CCEA GCSE SCIENCE Biology Answers 1 GCSE Science Single Award for CCEA Answers to Revision questions Unit 1 Biology 1 Food and energy 1 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]
20
Embed
Answers to Revision questions Answers Unit 1 Biology€¦ · · 2015-10-22Answers 1 Answers to Revision questions ... environments / higher yields [2] [4] CCEA GCSE SCIENCE ...
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
CCEA
GC
SE S
CIEN
CE
Bi
olog
y A
nsw
ers
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]
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]
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]
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]
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]
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]
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]
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]
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]
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]
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]
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]
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]