Cambridge A Level Information Technology (from 2017) 9626 — 2018 May/June Paper 3 · Variant 3

1 Video is streamed over networks and the internet at different bit rates. Fig. 1 shows a summary of the bit rates that are usually required for various video resolutions. Fig. 2 shows the bandwidths that are typically available over different mobile (cell) phone connections. Output video Bit rate Type of mobile Typical maximum resolution (Mbits/s) connection to bandwidth available (pixels) network/internet for download (Mbits/s) 320 × 240 0.4 480 × 270 0.7 3G mobile connection 0.31 1024 × 576 1.5 4G mobile connection 15 1280 × 720 2.5 Bluetooth® 1.1 0.5 connection 1920 × 1080 4.0 Wi-Fi (IEEE 802.1g) wireless 54 connection Fig. 1 Fig. 2 Using all the information in Fig. 1 and Fig. 2, explain how the viewing experience of a streamed video displayed on a mobile (cell) phone screen of resolution 1024 × 576 pixels is affected by bit rate and available bandwidth. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[8]

Mark scheme: Question Answer Marks 1 Eight from: 8 The more available bandwidth on the connection the higher quality of video that can be streamed Use of a 3G connection to the internet limits video/streaming to low bit rate of 400 Kb/s Buffers not filled completely so video pauses/stops/jerky if frames not received fast enough Provides video of 320 × 240 pixels without apparent stuttering/buffering/ stop-start issues This will be a poor video/low definition video as seen on the 1024 × 576 screen Use of a 4G connection with higher bandwidth of c. 15Mbit/s allows video with higher bitrates to be viewed properly This is 1024 × 576 is possible and this is HD quality Highest bit rates of 19 / 30 Mbit/s allowing resolutions of up to 1920 × 1080 pixels Available/can be streamed over Wi-Fi (IEEE 802.1 g) wireless connections.... Which have a maximum of 54 Mbit/s 1920 × 1080 pixels will have to be downscaled for viewing on the smartphone screen Which may lead to artefacts and loss of quality.

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2 The use of JavaScript within the HTML code of a web page allows the page to react to user intervention. The code below contains a function named checkreadpagefunction that will ask the user to confirm that the page has been read. Complete the JavaScript code by writing extra code that will capture the click event and execute the function. <html> <body> <p>Click on the button to confirm that you have read this page.</p> <button id="button1">Click here</button> <script> .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[6] function checkreadpagefunction() { alert ("I have read this page."); } </script> </body> </html> You may use the space below for any rough work.

Mark scheme: 2 A suitable line of code would be: 6 document.getElementById(“button1”).addEventListener(“click”, checkreadpagefunction); Six from: 1 mark for each of: Capturing the element: document.getElementById Identifying the button by name: “button1” Checking for the event: addEventListener Correct reference to click by mouse: “click”, Calling the correct function by name: checkreadpagefunction); All correct delimiters and all correct brackets: . between key words, , after click AND ; after function () around button1 () around parameter (“click”, checkreadpagefunction);

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3 Fig. 3 shows a switched network with computers at A, B, C and D. S1, S2, S3, S4, S5 and S6 are switches. A message is being sent between computers at A and B. The whole message is sent at once along the route shown by the arrows. A S1 S4 B Message Source Message Destination S3 S6 C D S2 S5 Network of switches Fig. 3 (a) Explain, with reference to Fig. 3, why this method of sending a message by the route shown is often called ‘store and forward’. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[8] (b) Describe two advantages of using the ‘store and forward’ method to send a message over this network. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[2]

Mark scheme: 3(a) Eight from: 8 S1 to S6 have their own storage devices for storing whole messages Message sent in its entirety from source to switch S1 ...S1 stores whole message on its storage device S1 connects to S3 and forwards whole message to S3 ...S3 stores whole message on its storage device ...message is deleted from S1 S3 connects to S5 and forwards whole message to S5 ...S1 stores whole message on its storage device ...message is deleted from S3 Process repeated between S5 and S6 where message is stored before forwarding to destination The source and destination of the message are not directly connected Message can be multiplexed with other messages on network Switches Method is called ‘message switching’. 3(b) Two from: 2 Improves/makes more efficient use of bandwidth because the data channels are shared among communication devices Network congestion can be reduced as messages can be stored temporarily at message switches Priorities may be used to manage network traffic Use of broadcast messaging/messages are delivered to multiple destinations makes more efficient use of network bandwidth Message can be stored until recipient decides to pick it up Process is transparent to applications the use it.

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4 An animator used a computer to produce an animation consisting of eight frames. The frames are shown in Fig. 4. 1 2 3 4 5 6 7 8 Fig. 4 The animator only drew some of the frames in this animation and the computer created the others. Explain how the sequence of frames was created. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[6]

Mark scheme: 4 Six from: 6 Animator drew frames 1 and 5 and 8 Frame 8 created by flipping/reflecting of frame 1 These are used as key frames Frame 1 was duplicated/copied (by computer) to create frames 2, 3 and 4 Frame 5 was duplicated/copied (by computer) to create frames 6 and 7 Key frames define the start and end point of transitions that can be used by a computer-based animation application Tweening was used to create frames in between.

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5 RockICT Sales sells hats to customers direct from its warehouse. It has a centralised ordering system that is linked to the warehouse and accounts systems. When a customer orders a hat, the system: • takes the orders from the customer • checks the stock status with the warehouse • sends messages to the customer advising of the status of the order • sends out a request for payment and processes the payment • requests the shipping of the hat from the warehouse • receives a shipping confirmation and a stock inventory update from the warehouse • sends stock inventory and payment updates to the accounts. Draw a Level 0 (context level) Data Flow Diagram of the system to show the external entities and the data flow between these and the ordering system. The ordering system has been drawn in the centre of this box for you. Ordering System [8]

Mark scheme: 5 A simple context DFD would be e.g.: 8 Customer Payment Warehouse for Order hat of Stock Order hat request status update Stock Request messages order Ordering forfor hat hat System for Shipping payment confirmation Acknowledgement Stock inventory/ Shipping of updated payment updates payments Accounts Eight from: Identify all three entities: customer, warehouse, accounts Order from customer to ordering system Payment from customer to ordering system Request for payment to customer from ordering system Messages re order status payment to customer from ordering system Stock (check) request from ordering system to warehouse Shipping order from ordering system to warehouse Stock update from warehouse to ordering system Shipping confirmation from warehouse to ordering system Stock inventory update from ordering system to accounts Acknowledgements from accounts to ordering system.

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6 (a) Describe how a bitmap (‘raster’) graphic is stored in a computer file. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[4] (b) Vector images are stored in computer files in a different format to how bitmap (‘raster’) images are stored. Explain why vector images must be converted to bitmap (‘raster’) images for display on a digital monitor. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[4]

Mark scheme: 6(a) Four from: 4 Made up of pixels Each pixel is represented by bits 1 to 64 bits per pixel Number of pixels depending on colour depth Bits representing pixels packed in rows for bmp Rows rounded to 32 bit words Padding needed for loading into memory locations Usually stored from bottom left up to top right of image. 6(b) Four from: 4 Vector images are stored as co-ordinates/geometric descriptions of shapes and colours Digital monitors cannot display co-ordinate-based graphics Because all digital monitors are pixel-based Graphics card/computer must convert the co-ordinates/ descriptions into pixels before sending to digital monitor... Uses an ADC-type action Resizes the image to suit the requirements of the user/monitor.

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7 Describe how holographic optical disk storage technology uses lasers to store vast amounts of data. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[6]

Mark scheme: 7 Six from: 6 Green and red lasers used Light from both is sent in parallel stream/collimated There is minimal divergence Output about 1 watt Green laser reads the data from top layer of disc Data stored as holographic laser interference patterns Red laser reads reference data stored on aluminium layer at/near bottom of disc layers This is the servo information for accurately aligning the read head position over the disc A (dichroic) mirror allows the red laser light to pass while reflecting the green layer Stores c. 60 000 bits per pulse in densely packed tracks Compared to a single/one bit per pulse for current optical storage Can store 100 GB to 1 TB Phase storage systems can store more data.

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8 Describe the benefits to workers of teleworking. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[6]

Mark scheme: 8 Six from: 6 Greater flexibility in scheduling work/tasks around other activities Greater focus on work activities in comfort of own home/surroundings Reduced stress due to commuting/other workers Greater flexibility/chances in employment opportunities as have experience of self-motivation/use of remote technologies Reduced time off sick as workers can schedule their own time around minor illnesses Possible tax benefits from use of home as office Reduced costs/time spent on travelling to/from work Employees can choose to live/can reside in a cheaper area/do not have to live close to/in expensive city centre offices No need to travel in extreme weather conditions to get to work.

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9 (a) Describe how vision enhancement technology can assist visually impaired people when walking around a shopping street. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[6] (b) Describe two other uses of vision enhancement technology. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[2]

Mark scheme: 9(a) Six from: 6 Enhance shape outlines for objects to make them more apparent Enlarge signs to make the words more readable Change colours of objects to make them more visible Detect signs/objects in visual range and produce warning sounds to accompany the images User learns sounds and associates with object for future reference Infra-red light amplified to enhanced vision in poor light dark conditions. 9(b) Two from e.g.: 2 Military operations at night to spot the enemy Enhance vision when night driving e.g. taxi, truck drivers Improving age-related vision problems Detecting chemicals for forensic purposes Detecting heat loss from e.g. buildings/people.

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10 Consuela is organising the building of her new house. Discuss the advantages and disadvantages of the various types of project management software for this task. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[8]

Mark scheme: 10 This question to be marked as a Level of Response. 8 Level 3 (7–8 marks) Candidates will discuss in detail advantage(s) and disadvantage(s) of a range of types of project management software. 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 advantage(s) and disadvantage(s) of various types of project management software. 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 the advantage(s) or disadvantage(s) of types of project management software. 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.: the various types of PMS with advantages/disadvantages of those mentioned: Desktop/single-user/personal: Suitable for smaller projects Only one person can use the PMS at any one time Can be used on mobile devices/smartphones/tablets May lack all the features of full software Collaborative: Allows multiple uses to edit sections of the project Changes reflected to other users Some areas may be read-only/unavailable when others are working on them Visual: Allows information to be filtered and presented in easier to understand manner to avoid information overload Used for fluctuating data Details not instantly available.

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11 Discuss the benefits and drawbacks of using satellites for television and radio broadcasting. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[8]

Mark scheme: 11 Eight from: 8 Geographical area that can be covered is much greater than other broadcasting methods Costs are less over greater distances/areas... No need for terrestrial transmitters to homes Can cover difficult terrain more cheaply Allows greater bandwidth for data transmission... Higher definition for TV/bit rate for radio for higher quality broadcasts More TV/radio channels are possible due to greater capacity Requires users/viewers/listeners to have (suitable) receiving equipment ...broadcasters may have a limited audience if few people have satellite receivers ...need line of sight view to satellite to be able to receive ...need to be professionally installed which takes time and can be costly Satellite technology has a huge setup cost Satellites do not have an unlimited lifespan ...may become space junk when lifespan is over Repair of orbiting satellites is almost impossible Signals to ground can be subject to interference/blockage due to weather/other signals Significant delays in signal propagation/travel time of signals/distance from uplink to receiver can cause anomalies e.g. time differences of several seconds in transmissions. Max six for all positives or all negatives. 1 mark available for a reasoned conclusion/opinion.

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12 Evaluate the impact of e-business on society. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ......................................................................................................................................................[8]

Mark scheme: 12 Eight from: 8 E-business can be more convenient for shoppers No need to travel/saves cost/time of going to shopping malls Reduction traffic congestion/environmental effects of traffic Less time used for ordering/buying goods than visiting a range of shops Greater availability/choice of goods to buy Information about goods is more available/price comparisons can be made more easily Online business can start up cheaper/quicker than conventional businesses so increasing the global economy E-business has created a range of new jobs/employment opportunities/skill sets E-business can operate all the time/24–7 with no shutdown time/shoppers can buy/trade at any time A global marketplace has been set up by e-businesses New marketing models have developed e.g. review forums/online advertising companies Loss of jobs around the world due to closure of conventional business/shops Increase in fraud due to online transactions not being secure Loss of personal contact with supplies leading to loss of confidence in business transactions. Max six for all positives or all negatives. 1 mark available for a reasoned conclusion/opinion.

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