Information Technology 9626/32 February/March 2019: question paper and mark scheme

Mark scheme

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.

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.

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.

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.

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 Bio-safety/hygiene/sanitary/cleanliness of production difficult to control at home Could be used/customised to produce illegal drugs.

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.

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.

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.

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.

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.

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.