Cambridge A Level Information Technology (from 2017) 9626 — 2019 Feb/March Paper 3 · Variant 2

1 Errors in JavaScript code can cause the code to fail to execute when run by a web browser. The code shown is intended to display a table on a web page when run in a web browser. The line numbers are shown only for your convenience when referencing the code in your answers. 1 <html> 2 <body> 3 <script language="JavaScript"> 4 tableout = "<table border='1' width='300' cellspacing='0' cellpadding='3'>" 5 for (b = 1; b <= 10; b++) { 6 tableout = tableout + "<tr>": 7 for (g = 1; g <= 10; g++) { 8 tableout = tableout + "<td>" + b * g + "</td>"; 9 } 10 tableout = tableout + "</tr>"; 11 } 12 tableout = tableout + "</table>"; 13 document.write (tableout); 14 </script> 15 </body> 16 </html> (a) The code does not run as intended in web browsers because there is an error in the code. Describe how the error in the code prevents the web browser from running as intended. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) Errors can be ‘trapped’ in order that the performance of the web browser is not affected. Explain how you can use error handling techniques to trap errors in JavaScript code. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [5]

Mark scheme: Question Answer Marks 1(a) Two from: 2 A colon (:) is shown instead of a semi-colon (;) in line 6 ...this is a syntax error Syntax errors prevent JavaScript from being executed/are fatal errors in code The web browser displays nothing at all from this code The variable ‘tableout’ has not been declared before it is used Some browsers will ignore/compensate/interpret this differently from others Results can be different/unexpected in different browsers. 1(b) Five from: 5 Add specific code to deal with the errors transparently/without affecting the web browser Specify block of code to be tested Add some code produce output that depends on (the type of) error encountered Use try() block of code to be tested Use catch() to define the error handling code Use final() to allow code to be executed/run Use throw() to display information about the error/error message Specify the text to be displayed on screen as a result of the error.

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2 (a) Describe the characteristics of online tutorials. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) Two types of online tutorial are ‘recorded’ and ‘interactive’. ‘Recorded’ tutorials do not require user input, but ‘interactive’ tutorials do. Describe the differences between these two types of online tutorial. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4]

Mark scheme: 2(a) Two from: 2 A self-study activity Has a specific learning outcome Delivered via internet/network. 2(b) Four from: 4 Recorded tutorial uses video/audio only in a linear sequence/one route through Interactive tutorial is a set of structured (web) pages/slides Navigated by different routes/routes chosen by the learner Interactive can use any combination of text/images/video/audio/animations in any order No user input required in recorded/user input required/mandatory in interactive tutorials.

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3 Evaluate the use of quantum cryptography when transmitting confidential data over public networks. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 3 Command word: Evaluate: discuss the importance of, weigh up, the 8 advantages and disadvantages, judge the overall effectiveness, weigh up your opinions. This question to be marked as a Level of Response. Level 3 (7–8 marks) Candidates will evaluate/explain in detail the benefits and drawbacks of the use of quantum cryptography when transmitting confidential data over public networks. The information will be relevant, clear, organised and presented in a structured and coherent format. There will be a reasoned conclusion/opinion. Subject specific terminology will be used accurately and appropriately. Level 2 (4–6 marks) Candidates will explain the benefits and drawbacks of the use of quantum cryptography when transmitting confidential data over public networks. For the most part, the information will be relevant and presented in a structured and coherent format. There may be a reasoned conclusion/opinion. Subject specific terminology will be used appropriately and for the most part correctly. Level 1 (1–3 marks) Candidates will describe a benefit and/or drawback of the use of quantum cryptography when transmitting confidential data over public networks. Answers may be in the form of a list. There will be little or no use of specialist terms. Level 0 (0 marks): Response with no valid content. Answers may make reference to e.g.: Allows use of cryptographic tasks that would be deemed impossible without the use of quantum cryptography, e.g. the guarantee that any interception/viewing/eavesdropping on/disturbance of the data is detected Calculations can be carried out extremely rapidly so much higher bi-length for keys can be used so increasing security of data when encrypted Does not do away with conventional cryptographic keys i.e. a mathematical algorithm is still needed for the actual encryption of the data Uses photons to carry data in terms of their ‘spin’ which is difficult to control/generate consistently/precise filters to determine the spin are difficult to manufacture/deploy Requires extremely pure fibres to transmit photons intact/undisturbed over anything but short distances – maximum so far is about 60 km/far shorter distance than conventional fibre use can reach Requires a new type/generation of computers to become a viable reality In theory, quantum techniques can break any encryption in a usefully short time.

4 Layers can be used when editing digital images. (a) Describe what is meant by a ‘layer’ in computer graphics. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1] (b) Describe how layers could be used to enhance a digital image. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4] (c) Discuss the impact on society of the use of image editing on photographs in fashion magazines. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [8]

Mark scheme: 4(a) One from: 1 Level at which an object/file is placed in an image Represents part of a graphic/image as pixels (in a bitmap). 4(b) Four from: 4 Can have transparency to allow other layers to show through/be seen Can be overlapped to create a composite image Can be replicated to show multiple instances of same image/object Can be replicated to hide/mask parts of an image Can be used to adjust the brightness/saturation of other layers. 4(c) Command word: Discuss: give important arguments for and against. Often 8 requires a conclusion. Eight from e.g.: Editing can enhance attractiveness/look/appearance of items/models Editing can attract attention of viewer to compensate for reduction in attention span in recent years Editing can make poor photos appear neat/presentable to clients/customers to increase sales Less expensive than taking exact/precise/perfect photographs Removing blemishes, wrinkles, flabby parts/altering body shape is flattering to the model/clothes A false/unrealistic body image can be created Viewing of only perfection in clothes/models can lower viewers self-esteem ...cause eating disorders ...cause unnecessary pressure to confirm to unrealistic ideals Editing can be time consuming /tedious and slow down production.

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5 3D printing is used in medicine. (a) Describe two benefits of being able to produce artificial blood vessels by 3D printing. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) Describe how 3D printing could be used, apart from producing drugs at home, to improve the effectiveness of the manufacture of prescription drugs. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4] (c) Describe the drawbacks of using 3D printing at home to produce prescription drugs. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4]

Mark scheme: 5(a) Two from: 2 No need to wait for real/native blood vessels to grow into implanted /repaired tissue Allows oxygen/O2 to be supplied immediately to implant which is more likely to survive/grow Vessels can be customised for the individual organ which is more likely to fit Less likely to be rejected by recipient than real blood vessels. 5(b) Four from: 4 Chemical components of the drug can be customised at molecular level to individual patient Drug can be customised to deal with patient specific issues/ethnic origin/DNA A chemical blueprint can be created so that the drug can be printed at any pharmacy/druggist/drug store ...using specific components/compounds Drug can be personalised for/targeted to a specific illness/infection. 5(c) Four from: 4 Human errors in use of blueprints/mislabelling can lead to incorrect drug being created ...incorrect dosage being used Difficult to validate/verify drug creation so, e.g. incorrect base materials may be used Difficult to regulate use of the drug/printing machines across (international) borders Difficult to regulate the supply of the drugs once blueprint is published/available to patient Bio-safety/hygiene/sanitary/cleanliness of production difficult to control at home Could be used/customised to produce illegal drugs.

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6 A company sells glass for installation into rectangular windows. The company cannot make glass for windows with dimensions smaller than width 12 cm and height 8 cm. The price of a window is calculated by working out the area of the window and multiplying it by the cost per square centimetre (cm2), which is 20₹. a Area of window = a × b Price = area × cost per cm2 b A spreadsheet with formulas has been created to carry out these calculations. A B C D 1 These cells will be validated using a range check 2 Input a 14 cm 3 Input b 9 cm 4 5 6 Area is: 126 cm2 7 Cost per cm2 is: 20 rupees 8 Price is: 2520 rupees 9 10 the spreadsheet b lan for this spread

Mark scheme: 6 Eight from: 8 Max Five for column headings from e.g.: Test Number/No. What is being tested Type of test data used Expected result Actual result Comments on results Action (to be) taken Max Four for Tests from e.g.: Use of normal, extreme and abnormal data for inputs a and b/in cells B2 and B3 Example data given/used for test Test of (any) message that appears when invalid data entered Calculation of area by formula in cell B6 Calculation of total price by formula in cell B8. Maximum of 8 marks in total.

7 Evaluate ways of combatting spyware. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 7 Command word: Evaluate: discuss the importance of, weigh up, the 8 advantages and disadvantages, judge the overall effectiveness, weigh up your opinions. Eight from: Use of anti-spyware software will prevent spyware being installed May not detect spyware already installed May not detect spyware disguised as legitimate feature of another program/application Use of antivirus software – will detect and remove some spyware but not all, so has limited effectiveness when used on its own Real time scanning of incoming programs/applications/data can provide protection by blocking spyware from entering the system provided the spyware is recognised/in its database/can be analysed to be spyware Dedicated anti-spyware can detect and remove spyware provided all areas of system are regularly scanned Lists of spyware must be up to date Options may include option to manually delete files if anti-spyware is ‘uncertain’ of status of detected file/data Spyware may resist attempts to be deleted/uninstalled« May recreate another running process to reinstall itself once deleted by anti- spyware software Using alternative web browsers may prevent spyware being installed as some are more vulnerable than others« Web browsers are not designed to detect spyware Using reputable sources for download of software may help prevent spyware being installed Reputable sources can be ‘infected’ Use of combination of methods is most successful but takes awareness and time to implement Using a firewall to prevent spyware from returning data to the spyware source One mark is available for a valid reasoned opinion/conclusion.

8 The owners of a bank are replacing its current system by transferring all accounts and processes to a new computer system. They have to be sure that the new system will carry out all the functions of the old system. It is essential that there is no interruption in the services provided by the bank’s computer system to its staff and customers. Choose the most appropriate method of implementation and explain how the new system will be implemented. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 8 Eight from: 8 Install and start the new system alongside the old system Copy/set up all accounts services to the new system Allow some staff and some/new customers to use services on new system Switch all services to new system once it is installed and running Compare results from new system/performance of new system with old/current system over a period of time Period of time long enough to test/try all provided services Keep old/current system running to ensure that no features are lost/in case new system fails Ensure that all services are duplicated properly/in full No perceived difference in services by staff or customers Revert to old/current system if new system needs to be updated/amended/maintained during testing/parallel running time period Once new system has proved successful complete switch to new system Retain old system as backup in case of failure of new system for a period of time/archive.

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9 The manager of a small shop is creating a new relational database that will store details of the goods sold by the shop. It will also store details of the suppliers of these goods. The manager collects the details that are shown on the labels attached to the goods. He gathers the details of the suppliers from a notebook that he keeps. Five examples of labels are shown: Item Beans Item Flour Quantity in pkt 100 g tin Quantity/pkt 2 kg sack Price $2 Price $3 Sell by date N/A Sell by date Dec 2019 Cost per 1000 g $20 Item Sugar Item Soya Quantity in pkt 2 kg bag Amount in pkt 1000 g bag Price $3 Price $5.46 Sell by date March 2020 Cost per 1000 g $5.46 Sell by date 20 Nov 2019 Item Rice Quantity/pkt 5 ½ kg sack Price 440 cents Sell by date 07 June 2029 The shop can obtain all of its goods from any of these four suppliers: Shop Suppliers Inc Sugar Suppliers plc General Shop Cash & Carry Goods Bury St Edmunds Wholesalers PO Box 2300 2500 Newmarket Rd 65a Board View Suffolk Cambridge Pennsylvania Av IP66 7ES CB6 5PE Milford Haven Washington DC Dyfed United Kingdom 20500 UK SA85 2NX Create a suitable data dictionary for the new relational database to store the shop’s goods and supplier details. [8]

Mark scheme: 9 Entities with attributes include: 8 Four from e.g.: Item text Quantity real number validation Type of packet text Price real number/currency validation Cost per 1 kg/1000 g real number/currency formula Sell by date date validation Four from e.g.: Name of supplier text Address line 1 text Address line 2 text Address line 3 text Address line 4 text Zip/Postal code text validation Mark allocation: max 5 goods entities max 4 supplier entities max 3 for correct attributes max 3 for correct indication of any validation required.

10 An international organisation provides communication services over the internet. It enables customers to communicate messages confidentially between their offices in different countries. It uses message, circuit and packet switching technologies for the communications. Describe the differences between these three technologies as used in communicating these messages. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 10 Eight from: 8 Packet switching breaks the message into discrete data packets whereas message and circuit may not do so Packet switching can introduce delays as packets may travel via different routes whereas message and circuit switching do not Packet and message switching make more efficient use of the capacity of the transmission medium than does circuit switching Circuit switching keeps the circuit connected for the whole of the duration of the transmission whereas message and switching do not Circuit switching uses the full bandwidth of the transmission medium whereas message and packet switching do not Circuit switching can guarantee a higher quality of service compared to the other methods Message switching can be less secure because messages are stored (temporarily) at nodes Circuit switching can guarantee a higher level of security of data compared to the other methods Others can use the same communication channel when packet switching is used whereas this is not possible when message and circuit switching is used.

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11 A company has developed a new product. Its market research department has decided to use chat rooms to gather information from potential customers about the product. Explain why they would use a chat room rather than other social networking methods to gather the customer information. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [6]

Mark scheme: 11 Six from: 6 Occur in real time so no delay in obtaining input from participants Can provide a secure online environment for discussion with numbers of participants Can be restricted to only those chosen to participate Participants can be in any location around the world Participants do not have to travel/incur costs of travel/leave their home/work location Employees are not removed from their work place so can continue working once chat is over The (text-based) discussion can be saved for future reference.

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