2021 MSHS Computing P1

Class/ Index Number / Centre Number/ ‘O’ Level Index Number / Name MARIS STELLA HIGH SCHOOL PRELIMINARY EXAMINATION SECONDARY FOUR COMPUTING 7155 Paper 1 Written 25 August 2021 2 hours Candidates answer on the Question Paper No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your class, index number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Approved calculators are allowed. Answer all the 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. For Examiner’s Use 80

2 This document consists of 12 printed pages. 1 Xavier is concerned about security threats that he may encounter when using the Internet. Two of the threats that he is concerned about are phishing and pharming. (a) Give one similarity and two differences between phishing and pharming. Similarity …………………………………………………………………………………….. ………………………………………………………………………………………………... ………………………………………………………………………………………………... Difference 1 ………………………………………………………………………………… ………………………………………………………………………………………………... ………………………………………………………………………………………………... Difference 2 ………………………………………………………………………………… ………………………………………………………………………………………………... ………………………………………………………………………………………………... [3] (b) State two other threats that Xavier could encounter when using the Internet. Threat 1 ……………………………………………………………………...…………….. Threat 2 …………………………………………………………………………...……….. [2] (c) Xavier uses a firewall to secure data on his computer. (i) Xavier tells his classmate that a firewall can only be software-based. Explain if you agree or disagree with him. …………………………………………………………………………………………. …………………………………………………………………………………………. [1] (ii) Describe how the firewall helps to keep Xavier’s data secured.

3 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. [4] 2 A paragraph is given about MAC addresses and IP addresses. Complete the paragraph using the list of terms given. Not all terms need to be used. compiled control identify principal similar computer dynamic packet protocol unique A MAC address is a media access ……………………………………………… address. A network device has a ……………………………………………… MAC address that can help ……………………………………………… the device in the network. An IP address is an Internet ……………………………………………… address. An IP address can be static or ……………………………………………… . [5] 3 (a) Five statements are given about storage devices. Tick (✓) to show if the statement applies to hard disk drive (HDD) storage or solid state drive (SSD) storage. Some statements can apply to both. Statement HDD (✓) SSD (✓) It uses magnetic properties to store data It is non-volatile storage It can be used as an external storage device to back up data It has moving parts It uses flash memory to store data [5] (b) Optical storage is another type of storage. Give two examples of optical storage. Example 1 …………………………………………………………………………………...

4 Example 2 …………………………………………………………………………………... [2]

5 4. Joshua wants to create a simple game using the programming language he is learning. (a) In the single-player computer game, the player has to shift brown blocks in order to create a clear path for the red block to reach the exit. The blocks can only move in either up and down directions or left and right directions. When the player successfully drags the red block to the exit sign, a message “Level Cleared” is shown and the next puzzle is unlocked. Players are given the choice to start from the last puzzle, choose a previously played puzzle or clear all current records and restart from the first puzzle. Before the program is written, the problem is decomposed into smaller, more manageable parts. Identify and describe three of these smaller parts. 1 ……………………………………………………………………………………………… ………………………………………………………………………………………………... 2 ……………………………………………………………………………………………… ………………………………………………………………………………………………... 3 ……………………………………………………………………………………………… ………………………………………………………………………………………………... [3] (b) In the process of creating the game, Joshua makes several programming errors. A logic error is one type of program error. Identify and describe two other types of program error. Error type 1 …………………………………………………………………………………. Description ………………………………………………………………………………….. ………………………………………………………………………………………………... Error type 2 …………………………………………………………………………………. Description ………………………………………………………………………………….. [4]

6 5 (a) Name and draw the single logic gate that can replace the given logic circuits. (i) A B X Name of gate: …………………….. Drawing of gate: [2] (ii) A B X Name of gate: …………………….. Drawing of gate: [2] (b) Complete the truth table for the given logic statement: X = (((A OR C) AND (NOT A AND NOT C)) NOR B) 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

7 1 1 1 [4]

8 6 (a) An algorithm has been written in pseudocode to input the names and marks of 35 students. The algorithm stores the names and marks in two arrays name[] and mark[]. The highest mark awarded is calculated and the number of students with that mark is counted. Both of these values are output. 01 highestmark = 100 02 highestmarkstudents = 0 03 FOR count = 0 to 34 04 OUTPUT “ Please enter student name: ” 05 INPUT name[count] 06 OUTPUT “Please enter student mark: ” 07 INPUT mark[counter] 08 IF mark[count] == highestmark 09 highestmarkstudents = highestmarkstudents - 1 10 ENDIF 11 IF mark[count] > highestmark 12 mark[count] = highestmark 13 highestmarkstudents = 1 14 ENDIF 15 NEXT 16 OUTPUT “There are ”, highestmarkstudents, “ with the highest mark of ”, highestmark State the line number in the algorithm where the four errors are found. Suggest a correction for each error. Error 1 line number ………………………………………………………………………… Correction ………………………………………………………………………….............. …………………………………………………………………………................................ Error 2 line number ………………………………………………………………………… Correction ………………………………………………………………………….............. …………………………………………………………………………................................ Error 3 line number ………………………………………………………………………… Correction ………………………………………………………………………….............. …………………………………………………………………………................................ Error 4 line number ………………………………………………………………………… Correction ………………………………………………………………………….............. …………………………………………………………………………................................ [4]

9 (b) Explain how you could extend the algorithm to also find the lowest mark awarded, count the number of students with that mark, and