Cambridge IGCSE Twenty-First Century Science 0608 — 2013 Oct/Nov Paper 4 · Variant 1

This document consists of 15 printed pages and 1 blank page. DC (LEG/SW) 65060/2 © UCLES 2013 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education * 9 3 8 1 3 1 3 7 4 2 * TWENTY FIRST CENTURY SCIENCE 0608/04 Paper 4 October/November 2013 1 hour 30 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. www.XtremePapers.com

2 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 1 This question is about different types of power station. (a) The block diagram shows the production of electricity in a nuclear power station. Write the three missing names in the empty boxes. boiler transformer [2] (b) In a nuclear power station, some energy is lost. One example is shown in the energy flow (Sankey) diagram below. energy losses per second 320 MJ total energy input each second 450 MJ electrical energy produced per second Calculate the efficiency of the power station. Show your working. Give your answer to two significant figures. efficiency= … % [2]

3 0608/04/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (c) People who work in nuclear power stations are at risk from nuclear radiation. Workers wear radiation monitors which measure the dose they have received. Suggest and explain how the power station managers can use the readings from the radiation monitors to make sure that any risk to the workers is kept low. … … … …[2] (d) In many countries, nuclear power stations are being replaced by power stations which use renewable energy sources. Name one such renewable energy source, and write down one disadvantage it has when compared with the use of nuclear power. renewable energy source … disadvantage compared with nuclear power … … …[1] [Total: 7]

4 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 2 This question is about the movement of tectonic plates. The diagrams below show how the Indian tectonic plate, which carries the land mass of India, has moved over the last 70 million years. Africa Asia India 70 million years ago Africa Asia India today Himalayas (a) 70 million years ago, the Indian plate was moving at a speed of 20 cm per year. (i) Calculate how far the Indian plate moved in 100 years. distance = … cm [2] (ii) When the Indian plate reached the mainland of Asia, it slowed down to 5 cm per year. At the same time, the mountains known as the Himalayas were formed. Explain why these two events happened at the same time. … … … …[2]

5 0608/04/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (b) The movement of India shown in the diagram opposite is caused by seafloor spreading. Explain how changes inside the Earth produced this movement. … … …[1] (c) About a hundred years ago, Wegener suggested that continents moved. At the time, scientists did not believe this. Give two reasons why scientists at the time did not believe Wegener’s idea. 1 … … 2 … …[2] [Total: 7]

6 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 3 This question is about the electromagnetic spectrum. (a) The list below shows the electromagnetic spectrum. It is arranged in order of the energy in each photon. Complete the list by filling in the empty boxes. … least energy per photon most energy per photon microwave … visible light … X-rays … [2] (b) Explain why exposure to X-rays is more dangerous for living organisms than exposure to visible light. … … … …[2] (c) Most scientific evidence suggests that the microwave radiation emitted by mobile phones cannot damage brain cells. Despite this, many people prefer not to let their children have mobile phones. Use the precautionary principle to explain why. … … … …[2] [Total: 6]

7 0608/04/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use 4 This question is about chemicals that are added to food. (a) Antioxidants are added to many processed foods to prolong their shelf lives. Explain how they work. … … … …[2] (b) Aspartame is an artificial sweetener. It is used to replace sugar in soft drinks. Aspartame has been found to cause cancer when fed in large doses to rats. Many people who know this, still drink products containing aspartame. They believe that the benefit outweighs the risk. Explain why they believe this. … … … … …[2] (c) In some countries food is eaten near where it is produced. In other countries food is transported long distances. Suggest two reasons for this difference. … … … … …[2] [Total: 6]

8 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 5 This question is about gases in the air. (a) The diagram shows information about some gases found in air. Draw a straight line from each name to the correct formula. Draw another straight line from each formula to the correct molecule diagram. Lines for two of the gases have already been done for you. carbon dioxide O2 oxygen CO2 SO2 nitrogen monoxide carbon monoxide CO nitrogen dioxide NO sulfur dioxide NO2 name formula molecule diagram [3]

9 0608/04/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (b) When methane burns in a plentiful supply of air, complete combustion takes place. The products are carbon dioxide and water. methane + + oxygen carbon dioxide water When methane burns in a limited supply of air, less oxygen is available for the combustion reaction. This is true for the burning of all hydrocarbons, such as those in petrol. Describe and explain the effect this has on the products of the combustion of hydrocarbons and how this affects air quality in cities. … … … … …[3] [Total: 6]

10 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 6 Scientists test the effect of adding a new plasticiser to a polymer. They make batches of the polymer with different percentages (%) of plasticiser. They measure how far samples of each batch of polymer bend when a force is applied. (a) The table shows the scientists’ results for the polymer containing 2.0% plasticiser. bend of polymer in mm sample 1 sample 2 sample 3 sample 4 sample 5 sample 6 15 17 25 14 16 18 Work out the best estimate for the bend of the polymer containing 2.0% plasticiser. best estimate = … mm [2] (b) The graph shows best estimates and ranges for the bend of the polymer containing other percentages of plasticiser. 0 0 5 10 15 20 25 0.5 1.0 1.5 2.0 2.5 3.0 bend of polymer in mm percentage (%) of plasticiser

11 0608/04/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (i) Finish the plotting of the graph by adding the best estimate and the range for 2.0% plasticiser. [1] (ii) David says that the data show that there is a linear relationship between percentage of plasticiser and bending of the polymer. This means that the data points on this graph lie on a straight line. Evaluate the results shown on the graph to suggest how much confidence can be placed in David’s conclusion. … … … … …[3] (c) The properties of this polymer could be changed by another modification. Describe a modification, other than adding plasticiser, and the change it would make to the properties of the polymer. … … … …[2] [Total: 8]

12 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 7 (a) Describe two functions of genes. … … …[2] (b) The diagram shows the genes for cystic fibrosis on two pairs of chromosomes. Cystic fibrosis is caused by a recessive allele. These pairs of chromosomes are found in the body cells of Sophie and Barney. genes for cystic fibrosis Sophie Barney normal allele (F) cystic fibrosis allele (f) Key (i) Sophie and Barney are expecting a baby. Complete the genetic diagram to show the possible combinations of alleles that their baby could have. Use F to represent the normal allele and f to represent the cystic fibrosis allele. Sophie … … Barney … … … … … … [2]

13 0608/04/O/N/13 © UCLES 2013 [Turn over For Examiner’s Use (ii) Calculate the probability of Sophie and Barney’s baby being a carrier of cystic fibrosis. probability = …[1] (iii) Sophie wants to have their foetus tested to see if it will suffer from cystic fibrosis. Her doctor says that the test is unnecessary. Use your genetic diagram in (b)(i) to suggest why. … …[1] (iv) Sophie and Barney are told by their doctor that they are having a baby boy, because the foetus has X and Y chromosomes. Describe how the sex of the baby is determined by its genes. … … …[2] (c) It is possible to test for a variety of genetic diseases. Many couples choose to have their foetus tested for alleles which cause genetic disease. Discuss the possible implications of this. … … …[2] [Total: 10]

14 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 8 The many different species of living things on Earth are believed to have evolved from very simple living things. (a) Complete the sentence. Life on Earth began about … million years ago. [1] (b) Darwin published his theory of natural selection in 1859. At the time, many people disagreed with his theory. Since then, new data have been found to support his theory. Draw a straight line from each reason why people disagreed with Darwin to the new data which now supports his theory. reason new data The Earth was not thought to be old enough. More fossils were discovered. Darwin couldn’t explain how variation occurred. Mendel published his ideas about inheritance. Darwin couldn’t explain how characteristics were passed on. The structure of DNA was discovered. There was not much evidence that species changed over time. The solar system was found to be about 5 thousand million years old. [2] (c) Scientists can compare the DNA of different organisms. Suggest how scientists could use this information to make conclusions about the evolutionary relationships between organisms. … … …[2] [Total: 5]

15 0608/04/O/N/13 © UCLES 2013 For Examiner’s Use 9 A virus is an example of a microorganism. Microorganisms can cause disease. Sarah has chickenpox. Chickenpox is a disease caused by a virus. (a) Explain how Sarah’s immune system will try to destroy the chickenpox virus. … … … … …[3] (b) It is possible to get your child vaccinated against chickenpox. However, in some countries only a small percentage of the population are vaccinated. Discuss the implications of this low uptake of vaccination. … … …[2] [Total: 5]

16 0608/04/O/N/13 © UCLES 2013 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. BLANK PAGE

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 2013 series 0608 TWENTY FIRST CENTURY SCIENCE 0608/04 Paper 4 (Extended Handwritten), maximum raw mark 60 This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the October/November 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components. www.XtremePapers.com

Page 2 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0608 04 © Cambridge International Examinations 2013 Question Expected Answers Mks Additional Guidance 1 (a) first box: reactor second box: turbine third box: generator [2] all correct = 2 marks 1/2 correct = 1 mark allow uranium/nuclear fuel for ‘reactor’ (b) useful output = 450 – 320 MJ = 130 MJ efficiency = 130 / 450 × 100 (1) = 28.88% = 29% to 2 s.f.(1) [2] correct answer = 2 marks 28.88%/28.9% etc. = 1 mark max (c) regular checks made on the (total) dose received by each worker (1) if limit reached, remove worker from high radiation area/find safer place to work (1) [2] ignore any reference to protective clothing etc. (d) renewable source and disadvantage [1] e.g. wind – not constant / low power available hydroelectric / geothermal – cannot be used in many places wave – not constant / low power / need sea coast Total: [7] 2 (a) (i) 20 cm × 100 (1) = 2000 cm (1) [2] allow conversion to 20 m if unit changed bald correct answer gets (2) (ii) push from Asian mainland slowed it down (1) two plates moving together pushed up mountains (1) [2] (b) movement in the mantle [1] (c) any two from: Wegener was an outsider (1) movement not detectable (1) insufficient evidence (1) alternative explanations possible (1) no plausible mechanism (1) [2] allow other reasonable suggestions, e.g. reactionary nature of establishment Total: [7]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0608 04 © Cambridge International Examinations 2013 3 (a) radio (waves) infrared ultraviolet gamma (rays / photons) [2] all correct = 2 marks 3 correct = 1 mark (b) X-rays are ionising and visible light is not ionising (1) ionising radiation can damage living cells (1) [2] allow ‘X rays more penetrating’ e.g. become cancerous, damage DNA (c) risk is unknown (1) but consequence could be severe (1) [2] Total: [6] 4 (a) prevent reaction of fats / oils (1) with oxygen in air (1) [2] needs ref to fats / oils (b) consideration of risk: rats are different from humans / doses are larger than realistic (1) consideration of benefit: suggestion relating to reduction of sugar intake, e.g. diabetes, obesity (1) [2] (c) any two from: some countries – have better transport (1) have refrigeration (1) can package food for longer shelf life (1) are cooler (1) have population concentrated in areas far from where food is grown (1) [2] allow ora in each case allow reasonable alternatives Total: [6] 5 (a) [3] 8 lines correct = 3 marks 6/7 lines correct = 2 marks 4/5 lines correct = 1 mark if a box has more than one line that box does not count

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0608 04 © Cambridge International Examinations 2013 (b) there is not enough oxygen to form carbon dioxide (1) carbon monoxide / carbon is formed (1) carbon monoxide is poisonous / carbon causes smog / breathing problems (1) [3] Total: [6] 6 (a) does not use sample 3 / 25 in calculation (1) works out average / mean = 16 (1) [2] one mark for 17.5 (b) (i) plots value calculated in (a) with correct range (expect value 16 range 14–18) [1] ecf from a allowed provided range bars go 14–25 in that case (ii) best-fit straight line plotted (1) relates conclusion to the fit of line to best- estimate points (1) relates conclusion to range bars(1) [3] by eye ecf own plotting should conclude ‘you cannot be confident in conclusion’ should note line outside some range bars (c) any pair of answers from: increase / add cross-linking (1) increase mp / hardness / strength (1) increase chain length (1) increase mp / hardness / strength (1) increase crystallinity (1) increase mp / hardness / strength (1) [2] ora allow other correct description of changes, e.g. decreased flexibility Total: [8] 7 (a) unit of inheritance / AW (1) codes for proteins (1) [2] accept any specific protein / enzyme (b) (i) Sophie F F Barney F FF FF f Ff Ff [2] one mark for correct parent genotypes one mark for correct completion of the grid (ii) 0.5 / ½ / 50% [1] ecf from (b)(i) (iii) there is no risk of her child having cystic fibrosis [1] (iv) gene on Y chromosome (1) [2]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2013 0608 04 © Cambridge International Examinations 2013 determines development of sex organs / testes (1) (c) will see if child will be affected (1) can lead to decisions about whether or not pregnancy should be terminated / allows preparation for child pre-birth (1) [2] allow other valid implications Total: [10] 8 (a) 3500 [1] ± 100 (b) reason new data the Earth is not old enough for natural selection to have occurred More fossils were discovered Darwin couldn’t explain how variation occurred Mendel published his ideas about inheritance Darwin couldn’t explain how characteristics were passed on the structure of DNA was discovered there were not many fossils available The solar system was found to be about 5 thousand million years old [2] all correct = 2 marks 3 or 2 correct = 1 mark (c) look at similarities and differences in DNA (1) more similarities = more closely related (1) [2] ora Total: [5] 9 (a) white cells (1) engulf and digest virus (1) produce antibodies (1) create memory cells (1) [3] any three (b) disease will spread / there will be epidemic (1) because there needs to be a high percentage uptake to prevent a continuing reservoir of infection (1) [2] Total: [5]