JYSS 2020 Computing P1 Solution

Mark Scheme – 2020 Sec 4E Computing Prelim Paper 1 Qn Answer Marks 1(a) One mark for each correct answer Application Storage Medium Storage of a text book in electronic form CD-ROM Storage of photographs in a mobile phone flash memory A offline backup of a complete PC file system external hard disk Storage of operating system and applications software internal hard disk Playback of video files DVD 5 1(b) (i) flash memory card 1 1(b) (ii) Any two from: • faster access time than magnetic or optical external storage • not vulnerable to drops, mechanical shocks, scratches or fingerprints • more robust / no moving parts • physically small and lighter in weight • low energy consumption • low heat generation 2

2 Qn Answer Marks 2 One mark for each correct line, each box must have only one connection. Network term Description Wired network A component that receives and forwards data packets using IP addressing Wireless network A combination of computers and components that are only connected using cables Bridge An internal component that allows a computer to connect to a network Router A combination of computers and components that are only connected using radio waves Network Interface Card (NIC) A combination of computing devices covering a large-scale geographical area Wide area network (WAN) A component that joins similar networks together 6

3 4E Computing P1 2020 Prelim [Turn over Qn Answer Marks 3(a) One mark for each correct 8-bit binary number 67 0 1 0 0 0 0 1 1 65 0 1 0 0 0 0 0 1 82 0 1 0 1 0 0 1 0 3 3(b) One mark for each correct hexadecimal number 0101 0000 50 0100 0101 45 0100 1110 4E 3 Qn Answer Marks 4 One mark for each correct point Inputs 200 books’ titles 200 corresponding number of copies of books sold Outputs Title of the best-selling book Corresponding number of copies sold Processes Store the data in lists Search for the book with the greatest number sold 6

4 Qn Answer Marks 5 The technique of decomposition is a method of breaking down a complex problem or process into smaller parts such that each part is more manageable and easier to understand. The technique of pattern recognition is a method of identifying similarities among two or more items. The technique of generalisation is a method of replacing two or more similar items with a single, more common item. 5

5 4E Computing P1 2020 Prelim [Turn over Qn Answer Marks 6(a) One mark for each correct gate, with the correct input(s) 4 6(b) Four marks for 8 correct outputs Three marks for 6 or 7 correct outputs Two marks for 4 or 5 correct outputs One mark for 2 or 3 correct outputs Input Working space Output A B C D E F X 0 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 0 0 1 1 1 0 1 1 0 0 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 0 1 1 1 1 1 1 0 0 0 0 4 A B X C D E F

6 Qn Answer Marks 7 One mark for each correct error and corresponding correction Error 1 Outside_Range = 1 Correction Outside_Range = 0 Error 2 IF number >= 5 OR number <= 25 THEN Correction IF number >= 5 AND number <= 25 THEN Error 3 Outside_Range = Outside_Range - 1 Correction Outside_Range = Outside_Range + 1 Error 4 Count = Count + 1 Correction (Not needed, remove this line) 8 Qn Answer Marks 8(a) One mark for each correct definition and one mark for each corresponding explanation of the threat they pose Spywares Definition: A hidden program that secretly collects personal information about its users and transmits this information to attackers without the users’ knowledge. Threat: The personal information can be used to hack into a user’s accounts. Trojan horses Definition: A computer program that pretends to be a harmless file or useful application. Threat: Once a Trojan horse is run, it does something harmful such as giving intruders unauthorised access to the computer instead. 4 8(b)(i) One mark for any correct answer from: Cookies, Pharming, Phishing, Spamming, Virus, Worm 1 8(b)(ii) One mark for each correct answer from: 1) Install Anti-Virus and Anti-Spyware Programs 2) Update Software Regularly 3) Do not click on dubious links in emails 4) Be careful of fake websites 1

7 4E Computing P1 2020 Prelim [Turn over Qn Answer Marks 9(a) One mark for each correct answer Social impact (any one from) 1) Technology has provided better videos, simulations and collaboration tools for lessons to be more engaging and relevant to students 2) The open sharing of information on the Internet has made education accessible to all, even learners from disadvantaged backgrounds. Economic impact (any one from) 1) The rise of open courseware has led to a large number of for-profit and non-profit organisations that offer customised lessons on a variety of topics for self-study online. 2) Many educational institutions have also invested heavily in the materials and infrastructure needed to conduct lessons over the Internet. 3) Some traditional educators find that they need to retrain and pick up new skills to better utilise these new technologies for education. 2 9(b)(i) One mark for any correct answer (or any other reasonable answers): 1) Plan a schedule for studying and relaxation time 2) Get someone to help monitor your device usage 3) Set phone control settings that can limit device usage time 1 9(b)(ii) One mark for each correct answer (or any other reasonable answers): 1) Technology has made it more challenging for educators as students’ attention spans are getting shorter due to the technology and social media that they are used to today 2) Some people use the Internet to reinforce their existing opinions or to spread rumours and misinformation which may lead to conflict in school 3) Technology can break down and cause disruptions in learning 2

8 Qn Answer Marks 10(a)(i) One mark for each correct column. All necessary numbers present and in correct order Number1 Number2 Number Output 6 4 2 2 4 10(a)(ii) To calculate the absolute difference between one pair of numbers 1 10(b)(i) One mark for any correct answer from: 1) Range check 2) Presence check 3) Format check 1 10(b)(ii) One mark for each correct answer set (or any other reasonable answers): Test case condition: Error condition Test data: a, b 2

9 4E Computing P1 2020 Prelim [Turn over Qn Answer Marks 11(a) One mark for each correct answer A1 - text B3 - number D2 - date 3 11(b)(i) PMT 1 11(b)(ii) SUM 1 11(b)(iii) COUNT or COUNTA 1 Qn Answer Marks 12 Sample program in pseudocode: largest = 0, shop1 = 0, shop2 = 0 for item = 1 to 100 input price1, price2 if price1 > price2 then shop1 = shop1 + 1 if price2 > price1 then shop2 = shop2 + 1 difference = price1 – price2 if difference < 0 then difference = - difference if difference > largest then largest = difference next item output shop1, shop2, largest