1. GCSEGCSESscienceFOUNDAFOUNDATIONDAT N ATION

2. Project DirectorsEditorsAngela Hall Emma Palmer Emma Palmer Carol UsherRobin Millar Mary Whitehouse Anne ScottMary Whitehouse Authors Ann FullickAndrew HuntEmily Perry Elizabeth SwinbankHelen Harden Neil Ingram Jacqueline Punter Vicky Wong Maria Pack David Sang 3. ContentsContentsHow to use this book4Making sense of graphs 9Structure of assessment 6Controlled assessment 12Command words 8B1 You and your genes 14 A Same and different16 F Making ethical decisions28 B Same but different18 G Genetic testing 30 C What makes you the way you are? 20 H Can you choose your child?34 D Male or female? 22 ICloning35 E A unique mix of genes Summary2338C1 Air quality 42A The air 44 G Where do all the atoms go?58 B The story of our atmosphere46 H How does air quality affect our health? 60 C What are the main air pollutants?48 I How can air quality be improved?64 D Measuring an air pollutant51Summary68 E How are air pollutants formed?54 F What happens during combustion? 56P1 The Earth in the Universe 72A Time and space 74 G Continental drift86 B Seeing stars76 H The theory of plate tectonics88 C Beyond the Solar System I Earthquakes and seismic waves78 91 D How big is the Universe?J Using seismic waves80 96 E How did the Universe begin?82 Summary 98 F Deep time84B2 Keeping healthy102 A Whats up, Doc? 104 FCirculation118 B Fighting back 106 G Causes of disease how do we know?121 CVaccines 109 H Changing to stay the same124 DSuperbugs112 I Water homeostasis126 E Where do new medicines come from?Summary 114 128 4. C2 Material choices132 A Choosing the right stuff 134 G Designer stuff 147 B Using polymers 136 H Designer polymers 150 C Testing times139 I Making crude oil useful 152 D Zooming in 142 JNanotechnology 154 E The big new idea 144 K Using nanotechnology 156 F Molecules big and small Summary146158P2 Radiation and life162 A Taking a chance with the Sun 164 F Climate change 174 B Radiation models 166 G Changing the future 178 C Absorbing electromagnetic radiation168 H Radiation carries information 181 D Risky side of the rainbow I Is there a health risk?170186 E Heating with microwaves Summary172188B3 Life on Earth 192 A The variety of life194 F Life on Earth is still evolving today 206 B Webs of life 196 G The story of Charles Darwin 208 C Depending on the Sun 198 H The birth of species 214 D Systems in balance 200 I Maintaining biodiversity 216 E Life on Earth has evolved Summary204220C3 Chemicals in our lives: Risks & benefits224A A journey through geological time 226 H Chemicals from salt a better way 240B Mineral wealth in Britain 228 I Protecting health and the 242C Salt: sources and uses230 environmentD Salt in food232 J Stages in the life of PVC 244E Alkalis and their uses234 K Benefits and risks of plasticisers 246F Chemicals from salt the foul way236 L From cradle to grave 248G Benefits and risks of water treatment 238 Summary 250P3 Sustainable energy 254GlossaryA Why do we need to know about energy? 256 G What happens in a power station? 270 B How much energy do things use?Index258 H What about nuclear power? 272 C How much energy does a person use? 260 I Renewables how do they work? 274 Appendices D A national and global problem262 J How is mains electricity distributed? 276 E How can we use less energy?264 K Which energy sources should we use? 278 F What are our sources of energy?266 Summary 280Glossary284Appendices293Index 290 5. How to use this bookWelcome to Twenty First Century Science. This book has been specially written bya partnership between OCR, The University of York Science Education Group, TheNuffield Foundation, and Oxford University Press.On these two pages you can see the types of page you will find in this book, and thefeatures on them. Everything in the book is designed to provide you with the supportyou need to help you prepare for your examinations and achieve your best.Module Openers Why study?: ThisThe Science: This explains how what box summarises the youre about to science behind the learn is relevant tomodule youre about everyday life.to study. What you already Find out about: know: This list is a Every module starts summary of the things with a short list ofyouve already learnt the things youll bethat will come up covering. again in this module. Check through them Ideas about Science:in advance and see if Here you can read there is anything that about the key ideas you need to recap on about science covered before you get started. in this module. Find out about: Questions: Use theseMain Pages For every part of the questions to see if book you can see ayouve understood list of the key pointsthetopic. explored in that section. Summary box: This box sums up the main ideas covered on these Worked examples:pages. These help you understand how to use an equation or to work through a calculation. You can check back whenever you use the calculation in your work to make sure you understand. 4 6. Science ExplanationsYou shouldVisual summary:know: This is a Another way to startsummary of therevision is to usemain ideas in the a visual summary,unit. You can use linking ideasit as a startingtogether in groupspoint for revision, so that you canto check that you see how one topicknow about therelates to another.big ideas covered.You can use thispage as a startingpoint for your ownsummary. Review Questions Ideas about Science andIdeas about ReviewScience: ForQuestions:every module this You can beginpage summarises to prepare forthe ideas about your examsscience thatby using theseyou need to questions tounderstand. test how wellyou know thetopics in thismodule. 5 7. Structure of assessmentMatching your courseWhats in each module?As you go through the book you should use the module opener pages to understand what youwill be learning and why it is important. The table below gives an overview of the main topicseach module includes.B1C1 P1 hat are genes and how do they affect the W hich chemicals make up air, and whichW hat do we know about the place of the W way that organisms develop?ones are pollutants? How do I make sense Earth in the Universe? hy can people look like their parents, brothers Wof data about air pollution? What do we know about the the Earth and and sisters, but not be identical to them? hat chemical reactions produce airWhow it is changing? ow can and should genetic information Hpollutants? What happens to these be used? How can we use our knowledge of pollutants in the atmosphere? genes to prevent disease? hat choices can we make personally, locally,W ow is a clone made? Hnationally or globally to improve air quality?B2C2 P2 ow do our bodies resist infection? H ow do we measure the properties ofH hat types of electromagnetic radiation W hat are vaccines and antibiotics and how Wmaterials and why are the results useful?are there? do they work? hy is crude oil important as a source ofW hich types of electromagnetic radiation W hat factors increase the risk of heart Wnew materials such as plastics and fibres? harm living tissue and why? disease? hy does it help to know about theW hat is the evidence for global warming, why W ow do our bodies keep a healthy water Hmolecular structure of materials such as might it be occuring? How serious a threat is it? balance? plastics and fibres? ow are electromagnetic waves used in H hat is nanotechnology and why is it important?Wcommunications?B3C3P3 ystems in balance how do different S hat were the origins of minerals in BritainW ow much energy do we use? H species depend on each other?that contribute to our economic wealth? ow can electricity be generated? H ow has life on Earth evolved? H here does salt come from; why is it important?W hich energy sources should we choose? W hat is the importance of biodiversity? W hy do we need chemicals such as alkalisWand chlorine and how do we make them? hat can we do to make our use of W chemicals safe and sustainable?How do the modules fit together?The modules in this book have beenGCSE Biology GCSE ChemistryGCSE Physicswritten to match the specification forGCSE Science. In the diagram to the rightB1 C1 P1GCSE Scienceyou can see that the modules can also beused to study parts of GCSE Biology, GCSE B2 C2 P2Chemistry, and GCSE Physics courses. B3 C3 P3GCSE Additional B4 C4 P4 Science B5 C5 P5 B6 C6 P6 B7 C7 P76 8. GCSE Science assessmentThe content in the modules of this book matches the modules of thespecification.Twenty First Century Science offers two routes to the GCSE Sciencequalification, which includes different exam papers depending on theroute you take.The diagrams below show you which modules are included in each exampaper. They also show you how much of your final mark you will beworking towards in each paper. MarksUnit Modules Tested Percentage TypeTimeAvailableA161 B1B2 B3 25%Written Exam 1h 60Route 1A171C1 C2 C3 25%Written Exam 1h 60A181 P1P2 P3 25%Written Exam 1h 60A144 Controlled Assessment 25% 9h 64A141 B1C1 P1 25%Written Exam 1h 60Route 2A142 B2C2 P2 25%Written Exam 1h 60A143 B3C3 P3 25%Written Exam 1h 60A144 Controlled Assessment 25% 9h 647 9. Controlled wordsCommand assessmentThe list below explains some of the common words you will see used in exam questions.CalculateJustifyWork out a number. You can use your calculator Give some evidence or write down an explanation toto help you. You may need to use an equation.tell the examiner why you gave an answer.The question will say if your working must beshown.(Hint: dont confuse with Estimate orOutline Predict.)Give only the key facts of the topic. You may need to set out the steps of a procedure or process makeComparesure you write down the steps in the correct order.Write about the similarities and differencesbetween two things.Predict Look at some data and suggest a realistic value orDescribe outcome. You may use a calculation to help. DontWrite a detailed answer that covers what guess look at trends in the data and use yourhappens, when it happens, and where it happens.knowledge of science. (Hint: dont confuse withTalk about facts and characteristics. (Hint: dont Calculate or Estimate.)confuse with Explain.) ShowDiscussWrite down the details, steps, or calculations neededWrite about the issues related to a topic. You may to prove an answer that you have given.need to talk about the opposing sides of a debate,and you may need to show the difference betweenSuggestideas, opinions, and facts.Think about what youve learnt and apply it to a new situation or context. Use what you have learnt toEstimate suggest sensible answers to the question.Suggest an approximate (rough) value, withoutperforming a full calculation or an accurate Write downmeasurement. Dont just guess use your Give a short answer, without a supporting argument.knowledge of science to suggest a realistic value.(Hint: dont confuse with Calculate andPredict.) Top TipsExplain Always read exam questions carefully, even if youWrite a detailed answer that covers how and why recognise the word used. Look at the information in thea thing happens. Talk about mechanisms andquestion and the number of answer lines to see howreasons. (Hint: dont confuse with Describe.) much detail the examiner is looking for.You can use bullet points or a diagram if it helps yourEvaluate answer.You will be given some facts, data, or other kindIf a number needs units you should include them,of information. Write about the data or facts andunless the units are already given on the answer line.provide your own conclusion or opinion on them.8 10. Controlled assessment Making sense of graphsScientists use graphs and charts to present data clearly and to look forpatterns in the data. You will need to plot graphs or draw charts topresent data and then describe and explain what the data is showing.Examination questions may also give you a graph and ask you todescribe and explain what a graph is telling you.Reading the axesLook at these two charts, which both provide data about daily energyuse in several countries.United StatesUnited Kingdom Switzerland KenyaIndiaFrance China0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000national daily energy use 2007 (GWh/day)United StatesUnited Kingdom Switzerland KenyaIndiaFrance China050 100 150200 250 300daily energy use per person (kWh per person/day) Graphs to show energy use in a range of countries, total and per capita.Why are the charts so different if they both represent information aboutenergy use?Look at the labels on the axes.One shows the energy use per person per day, the other shows theenergy use per day by the whole country.For example, the first graph shows that China uses a similar amount ofenergy to the US. But the population of China is much greater so theenergy use per person is much less.First rule of reading graphs: read the axes and check the units. 9 11. Describing the relationship between variables The pattern of points plotted on a graph shows whether two factors are related. Look at this scatter graph.500400300 boiling point (C)20010000 5 1015 20 253035 100 200number of carbon atoms in hydrocarbonGraph to show the relationship between the number of carbonatoms in a hydrocarbon and the boiling point. There is a pattern in the data; as the number of carbon atoms increases, the boiling point increases. But it is not a straight line, it is quite a smooth curve, so we can say more than that. When the number of carbon atoms is small the boiling point increases quickly with each extra carbon atom. As the number of carbon atoms gets bigger, the boiling point still increases, but less number of salmonella bacteria in patients stomach (millions) quickly. Another way of describing this is to say that the slope of the 5 graph the gradient gets less as the number of carbon atoms4 increases.3 Look at the graph on the right, which shows how the number of bacteria2 infecting a patient changes over time. 1 How many different gradients can you see? 0 0 1 2 345 6 7 There are three phases to the graph, each with a different gradient. So time (days) you should describe each phase, including data if possible:Graph of bacteria population against time. The number of bacteria increases rapidly for the first day untilthere are about 4.5 million bacteria. For about the next three days the number remains steady at about4.5 million. After the fourth day the number of bacteria declines to less than amillion over the following two to three days. Second rule of reading graphs: describe each phase of the graph, and include ideas about the gradient and data, including units.10 12. Is there a correlation?0.6global temperature anomaly (C)annual mean 0.45-year running meanSometimes we are interested in whether one thingchanges when another does. If a change in one factor 0.2goes together with a change in something else, we0say that the two things are correlated.0.2The two graphs on the right show how global0.4temperatures have changed over time and how levels 188019001920 19401960 1980 2000of carbon dioxide in the atmosphere have changedyearover time.400 (parts per million)atmospheric samples (Mauna Loa) carbon dioxideIs there a correlation between the two sets of data?ice core (Law Dome)350Look at the graphs why is it difficult to decide if300there is a correlation?0The two sets of data are over different periods of1750 1800 18501900 19502000time, so although both graphs show a rise with time, year Graphs to show increasing global temperatures and carbonit is difficult to see if there is a correlation. dioxide levels. Source: NASA.It would be easier to identify a correlation if bothsetsof data were plotted for the same time periodandplaced one above the other, or on the same axes,like this: carbon dioxide (parts per million) 0.6global temperature anomaly (C) 400annual mean temperature 0.45-year running mean temperatureCO2 level 350 0.2 0 3000.20.4 0 1880190019201940 1960 1980 2000 yearGraph to show the same data as the above two graphs, plotted onone set of axes.When there are two sets of data on the same axes take care to look atwhich axis relates to which line.Third rule for reading graphs: when looking for a correlationbetween two sets of data, read the axes carefully.Explaining graphsWhen a graph shows that there is a correlation between two sets of data,scientists try to find out if a change in one factor causes a change in theother. They use science ideas to look for an underlying mechanism toexplain why two factors are related.11 13. Controlled assessment In GCSE Science the controlled assessment counts for 25% of your total grade. Marks are given for aTip case study and a practical data analysis task.The best advice is plan ahead. Give your work the time it needs and work steadily and evenly Your school or college may give you the mark over the time you are given. Your deadlines will schemes for this. come all too quickly, especially if you have This will help you understand how to get the most coursework to do in other subjects. credit for your work.Case study (12.5%) Selecting informationEveryday life has many questions science can help Collect information from different places to answer. You may meet these in media reports, books, the Internet, newspapers.for example, on television, radio, in newspapers, Say where your information has come from.and in magazines. A case study is a report that Choose only information that is relevant to theweighs up evidence about a scientific question. question you are studying. Decide how reliable each source ofOCR will provide a news sheet with a variety ofinformation is.articles about some of the science topics you havestudied in this course.Understanding the questionYou will choose an issue from the news sheet as the Use scientific knowledge and understanding tobasis for your case study, and identify a questionexplain the topic you are studying.that you can go on to answer. Your question will When you report what other people have said,probably fit into one of these categories:say what scientific evidence they used (from a question where the scientific knowledge is not experiments, surveys, etc.). certain, for example, Does using mobile phones Reaching your own conclusion cause brain damage? Compare different evidence and points of view. a question about decision making using Consider the benefits and risks of different scientific information, for example, Should carscourses of action. be banned from a shopping street to reduce air Say what you think should be done, and link pollution? or Should the government stopthis to the evidence you have reported. research into human cloning? a question about a personal issue involving Presenting your study science, for example, Should my child have the Make sure your report is laid out clearly in a MMR vaccine?sensible order use a table of contents to helporganise your ideas.You should find out what different people have said You may use different presentation styles, forabout the issue. Then evaluate this information andexample, a written report, newspaper article,reach your own conclusion.PowerPoint presentation, poster or booklet, orYou will be awarded marks for:web page. Use pictures, tables, charts, graphs, and so on topresent information. Take care with your spelling, grammar, andpunctuation, and use scientific terms wherethey are appropriate.12 14. When will I do my controlledCreating a case study assessment?Your case study will be written in class time over aWhere do I start? series of lessons.Read the news sheet local public library You may also do some research out of class.you are given and think your science textbookof a question you wantYour practical data analysis task will be done in and notesto find the answer to.class time over a series of lessons. TVSources of information radioYour school or college will decide when you docouldinclude: newspapers and your controlled assessment. If you do more than Internetmagazinesone case study or practical data analysis, they will school library museums and exhibitions. choose the one with the best marks. Practical data analysis (12.5%) them?Wouldyougetthesameresultsif you Scientists collect data from experiments and studies. repeated the experiment? They use this data to explain how something happens. Comment on the repeatability of your data, You need to be able to assess the methods and dataaccount for any outliers in the data, or explain from scientific experiments. This will help you decidewhy there are no outliers. how reliable a scientific claim is. Suggest some improvements or extra data you could collect to be more confident in your conclusions. A practical data analysis task is based on a practical experiment that you carry out. The experiment will beReviewing the hypothesis designed to test a hypothesis suggested by your Use your scientific knowledge to decide whether teacher. You may do the experiment alone or work in the hypothesis is supported by your data. groups and pool all your data. Then you interpret and Suggest what extra data could be collected to evaluate the data.increase confidence in the hypothesis. Youwillbeawardedmarksfor: Presenting your report Make sure your report is laid out clearly in a Choosing how to collect the data sensible order. Carry out the experiment in ways that will give you Use diagrams, tables, charts, and graphs tohigh-quality data. present information. Explain why you chose this method. Take care with your spelling, grammar, and Explain how you worked safely. punctuation, and use scientific terms where they Interpreting data are appropriate. Present your data in tables, charts, or graphs. Say what conclusions you can reach from your data. Explain your conclusions using your scientificknowledge and understanding. Evaluating the method and quality of data Look back at your experiment and say how youcould improve the method. Explain how confident you are in your evidence.Haveyougotenoughresults?Dotheyshowaclearpattern?Haveyourepeatedmeasurementstocheck 13 15. B1 You and yourgenes14 16. B1: You and your genesWhy study genes?What makes me the way that I am? How are features passed on from parentsto children? Your ancestors probably asked the same questions. You maylook like your relatives, but you are unique. Only in the last few generationshas science been able to answer questions like these.What you already knowThe Science In sexual reproduction fertilisation happensYour environment has when a male and female sex cell join together.a huge effect on you, for example, on your Information from two parents is mixed to appearance, your body, make a new plan for the offspring. The and your health. But offspring will be similar but not identical to these features are also their parents. affected by your genes. In There are variations between members of the this Module youll find out same species that are due to environmental as how. Youll discover the well as inherited causes. story of inheritance. Clones are individuals with identical genetic information. The science of cloning raises ethical issues. Ideas about ScienceFind out about In the future, science could help you to change how genes and your environment make your babys genes before it is born. Cloned youunique embryos could provide how and why people find out about theirgenes cells to cure diseases. how we can use our knowledge of genes But, as new technologies are developed, we must whether we should allow this. decide how they should be used. These can be questions of ethics decisions about what is right and wrong. 15 17. A Same and differentChildrenlookliketheirparents.Theyinheritinformation Find out about fromthem.Thisinformationisingenes.Genescontrolhow D what makes us allneworganismsdevelopandfunction. differentAllpeopleareverysimilar.Lookatthepeoplearound D what genes are and youthedifferencesbetweenusareverysmall.Butthey what genes doareinterestingbecausetheymakeusunique. Both the information you inherit and your environment affect most of your features. Summary box D You inherit genesThese sisters have some features in common. from your parents. D Your genes and yourEnvironment makes a difference environment make you unique.Theinformationyouinheritedfromyourparentsaffects D The nuclei of your almostallof yourfeatures.Forexample,yourbloodgroup cells containdependsonthisinformation.Somefeaturesaretheresultof chromosomes. onlyyourenvironment,suchasscarsandtattoos. Chromosomes are made of DNA. Butmostof yourfeaturesareaffectedbybothyourgenesand D A gene is a sectionyourenvironment.Forexample,yourweightdependson of DNA.inheritedinformation.Butif youeattoomuch,youwill D Genes have the becomeheavier. information to make proteins. D Structural proteins Questions make up the fabric of your body. 1 Choose two of the students in the photograph on D Enzymes are theleft. Write down five ways they look different. proteins; they 2 What two things can affect how you develop? controlchemical reactions in the body.3 explain what is meant by inherited information.16 18. B1: You and Your genesWhere is all the information kept?Livingorganismsaremadeupof cells.Mostcellscontainnuclei.Insideeachnucleusarelongthreadscalledchromosomes.Eachchromosomehasthousandsof genes.Genescontrolhowyoudevelop.nucleus genes genetic material (chromosomes)cell chromosome0.25 mmnucleusThe nucleus of a cell has all the information to make a whole human being.The nucleus is just 0.006 mm across!What are chromosomes made of?Chromosomesaremadeof verylongmoleculesof DNA.DNAscientists have stained these plantcells to show up their nuclei. oneisshortfordeoxyribonucleicacid.Ageneisasectionof acell is dividing. TheseparatingDNAmolecule. chromosomes can be seen.How do genes control your development? enzymes speed upGenesareinstructionsformakingproteins.Eachgeneisthemovechemical muscles reactions inrecipeformakingadifferentprotein.build the bodycellsWhats so important about proteins?Therearemanydifferentproteinsinthebody,andeachonehasanimportantjob.Theymaybe: structuralproteinstobuildthebody,egcollagen(theproteinfoundintendons)fightsend chemical functional proteinstotakepartinthechemicalreactions bacteriacarry messagesand viruses oxygenof thebody,egenzymessuchasamylasein the round thebloodbodyGenescontrolwhichproteinsacellmakes.ThisishowtheyThere are about 50 000 typesdirectwhatthecelldoesandhowanorganismdevelops. of proteins in the human body. Questions 4 Write these cell parts in order starting6 a List two kinds of job that proteins do in withthe smallest:the human body. chromosome, gene, cell,nucleus b name two proteins in the human body 5 explain how genes control what a cell does. and say what they do.A: saMe and dIFFerenT 17 19. B Same but differentGenesdecidealotabouthowababywillgrowanddevelop. Find out about Afewcharacteristics,likedanglyearlobesordimples,are D why identical twinsdecidedbyonepairof genesonly.Mostlyseveraldifferent look like each other genesworktogether.Inthiswaytheydecidecharacteristics D why identical twinssuchasyourheight,yourweight,andyoureyecolour.But do not stay identicalyourgenesdonttellthewholestory. D what a clone isTwins and the environment Summary box D Identical twins have the same genetic information. D There may be differences in some characteristics because of the environment. D A clone is a living organism with the same genetic information as Identical twins have the same genes but they dont look exactly the same. another living organism.Sometimesafertilisedeggstartstodivideandsplitstoformtwobabiesinsteadof one.Theseareidenticaltwins.Eachbabyhasthesamegenes.Anydifferencesbetweenthemmustbebecauseof theenvironment.Mostidenticaltwinsgrowupinthesamefamily.Their Questionsenvironmentisverysimilar.Butsometimestwinsare 1 how are dimples, separatedafterbirthandadoptedbydifferentparents.Then green eyes, and beingscientistscanfindoutwhatdifferencetheenvironmentmakes 2m tall inherited tothetwinscharacteristics. differently?Oftentheseparatedtwinsarestillveryalike.Geneshavea 2 Why do scientists findverystronginfluence.Butsomethings,likeweight,aremore studying identicaldifferentintwinswhogrowupapartthantwinswholiveinthe twins so useful?sameenvironment.18 20. B1: You and Your genesCloningWecallanygeneticallyidenticalorganismsclones.Soidenticaltwinsarehumanclones!Scientistscanuseclonestofindouttheeffectof theenvironmentongrowthanddevelopment.Butitwouldbewrongforscientiststoseparatebabies.Forthisreasonscientistsoftenstudyplants.Plantclonesarequitecommon.Forexample,strawberryplantsandspiderplantsmakeplantclonesattheendof runners.Bulbs,likedaffodils,alsoproduceclones.Cloning plantsItiseasyforpeopletocloneplantsartificially.Apieceoftheadultplantiscutoff.Itsoonformsnewrootsandstemstobecomeasmallplant.Thenewplantisaclone.Ithasthesameeach of these baby spider plants isgenesastheparentplantandisidentical. a clone of its parent plant and ofall the other baby plants.Youcanalsoplacetinypiecesof aplantonspecialjelly,calledagar.Theygrowintoplants,whichareallclones.Inthisway,youcanmakehundredsof clonesfromasingleplant.Cloned plants are usefulYoucanuseclonestolookathowtheenvironmentaffectsthem.If theparentplantgrewverytall,thatwillbepartlydowntoitsgenes.Butwhathappensif itdoesntgetenoughnutrientsorwater?Willitstillgrowtall?Wecanlookattheeffectsof differentfactorsonthecharacteristicsof clonedplants.Thishelpsustounderstandhowgenesandtheenvironmentinteract. Questions 3 What is a clone? 4 Why are cloned plants so useful to scientists? 5 The environment affects the appearance of plants. describe how you could use cloned plants to show this.You may make cauliflowercloneslike these. B: saMe BuT dIFFerenT19 21. C What makes you the way you are?Peopleinafamilylooklikeeachother.Youmayhaveinherited Find out about afeatureyoudontlike,suchasyourdadsbigears.Butfamily D how you inheritlikenessescanbeveryserious. genes D Huntingtons disease Roberts story (an inherited illness) Imsofrustrated.Icantsitstillinachair.ImmoreandmoreforgetfulandIfallover.ThedoctorhassaiditmightbeHuntingtons disease.ShesaidIcanhaveabloodtesttofindout.Huntingtons diseaseYoucantcatchHuntingtonsdisease.Itsaninheriteddisorder.Parentspassthediseaseontotheirchildren.Thesymptomsof Huntingtonsdiseasedonthappenuntilmiddleage.Theyare: difficultycontrollingmuscles,whichshowsupastwitching becomingforgetful difficultyunderstandingthingsandconcentrating moodchanges.Afterafewyears,suffererscantcontroltheirmovements.Sadly,theconditionisfatal.Robert, 56Eileen, 58Ive been Roberts mumforgettingwas just thethings andsame. Davidstumbling.looks just likehis father. robert and his grandson Craig.Sarah, 32David, 35Clare, 33 Im definitely Im not having a Davids got the right having the testtest. It wont idea, just getting on if Dads got it. change whatwith his life. Mind Questions I need to know so I can planhappens to me. you, Im really worried about him now and my life.Craig and Hannah. 1 List the symptoms of huntingtons disease. Craig, 16 Hannah, 14 Its not fair. I want No-one seems 2 explain why to find out but they wont let me. They to want to tell me anything huntingtons disease is think Im too young about it at all. to understand. called an inherited disorder. Craigs family.20 22. B1: You and your genesHow do you inherit your genes? QuestionsIn some families brothers and sisters look like each other. Inothers they look very different. They may also look different3aDraw a diagram tofrom their parents. This is because of genes.show a sperm cell, an egg cell, and theParents pass on genes in their sex cells. In animals these are fertilised egg cellsperm and egg cells. Sex cells have copies of half the parents they make.chromosomes. When a sperm cell fertilises an egg cell, the bExplain why thefertilised egg cell gets a full set of chromosomes. It is called fertilised egg cell hasanembryo. pairs of chromosomes. 4 Explain why childrenThe number of chromosomes in each cellmay look a bit likeChromosomes come in pairs. Every human body cell haseach of their parents.23pairs of chromosomes. The chromosomes in most pairs arethe same size and shape. They carry the same genes in the same genesame place. So your genes also come in pairs.Sex cells have single chromosomesSex cells are made with copies of half the parentschromosomes. This makes sure that the fertilised egg cell hasthe right number of chromosomes 23 pairs. One chromosome chromosomechromosome from father from mothercame from the egg cell. The other came from the sperm cell.Each chromosome carries thousands of genes. Each chromosome pairchromosome in a pair carries the same genes along its length. These chromosomes are a pair.So the fertilised egg cell has a mixture of the parents genes.Half of the new babys genes are from the mother. Half are fromSummary boxthe father. This is why children resemble both their parents.DDYour sex cells only have one of each 46 chromosomes 23 chromosomes chromosome pair. DDAn egg cell and a46 chromosomes sperm cell join to male body cellsperm cell form an embryo. fertilisation DDYou inherit half of your genes from 46 chromosomes your mother and half fertilised egg cell from your father. egg cellDDHuntingtons disease 23 chromosomes is caused by a faultyfemale body cell gene. It is passed on The cells in this diagram are not drawn to scale. A human egg cell is or inherited from one 0.1 mmacross. This is 20 times larger than a human sperm cell. of your parents. C: What makes you the way you are?21 23. D Male or female?What decides an embryos sex?Find out aboutAfertilisedhumaneggcellhas23pairsof chromosomes.D what decides if you MaleshaveanXchromosomeandaYchromosomeXY.are male or femaleFemaleshavetwoXchromosomesXX.D how a Y chromosomemakes a baby male Question 1 What sex chromosome(s) would be in the nucleus of: a a mans body cell? b an egg cell? c a womans body cell?XY d a sperm cell? Women have two X chromosomes.These chromosomes are from the Men have anXand a Y. nucleus of a womans body cell.They are lined up in pairs.Whats the chance of being male or female?Aparentschromosomesareinpairs.Whensexcellsaremadetheyonlygetonechromosomefromeachpair.Sohalf amansspermcellsgetanXchromosomeandhalf geta Summary boxYchromosome.AwomanseggcellsallgetanXchromosome. D Males have XYWhenaspermcellfertilisesaneggcellthechancesare50%that chromosomes.itwillbeanXspermand50%thatitwillbeaYsperm.This D Females have XX chromosomes. meansthatthereisa50%chancethatthebabywillbeaboyand50%chanceagirl. X male bodycellfemale body ALLcellegg cellsXYOR XXX Y22 24. A unique mix of genes EWillthisbabybetallandhaveredhair?Willshebegoodatmusicorsport?BothherenvironmentandhergeneswillaffectFind out aboutthesefeatures.Afewfeaturesarecontrolledbyjustonegene. D how pairs of genesWecanunderstandthesemoreeasily. control some features D cystic fibrosis (an inherited illness) D testing a babys genes before they are born This baby has inherited a unique mix of genetic information.Genes come in different versionsBothchromosomesinapaircarrygenesthatcontrolthesamefeatures.Eachpairof genescontrollingafeatureisinthesameplaceonthechromosomes.Butgenesinapaircanbeslightlydifferentversions.Youcanthinkaboutitlikefootballstrips.Ateamshomeandawaystripsarebothbasedonthesamepattern,buttheyrenotthesame.Differentversionsof thesamegenesarecalledalleles. do you have dimples whenThegenethatcontrolsdimpleshastwoalleles.TheDalleleyousmile?givesyoudimples.Thedallelewontcausedimples.This diagram shows one Question pairof chromosomes. Thegene controlling dimples 1 Write down what ismeant by the wordallele. iscoloured in.E: a unIQue MIX oF genes 23 25. dimples Dominant alleles theyre in chargeDD The D allele is dominant. You only need one copy of a dominant allele to have its feature. The d allele is recessive. You must have two copies of a recessive allele to have its feature in this case no dimples. This person inherited a D allele from both parents. They have dimples. Which alleles can a person inherit? Sex cells get one chromosome from each pair of their parents no dimpleschromosomes. If a parent has two D or two d alleles, they can only pass on a D or a d allele to their children.d d But a parent could have one D and one d allele. Then half of their sex cells will get the D allele and half will get the d allele. This person inherited a d allele The human lottery from both parents. They dont We dont know which egg and sperm cells will meet at have dimples. fertilisation. This genetic diagram is called a Punnett square. Itshows all the possibilities for one couple.dimplesA father with d d father Dd two d alleles(no dimples) One of the alleles goes in each sperm cell This person inherited one D and sex cellsd d one d allele. They have dimples.One of the alleles goes in each egg cell mother D D d D dD dd d d d d children There is a A mother with50% chance of a one D and onechild having dimples d allele (dimples)Questions2 Explain how you inherit two alleles for each gene.3 Explain the difference between a dominant and a recessive allele.24 26. B1: You and Your genesWhy dont brothers and sisters lookthesame? Summary boxD There are differentHumanbeingshaveabout23000genes.Eachgenehasversions of genesdifferentalleles.Bothof theallelesyouinheritcanbethe they are calledsameordifferent.alleles.D If you have oneBrothersandsistersaredifferentbecausetheyeachgeta copyof a dominantdifferentmixtureof allelesfromtheirparents.Exceptfor allele, you will haveidenticaltwins,eachoneof ushasauniquesetof genes.that feature.D You have to havetwo copies of arecessive allele toshow that feature. The allele that gives you The allele that gives you hair on straight thumbs is dominant the middle of your fingers is (T). The allele for curveddominant (r). The allele for no thumbs is recessive (t).hairis recessive (r).What about the family?Asmallnumberof disordersarecausedbyfaultyallelesof asinglegene.Huntingtonsdiseaseiscausedbyadominantallele.Youonlyneedtoinherittheallelefromoneparenttohavethecondition.CraigandHannahsgrandfather,Robert,hasHuntingtonsdisorder.Sotheirdad,David,mayhaveinheritedthisfaultyallele.AtthemomenthehasdecidedIm not having the test. It wontnottohavethetesttofindout.change what happens to me. Questions 4 What are the possible pairs of alleles a 5 use a diagram to explain why a couple person could have for: who have dimples could have a child a dimples? with no dimples. b straight thumbs? 6 use a diagram to work out the chance c no hair on the second part of theirthat david has inherited the huntingtons ringfinger? disease allele. E: a unIQue MIX oF genes25 27. Dear Clare, y husband Huw Please help us. Men told that ourCystic fibrosis in depth and I have just be first child has cy one in our familystic fibrosis. No has ever had Did I doW eve had a huge postbag in response to last months letter from Emma.Sothis month were looking in depth at cystic fibrosis, a disease thatone in 25 of us carries in the UK.this disease before. during mysomething wrong pregnancy? Im soworried.What is cystic fibrosis?YDear Emma,ou cant catch cystic fibrosis. It is a genetic disorder. It is passed on from Yours sincerely What a difficult time forparents to their children.Emma you all. First of all, The cells that make mucus in the body are faulty. The mucus is too thick. nothing you did during Thiscauses problems for breathing, digestion, and reproduction. There is your pregnancy could nocure at the moment. But treatments are getting better and life have affected this, so dont expectancy is increasing. feel guilty. Cystic fibrosis is an inherited disorder Problem Symptom Treatment Mucus blocks up lungs. Difficult to breathe. Physiotherapy. People with CF get Use of enzyme spray breathless. thins out mucus in the Lots of chest pains.lungs. This makes it Emmas parentsHuws parents easier to clear mucus. Antibiotics. Mucus blocks up tubes that Shortage of enzymes in Take tablets of missing EmmaHuw take enzymes from the the gut.gut enzymes. pancreas to the gut. Food is not digested properly. People with CF can be Emma and Huws childshort of nutrients.with cystic fibrosis Mucus blocks up tubes inCant have children. Female with dominant allele F reproductive system. Female with recessive allele f Male with dominant allele F Male with recessive allele f This family tree shows how Emma F f father This diagram shows how and Huws child inherited CF. healthy parents who are both carriers of the faulty cystic brosis allele can have a child affected by the disease. The allele is recessive.F fsex cellsmother f Fff fFfchildren There is a 25%chance that a child fromthe carrier parents will F FFf Fhave cystic fibrosis.26 28. B1: You and Your genesHow do you get cystic fibrosis?What are the options?M ost people who have CF cant have children. Babies with CFare usually born to healthy parents. How can this be?If a couple know there is a risk they could havechildren with cystic fibrosis, they could have tests. During pregnancy,The CF gene has two versions. One is dominant. It tells cells to doctors can collectmake normal mucus. The other is a faulty recessive gene. There cells from the developing fetus. The couple should beare errors in the DNA. Itinstructs cells to make thick mucus. aware of theA person with one normal (F) dominant allele and a faulty (f)following about the tests:recessive allele will not have CF But they can pass the faulty. there is a risk of up to 1% that they could lose thegene on to their children. They are carriers. baby (miscarriage)Half the sex cells of CF carriers contain the normal allele and half there is a very small risk of infectioncontain the faulty allele. If two faulty alleles meet at the results are not 100% reliable.fertilisation, the baby will have CF One in 25 people in the UK.carry the CF allele.Amniocentesis test.amniotic fluidwithdrawn ultrasound probe syringe needle womb (uterus)placenta fetusamniotic fluidThe results of the testscontaining somecervixfetal cellsDoctors examine the genes. If the fetus has two faulty (ff) CF alleles, thechild will havecystic fibrosis. Then the parents may chooseto end the pregnancy. This is done with amedical operation called a termination(abortion).The fetal cells for the genetic test can be 1% miscarriage risk very small risk of infection collected in an amniocentesis test. results at 1518 weeks results not 100% reliableQuestionsSummary box D A recessive allele causes 7 The magazine doctor is sure that nothing emma cystic fibrosis. It causes a did during her pregnancy caused her baby to haveperson to have thick cystic fibrosis. how can she be so sure?mucus. If a person has only 8 People with cystic fibrosis make thick, sticky mucus. one faulty CF allele, they have normal mucus. They describe the health problems that this may cause. are carriers. Agenetic test 9 explain what it means when someone is a carrier of a fetus may show two of cystic fibrosis. faulty CF alleles. The baby would have cystic fibrosis. A couple could have a termination.E: a unIQue MIX oF genes 27 29. F Making ethical decisions Elainesnephewhascysticfibrosis.Whentheyfoundout,Find out about ElaineandPeterbecameworriedaboutanychildrentheyD how people makemighthave.Theybothhadagenetic test.Thetestsshowedethical decisionsthattheywerebothcarriersforcysticfibrosis.D how geneticinformation couldbeused We had a test for each of my pregnancies, says elaine. sadly we felt wehad to terminate the first one, because the fetus had CF. We are lucky enough now to have two healthy children and we know we havent got towatch them suffer. ElaineandPeterdecidedtohaveaprenatalgenetictestof the fetuswhenElainewaspregnant.Thetestwaspositive. ElaineandPetersunbornchildwouldhavecysticfibrosis. Theydecidedtoendthepregnancy.Thiswasaveryhard decision. Whenapersonhastomakeadecisionaboutwhatisthe rightorwrongthingtodo,theyarethinkingaboutethics. Decidingwhethertohaveaterminationisanexampleof an ethicalquestion. Summary box Ethics right and wrong D Ethics is about Forsomeethicalquestions,therightanswerisclear.For deciding whether example,shouldyoufeedyourpet?Butinsomesituations something is rightor wrongtheremaynotbeonerightanswer.Peoplethinkaboutethical questionsindifferentways.28 30. B1: You and Your genesWeighing up the consequencesElaineandPeterhadtodecidetoeithercontinuewiththepregnancyorhaveatermination.Theythoughtabouthoweachchoicewouldaffectallthepeopleinvolved.Theyjudgedtheproblemstheirunbornchildwouldface.ElaineandPeteralsohadtothinkabout: theeffectsthatanillchildwouldhaveontheirlivesandalsoonthelivesof anyotherchildrentheymighthave whethertheyfeeltheycouldcopewithcaringforachildJo has a serious genetic disorder.her parents believe that terminationwithaseriousgeneticdisorder.is wrong. They decided not to havemore children, rather than useDifferent choices information from a test.Noteveryoneweighinguptheconsequencesof eachchoicewouldhavecometothesamedecisionasthiscoupledid. What are theethical argumentsSomepeoplefeelthatanyillnesswouldmakeapersonsquality for a decision?of lifeterrible.Butsomepeopleleadveryhappy,fullliveswithveryseriousdisabilities.When you believe that an action is wrongForsomepeoplehavingaterminationiscompletelywrongThe right decision isinitself.Theybelievethatanunbornchildhastherighttothe one which leads to the best outcome forlife.Otherpeoplebelievethatterminatingapregnancyisthe most people.unnatural,andthatweshouldnotinterfere.Theseviewpointscouldbetheirownpersonalbeliefsortheirreligiousbeliefs.Some actions areElaineandPetermayhavefeltthatterminationwaswrong. wrong and should never be done.Theycouldhavedecidednottohavechildrenatall.Thiswouldmeanthattheycouldnotpassonthefaultyallele.Ortheycoulddecidetohavechildren,andtocareforanychildthatdidinheritthedisease. QuestionsIts wrong to have atermination. Well look after 1 explain what is meant by an ethical question.our baby whatever. 2 describe three different points of view that a couple in elaine and Peters position might take. Is it fair for us tohave a baby knowing it is going to sufferso much? F: MakIng e ThICaL deCIsIons 29 31. GGenetic testingHow reliable are genetic tests? Find out about Someallelescausegeneticdisorders.Agenetictestcanspot D what a genetic test is thefaultyalleles.PeoplelikeElaineandPeterhavetodecide D what genetic abouthavingchildren.Theycanusetheinformationfrom screeningis geneticteststohelp.GenetictestshelpedElaineandPetertodecidewhethertocontinuewiththepregnancyornot.Itisimportanttorealisethatthetestsarenotcompletelyreliable. InaveryfewcasesitwillnotdetectCF.Thenthetestwillshowthebabytobehealthy.ButitwouldbebornwithCF.Thisiscalledafalse negative.ThetestonlylooksforcommonDNAerrorsinthefaultyCFgene. False positivetestsareevenlesscommon.Buttheycanhappenduetotechnicalfailureof thetest.Thenababy,whotestedpositiveforCF,ishealthy.Why do people have genetic tests?Somepeople,likeElaineandPeter,knowtheyhaveageneticdisorderintheirfamily.Theymighthaveagenetictest.Mostpeoplewhoarecarriersof CFdonotknow.Theyonlyfindout This couple are both carriers ofwhentheirchildhasCF.So,theywouldnothavehadagenetic cystic fibrosis. They had an amniocentesis test during theirtestduringpregnancy. pregnancy. The results showed that the baby did not have CF.EverybabyintheUKisnowscreenedforcysticfibrosisat When their daughter was born birth.Theyhaveabloodtest.Thisdoesnottestgenes.If the she was completely healthy.bloodtestispositiveforCF,thebabywillbegeneticallytestedtoconfirmCF. QuestionsTreatmentcanstartbeforethelungsaretoobadlydamaged.Thebloodtestdoesnotshowupbabieswhoarecarriersof the 1 What are false negative and false CFallele. positive results? Genetictestingthewholepopulationorlargegroupsfora 2 Why is it important forgeneticdiseaseiscalledgenetic screening. people to know about false results? 3 explain what is meant by the term genetic screening.30 32. B1: You and Your genesGenetic screening of adults for diseasesTay-sachsRabbiJosephEksteinhadfourchildren.TheyalldiedfromTay-Sachsdisease.Thisisaseveregeneticcondition.Arecessiveallelecausesit.InthegeneralpopulationTay-Sachsisveryrare.Butinthe1980s,itwasquitecommoninEuropeanJewishfamilies.Oneinevery3600babieswasaffectedanddied.In1983RabbiEksteinsetupageneticscreeningprogramme.Somecouples,whowereplanningtomarry,hadagenetictest.If bothcarriedtherecessivealleleforTay-Sachs,theywere dna testing can be done atadvisednottomarry.If theymarried,theycouldhavetheirhome with simple kits like this.unbornbabyscreenedandterminateaffectedpregnancies.Tay-SachshasalmostdisappearedfromJewishcommunitiesSummary boxworldwidebecauseof geneticscreening.D Genetic tests lookfor faulty alleles thatTesting your genescause diseases.YoucanbuyDNAtestingkitsnow.Theycantellyouif youareGenetic screeningcarryingfaultyallelesthatcauseover100geneticdiseases,like tests a large groupof people.cysticfibrosisandTay-Sachs.SomescientistshopethesetestsD Sometimes faultywillhelptopreventmanygeneticdiseases.Otherscientists alleles are found,thinkthatscreeningisnotworthwhile.Theriskof being and the person isaffectedbytheseraregeneticdiseasesislow.Itcostsmoney healthy. This is aandmaycausepeopletoworry.false positive. Inother cases the testScientistscanalreadyworkoutthecompleteDNAsequencecould show the(thegenome)of anyonewhohasenoughmoneytopayalleles are normal,thousandsof pounds.Infiveyearstimeitmaybesocheap but the person hasthe disorder. This isthateveryonewillbeabletohaveitdone.Thegenomeof a false negative.everynewbornbabymaybeworkedout.Howcanweusethisinformation? Question 4 Babies are born with terrible genetic diseases. how can the genetic testing of adults prevent them being born? G: gene TIC TesTIng 31 33. Finding the right medicine In2009CarolynMajorhadcancer.Shestartedtotakemedicine thatshehopedwouldhelpcureher.Fourdayslatershewasin anintensivecareward.Herheartwasstrugglingtokeepgoing. Carolynsbodyreactedverybadlytotheanti-cancerdrug.This onlyhappenstoasmallgroupof people.Luckily,sherecovered withnopermanentdamagedonetoherheartthecancer hasntreturnedeither! Carolyn had a dangerous Genetic testing before prescribing drugs reaction to drugs. genetic testing may help to avoid this. Takingthewrongmedicinemaybeathingof thepast.Wecan usegeneticstomatchmedicinestopatients.Somepeoplehave enzymesthatbreakdowndrugsveryquickly.Theyneed Questions higherdosesof amedicinethanmostof us.Otherpeoplecant 5 how might genetic breakdowncertaindrugsintheirbody.Somedicinesthatare testing make medicinesmeanttohelpthempoisontheminstead.Infuture,genetic more effective? testingmaymeanwecanallbegiventhedrugsthatworkbest forourbodies. 6 What problems might genetic testing for effective medicines Helping us to help ourselves? cause?Youmayhaveinheritedgenesthatincreaseyourriskof heart diseaseordifferenttypesof cancer.Geneticscreeningmaybe 7 What do you think are abletotellyouthisinthefuture.Butremember,yourgenes the advantages and andyourlifestyleaffectthesediseases. disadvantages of testing adults? Thisinformationcouldbeveryhelpful.Forexample,youfind outthatyouhaveahigher-than-averageriskof developing heartdiseasebecauseof yourgenes.Youmightdecidetonot Summary box smoke,toeatahealthydiet,andtotakelotsof exercise.Then D Genetic screening youwouldloweryourenvironmentalriskof heartdisease. ofadults can Thismighthelptobalanceyourincreasedgeneticrisk. givepeople the Yourgenesmaymeanyouhaveanincreasedriskof gettinga information to: choose whetherparticulartypeof cancer.Regularscreeningwillhelptocatchto have children thediseaseasearlyaspossibleif itdevelops. decide whetherto have pre-natalgenetic testing have the bestmedicine anddose for them.32 34. B1: You and your genesWho decides about genetic screening?NHS trusts are responsible for the healthcare of their Its verylocalpeople. The governments Department of Health give dangerous. People shouldnt have to worryfunds to local NHS trusts. They decide if they should useabout this information.genetic screening.Theres nothing wrongin having a child withan illness.Local NHS trusts might consider: the costs of testing everyone for the allele We shouldnt interferewith having children. Its a the benefits of testing everyone for the allelenatural process. So theresno point in testing for whether it is better to spend the money on other things, sucha disease. as hip-replacement operations and treating people who already have cystic fibrosis.Is it right to use genetic screening?It is easy to see why people may want genetic screening.We should give people all the informationAcouples children may be at risk of inheriting a disorder. we can about their health.Then they can make anGenetic screening would help them find out. It may seem likeinformed decision.the best course of action for everyone.What is the right decision? I want to chooseBut the best decision for most people is not always the right my medical treatments not have them forceddecision. There are ethical questions to consider about geneticupon me!screening for cystic fibrosis and other disorders. These include: who should know the test results What if my husband what effect could the test result have on peoplesand I both had the faulty allele? Wed be very worried futuredecisions about having children. should people be made to have screening should they be able to opt out is it right to interfere?About 1 in 25 people in the UK carries the allele for cysticfibrosis. Having this information might be useful. But there aregood reasons why not everyone agrees. A decision may benefit People have different ideas aboutmany people. But it could harm a few people. Then it may bewhether genetic screening for cysticthe wrong decision.fibrosis would be a good thing. Question 8 Give two arguments for and two against geneticscreening for cystic fibrosis.G: Gene tic testing 33 35. HCan you choose your child?Manypeopledonotagreewithtermination.If theyareatriskFind out aboutof havingachildwithageneticdisease,whatcantheydo?D how new techniquesTheymaydecidenottohavechildren,ortheycannowhavecan allow people to anothertreatment.Itusesinvitrofertilisation(IVF).Inthisselect embryostreatmentthemotherseggcellsarefertilisedoutsideherbody.Thistreatmentisalsousedtohelpcoupleswhocannotconceiveachildnaturally. Sally takes a fertility drug so that she releases several eggs. The doctor collects the eggs. Bobs sperm fertilise the eggsEmbryo selection in a Petri dish. BobandSallywantchildren,butBobhasthealleleforHuntingtonsdisease.Sallyhasbecomepregnanttwice.TestsshowedthatboththefetuseshadtheHuntingtonsallele.Thepregnancieswereterminated.TheirdoctorsuggestedthattheyshoulduseIVF.DoctorsselectfertilisedeggsorembryoswithouttheHuntingtonsallele.TheseareputbackorimplantedintoSallyswombsotheycandevelop.Sallystreatmentisexplainedintheflowchart. When the embryos reach the eight-cellThisprocedurewasfirstcarriedoutin1989.Atthemoment, stage, one cell is removed from each.embryo selectionisonlyallowedforfamilieswithparticularinheritedconditions.New technology new decisionsIntheUK,Parliamentmakeslawstocontrolresearchandtechnologiestodowithgenes.Scientistscannotdoresearchon The cells are tested. Only embryos whatevertheylike.FromtimetotimeParliamentupdatesthe without the Huntingtons allele arelaw.ButParliamentcantmakedecisionscasebycase.Sothe implanted in Sallys uterus.Governmenthassetupgroupsof peopletodecidewhichcasesarewithinthelawonreproduction.Thegroupsalsodecidewhenembryoselectioncanbeused.Summary boxD Eggs are fertilisedoutside the womb byQuestionsperm. The embryosare then screened1 everyone who has embryo selection has to use IVFfor genetic diseases.treatment in order to become pregnant. explain why.Healthy embryos areimplanted into thewomans womb, sothey can develop.34 36. CloningICloning: a natural processManylivingthingsonlyneedoneindividualtoreproduce.This Find out aboutiscalledasexual reproduction.Single-celledorganismslikeD asexualthebacteriuminthepictureuseasexualreproduction. reproductionThebacteriumdividestoformtwonewcells.Thetwocells D cloning and stem cellshaveidenticalgenestoeachother.Theyareclones.Allof thedifferencesbetweenthemwillbecausedbytheirenvironment.Asexual reproductionLargerplantsandanimalshavedifferenttypesof cellsfordifferentjobs.Asanembryogrows,cellsbecomespecialised.Someexamplesarebloodcells,musclecells,andnervecells.Plantskeepsomeunspecialisedcellsalltheirlives.Thesecellscanbecomeanythingthattheplantmayneed.Forexample,a bacterium cell grows andtheycanmakenewstemsandleavesif theplantiscutdown.then splits into two new cells.Thesecellscanalsogrowwholenewplants.Sotheycanbe (Mag: 7500 approx.)usedforasexualreproduction.Somesimpleanimals,liketheHydrainthepictureopposite,alsouseasexualreproduction.Cloningisveryuncommoninanimals.Sexual reproductionMostanimalsusesexual reproduction.Thenewoffspringhavetwoparentssotheyarenotclones.Butclonesaresometimesproducedwecallthemidenticaltwins. sperm cell babyfertilisation Hydra.splitsfertilised egg cellQuestions 1 What is asexual babyreproduction? egg cell2 What do plants useIdentical twins have the same genes. But their genes came from bothunspecialised cells for?parents. so they are clones of each other, but not of either parent.I: CLonIng35 37. Cloning human embryosMostscientistsdontwanttocloneadulthumanbeings.Butsomescientistsdowanttoclonehumancells.Theythinkthatsomeclonedcellscouldbeusedtotreatdiseases.Theusefulcellsarecalledstem cells.What are stem cells?Stemcellsareunspecialisedcells.Allthecellsinanearlyembryoarestemcells.Theseembryoniccellscangrowintoanytypeof cellinthehumanbody.Cells from eight-cell embryoslike this one can develop intoAdultsdohavestemcells.Theyhavetheminmanytissueslikeany type of body cell. They starttheheart,bonemarrow,andbrain.Thoseunspecialisedcellsto become specialised whentheembryo is five days old.candevelopintomanytypesof cell.Butitisdifficulttodo(Mag: 500 approx) this.Bonemarrowcellsarealreadyusedintransplantstotreatleukaemia. QuestionsStemcellscanbetakenfromembryosthatareafewdaysold.Researchersusehumanembryosthatareleftoverfrom 3 how are stem cellsfertilitytreatment. different from othercells?Stem cell treatment 4 explain why scientistsScientistswanttogrowstemcellstomakenewcellstotreat think stem cells wouldpatientswithsomediseases.Forexample,newbraincells be useful in treatingcouldbemadeforpatientswithParkinsonsdisease. Parkinsons disease.Thesenewcellswouldneedtohavethesamegenesasthe 5 For each of these cells, say whether or not yourpersongettingthemasatreatment.Whensomeoneelsescells body would reject it:areusedinatransplanttheyarerejected. a bone marrow from your identical twinCloning to make stem cells b your own skin cellsEmbryoshavestemcells.Scientistsmaybeabletoproduce c a cloned embryoanembryothatisacloneof thepatient.Stemcellsfromthis stemcell. embryowouldhavethesamegenesasthepatient.Socells 6 For embryo cloning toproducedfromtheembryocouldbeusedtotreattheirillness. make stem cells: Theywouldnotberejectedbythepatientsbody. a describe one Doctorshaveonlyjuststartedtoexplorethis.Successis viewpoint in favourstillyearsaway.Millionsof peoplecouldbenefitif itismade b describe two towork. different viewpoints against.36 38. B1: You and Your genes Summary boxJames has Parkinsonsdisease. his brain cells do D Asexualnot communicate with reproduction iseach other properly. hewhen only onecannot control his organism is neededmovements. to reproduce. The offspring has the same genes as the original organism. Itis a clone. D Sexual reproduction is when offspring have genetic information from two parents. D Stem cells areShould human embryo cloning be allowed?unspecialised cells. They can develop into different typesWith some things theres no argument.Research of cell. Other cells Murder is just wrong in the sameon embryos is are specialised.way that lying and stealing are wrong. Killing an embryo at any age is as legal up to 14 days. If D Stem cells can bewrong as killing a child or an something isused to treat someadult. legal it cantbe wrong. illnesses.Whether itsright or not depends An embryoon how much good it does is human so it has versus how much harm. If yourhuman rights. Its age best friend was paralysed in an doesnt make anyaccident, you wouldnt think it wasdifference. You cant wrong to sacrifice a five-day-oldexperiment on aembryo made of 50 cells. Not if child or an those cells could be used toadult. make nerve tissue torepair your friends damaged Creatingnerves. embryos for medical treatmentsis wrong. Its creating a life that is then destroyed. This lowersthe value of life.If research oncloning is allowed, it could lead toreproductive cloning. Once the technology to produce a human clone is developed, it will bedifficult to stop someone using it to produce a cloned adult human.I: CLonIng 37 39. ScienceExplanationsIn this module, you will learn about inheritance, that genes are the units ofinheritance, the relationship between genes and the environment, and thatsexual reproduction is a source of variation.ow:You should kn thatgenesaresectionsof DNAandformpartof chromosomes;theyarefoundincellsnucleiandinstructcellstomakeproteins howsinglegenescandeterminesomehumancharacteristics,suchasdimples;severalgenesworkingtogetherdeterminest rmanycharacteristics,suchaseyecolour;featuressuchasscarsuc proaredeterminedbytheenvironment;othercharacteristics,such tu ralteiasweight,aredeterminedbybothgenesandtheenvironmentnsgenes thatapairof chromosomescarriesthesamegeneinthesameproteins asplace;allelesaredifferentversionsof thesamegeneenzymes aboutthedifferencebetweendominantandrecessivealleles howsexcellscontainonechromosomefromeachpairandhowgenesfrombothparentscometogetherduringsexualreproduction whyoffspringaresimilartobothparentsbutarenotthesamebecausetheyinheritgenesfrombothparents thatgeneticdiagramsareusedtoshowinheritance thatthesymptomsof Huntingtonsdiseaseappearlaterinlifeandincludeclumsiness,tremors,memoryloss,andmoodchanges thatHuntingtonsdiseaseiscausedbyafaultydominantallele thatafaultyrecessiveallelecausescysticfibrosisgtons thatcysticfibrosisisaconditionwherecellsproducethickmucus huntinthatcauseschestinfectionsanddifficultiesbreathinganddigestingfood howgenetictestingisusedtoscreenadults,children,andembryosforfaultyalleles howtheinformationfromgenetictestingisusedtomakefibrosiscysticdecisionsandwhythishasimplications thatclonesareorganismswithidenticalgenes;therearealsonaturalclones aboutunspecialisedcells,calledstemcells,thatcandevelopintoothertypesofcellandhowtheycanbeusedtotreatsomeillnesses.38 40. B1: You and Your genesmulti np tioht a igle inweerm gen ne tio det mas for sex dim iting in plesinhers ca r stonstt genetic tingne uns arePun env h ironsqu m en talrees cystic variafamily t fibrosistic iontsneam gegrdiaYOU AND dna YOUR GENESctionesge ner yo selechromosomtic embtes tin gpredictive testingfor disease n esidentical twinclos ns prapes tio p cr i bin lica ropr g iatimpedrugallndsasethical sellb ebu rsne nru t i na ndomaccess information de cidin eg et ssivhical issues e regrecula ry tobody B1: You and Your genes 39 41. Ideas about Science Theapplicationof scienceandtechnologyhas manyimplicationsforsociety.Ethicalissuesare oftenraisedbyscience.Thescientificapproach cannotalwaysanswerthesequestionsandsociety asawholeneedstodiscusstheseissuesandreach adecisiontogether. Oftenthedevelopmentandapplicationof science isregulated.Youwillneedtobeabletodiscuss examplesof whenthishappens,forexample: theroleof theregulatorybodyforUKembryo research makingdecisionsaboutgenetictestingon adultsandselectingembryosbefore implantation. Somequestionscannotbeansweredbyscience, forexample,thoseinvolvingvalues.Youwillneed certainactionsarerightorwrongwhatever torecognisequestionsthatcanbeansweredbytheconsequences;wrongactionscannever usingascientificapproachfromthosethat bejustified. cannot,suchas: isitrighttotestembryosforgeneticdiseases? shouldapregnancybeterminatedornot? Someformsof scientificworkhaveethical implicationsthatsomepeoplewillagreewithand otherswillnot.Whenanethicalissueisinvolved, youneedtobeableto: stateclearlywhattheissueis summarisethedifferentviewsthatpeoplemighthold. Whendiscussingethicalissues,youwillneedto beabletoidentifyexamplesof common argumentsbasedontheideasthat: therightdecisionistheonethatleadstothebestoutcomeforthemajorityof thepeopleinvolved40 42. B1: You and Your genesReviewQuestions1 Cysticfibrosisisageneticdisorder.3 Clonescanbeproducedartificially.a hoosethetwowordsthatdescribethe Ca Whichof theexamplesbelowarenatural allelethatcausescysticfibrosis: clones?faulty normalA woplantsmadebyasexualTdominant recessive reproductionfromthesameparent. A B wobacteriaproducedfromoneTbacterium.B CD C Identicaltwins. D Twospermcellsfromthesameman. Female without cystic fibrosis Female with cystic fibrosis Male without cystic fibrosis Male with cystic fibrosis b Clonescanlookdifferent.b hefamilytreeshowstheinheritance TWhichfactorscancauseclonestolook ofcysticfibrosis.different?Choosethecorrectanswer. i hichperson,A,B,C,orD,isaWfemalewhohasinheritedtwofaultygenetic factors onlycysticfibrosisalleles? environmental factors only ii hichpeoplefromA,B,C,andDareW both genetic andcarriers? environmental factors iii ersonBhasadaughter.WecannotPtellfromthefamilytreeif theneither genetic nordaughterisacarrier.Explainwhy. environmental factors2 Sciencecanshowhowgenetictestingcanbecarriedout.Itcannotexplainwhetheritshouldbecarriedout.a escribesomeimplicationsof carrying D outgenetictestingonhumanbeings.b xplainsomeethicalissuesinvolved. Ec Statethedifferentviewsthatmightbe held,includingatleastoneargumentfor genetictestingandoneagainst. B1: You and Your genes41