Pathlight 2022 Prelim 4E Computing P1 QP

PATHLIGHT SCHOOL PRELIMINARY EXAMINATION SECONDARY 4 EXPRESS CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER COMPUTING 7155/01 Paper 1 Written August 2022 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, Index number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Approved calculators are allowed. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You should show all your working. The total number of marks for this paper is 80. This document consists of 14 printed pages and 2 blank pages. [Turn over

2 1 Information stored in our computers can be susceptible to data corruption. (a) What is data corruption? …...……………………………………………………………………………………………… …...…..…………………………………………………..………………………………….. [1] (b) State three ways in which data can become corrupted. 1 ………………………………………………………..……………………………………. 2 …………………………………………………………..…………………………………. 3 …………………………………………………………..……………………………… [3] (c) State one way to prevent data corruption and loss. …...……………………………………………………………………………………………… …………………………………………………………………….…………………………. [1] 2 (a) Convert the hexadecimal number A3 to denary. Show your working. ……...…………………………………………………………………………………………… ……...…………………………………………………………………………………………… ……...…………………………………………………………………………………………… ….………………………………………………………………………………………..….. [2] (b) Convert the binary number 1011011 to denary. Show your working. ……...…………………………………………………………………………………………… ……...…………………………………………………………………………………………… ……...…………………………………………………………………………………………… ….………………………………………………………………………………………..….. [2]

3 (c) Convert the denary number 105 to an 8-bit binary number. Show your working. ……...…………………………………………………………………………………………… ……...…………………………………………………………………………………………… ……...…………………………………………………………………………………………… ….………………………………………………………………………………………..….. [2]

4 3 A company uses spreadsheet software to monitor its monthly sales. The company records: • each sale that is transacted • whether the Goods and Sales Tax (GST) is inclusive (absorbed by the company). (a) Identify the most appropriate data type for the data in the following cell references: Cell Data type A1 A2 B3 F1 [4] (b) The cell F8 will calculate the total sales. Identify the function that will need to be entered into F8. …………….……………………………………………………………………………… [1] (c) The cell F9 will calculate the total for the sales that are GST-inclusive. The company uses one function to calculate this value. Describe the formula that will need to be entered in cell F9. ………………………………….…………………………………………………………… ………………………………….…………………………………………………………… ………………………………….…………………………………………………………… ………………………………….…………………………………………………………… …………….……………………………………………………………………………… [3]

5 4 Six types of security threats are on the left, and seven descriptions on the right. Draw one line to link each security threat to its correct description. Security Threat Description [6] Cookie A computer program that pretends to be a harmless file or useful application Pharming Phishing Spamming A small file used by websites to store personal information on a user’s web browser A computer program that attaches itself to a normally harmless program and modifies it The use of emails and fake websites that appear to be from reputable companies in order to steal personal information such as passwords and credit card numbers from users The use of data owned by someone by someone else, such as an intruder, without permission Trojan Horse The mass distribution of unwanted messages or advertising to email addresses collected from sources such as public mailing lists, social networking sites, company websites and blogs Virus The interception of requests sent from a computer to a legitimate website and redirection to a fake website to steal personal data or credit card details

6 5 (a) Draw the logic circuit to represent the following Boolean statement. Do not simplify the statement. X = ((A AND B) AND (A OR NOT C)) OR (B AND NOT C) [6] (b) Complete the truth table for the Boolean statement: X = ((A AND B) AND (A OR NOT C)) OR (B AND NOT C) A B C Working Space X 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [4]

7 6 Ashley is setting up a home network. There are two desktop computers that use a wired connection. There are three wireless devices: one laptop, one tablet and one mobile phone. (a) The home network has a router, but does not have a switch. (i) A router and a switch are examples of network hardware. Give one other feature that is the same in both a switch and a router, and one difference. Feature that is the same …………………………………………………………………. ………………………………………………………………………………………………. Difference ………………………………………………………………………………..... ………………………………………………………………………………………….. [2] (ii) Identify and describe the function of one other network device that could be part of the home network. Device …..……………………………………………………………………………….. Function ………………………………………………………………………………….. ….………………………………………………………………………………………….. [2] (b) Tick (✓) one box to indicate whether Ashley’s home network is a LAN or a WAN. Give reasons for your choice. LAN WAN Reasons …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………….………………………...…………………………………………..… [3]

8 7 The following algorithm compares whole numbers between 0 and 10 (inclusive). (a) The algorithm is tested using the following numbers as input: 7,2,4,4,6,8,10 Complete the following trace table for the algorithm. Count Number1 Number2 OUTPUT [4] (b) (i) The algorithm does not include validation for input. Name and describe one validation check that could be added to validate the input. ………………………………………………………………………………………..……. ……………………………………………………………………………………………... ……………………………………………………………………………………………... …………………………………………………………………………………….…… [2] 01 Count = 0 02 WHILE Count < 3 DO 03 INPUT Number1 04 INPUT Number2 05 IF Number1 > Number2 THEN 06 OUTPUT “Win” 07 ELSE 08 IF Number1 == Number2 THEN 09 OUTPUT “Draw” 10 ELSE 11 12 13 14 OUTPUT “Lose” ENDIF ENDIF Count = Count + 1 15 ENDWHILE

9 (ii) Name two different validation checks other than your answer to part (b)(i). 1 ………………………………………………………………………………………. 2 …………………………………………………………………………………… [2] (c) Once complete, the algorithm is tested with data for normal conditions. Identify two other test case conditions that could be used to test the algorithm. For each test case condition, give an example of test data for this algorithm. Test case condition Test data [4]

10 8 Alex has created a computer program which he has intended for his personal use. However he would also like to protect his creative work to pre