [7]


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11 Hard water, recycling and exploitation of Earth’s resources

1 a) C [1]

b) D [1]

c) A [1]

d) B [1]

e) i) magnesium hydrogencarbonate → magnesium carbonate + carbon dioxide + water [3]

ii) Using heat [1]; to break a compound down [1] [9]

2 Boil the water until it evaporates [1]; the compounds causing hardness are left behind/do not evaporate [1]; the condenser cools the water vapour and it condenses as soft water [1] [3]

3 a) Ca(HCO3)2 → CaCO3 [1] + CO2 [1] + H2O [1]

b) Add hydrochloric acid [1]; to the calcium carbonate [1]; it breaks down to calcium chloride, carbon dioxide and water [1] [6]

4 a) 45 - 15 [1]; 30 ÷ 15 × 100 = 200% [1]

b) Any one from: many resources are non-renewable; save energy; reduce global warming (from energy production); reduce landfill [1]

c) Biodegrades to form compost [1] [4]

5 The glass is collected / transported to a reprocessing centre [1]; broken up into cullet [1]; it is melted and remoulded to form new glass products [1] [3]


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12 Using materials to fight crime1 Dust with aluminium powder [1]; brush off excess powder [1]; press

sticky tape against the fingerprint [1]; transfer to a black card [1] [4]

2 a) Any two from: the proportions of different types of fibre; the type of weave/knitted pattern; the colour of the fibres; any stains e.g. sweat [2]

b) The fibres are not unique / fingerprints are unique [1] [3]

3 a) Any three from: fitting alarm systems; keeping doors and windows locked; marking valuables with a security pen; cancelling papers/deliveries when on holiday; asking neighbours to keep an eye on the house when away [3]

b) Any three from: the special quality of the paper used in making banknotes; the hologram; watermarks; bar codes; the metal strip; special ink [3] [6]

4 Metal Flame colour

lithium red [1]

sodium [1] orange-yellow

potassium lilac [1] [3]


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Unit 3 Physics13 Electrical circuits1 a) Circuit B [1]

b) In circuit A, 3 V [1]; the voltage is shared between the bulbs in a series circuit [1]

In circuit B, 6 V [1]; the bulbs in a parallel circuit get the full voltage [1]

c) In circuit A, the current will stop flowing and neither bulb will light [1]

In circuit B, bulb 2 will go out but bulb 1 will stay lit [1] [7]

2 Connect an ammeter [1]; in series [1] [2]

3 Resistance = 51.25

[1]; = 4 ohms [1] [2]

4 a) Any four from: set up a circuit with cell/battery and wire (e.g. nichrome); measure the voltage across the resistance wire using a voltmeter connected in parallel; measure the current using an ammeter connected in series; calculate the resistance using R = V

I ; repeat for different thicknesses of wire [4]

b) Any two from: same type of wire; same length of wire; same battery [2] [6]


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14 Household electricity1 a) Casing made of plastic [1]; cable grip holds cable in place [1]; fuse

melts if the current gets too high [1]

b) To provide little resistance allowing current to flow quickly to earth [1] [4]

2 a) As the number of cells in the battery increases, the voltage / current increases [1]

b) 4 W (8 × 0.5) [1] [2]

3 a) Moving a magnet [1]; in a coil of wire [1]

b) Rotates/spins when driven by steam from a boiler [1]; which turns the generator that produces electricity [1] [4]

4 Energy = 3.5 kW × 24 [1]; = 84 kWh [1]

Cost = 84 × 15 = 1260 p / £12.60 [units needed] [1] [3]

5 a) X – national grid [1]; Y − step-down transformer [1]

b) Increases voltage [1]; decreases current [1]; to reduce energy/heat loss [1] [5]


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15 Waves and communication1 a) 4 m [1]

b) 10 m [1]

c) 5 ÷ 10 s [1]; = 0.5 Hz [1]

d) Hertz / Hz [1]

e) The particles vibrate [1]; at right angles to the direction of wave travel [1] [7]

2 a) 1500 m/s × 5 s = 7500 m [1]; ÷ 2 = 3750 m [1]

b) One of: echo reflected from a shoal of fish; a submarine [1]

c) wavelength = speedfrequency

[1]; = 150025 000

[1]; = 0.06 m [1] [6]

3 a) Ultraviolet [1]; infrared [1] (correct positions)

b) Any one of: they carry energy; travel as transverse waves; travel at the same speed through a vacuum [1]

c) Damage cells / cause cancer [1] [4]

4 Signal sent as microwaves [1]; to the nearest mast [1]; signal relayed from mast to mast / repeater stations / cells [1] [3]


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16 Vision1 Converging lenses refract light rays [1]; causing them to converge [1] [2]

2 Light entering the eye is refracted at the cornea [1]; further refraction takes place at the lens [1]; most refraction takes place at the cornea [1] [3]

3 a) The eye lens is too weak / converges light rays too little [1]; the focal point is behind the retina [1]

b) Long sight [1]

c) Supporting a convex lens in front of the eye [1] [4]

4 a) The eye lens is too strong [1]

b) Light rays are focused in front of the retina [1]

c) Supporting a diverging/concave lens in front of the eye [1] [3]


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17 Energy1 a) Remains of plants/animals [1]; subjected to pressure/compression

[1]; for millions of years [1]

b) They are non-renewable / running out [1]; they release carbon dioxide when burned / contribute to global warming [1] [5]

2 a) 412

[1]; 0.25 / 25% [1]

b) They are more efficient [1]; they use less electricity/energy [1]

c) As heat [1] [5]

3 created [1]; destroyed [1]; transformed [1] [3]


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18 Transport and road safety1 a)

Speed/mphThinking distance/m

Braking distance/m

Stopping distance/m

25 7 14 21

50 15 40 55 [1]

75 24 [1] 80 104

b) As speed increases, the stopping distance increases (or converse) [1]

c) Any two from: state of road (dry, wet or ice, or surface type); condition of tyres; condition of brakes [2] [5]

2 a) Any two from: airbags; crumple zones; rigid passenger cells [2]

b) i) Cars travel slower [1]; less likely to be involved in a collision / injuries are less likely to be serious [1]

ii) Any one from: increases emergency response time; more fuel is used in accelerating and decelerating; more brake or tyre wear [1] [5]

3 a) 90 m [1]

b) B [1]

c) A [1]; B stopped for 30 s [1]; A stopped for 60 s [1]

d) average speed = 120180

[1]; = 0.67 m/s [1] [7]

4 Momentum = (50 + 15) × 20 [1]; = 1300 [1] kg m/s [1] [3]

5 a) Resultant (forward) force = forward force + frictional force [1]; = 5000 + 10 000 = 15 000 N [1]

b) i) The car is accelerating [1]

ii) Reduce the forward force by reducing acceleration / increase the frictional force by braking [1] [4]


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19 Radioactivity1 They have an unstable nucleus / unstable combinations of protons and

neutrons [1]; causing the nuclei to decay/disintegrate [1] [2]

2 a) Radiation that is (naturally) all around us [1]

b) Any one of: radon / carbon-14 / cosmic rays / nuclear reactors [1] [2]

3 a) Radioactivity / counts per minute decreases over time [1]

b) 2 days [1] [2]

4 a) Put sheets of paper, then aluminium, then lead between the source and the detector [1]; if paper reduces the count the source is alpha [1]; if paper has no effect but aluminium does it is beta [1]; if neither paper nor aluminium has an effect but lead does, it is gamma [1]

b) Any two from: same source; same distance between source and detector; source placed in same position [2]

c) There is always background radiation [1] [7]

5 a) It can to penetrate the body [1]; killing cancer cells [1]

b) Sterilise surgical instruments / preserve perishable fresh food [1] [3]


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20 The Earth in space1 a) Planets [1]

b) Moons [1]

c) Galaxies [1] [3]

2 a) Mercury [1]

b) Mars is closer to the Sun than Neptune [1]

c) Heliocentric [1] [3]

3 The Moon is smaller than the Earth [1]; gravity is less [1]; the smaller the gravity, the less the weight (or converse) [1] [3]

4 a) The distance [1]; light travels in one year [1]

b) Distances in space are so large that using normal units of length would be meaningless / bigger unit [1] [3]

5 a) star < Solar System < galaxy < Universe [1]

b) i) Red-shift [1]

ii) Galaxy B is further away than galaxy A / is travelling faster [1]

iii) Lines would be to the left of both galaxy A and B [1]; no red-shift [1]; because the Milky Way is closer / our galaxy [1] [6]


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Answers to Revision questions Answers Unit 1 Biology€¦ · · 2015-10-22Answers 1 Answers to Revision questions ... environments / higher yields [2] [4] CCEA GCSE SCIENCE