C3 Specification

Module C3: Chemicals in our lives – risks and benefits

C3.1 What were the origins of minerals in Britain that contribute to our economic wealth?

1. understand that geologists explain most of the past history of the surface of the Earth in terms

of processes than can be observed today

2. understand that movements of tectonic plates mean that the parts of ancient continents that

now make up Britain have moved over the surface of the Earth

3. understand how geologists use magnetic clues in rocks to track the very slow movement of

the continents over the surface of the Earth

4. understand that the movements of continents means that different rocks in Britain formed in

different climates

5. understand how processes such as mountain building, erosion, sedimentation, dissolving and

evaporation have led to the formation of valuable resources found in England including coal,

limestone and salt

6. understand how geologists study sedimentary rocks to find evidence of the conditions under

which they were formed, to include:

a. fossils

b. shapes of water borne grains compared to air blown grains

c. presence of shell fragments

d. ripples from sea or river bottom

7. understand that chemical industries grow up where resources are available locally, eg salt,

limestone and coal in north west England.

C3.2 Where does salt come from and why is it so important?

1. understand the importance of salt (sodium chloride) for the food industry, as a source of

chemicals and to treat roads in winter

2. recall that salt can be obtained from the sea or from underground salt deposits

3. understand how underground salt can be obtained by mining, or by solution in water

4. understand why the method used to obtain salt may depend on how the salt is to be used

5. understand how the methods of obtaining salt can have an impact on the environment

6. understand the advantages of adding salt to food as flavouring and as a preservative

7. recall the health implications of eating too much salt

8. be able to evaluate data related to the content of salt in food and health

9. recall that Government departments, such as the Department of Health and the Department

for Environment, Food and Rural Affairs, have a role in:

a. carrying out risk assessments in relation to chemicals in food

b. advising the public in relation to the effect of food on health.

C3.3 Why do we need chemicals such as alkalis and chlorine and how do we make them?

1. recall that, even before industrialisation, alkalis were needed to neutralise acid soils, make

chemicals that bind natural dyes to cloth, convert fats and oils into soap and to manufacture

glass

2. recall that traditional sources of alkali included burnt wood or stale urine

3. understand that alkalis neutralise acids to make salts

4. recall that soluble hydroxides and carbonates are alkalis

5. predict the products of the reactions of soluble hydroxides and carbonates with acids

6. understand that increased industrialisation led to a shortage of alkali in the nineteenth century

7. understand that the first process for manufacturing alkali from salt and limestone using coal

as a fuel caused pollution by releasing large volumes of an acid gas (hydrogen chloride) and

creating great heaps of waste that slowly released a toxic and foul smelling gas (hydrogen

sulfide)

8. understand that pollution problems can sometimes be solved by turning wastes into useful

chemicals

9. understand that oxidation can convert hydrogen chloride to chlorine, and that the properties of

a compound are completely different from the elements from which it is made

10. recall that chlorine is used to kill microorganisms in domestic water supplies and as a bleach

11. understand how the introduction of chlorination to treat drinking water made a major

contribution to public health

12. interpret data about the effects of polluted water on health and the impact of water treatment

with chlorine to control disease

13. understand that there may be disadvantages of chlorinating drinking water, including possible

health problems from traces of chemicals formed by reaction of chlorine with organic materials

in the water

14. understand that an electric current can be used to bring about chemical change and make

new chemicals through a process called electrolysis

15. recall that chlorine is now obtained by the electrolysis of salt solution (brine)

Technical details and the ionic reactions are not required

16. recall examples of important uses by industry of the sodium hydroxide, chlorine and hydrogen

produced by electrolysis of brine

17. interpret data about the environmental impact of the large scale electrolysis of brine.

C3.4 What can we do to make our use of chemicals safe and sustainable?

1. understand that there is a large number of industrial chemicals with many widespread uses,

including consumer products, for which there is inadequate data to judge whether they are

likely to present a risk to the environment and/or human health

2. understand that some toxic chemicals cause problems because they persist in the

environment, can be carried over large distances, and may accumulate in food and human

tissues

3. recall that PVC is a polymer that contains chlorine as well as carbon and hydrogen

4. understand that the plasticizers used to modify the properties of PVC can leach out from the

plastic into the surroundings where they may have harmful effects

5. understand that a Life Cycle Assessment (LCA) involves consideration of the use of resources

including water, the energy input or output, and the environmental impact, of each of these

stages:

a. making the material from natural raw materials

b. making the product from the material

c. using the product

d. disposing of the product

6. when given appropriate information from a Life Cycle Assessment (LCA), compare and

evaluate the use of different materials for the same purpose.

© OCR 2011 GCSE Science A

C2 Specification

Module C2: Material choices

C2.1 How do we measure the properties of materials and why are the results useful?

1. interpret information about how solid materials can differ with respect to properties such as

melting point, strength (in tension or compression), stiffness, hardness and density

2. relate properties to the uses of materials such as plastics, rubbers and fibres

3. relate the effectiveness and durability of a product to the materials used to make it

4. interpret information about the properties of materials such as plastics, rubbers and fibres to

assess the suitability of these materials for particular purposes.

C2.2 Why is crude oil important as a source of new materials such as plastics and fibres?

1. recall that the materials we use are chemicals or mixtures of chemicals, and include metals,

ceramics and polymers

2. recall that materials can be obtained or made from living things, and give examples such as

cotton, paper, silk and wool

3. recall that there are synthetic materials that are alternatives to materials from living things

4. recall that raw materials from the Earth’s crust can be used to make synthetic materials

5. interpret representations of rearrangements of atoms during a chemical reaction

6. understand that in a chemical reaction the numbers of atoms of each element must be the

same in the products as in the reactants

7. recall that crude oil consists mainly of hydrocarbons, which are chain molecules of varying

lengths made from carbon and hydrogen atoms only

8. recall that only a small percentage of crude oil is used for chemical synthesis and that most is

used as fuels

9. understand that the petrochemical industry refines crude oil by fractional distillation;

hydrocarbons are separated into fractions of different boiling points, to produce fuels,

lubricants and the raw materials for chemical synthesis

10. relate the size of the forces between hydrocarbon molecules to the size of the molecules

11. relate the strength of the forces between hydrocarbon molecules in crude oil to the amount

of energy needed for them to break out of a liquid and form a gas, and to the temperature at

which the liquid boils

12. understand that some small molecules called monomers can join together to make very long

molecules called polymers, and that the process is called polymerisation

13. recall two examples of materials that, because of their superior properties, have replaced

materials used in the past.

C2.3 Why does it help to know about the molecular structure of materials such as plastics and fibres?

1. understand that it is possible to produce a wide range of different polymers with properties that

make them each suited to a particular use

2. understand how the properties of polymers depend on how their molecules are arranged and

held together

3. relate the strength of the forces between the molecules in a polymer to the amount of energy

needed to separate them from each other, and therefore to the strength, stiffness, hardness

and melting point of the solid

4. understand how modifications in polymers produce changes to their properties (see C2.1), to

include modifications such as:

a. increased chain length

b. cross-linking

c. the use of plasticizers

d. increased crystallinity.

C2.4 What is nanotechnology and why is it important?

1. recall that nanotechnology involves structures that are about the same size as some

molecules

2. understand that nanotechnology is the use and control of structures that are very small (1 to

100 nanometres in size)

3. understand that nanoparticles can occur naturally (for example in seaspray), by accident (for

example as the smallest particulates from combustion of fuels), and by design

4. understand that nanoparticles of a material show different properties compared to larger

particles of the same material, and that one of the reasons for this is the much larger surface

area of the nanoparticles compared to their volume

5. understand that nanoparticles can be used to modify the properties of materials, and give

examples including:

a. the use of silver nanoparticles to give fibres antibacterial properties

b. adding nanoparticles to plastics for sports equipment to make them stronger

6. understand that some nanoparticles may have harmful effects on health, and that there is

concern that products with nanoparticles are being introduced before these effects have been

fully investigated.

© OCR 2011 GCSE Science A

C1 Specification

Module C2: Air Quality

C1.1 Which chemicals make up air, and which ones are pollutants? How do I make sense of data about air pollution?

1. recall that the atmosphere (air) that surrounds the Earth is made up mainly of nitrogen, oxygen

and argon, plus small amounts of water vapour, carbon dioxide and other gases

2. understand that air is a mixture of different gases consisting of small molecules with large

spaces between them

3. recall that the relative proportions of the main gases in the atmosphere are approximately 78%

nitrogen, 21% oxygen and 1% argon

4. understand that other gases or particulates may be released into the atmosphere by human

activity or by natural processes (eg volcanoes), and that these can affect air quality

5. understand how the Earth’s early atmosphere was probably formed by volcanic activity and

consisted mainly of carbon dioxide and water vapour

6. understand that water vapour condensed to form the oceans when the Earth cooled

7. explain how the evolution of photosynthesising organisms added oxygen to, and removed

carbon dioxide from, the atmosphere

8. explain how carbon dioxide was removed from the atmosphere by dissolving in the oceans

and then forming sedimentary rocks, and by the formation of fossil fuels

9. understand how human activity has changed the composition of the atmosphere by adding:

a. small amounts of carbon monoxide, nitrogen oxides and sulfur dioxide to the

atmosphere

b. extra carbon dioxide and small particles of solids (eg carbon) to the atmosphere

10. understand that some of these substances, called pollutants, are directly harmful to humans

(eg carbon monoxide reduces the amount of oxygen that blood can carry), and that some are

harmful to the environment and so cause harm to humans indirectly (eg sulfur dioxide causes

acid rain).

C1.2 What chemical reactions produce air pollutants? What happens to these pollutants in the atmosphere?

1. recall that coal is mainly carbon

2. recall that petrol, diesel fuel and fuel oil are mainly compounds of hydrogen and carbon

(hydrocarbons)

3. understand that, when fuels burn, atoms of carbon and/or hydrogen from the fuel combine

with atoms of oxygen from the air to produce carbon dioxide and/or water (hydrogen oxide)

4. understand that a substance chemically combining with oxygen is an example of oxidation,

that loss of oxygen is an example of reduction, and that combustion reactions therefore

involve oxidation

5. understand that fuels burn more rapidly in pure oxygen than in air

6. recall that oxygen can be obtained from the atmosphere and can be used to support

combustion (eg in oxy-fuel welding torches)

7. understand that in a chemical reaction the properties of the reactants and products are

different

8. understand that atoms are rearranged during a chemical reaction

9. interpret representations of the rearrangement of atoms during a chemical reaction

10. understand that during the course of a chemical reaction the numbers of atoms of each

element must be the same in the products as in the reactants, thus conserving mass

11. understand how sulfur dioxide is produced if the fuel that is burned contains any sulfur

12. understand how burning fossil fuels in power stations and for transport pollutes the

atmosphere with:

a. carbon dioxide and sulfur dioxide

b. carbon monoxide and particulate carbon (from incomplete burning)

c. nitrogen oxides (from the reaction between atmospheric nitrogen and oxygen at the high

temperatures inside engines)

13. relate the formulae for carbon dioxide CO2, carbon monoxide CO, sulfur dioxide SO2,

nitrogen monoxide NO, nitrogen dioxide NO2 and water H2O to visual representations of their

molecules

14. recall that nitrogen monoxide NO is formed during the combustion of fuels in air, and

is subsequently oxidised to nitrogen dioxide NO2 (NO and NO2 are jointly referred to as

‘NOx’)

15. understand that atmospheric pollutants cannot just disappear, they have to go somewhere:

a. particulate carbon is deposited on surfaces, making them dirty

b. sulfur dioxide and nitrogen dioxide react with water and oxygen to produce acid rain

which is harmful to the environment

c. carbon dioxide is used by plants in photosynthesis

d. carbon dioxide dissolves in rain water and in sea water.

C1.3 What choices can we make personally, locally, nationally or globally to improve air

quality?

1. understand how atmospheric pollution caused by power stations that burn fossil fuels can be

reduced by:

a. using less electricity

b. removing sulfur from natural gas and fuel oil

c. removing sulfur dioxide and particulates from the flue gases emitted by coal-burning

power stations

2. understand how the acid gas sulfur dioxide is removed from flue gases by wet

scrubbing:

a. using an alkaline slurry eg a spray of calcium oxide and water

b. using sea water

Candidates are not required to write word or symbol equations

3. understand that the only way of producing less carbon dioxide is to burn less fossil fuels

4. understand how atmospheric pollution caused by exhaust emissions from motor vehicles can

be reduced by:

a. burning less fuel, for example by having more efficient engines

b. using low sulfur fuels

c. using catalytic converters (in which nitrogen monoxide is reduced to nitrogen by loss of

oxygen, and carbon monoxide is oxidised to carbon dioxide by gain of oxygen)

d. adjusting the balance between public and private transport

e. having legal limits to exhaust emissions (which are enforced by the use of MOT tests)

5. understand the benefits and problems of using alternatives to fossil fuels for motor

vehicles, limited to biofuels and electricity.

© OCR 2011 GCSE Science A

Physics Questions

XKCD What If is a brilliant website by a NASA physicist turned cartoonist where he investigates questions sent in by various readers.

There are quite a few about falling objects and various changes in momentum, so they link well to P4 - Explaining Motion. Here are a few examples:
http://what-if.xkcd.com/51/ - What place on Earth would allow you to freefall the longest by jumping off it?

http://what-if.xkcd.com/44/ - How high can a human throw something?

http://what-if.xkcd.com/39/  - How hard would a puck have to be shot to be able to knock the goalie himself backwards into the net?

http://what-if.xkcd.com/28/ - From what height would you need to drop a steak for it to be cooked when it hit the ground?

http://what-if.xkcd.com/18/ - What would it take to stop an out-of-control freight train using only b.b. guns?

B3 Specification

Module B3: Life on Earth

B3.1 Systems in balance – how do different species depend on each other?

1. understand that a species is a group of organisms that can breed together to produce fertile

offspring

2. understand that adaptation of living organisms to their environment increases the species’

chance of survival by making it more likely that individuals will survive to reproduce

3. recall, and recognise when given relevant data, examples of how different organisms are

adapted to their environment, and explain how the adaptations increase the organism’s

chance of surviving to successfully reproduce

4. understand that living organisms are dependent on the environment and other species for

their survival

5. understand that there is competition for resources between different species of animals or

plants in the same habitat

6. relate changes affecting one species in a food web to the impact on other species that are part

of the same food web

7. explain the interdependence of living organisms by using food webs

8. understand that a change in the environment may cause a species to become extinct, for

example, if:

 a. the environmental conditions change beyond its ability to adapt

 b. a new species that is a competitor, predator or disease organism of that species is

introduced

 c. another species (animal, plant or microorganism) in its food web becomes extinct

9. understand that nearly all organisms are ultimately dependent on energy from the Sun

10. recall that plants absorb a small percentage of the Sun’s energy for the process of

photosynthesis

11. recall that this absorbed energy is stored in the chemicals which make up the plants’ cells

12. understand that energy is transferred between organisms in an ecosystem:

 a. when organisms are eaten

 b. when dead organisms and waste materials are fed on by decay organisms

(decomposers and detritivores)

13. explain how energy passes out of a food chain at each stage via heat, waste products and

uneaten parts, limiting the length of food chains

14. calculate from given data the percentage efficiency of energy transfer at different stages of a

food chain

15. understand how carbon is recycled through the environment to include the processes of

combustion, respiration, photosynthesis and decomposition

16. understand the importance of the role of microorganisms in the carbon cycle

17. understand how nitrogen is recycled through the environment in the processes of:

 a. nitrogen  fixation to form nitrogen compounds including nitrates

 b. conversion of nitrogen compounds to protein in plants and animals

 c. transfer of nitrogen compounds through food chains

 d. excretion, death and decay of plants and animals resulting in release of nitrates into the

soil

 e. uptake of nitrates by plants

 f. denitrification

  Foundation tier candidates are not expected to recall details of conversion of

atmospheric nitrogen to nitrates, or nitrates to atmospheric nitrogen

18. understand the importance of the role of microorganisms in the nitrogen cycle, including

decomposition, nitrogen  fixation and denitrification

19. interpret simple diagrams of the carbon cycle and nitrogen cycle

  Foundation tier candidates are not expected to recall nitrogen  fixation or denitrification

20. understand how environmental change can be measured using non-living indicators, including

nitrate levels, temperature and carbon dioxide levels

21. understand how climate and environmental change can be measured using living indicators,

including phytoplankton, lichens and aquatic river organisms such as may y nymphs

22. interpret data obtained from living and non-living indicators to investigate environmental

change.

B3.2 How has life on Earth evolved?

1. recall that life on Earth began approximately 3500 million years ago

2. understand that life on Earth (including species that are now extinct) evolved from very simple

living things

3. understand that there is variation between individuals of the same species and that some of

this variation is genetic so can be passed on to offspring

4. understand that genetic variation is the result of changes that occur in genes (mutations)

5. understand that mutated genes in sex cells can be passed on to offspring and may

occasionally produce new characteristics

6. understand the process of natural selection in terms of the effects of genetic variation and

competition on survival and reproduction, leading to an increase in the number of individuals

displaying beneficial characteristics in later generations

7. describe the similarities and differences between natural selection and selective breeding

8. interpret data on changes in a species in terms of natural selection

9. understand how the combined effect of mutations, environmental changes, natural selection

and isolation can produce new species in the process of evolution

10. understand that evidence for evolution is provided by the fossil record and from analysis of

similarities and differences in the DNA of organisms

11. understand that Darwin’s theory of evolution by natural selection was the result of many

observations and creative thought and why it is a better scientific explanation than Lamarck’s

(eg.  ts with advances in understanding of genetics, no evidence or mechanism for

inheritance of acquired characteristics).

B3.3 What is the importance of biodiversity?

1. understand that organisms are classified into groups according to similarities and differences

in characteristics including:

 a. physical features (eg  flowers in  flowering plants and the skeleton in vertebrates)

 b. DNA

  Candidates will not be expected to give examples of characteristics of particular

taxonomic groups

2. understand that organisms are classified at different levels, and that these levels can be

arranged in an order progressing from large groups containing many organisms with a

small number of characteristics in common (eg kingdom) to smaller groups containing fewer

organisms with more characteristics in common (eg species)

  Candidates will not be expected to recall the names of taxa other than kingdom and

species

3. understand that the classification of living and fossil organisms can help to:

 a. make sense of the enormous diversity of organisms on Earth

 b. show the evolutionary relationships between organisms

4. understand that biodiversity refers to the variety of life on Earth including:

 a. the number of different species

 b. the range of different types of organisms, eg plants, animals and microorganisms

 c. the genetic variation within species

5. understand why biodiversity is important for the future development of food crops and

medicines

6. understand that the rate of extinction of species is increasing and why this is likely to be due to

human activity

7. understand that maintaining biodiversity to ensure the conservation of different species is one

of the keys to sustainability

8. understand that sustainability means meeting the needs of people today without damaging the

Earth for future generations

9. understand that large-scale monoculture crop production is not sustainable because it does

not maintain biodiversity

10. describe and explain how sustainability can be improved, for example in the use of packaging

materials, by considering the materials used, energy used and pollution created

11. understand why it is preferable to decrease the use of some materials, including packaging

materials, even when they are biodegradable, because of:

 a. use of energy in their production and transport

 b. slow decomposition in oxygen deficient land fill sites.

© OCR 2012 GCSE Additional Science

B2 Specification

Module B2: Keeping Healthy

B2.1 How do our bodies resist infection?

1. understand that symptoms of an infectious disease are caused by damage done to cells by

microorganisms or the poisons (toxins) they produce

2. understand why, in suitable conditions such as those inside a human body, microorganisms

(eg bacteria and viruses) can reproduce rapidly to produce very large numbers

3. calculate the population growth of microorganisms given appropriate data

4. understand that white blood cells are part of the body’s immune system and can destroy

microorganisms by engulfing and digesting them or by producing antibodies

5. understand that antibodies recognise microorganisms by the antigens that they carry on their

surface, that different microorganisms have different antigens, and that a different antibody is

therefore needed to recognise each different type of microorganism

6. understand that once the body has made the antibody to recognise a particular

microorganism, memory cells can make that antibody again very quickly, therefore protecting

against that particular microorganism in the future (immunity).

B2.2 What are vaccines and antibiotics and how do they work?

1. understand that vaccinations provide protection from microorganisms by establishing memory

cells that produce antibodies quickly on re-infection

2. understand that a vaccine usually contains a safe form of a disease-causing microorganism

3. understand why, to prevent epidemics of infectious diseases, it is necessary to

vaccinate a high percentage of a population

4. understand that vaccines and drugs (medicines) can never be completely risk-free, since

individuals have varying degrees of side effects to them

5. understand that due to genetic differences, people react differently to drugs and vaccines

6. understand that chemicals called antimicrobials can be used to kill, or inhibit, bacteria, fungi

and viruses

7. recall that antibiotics are a type of antimicrobial that are effective against bacteria but not

viruses

8. understand that over a period of time bacteria and fungi may become resistant to

antimicrobials

9. understand that random changes (mutations) in the genes of these microorganisms

sometimes lead to varieties which are less affected by antimicrobials

10. understand that to reduce antibiotic resistance we should only use antibiotics when necessary

and always complete the course

11. understand that new drugs and vaccines are  first tested for safety and effectiveness using

animals and human cells grown in the laboratory

12. recall that human trials may then be carried out:

 a. on healthy volunteers to test for safety

 b. on people with the illness to test for safety and effectiveness

13. describe and explain the use of ‘open-label’, ‘blind’ and ‘double-blind’ human trials in

the testing of a new medical treatment

14. understand the importance of long-term human trials

15. understand the ethical issues related to using placebos in human trials.

B2.3 What factors increase the risk of heart disease?

1. describe the role of the heart as a double pump in the circulatory system

2. understand why heart muscle cells need their own blood supply

3. understand how the structure of arteries, veins and capillaries is related to their function

4. understand that heart rate can be measured by recording the pulse rate

5. understand that blood pressure measurements record the pressure of the blood on the walls

of the artery

6. understand that a blood pressure measurement is given as two numbers, the higher value

when the heart is contracting and the lower value when the heart is relaxed

7. understand that ‘normal’ measurements for factors such as heart rate and blood pressure are

given within a range because individuals vary

8. understand how fatty deposits in the blood vessels supplying the heart muscle can produce a

‘heart attack’

9. understand that heart disease is usually caused by lifestyle factors and/or genetic factors

10. understand that lifestyle factors that can increase the risk of heart disease include:

 a. poor diet

 b. stress

 c. cigarette smoking

 d. misuse of drugs

11. understand that regular moderate exercise reduces the risk of developing heart disease

12. relate differences in lifestyle factors in the UK and non-industrialised countries to the

prevalence of heart disease

13. understand how factors that can increase the risk of heart disease are identi ed via

epidemiological and large scale genetics studies

14. assess levels of heart disease risk, and actions that could be taken to reduce risk, when

provided with lifestyle and genetic data

15. understand that high blood pressure increases the risk of heart disease

16. understand that the misuse of drugs (eg Ecstasy, cannabis, nicotine and alcohol) can have an

adverse effect on health, including heart rate and blood pressure, increasing the risk of a heart

attack.

B2.4 How do our bodies keep a healthy water balance?

1. understand that nervous and hormonal communication systems are involved in maintaining a

constant internal environment (homeostasis)

2. understand that automatic control systems throughout the body maintain a range of factors at

steady levels and that this is required for cells to function properly

3. recall that these control systems have:

 a. receptors to detect changes in the environment

 b. processing centres to receive information and coordinate responses automatically

 c. effectors to produce the response

4. understand the principle of negative feedback

5. understand that negative feedback between the effector and the receptor of a control

system reverses any changes to the system’s steady state

6. understand that a balanced water level is important for maintaining the concentration of cell

contents at the correct level for cell activity

7. understand that water levels are controlled by balancing gains from drinks, food and

respiration and losses through sweating, breathing, faeces and the excretion of urine

8. understand that the kidneys play a vital role in balancing levels of water, waste and other

chemicals in the blood

  Candidates are not expected to recall details of kidney structure

9. understand that the kidneys balance water levels by producing dilute or concentrated urine

as a response to concentration of blood plasma, which is affected by external temperature,

exercise level and intake of  fluids and salt

10. understand that concentration of urine is controlled by a hormone called ADH, which is

released into the bloodstream by the pituitary gland

11. understand how ADH secretion is controlled by negative feedback

12. understand that alcohol results in the production of a greater volume of more dilute urine, due

to ADH suppression, which can lead to dehydration and adverse effects on health

13. understand that the drug Ecstasy results in a smaller volume of less dilute urine, due to

increased ADH production.

© OCR 2012 GCSE Additional Science

B1 Specification

Module B1: You and your genes

B1.1 What are genes and how do they affect the way that organisms develop?

1. recall that instructions to control how an organism develops and functions are found in the

nucleus of its cells and are called genes

2. recall that genes are instructions for a cell that describe how to make proteins

3. recall that proteins may be structural (eg collagen) or functional (eg enzymes such as

amylase)

4. recall that genes are sections of very long DNA molecules that make up chromosomes in the

nuclei of cells

5. understand that some characteristics are determined by genes (eg dimples), some are

determined by environmental factors (eg scars), and some are determined by a combination

of genes and the environment (eg weight)

6. understand that many characteristics are determined by several genes working together (eg

eye colour).

B1.2 Why can people look like their parents, brothers and sisters, but not be identical to them?

1. recall that body cells contain pairs of chromosomes and that sex cells contain only one

chromosome from each pair

2. understand that chromosomes in a pair carry the same genes in the same place, but that

there may be different versions of genes called alleles

3. recall that an individual usually has two alleles for each gene

4. recall that in an individual the two alleles of each gene can be the same (homozygous) or

different (heterozygous)

5. understand that during sexual reproduction genes from both parents come together and

produce variation in the offspring

6. understand that offspring have some similarities to their parents because of the combination of

maternal and paternal alleles in the fertilised egg

7. understand that different offspring from the same parents can differ from each other because

they inherit a different combination of maternal and paternal alleles

8. understand that an allele can be dominant or recessive, and that:

 a. an individual with one or both dominant alleles (in a pair of alleles) will show the

associated dominant characteristic

 b. an individual with one recessive allele (in a pair of alleles) will not show the associated

recessive characteristic

 c. an individual with both recessive alleles (in a pair of alleles) will show the associated

recessive characteristic

9. recall that human males have XY sex chromosomes and females have XX sex chromosomes

10. understand that the sex-determining gene on the Y chromosome triggers the

development of testes, and that in the absence of a Y chromosome ovaries develop

11. use and interpret genetic diagrams (family trees and Punnett squares) showing:

 a. the inheritance of single gene characteristics with a dominant and recessive allele

 b. the inheritance of sex chromosomes

12. understand that the term genotype describes the genetic make-up of an organism

(the combination of alleles), and the term phenotype describes the observable

characteristics that the organism has.

B1.3 How can and should genetic information be used? How can we use our knowledge of

 genes to prevent disease?

1. understand that a small number of disorders are caused by faulty alleles of a single gene,

including Huntington’s disease and cystic  brosis

2. recall that disorders may be caused by dominant alleles (eg Huntington’s disease) or

recessive alleles (eg cystic  fibrosis)

3. recall the symptoms of Huntington’s disease and cystic  fibrosis, to include:

 a. Huntington’s disease – late onset, tremor, clumsiness, memory loss, inability to

concentrate, mood changes

 b. cystic  fibrosis – thick mucus, dif culty breathing, chest infections, difficulty in digesting

food

4. understand that a person with one recessive allele (in a pair of alleles) will not show the

symptoms of the disorder, but is a carrier and can pass the recessive allele to their children

5. interpret through genetic diagrams (family trees and Punnett squares) the inheritance of a

single gene disorder, including the risk of a child being a carrier

6. describe uses of genetic testing for screening adults, children and embryos, limited to:

 a. testing embryos for embryo selection (pre-implantation genetic diagnosis)

 b. predictive testing for genetic diseases

 c. testing an individual before prescribing drugs

7. understand that testing adults and fetuses for alleles that cause genetic disorders has

implications that need to be considered, including:

 a. risk of miscarriage as a result of cell sampling for the genetic test

 b. using results that may not be accurate, including false positives and false negatives

 c. whether or not to have children at all

 d. whether or not a pregnancy should be terminated

 e. whether other members of the family should be informed

8. understand the implications of testing embryos for embryo selection prior to

implantation

9. understand the implications of the use of genetic testing by others (for example, for genetic

screening programmes by employers and insurance companies).

B1.4 How is a clone made?

1. understand that bacteria, plants and some animals can reproduce asexually to form clones

(individuals with identical genes)

2. understand that any differences between clones are likely to be due only to environmental

factors

3. understand that clones of plants occur naturally when plants produce bulbs or runners

4. understand that clones of animals occur:

 a. naturally, when cells of an embryo separate (identical twins)

 b. artificially, when the nucleus from an adult body cell is transferred to an empty

unfertilised egg cell

5. understand that there are different types of stem cells:

 a. adult stem cells which are unspecialised cells that can develop into many, but not all,

types of cells

 b. embryonic stem cells which are unspecialised cells that can develop into any type of cell

6. understand that, as a result of being unspecialised, stem cells from embryos and adults offer

the potential to treat some illnesses

7. understand that the majority of cells of multicellular organisms become specialised during the

early development of the organism.

© OCR 2012 GCSE Additional Science

Are 1p coins worth more than 1p?

When talking about C5 and metal purification, a student asked the question: if copper is so expensive, why do we make our lowest value coins from this metal?

The short answer is: we don't.  1p and 2p coins used to be about 97% copper, but as the metal became more expensive, the Royal Mint (the organisation that make the money we use) changed the materials they use to make these coins. Any coppers made after 1992 will be made from copper-plated steel (although in 1998 they did make some 2p coins from the 97% copper blend).

Steel is made with iron, and because iron is magnetic, the new coins should be attracted to a magnet, whereas the old coins will not.

So there you go.

General Revision sites

If you're struggling with a topic, or wanting to improve your knowledge and understanding, there are a number of websites designed to help Science revision:

BBC Bitesize: http://www.bbc.co.uk/schools/gcsebitesize/science/ Click on OCR 21st Century Science (Core or Additional) to get to topics you need

S-cool: http://www.s-cool.co.uk/gcse This website doesn't specifically follow the OCR specification, but the information is thorough and easy to read

Revision World: http://revisionworld.co.uk/gcse-revision This might be a little harder to navigate than the other resources, but the diagrams can be useful

GCSE Science: http://www.gcsescience.com/index.html Apparently approved by the UK government

Doc Brown: http://www.docbrown.info/index.htm The page layout will not be to everyone's taste. A focused look at the topics using the specification

C5 Specification

For classes that are currently studying C5 - Chemicals of the Natural Environment, the specification is below:

C5.1 What types of chemicals make up the atmosphere?

1. recall that dry air consists of gases, some of which are elements (for example, oxygen,

 nitrogen and argon) and some of which are compounds (for example, carbon dioxide)

2. recall that the relative proportions of the main gases in the atmosphere are about 78%

 nitrogen, 21% oxygen, 1% argon and 0.04% carbon dioxide

3. recall the symbols for the atoms and molecules of these gases in the air

4. recall that most non-metal elements and most compounds between non-metal elements are

 molecular

5. understand that molecular elements and compounds with small molecules have low melting

 and boiling points

6. interpret quantitative data (for example, melting and boiling points) and qualitative data about  

the properties of molecular elements and compounds

7. understand that molecular elements and compounds, such as those in the air, have low

melting and boiling points, and are gases at room temperature, because they consist of

small molecules with weak forces of attraction between the molecules

8. understand that pure molecular compounds do not conduct electricity because their

molecules are not charged

9. understand that bonding within molecules is covalent and arises from the electrostatic 

attraction between the nuclei of the atoms and the electrons shared between them

10. understand that covalent bonds are strong, in contrast to the weak forces of attraction

between small covalent molecules

11. translate between representations of molecules including molecular formulae, 2-D diagrams

in which covalent bonds are represented by lines, and 3-D diagrams for:

a. elements that are gases at 20°C

b. simple molecular compounds.

C5.2 What reactions happen in the hydrosphere?

1. recall that the Earth’s hydrosphere (oceans, seas, lakes and rivers) consists mainly of water

with some dissolved compounds, called salts

2. understand that the ions in crystals of a solid ionic compound are arranged in a regular way  

forming a lattice

3. understand that ions in a crystal are held together by forces of attraction between oppositely  

charged ions and that this is called ionic bonding

4. understand how the physical properties of solid ionic compounds (melting point, boiling  

point, electrical conductivity) relate to their bonding and giant, three-dimensional structures 

5. describe what happens to the ions when an ionic crystal dissolves in water

6. explain that ionic compounds conduct electricity when dissolved in water because the ions  

are charged and they are able to move around independently in the solution

7. work out the formulae for salts in seawater given the charges on ions (for example 

sodium chloride, magnesium chloride, magnesium sulfate, sodium sulfate, potassium 

chloride and potassium bromide)

8. understand that the ions in an ionic compound can be detected and identified because they  

have distinct properties and they form compounds with distinct properties

9. understand that an insoluble compound may precipitate on mixing two solutions of ionic  

compounds

10. be able to write ionic equations for precipitation reactions when given appropriate 

information

11. interpret given information on solubility to predict chemicals that precipitate on 

mixing solutions of ionic compounds

12. understand that some metal ions can be identified in solution by adding alkali because they  

form insoluble hydroxides with characteristic colours

13. interpret the results of adding aqueous sodium hydroxide to solutions of salts, given a data  

sheet of tests for positively charged ions and appropriate results

14. understand that some negative ions in salts can be identified in solution by adding a reagent  

that reacts with the ions to form an insoluble solid

15. interpret the results of tests for carbonate, chloride, bromide, iodide and sulfate ions given  

a data sheet of tests for negatively charged ions and appropriate results (using dilute acid,

lime water, silver nitrate and barium chloride or barium nitrate as the reagents).

C5.3 What types of chemicals make up the Earth’s lithosphere?

1. recall that the Earth’s lithosphere (the rigid outer layer of the Earth made up of the crust and  

the part of the mantle just below it) is made up of a mixture of minerals

2. recall that diamond and graphite are minerals, both of which are composed of carbon atoms 

3. explain the properties of diamond in terms of a giant structure of atoms held together by  

strong covalent bonding (for example, melting point, boiling point, hardness, solubility and  

electrical conductivity)

4. understand how the giant structure of graphite differs from that of diamond, and how this  

affects its properties

5. recall that silicon, oxygen and aluminium are very abundant elements in the Earth’s crust 

6. interpret data about the abundances of elements in rocks

7. recall that much of the silicon and oxygen is present in the Earth’s crust as the compound  

silicon dioxide

8. understand that silicon dioxide is another giant covalent compound and so has properties  

similar to diamond.

C5.4 How can we extract useful metals from minerals?

1. recall that ores are rocks that contain varying amounts of minerals from which metals can be  

extracted

2. understand that for some minerals, large amounts of ore need to be mined to recover small  

percentages of valuable minerals (for example, in copper mining)

3. recall that zinc, iron and copper are metals that can be extracted by heating their oxides with  

carbon, and write simple word equations for these reactions

 Technical details not required

4. understand that when a metal oxide loses oxygen it is reduced, while the carbon gains

oxygen and is oxidised

5. understand that some metals are so reactive that their oxides cannot be reduced by carbon

6. write word equations when given appropriate information

7. interpret symbol equations, including the number of atoms of each element, the number  

of molecules of each element or covalent compound and the number of ‘formulas’ of ionic  

compounds, in reactants and products

 In this context, ‘formula’ is used in the case of ionic compounds as an equivalent 

to molecules in covalent compounds; the concept of the mole is not covered in the 

specification

8. balance unbalanced symbol equations

9. write balanced equations, including the state symbols (s), (l ), (g) and (aq), when given 

appropriate information

10. recall the state symbols (s), (l ), (g) and (aq) and understand their use in equations 

11. use the Periodic Table to obtain the relative atomic masses of elements

12. use relative atomic masses to calculate relative formula masses

13. calculate the mass of an element in the gram formula mass of a compound

14. calculate the mass of the metal that can be extracted from a mineral given its formula 

or an equation

15. describe electrolysis as the decomposition of an electrolyte with an electric current

16. understand that electrolytes include molten ionic compounds

17. describe what happens to the ions when an ionic crystal melts

18. understand that, during electrolysis, metals form at the negative electrode and non-metals  

form at the positive electrode

19. describe the extraction of aluminium from aluminium oxide by electrolysis

20. understand that during electrolysis of molten aluminium oxide, positively charged 

aluminium ions gain electrons from the negative electrode to become neutral atoms

21. understand that during electrolysis of molten aluminium oxide, negatively charged 

oxide ions lose electrons to the positive electrode to become neutral atoms which 

then combine to form oxygen molecules

22. use ionic theory to explain the changes taking place during the electrolysis of a 

molten salt to account for the conductivity of the molten salt and the changes at the 

electrodes

23. understand that the uses of metals are related to their properties (limited to strength,  

malleability, melting point and electrical conductivity)

24. explain the physical properties of high strength and high melting point of metals in terms of a

giant structure held together by strong bonds (metallic bonding)

25. understand that in a metal crystal there are positively charged ions, held closely 

together by a sea of electrons that are free to move, and use this to explain the 

physical properties of metals, including malleability and conductivity

26. evaluate, given appropriate information, the impacts on the environment that can arise from  

the extraction, use and disposal of metals.

© OCR 2012 GCSE Additional Science