The glucose produced in photosynthesis may be:

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1 Bilgy - Cells Label diagrams f animal and plant cells. Describe the functin f the main rganelles. Prepare slides f plant and animal cells and describe the prcedure. Crrectly use a micrscpe t bserve cells under different magnificatins. Describe the rder f size f: cell, nucleus, chrmsme and gene. Explain the need fr differentiatin in a multicellular rganism. Describe the differences between differentiatin in plants and in animals. Explain hw specialised cells are adapted fr their functin. Describe where stem cells can be fund in animals and plants. Describe in simple terms hw nerve cells genetically identical t a patient culd be btained. Describe hw stem cells culd be used t help treat sme medical cnditins. Evaluate risks and benefits, as well as the scial and ethical issues cncerning the use f stem cells frm embrys in medical research and treatments. Define the term stem cell. Identify plant, animal and bacterial cells and classify them as eukarytic r prkarytic cells. Label diagrams f bacterial cells. Describe the differences between eukarytic and prkarytic cells in terms f structure and size. Describe the differences in magnificatin and reslutin f light and electrn micrscpes. Explain hw electrn micrscpy has increased understanding f rganelles. Calculate the magnificatin f a light micrscpe. Carry ut calculatins using the frmula: The glucse prduced in phtsynthesis may be: used fr respiratin cnverted int insluble starch fr strage used t prduce fat r il fr strage used t prduce cellulse, which strengthens the cell wall used t prduce amin acids fr prtein synthesis. T prduce prteins, plants als use nitrate ins that are absrbed frm the sil. Bilgy Earth Science and Resurces Fr 200 millin years, the prprtins f different gases in the atmsphere have been much the same as they are tday: abut fur-fifths (apprximately 80%) nitrgen abut ne-fifth (apprximately 20%) xygen small prprtins f varius ther gases, including carbn dixide, water vapur and nble gases. Theries abut what was in the Earth s early atmsphere, and hw the atmsphere was frmed, have changed and develped ver time. Evidence fr the early atmsphere is limited because f the time scale f 4.6 billin years. One thery suggests that during the first billin years f the Earth s existence there was intense vlcanic activity that released gases that frmed the early atmsphere and water vapur that cndensed t frm the ceans. At the start f this perid the Earth s atmsphere may have been like the atmspheres f Mars and Venus tday, cnsisting f mainly carbn dixide with little r n xygen gas. Vlcanes als prduced nitrgen which gradually built up in the atmsphere and there may have been small prprtins f methane and ammnia. When the ceans frmed, carbn dixide disslved in the water and carbnates were precipitated prducing sediments, reducing the amunt f carbn dixide in the atmsphere. Algae and plants prduced the xygen that is nw in the atmsphere by phtsynthesis, which can be represented by the equatin: Rearrange the equatin t calculate image size r magnificatin. Cnvert values fr the units: cm, mm, µm and nm. Describe what a chrmsme is and where chrmsmes are fund in the cell. Describe simply hw and why bdy cells divide by. Knwledge and understanding f the stages in mitsis are nt required. Draw simple diagrams t describe mitsis. Draw a simple diagram t describe the cell cycle in terms f: cell grwth, when the number f rganelles increases replicatin f chrmsmes, s the genetic material is dubled separatin f the chrmsmes: divisin f the nucleus divisin f the cell t frm tw identical cells. Define the term diffusin. Explain hw temperature, cncentratin gradient and surface area affect the rate f diffusin. Give examples f substances that diffuse int and ut f cells. Calculate and cmpare surface area: vlume ratis. Explain hw the small intestine and lungs in mammals, and rts and leaves in plants, are adapted fr exchange f substances. Describe and explain hw an exchange surface is made mre effective. Define the term smsis. Apply knwledge f smsis t unfamiliar situatins and make predictins. Bilgy: Phtsynthesis Phtsynthesis is represented by: Phtsynthesis is an endthermic reactin. Energy is transferred frm the envirnment t the chlrplast by light. The rate f phtsynthesis may be affected by: temperature level f carbn dixide light intensity amunt f chlrphyll. carbn dixide + water glucse + xygen Algae first prduced xygen abut 2.7 billin years ag and sn after this xygen appeared in the atmsphere. Over the next billin years plants evlved and the percentage f xygen gradually increased t a level that enabled animals t evlve. Greenhuse gases in the atmsphere maintain temperatures n Earth high enugh t supprt life. Water vapur, carbn dixide and methane are greenhuse gases. Sme human activities increase the amunts f greenhuse gases in the atmsphere. These include: carbn dixide methane Based n peer-reviewed evidence, many scientists believe that human activities will cause the temperature f the Earth s atmsphere t increase at the surface and that this will result in glbal climate change. An increase in average glbal temperature is a majr cause f climate change. The carbn ftprint is the ttal amunt f carbn dixide and ther greenhuse gases emitted ver the full life cycle f a prduct, service r event. The carbn ftprint can be reduced by reducing emissins f carbn dixide and methane The cmbustin f fuels is a majr surce f atmspheric pllutants. Mst fuels, including cal, cntain carbn and/r hydrgen and may als cntain sme sulfur. The gases released int the atmsphere when a fuel is burned may include carbn dixide, water vapur, carbn mnxide, sulfur dixide and xides f nitrgen. Slid particles and unburned hydrcarbns may als be released that frm particulates in the atmsphere.

2 Carbn mnxide is a txic gas. It is clurless and durless and s is nt easily detected. Sulfur dixide and xides f nitrgen cause respiratry prblems in humans and cause acid rain. Water f apprpriate quality is essential fr life. Fr humans, drinking water shuld have sufficiently lw levels f disslved salts and micrbes. Water that is safe t drink is called ptable water. Ptable water is nt pure water in the chemical sense because it cntains disslved substances. The methds used t prduce ptable water depend n available supplies f water and lcal cnditins. In the UK, rain prvides water with lw levels f disslved substances (fresh water) that cllects in the grund, in lakes and rivers, and mst ptable water is prduced by: chsing an apprpriate surce f fresh water passing the water thrugh filter beds sterilising. Sterilising agents used fr ptable water include chlrine, zne r ultra-vilet light. If supplies f fresh water are limited, desalinatin f salty water r sea water may be required. Desalinatin can be dne by distillatin r by prcesses that use membranes such as reverse smsis. These prcesses require large amunts f energy. Sewage treatment includes: screening and grit remval sedimentatin t prduce sewage sludge and effluent anaerbic digestin f sewage sludge aerbic bilgical treatment f effluent. The Earth s resurces f metal res are limited. Cpper res are becming scarce and new ways f extracting cpper frm lwgrade res include phytmining and bileaching. These methds avid traditinal mining methds f digging, mving and dispsing f large amunts f rck. Phytmining uses plants t absrb metal cmpunds. The plants are harvested and then burned t prduce ash that cntains metal cmpunds. Bileaching uses bacteria t prduce leachate slutins that cntain metal cmpunds. The metal cmpunds can be prcessed t btain the metal. Fr example, cpper can be btained frm slutins f cpper cmpunds by displacement using scrap irn r by electrlysis Life Cycle Assessments (LCAs) are carried ut t assess the envirnmental impact f prducts in each f these stages: extracting and prcessing raw materials manufacturing and packaging use and peratin during its lifetime dispsal at the end f its useful life, including transprt and distributin at each stage. Use f water, resurces, energy surces and prductin f sme wastes can be fairly easily quantified. Allcating numerical values t pllutant effects is less straightfrward and requires value judgements, s LCA is nt a purely bjective prcess. Selective r abbreviated LCAs can be devised t evaluate a prduct but these can be misused t reach pre-determined cnclusins, eg in supprt f claims fr advertising purpses. The reductin in use, reuse and recycling f materials by end users reduces the use f limited resurces, energy cnsumptin, waste and envirnmental impacts. Metals, glass, building materials, clay ceramics and mst plastics are prduced frm limited raw materials. Much f the energy used in the prcesses cmes frm limited resurces. Obtaining raw materials frm the Earth by quarrying and mining causes envirnmental impacts. Sme prducts, such as glass bttles, can be reused. Glass bttles can be crushed and melted t make different glass prducts. Other prducts cannt be reused and s are recycled fr a different use Metals can be recycled by melting and recasting r refrming int different prducts. The amunt f separatin required fr recycling depends n the material and the prperties required f the final prduct. Fr example, sme scrap steel can be added t irn frm a blast furnace t reduce the amunt f irn that needs t be extracted frm irn re Crrsin is the destructin f materials by chemical reactins with substances in the envirnment. Rusting is an example f crrsin. Bth air and water are necessary fr irn t rust. Crrsin can be prevented by applying a cating that acts as a barrier, such as greasing, painting r electrplating. Aluminium has an xide cating that prtects the metal frm further crrsin. Sme catings are reactive and cntain a mre reactive metal t prvide sacrificial prtectin, eg zinc is used t galvanise irn.. Mst metals in everyday use are allys. Brnze is an ally f cpper and tin. Brass is an ally f cpper and zinc. Gld used as jewellery is usually an ally with silver, cpper and zinc. The prprtin f gld in the ally is measured in carats, with pure gld being 24 carat. 18 carat gld is 75% gld. Steels are allys f irn that cntain specific amunts f carbn and ther metals. High carbn steel is strng but brittle. Lw carbn steel is sfter and mre easily shaped. Steels cntaining chrmium and nickel (stainless steels) are hard and resistant t crrsin. Aluminium allys are lw density. Mst f the glass we use is sda-lime glass, made by heating a mixture f sand, sdium carbnate and limestne. Brsilicate glass, made frm sand and brn trixide, melts at higher temperatures than sda-lime glass. Clay ceramics, including pttery and bricks, are made by shaping wet clay and then heating in a furnace. The prperties f plymers depend n what mnmers they are made frm and the cnditins under which they are made. Fr example, lw density (LD) and high density (HD) ply(ethene) are prduced frm ethene. Thermsftening plymers melt when they are heated. Thermsetting plymers d nt melt when they are heated. Mst cmpsites are made f tw materials, a matrix r binder surrunding and binding tgether fibres r fragments f the ther material, which is called the reinfrcement. Physics Electricity Circuit diagrams use standard symbls: Fr electrical charge t flw thrugh a clsed circuit the circuit must include a surce f ptential difference. Electric current is a flw f electrical charge. The size f the electric current is the rate f flw f electrical charge. Charge flw, current and time are linked by the equatin: charge flw, Q, in culmbs, C current, I, in ampere, A

3 time, t, in secnds, s The current at any pint in a series circuit has the same value as the current at any ther pint in the same circuit.. The current thrugh a cmpnent depends n bth the resistance f the cmpnent and the ptential difference acrss the cmpnent. The greater the resistance f the cmpnent the smaller the current fr a given ptential difference (p.d.) acrss the cmpnent Current, ptential difference r resistance can be calculated using the equatin: pwer, P, in watts, W ptential difference, V, in vlts, V current, I, in amperes, A resistance, R, in hms, Ω ptential difference, V, in vlts, V current, I, in amperes, A resistance, R, in hms, Ω Explain the design and use f a circuit t measure the resistance f a cmpnent by measuring the current thrugh, and ptential difference acrss, the cmpnent. The current thrugh an hmic cnductr (at a cnstant temperature) is directly prprtinal t the ptential difference acrss the resistr. This means that the resistance remains cnstant as the current changes. The resistance f cmpnents such as filament lamps, dides, thermistrs and LDRs is nt cnstant; it changes with the current thrugh the cmpnent. The resistance f a filament lamp increases as the temperature f the filament increases. The current thrugh a dide flws in ne directin nly. The dide has a very high resistance in the reverse directin. The resistance f a thermistr decreases as the temperature increases. The resistance f an LDR decreases as light intensity increases. There are tw ways f jining electrical cmpnents, in series and in parallel. Sme circuits include bth series and parallel parts. Fr cmpnents cnnected in series: there is the same current thrugh each cmpnent the ttal ptential difference f the pwer supply is shared between the cmpnents. the ttal resistance f tw cmpnents is the sum f the resistance f each cmpnent. resistance, R, in hms, Ω Fr cmpnents cnnected in parallel: the ptential difference acrss each cmpnent is the same the ttal current thrugh the whle circuit is the sum f the currents thrugh the separate cmpnents The ttal resistance f tw resistrs is less than the resistance f the smallest individual resistr. Explain why adding resistrs in series increases the ttal resistance, while adding resistrs in parallel decreases the ttal resistance. The ptential difference acrss cells and batteries is always in the same directin. The ptential difference des nt change plarity. The ptential difference f mains electricity changes directin. The ptential difference changes plarity. Mains electricity is an a.c. supply. In the UK it has a frequency f 50 Hz and is abut 230 V. Mst electrical appliances are cnnected t the mains using three-cre cable. The insulatin cvering each wire is clur cded fr easy identificatin: live wire brwn neutral wire blue earth wire green and yellw stripes. Everyday electrical appliances are designed t bring abut energy transfers. Describe hw different dmestic appliances transfer energy frm batteries r a.c. mains t the kinetic energy f electric mtrs r the energy f heating devices. The amunt f energy an appliance transfers depends n hw lng the appliance is switched n fr and the pwer f the appliance Wrk is dne when charge flws in a circuit. The amunt f energy transferred by electrical wrk can be calculated using the equatin: energy transferred, E, in jules, J pwer, P, in watts, W time, t, in secnds, s charge flw, Q, in culmbs, C ptential difference, V, in vlts, V The Natinal Grid is a system f cables and transfrmers linking pwer statins t cnsumers. Electrical pwer is transferred frm pwer statins t cnsumers using the Natinal Grid. Step-up transfrmers are used t increase the ptential difference frm the pwer statin t the transmissin cables then step-dwn transfrmers are used t decrease, t a much lwer value, the ptential difference fr dmestic use. This is dne because, fr a given pwer, increasing the ptential difference reduces the current, and hence reduces the energy lsses due t heating in the transmissin cables. Physics Waves Waves may be either transverse r lngitudinal. In a transverse wave the scillatins are perpendicular t the directin f energy transfer. The ripples n a water surface are an example f a transverse wave. In a lngitudinal wave the scillatins are parallel t the directin f energy transfer. Lngitudinal waves shw areas f cmpressin and rarefactin. Sund waves travelling thrugh air are lngitudinal Waves are described by their amplitude, wavelength, frequency and perid. The amplitude f a wave is the maximum displacement f a pint n a wave away frm its undisturbed psitin. The wavelength f a wave is the distance frm a pint n ne wave t the equivalent pint n the adjacent wave. The frequency f a wave is the number f waves passing a pint each secnd. perid, T, in secnds, s frequency, f, in hertz, Hz The perid f a wave is hw lng it takes fr ne wave t pass a pint. The wave speed is the speed at which the energy is transferred (r the wave mves) thrugh the medium. All waves bey the wave equatin: The live wire carries the alternating ptential difference frm the supply. The neutral wire cmpletes the circuit. The earth wire is a safety wire t stp the appliance becming live. The ptential difference between the live wire and earth (0 V) is abut 230 V. The neutral wire is at r clse t earth ptential (0 V). The earth wire is at 0 V, it nly carries a current if there is a fault. The pwer f a device is related t the ptential difference acrss it and the current thrugh it by the equatin: wave speed, v, in metres per secnd, m/s frequency, f, in hertz, Hz wavelength, λ, in metres, m Electrmagnetic waves are transverse waves that transfer energy frm the surce f the waves t an absrber. Electrmagnetic waves frm a cntinuus spectrum and all types f electrmagnetic wave travel at the same velcity thrugh a vacuum (space) r air. The waves that frm the electrmagnetic spectrum are gruped in terms f their wavelength and their frequency. Ging frm lng t shrt wavelength (r frm lw

4 t high frequency) the grups are: - radi, micrwave, infra-red, visible light (red t vilet), ultra-vilet, X-rays and gamma-rays. Our eyes detect visible light and s nly detect a limited range f electrmagnetic waves. Electrmagnetic waves have many practical applicatins. Fr example: Chemistry: Fundamentals radi waves televisin and radi micrwaves satellite cmmunicatins, cking fd infrared electrical heaters, cking fd, infra-red cameras visible light fibre ptic cmmunicatins ultravilet energy efficient lamps, sun tanning X-rays medical imaging and treatments. Use the names and symbls f the first 20 elements in the peridic table, the elements in Grups 1 and 7 Name cmpunds f these elements frm given frmulae r symbl equatins. Write frmulae and balanced chemical equatins Describe, explain and give examples f the specified prcesses f separatin. Suggest suitable separatin and purificatin techniques fr mixtures when given apprpriate infrmatin. Describe hw and why the atmic mdel has changed ver time. Describe the difference between the plum-pudding mdel f the atm and the nuclear mdel f the atm. Describe why the new evidence frm the scattering experiment led t a change in the atmic mdel. Recall the different charges f the particles that make up an atm. Describe why atms have n verall charge. Recall what atmic number represents. Use the peridic table t identify number f prtns in different elements. Calculate the numbers f prtns, neutrns and electrns in an atm r in, given its atmic number and mass number fr the first 20 elements. Be able t relate size and scale f atms t bjects in the physical wrld. Be able t calculate the relative atmic mass f an element given the percentage abundance f its istpes. Be able t represent the electrnic structures f the first twenty elements f the peridic table in bth frms. Students may answer questins in terms f either energy levels r shells. Explain hw the psitin f an element in the peridic table is related t the arrangement f electrns in its atms and hence t its atmic number. Predict pssible reactins and prbable reactivity f elements frm their psitins in the peridic table. Describe these steps in the develpment f the peridic table. Describe and explain hw testing a predictin can supprt r refute a new scientific idea. Explain the differences between metals and nn-metals n the basis f their characteristic physical and chemical prperties. Explain hw the atmic structure f metals and nn-metals relates t their psitin in the peridic table. Explain hw the reactins f elements are related t the arrangement f electrns in their atms and hence t their atmic number. Explain hw prperties f the elements in Grup 0 depend n the uter shell f electrns f the atms. Predict prperties frm given trends dwn the grup. Describe the nature f the cmpunds frmed when chlrine, brmine and idine react with metals and nn-metals. Explain hw prperties f the elements in Grup 7 depend n the uter shell f electrns f the atms. Predict prperties frm given trends dwn the grup. Chemistry Structure and Bnding There are three types f strng chemical bnds: inic, cvalent and metallic. Fr inic bnding the particles are ppsitely charged ins. Fr cvalent bnding the particles are atms which share pairs f electrns. Fr metallic bnding the particles are atms which share delcalised electrns. Inic bnding ccurs in cmpunds frmed frm metals cmbined with nnmetals. Cvalent bnding ccurs in nn-metallic elements and in cmpunds f nnmetals. Metallic bnding ccurs in metallic elements and allys When a metal atm reacts with a nn-metal atm, electrns in the uter shell f the metal atm are transferred. Metal atms lse electrns t becme psitively charged ins. Nn-metal atms gain electrns t becme negatively charged ins. The ins prduced by metals in Grups 1 and 2 and by nn-metals in Grups 6 and 7 have the electrnic structure f a nble gas (Grup 0). The electrn transfer during the frmatin f an inic cmpund can be represented by a dt and crss diagram, eg fr sdium chlride: The charge n the ins prduced by metals in Grups 1 and 2 and by nn-metals in Grups 6 and 7 relates t the grup number f the electrns An inic cmpund is a giant structure f ins. Inic cmpunds are held tgether by strng electrstatic frces f attractin between ppsitely charged ins. These frces act in all directins in the lattice and this is called inic bnding. The structure f sdium chlride can be represented in the fllwing frms: When atms share pairs f electrns, they frm cvalent bnds. These bnds between atms are strng. Cvalently bnded substances may cnsist f small mlecules. Sme cvalently bnded substances have very large mlecules, such as plymers. Sme cvalently bnded substances have giant cvalent structures, such as diamnd and silicn dixide. The cvalent bnds in mlecules and giant structures can be represented in the fllwing frms: Plymers can be represented in the frm: where n is a large number. Metals cnsist f giant structures f atms arranged in a regular pattern. The electrns in the uter shell f metal atms are delcalised and s are free t mve thrugh the whle structure. The sharing f delcalised electrns gives rise t strng metallic bnds. The bnding in metals may be represented in the fllwing frm: Inic cmpunds have regular structures (giant inic lattices) in which there are strng electrstatic frces f attractin in all directins between ppsitely charged ins. These cmpunds have high melting pints and high biling pints because f the large amunts f energy needed t break the many strng bnds. When melted r disslved in water, inic cmpunds cnduct electricity because the ins are free t mve and s charge can flw. Substances that cnsist f small mlecules are usually gases r liquids that have relatively lw melting pints and biling pints. These substances have nly weak frces between the mlecules (intermlecular frces). It is these intermlecular frces that are vercme, nt the cvalent bnds, when the substance melts r bils. The intermlecular frces increase with the size f the mlecules, s larger mlecules have higher melting and biling pints. These substances d nt cnduct electricity because the mlecules d nt have an verall electric charge. Substances that cnsist f giant cvalent structures are slids with very high melting pints. All f the atms in these structures are linked t ther atms by strng cvalent bnds. These bnds must be vercme t melt r bil these substances. Diamnd and graphite (frms f carbn) and silicn dixide (silica) are examples f giant cvalent structures Nanscience refers t structures that are nm in size, f the rder f a few hundred atms. Nanparticles are smaller than fine particles (PM 2.5), which have

5 diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m). Carse particles (PM 10) have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Carse particles are ften referred t as dust. As the side f cube decreases by a factr f 10 the surface area t vlume rati increases by a factr f 10. Nanparticles may have prperties different frm thse fr the same materials in bulk because f their high surface area t vlume rati. It may als mean that smaller quantities are needed t be effective than fr materials with nrmal particle sizes. Nanparticles have many applicatins in medicine, in electrnics, in csmetics and sun creams, as dedrants, and as catalysts. New applicatins fr nanparticulate materials are an imprtant area f research. Useful websites Specific tasks have been set t help with this revisin: Lgin details Schl ID: GU2 KC2 Lgin: DOBinitials eg mt Passwrd: Lgin: DOBinitials eg mt Recmmended thers: bbc bitesize