Cambridge IGCSE Twenty-First Century Science 0608 — 2010 May/June Paper 4 · Variant 1

This document consists of 15 printed pages and 1 blank page. DC (LEO/KN) 20146/2 © UCLES 2010 [Turn over UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education 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. 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. * 3 2 7 7 3 2 7 3 1 5 * TWENTY FIRST CENTURY SCIENCE 0608/04 Paper 4 May/June 2010 1 hour 30 minutes Candidates answer on the Question Paper. No Additional Materials are required. For Examiner’s Use 1 2 3 4 5 6 7 8 9 Total www.XtremePapers.com

2 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 1 Scientists compare the hardness of two metals, A and B. They use a machine to press a steel pin into samples of each metal. The machine presses with the same force each time. steel pin dent metal sample The depth of the dent produced is measured on a scale of 0 to 100. Their results are shown in the table. depth of the dent sample 1 sample 2 sample 3 sample 4 sample 5 mean metal A 25 23 26 15 26 metal B 68 65 66 66 65 66 (a) (i) The scientists use five samples of each metal. Explain why this is better than using only one sample of each metal. … … … [2] (ii) The scientists get a best estimate for the hardness of metal A by calculating the mean (average) of the depth of the dent for each sample. Use the results to get a best estimate for the depth of the dent for metal A. best estimate = … [2]

3 0608/04/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (b) (i) The scientists conclude that there is a real difference between the hardness of each metal. How do the results show this? … … [1] (ii) Metal A is harder than metal B. Explain how the results show this. … … … [2] [Total: 7]

4 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 2 Carbon dioxide, nitrogen dioxide and sulfur dioxide are pollutant gases. (a) (i) A source of carbon dioxide is the burning of fossil fuels such as methane. Complete the diagram to show this reaction. + + methane oxygen carbon dioxide water [2] (ii) Carbon dioxide is removed from the air by several processes. State two of these processes. 1 … 2 … [2] (b) (i) When a fossil fuel containing sulfur is burned, sulfur dioxide is produced. Write a symbol equation for this reaction. … [1] (ii) Acid rain can be formed when sulfur dioxide is released into the air. Explain how this acid rain is formed. … … [1] [Total: 6]

5 0608/04/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use 3 In some developing countries farmers use a ‘slash and burn’ method of agriculture. Areas of forest are cut down and the trees burned. Crops are grown on the cleared land for a few years. The farmer then moves to another area of forest and repeats the process. (a) The first year that the cleared land is used, crop yields are good. Yields then decrease each year. Explain why. … … … … … [3] (b) Slash and burn farming is not a sustainable development. Explain why. … … … [2] (c) Crops grown in slash and burn agriculture are likely to be affected more by pests than those grown in developed countries. Suggest and explain a reason for this. … … … … [2] [Total: 7]

6 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 4 Chromosomes in the nucleus of human body cells are found in 23 pairs. (a) Why are the chromosomes found in pairs? … … [1] (b) One pair of chromosomes determines the sex of a human embryo. Describe how. … … [1] (c) (i) Complete the genetic diagram to show how the sex of the baby is inherited. MOTHER FATHER X X X X [2] (ii) Rosie and David have three boys. Rosie is pregnant again. What is the probability that this baby is also a boy? … [1]

7 0608/04/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (d) Pre-implantation genetic diagnosis (PGD) allows the genes of an embryo to be tested. PGD can allow parents to choose the sex of their baby. Read these different views on PGD. Embryo selection will help to reduce the number of people suffering from genetic diseases. This has to be a good thing for everyone. Dao It is personal choice whether a couple should use embryo selection. It will depend on their own circumstances. One rule cannot be made for all. Chipo Just because we are able to select an embryo does not mean it is the right thing to do. Who knows where this may lead? One day we could all be choosing our ‘perfect’ babies, and I don’t think this should be allowed. Amir It is okay to select embryos without genetic diseases but you shouldn’t be allowed to select an embryo just because it is a particular sex. Ellen Embryo selection should not be allowed under any circumstances. It is unnatural and wrong. Badr (i) Who gives a reason for and against embryo selection? … [1] (ii) Who explains that different courses of action may be taken in different social and environmental contexts? … [1] (iii) Who distinguishes between what can be done and what should be done? … [1] [Total: 8]

8 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 5 Mandy has a chest infection caused by bacteria. The doctor gives Mandy an antibiotic. (a) What is an antibiotic? … … … [2] (b) The doctor tells Mandy that it is important for her to complete the course of the antibiotics. Suggest why this is important. … … [1] (c) Penicillin is an antibiotic. Penicillin does not affect all bacteria. The graph shows the percentage of bacteria that were not affected by Penicillin from 1940 to 1980. 1940 1950 1960 Year 1970 1980 0 20 40 60 80 100 percentage of bacteria not affected by Penicillin (i) Describe the pattern shown by the graph. … … … … [2]

9 0608/04/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (ii) Explain the mechanism that may have led to the pattern shown in the graph. … … … … … [2] [Total: 7]

10 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 6 The evolution of multi-cellular organisms has led to the development of nervous and hormonal communication systems. (a) State two differences between the nervous and hormonal communication systems. 1 … … 2 … … [2] (b) Read the statements (A to F) about human evolution. A Hominids are extinct. B Bigger brains enabled human beings to walk upright. C Hominids could walk upright and had a smaller brain than human beings. D Human beings have bigger brains than apes. E Apes cannot walk upright. F Apes, humans and hominids evolved from a common ancestor. Use the statements to complete the following questions. Write A, B, C, D, E or F in the spaces provided. (i) Which statement is an explanation? … [1] (ii) Which two statements when put together would increase confidence in the explanation but not prove it is correct? … and … [1] (iii) Which statement is an observation that would decrease confidence in the explanation? … [1] [Total: 5]

11 0608/04/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use 7 Many scientists think that the dinosaurs died after an asteroid collided with the Earth 65 million years ago. (a) The asteroid which may have killed the dinosaurs landed near Mexico. Explain how one asteroid landing near Mexico may have killed all the dinosaurs. … … … [2] (b) This scientist has a different theory for the death of the dinosaurs. He makes six statements, A, B, C, D, E and F. Fossil records show that the dinosaurs started dying out before 65 million years ago. A Massive volcanic eruptions in India could have had the same effects as an asteroid impact. B Rocks in India show that these eruptions started before the asteroid crashed in Mexico. C Fossils show that many species became extinct in the Permian extinction, which happened 250 million years ago. D There are enormous layers of volcanic lava in Russia dating from about the same time as the Permian extinction. E Massive volcanic eruptions are the most likely cause of mass extinctions. F Some of these statements contain data. Write down the letters of the statements which contain data. Choose from A, B, C, D, E and F. … [1] (c) Some scientists prefer the asteroid explanation and some prefer the volcano explanation for the death of the dinosaurs. Suggest and explain one reason why they cannot agree on an explanation. … … … … [2] [Total: 5]

12 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 8 Many people from colder countries spend summer holidays in much hotter ones. They are at risk from the Sun’s ultraviolet radiation because they are fair-skinned. The visible light and infrared radiation are not so dangerous. (a) How does exposure to different amounts of ionising radiation, such as ultraviolet, affect living cells? … … … [2] (b) Most of the Sun’s ultraviolet radiation that reaches the Earth’s atmosphere is absorbed by the ozone layer. Explain how the ozone layer continually absorbs ultraviolet radiation. … … … [2] (c) These four young people from Northern Europe are going to spend a week in the sunny Canary Islands. I’ll stay indoors while the Sun is out. I’ll put on plenty of sunscreen and wear a tee-shirt. Barry Abby The Sun’s ultraviolet is healthy if you don’t get too much. It makes vitamin D in your skin. Carl I’m looking forward to a week in the Sun! Having a nice suntan makes you look good and feel good! Dana

13 0608/04/M/J/10 © UCLES 2010 [Turn over For Examiner’s Use (i) Who mentions both risk and benefit? Put a tick (✓) in the box next to the correct answer. Abby Barry Carl Dana [1] (ii) Who is saying something which shows they realise there is a risk from the Sun’s ultraviolet radiation? Put a tick (✓) in the box next to each of the correct answers. Abby Barry Carl Dana [1] (iii) Who is planning to do something which will reduce this risk? Put a tick (✓) in the box next to each of the correct answers. Abby Barry Carl Dana [2] [Total: 8]

14 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use 9 The bar chart compares different ways in which electrical energy was generated globally in 2004. (One exajoule = 1 million million million joules.) 0 20 40 energy source 60 80 100 120 140 160 180 200 electrical energy generated (in exajoules) coal gas nuclear oil hydroelectric other renewables (a) Which energy sources each generated more than 20% of the total amount of electrical energy generated in 2004? … [2] (b) What was the total electrical energy produced by burning carbon fuels in 2004? energy from carbon fuels = … exajoules [1]

15 0608/04/M/J/10 © UCLES 2010 For Examiner’s Use (c) It is claimed that globally a quarter of all electricity is produced from nuclear power. Use the data in the bar chart to show that this statement is false. Show your working. [2] (d) The following energy flow diagram (Sankey diagram) shows the electrical energy generated in a power station burning a carbon fuel. The energies shown, in megajoules (MJ), are those released when 1 kg of the fuel is burnt. heat lost in cooling water 17 MJ heat lost in exhaust gases 9 MJ electrical energy produced total energy released by burning fuel 56 MJ Use the information in the diagram to calculate the efficiency of electrical energy generation in the power station. Show your working. efficiency = … [2] [Total: 7]

16 0608/04/M/J/10 © UCLES 2010 BLANK PAGE 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.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2010 question paper for the guidance of teachers 0608 TWENTY FIRST CENTURY SCIENCE 0608/04 Paper 4 (Extended Written), 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 must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses. www.XtremePapers.com

Page 2 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0608 04 © UCLES 2010 Expected Answers Mks Additional Guidance 1 (a) (i) it gives a more reliable best estimate; it allows outliers to be found and ignored; one sample may be faulty; one experiment may be in error; [2] Any two (ii) 25+23+26+26/4; = 25; [2] Allow one mark for 23 (b) (i) the mean of metal B/66 is not within the range of metal A/the mean of metal A/25/23 is not within the range of metal B; [1] (ii) depth of dent is smaller for metal A; the harder the metal the less the depth of the dent; [2] Total [7] Expected Answers Mks Additional Guidance 2 (a) (i) one carbon dioxide for 1 mark; two water for second mark; [2] (ii) photosynthesis; dissolving in rain/seas; [2] (b) (i) S + O2
SO2; [1] (ii) sulfur dioxide reacts with water and oxygen in the air; [1] Total [6] Expected Answers Mks Additional Guidance 3 (a) plants need nitrogen to make protein; crops take nitrogen from the soil; no fertiliser is added to put the nitrogen back; [3] (b) abandoned areas cannot be used again; eventually all of forest is used up; [2] (c) in developed countries pesticides are used; farmers in developing countries cannot afford pesticides/pesticides may not be available; [2] Climatic differences acceptable: factor (1) development (1) Total [7]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0608 04 © UCLES 2010 Expected Answers Mks Additional Guidance 4 (a) one from mother and one from father; [1] (b) gene on Y chromosome; [1] Allow description of e.g. X + X = girl, X + Y = boy (c) (i) MOTHER X X X XX XX FATHER Y XY XY [2] One mark for parent genotypes One mark for correct outcomes (ii) 50% / 0.5 / ½ / 1 in 2; [1] (d) (i) Ellen; [1] (ii) Chipo; [1] (iii) Amir; [1] Total [8] Expected Answers Mks Additional Guidance 5 (a) chemicals; can kill bacteria/fungi; [2] (b) to prevent bacteria becoming resistant; [1] (c) (i) increase in % of bacteria not affected; faster increase between 1940 and 1950/steadier increase now; [2] Must describe pattern of increase for second mark (ii) mutation in genes of bacteria; resistance passed onto next generation; [2] Allow explanation of sudden increase and then slower increase e.g. new antibiotic at start Total [7]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0608 04 © UCLES 2010 Expected Answers Mks Additional Guidance 6 (a) nervous is electrical whereas hormone is chemical; nervous is faster than hormonal/ora; nervous are shorter lived response/ora; [2] Any two (b) (i) B; [1] (ii) D and E; [1] (iii) C; [1] Total [5] Expected Answers Mks Additional Guidance 7 (a) clouds of dust produced (1); blocked out Sun’s radiation (for a long time) (1); cooled Earth below temperature at which they could survive (1); plants to feed (some of) them died due to darkness (1) [2] Any two points. Ignore any strictly local effects, e.g. blast (b) A, D and E [1] In any order. All 3 and no others for 1 mark. (c) data of extinctions not precise enough (1); fossil record not complete (1); may be other data not yet discovered (e.g. asteroid craters, lava flows) (1); other theories may be possible (1); scientists tend to stick with accepted theory (1); [2] First mark for clear indication of reason and second for explanation /clarification Total [5] Expected Answers Mks Additional Guidance 8 (a) ionise/split up molecules (1); these ions/molecule fragments react chemically (1); consequent damage to cell can kill cell/cause cancer (1); [2] Any two points (b) ozone molecules absorb UV and are chemically changed (1); these changes are reversible and ozone is restored (1); [2] (c) (i) Carl; [1] (ii) Abby, Barry and Carl; [1] All three and NOT Dana for the mark. (iii) Abby and Barry; [2] One mark each. Subtract one mark for each extra tick. Total [8]

Page 5 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0608 04 © UCLES 2010 Expected Answers Mks Additional Guidance 9 (a) coal, gas and oil;; [2] All three (in any order) for two marks. At least two for one mark. Deduct one mark for each other fuel in list. (b) 410 EJ (allow 405 – 415 EJ); [1] (c) Total energy in range = above+30+30+3EJ = 473 EJ (Allow 470 – 480 EJ) (1); ¼ of this = 120 EJ while nuclear = 30 EJ so claim is false (1); [2] Ora e.g. nuclear = 30 GJ (1) so claim is false as gas/coal/oil alone > 3 × this (1) (d) Electrical energy = 56 - (17 + 9) = 30 MJ (1); efficiency = (30 / 56)×100 = 54% (1); [2] Total [7] Paper Total [60]