OCR Oxford Cambridge and RSA Monday 16 May 2022 - Afternoon GCSE (9—1) Computer Science J277101 Computer Systems Time allowed: 1 hour 30 minutes

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Answer all the questions. 1 Computers represent data in binary form. (a) Tick (3) one box in each row to identify the binary unit equivalent of each of the given file sizes. File size 2 megabytes... 2 petabytes 2 kilobytes 2 bytes 2 gigabytes 2000 bytes 2000 terabytes 16 bits 4 nibbles [4] (b) Convert the denary number 221 into 8 bit binary. Show your working. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] (c) Convert the hexadecimal number 2F into denary. Show your working. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] (d) Convert the binary number 10110000 into hexadecimal. ................................................................................................................................................... .............................................................................................................................................. [1] (e) Identify how many unique values can be represented by 4 bits. .............................................................................................................................................. [1] (f) Perform a binary shift of 3 places right on the binary number 10001110. .............................................................................................................................................. [1] 3 © OCR 2022 Turn over 2 Complete the table by writing the missing definition or name of each of the common CPU components and registers. CPU component or register Definition Stores the address of the next instruction to be fetched from memory. Increments during each fetch-execute cycle. CU (Control Unit) Stores the address of the data to be fetched from or the address where the data is to be stored. Performs mathematical calculations and logical operations. [4] 4 © OCR 2022 3 A library has a LAN (Local Area Network). (a) The LAN allows access by both wired and wireless devices. Users have reported that the network sometimes runs very slowly. (i) Explain why the number of devices using the network at the same time can affect the performance of the network. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3] (ii) Identify one other factor that can affect the performance of the network. ........................................................................................................................................... ...................................................................................................................................... [1] (b) Users can access websites from the library computers. Complete the description of accessing websites using the given list of terms. Not all terms will be used. 0 1 127 128 255 256 Colon Domain Name Server Embedded systems File server Full stop Hyphen Internet protocol MAC address Router Uniform Resource Locator Web server Clients A website is hosted on a ..................................................................... . The computers that access the websites are called ..................................................................... . The user enters the ..................................................................... into a web browser. The web browser sends a request to the ..................................................................... for the matching IP (Internet Protocol) address. If found the IP address is returned. A request is then sent to this IP address. An IPv4 address is made of 4 groups of digits. Each group can be between the denary values ..................... and ..................... . The groups of digits are separated by a ..................................................................... . [7] 5 © OCR 2022 Turn over (c) The wired connection is an Ethernet connection. Ethernet is considered a standard. Explain why Ethernet is a standard. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] (d) The network has several routers. Identify three tasks carried out by a router. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... 3 ................................................................................................................................................ ................................................................................................................................................... [3] (e) The library does not use encryption when data is transmitted through the network. Give two reasons why the library should use encryption. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2] (f) Protocols are used to transmit data through the network and over the internet. Identify one protocol that can be used to perform each of the following tasks: Send an email ........................................................................................................................... Access a website securely ....................................................................................................... [2] 6 © OCR 2022 4* Social networking websites use artificial intelligence (AI) to monitor posts from users. Discuss the positive and negative uses of AI by social networking websites including: • Legal issues • Ethical issues • Privacy issues .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... 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.......................................................................................................................................................... 7 © OCR 2022 Turn over .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... 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[8] 8 © OCR 2022 5 A software development company wants to protect their computer systems and data from unauthorised access. (a) Identify two methods of physical security that the company could use to protect their computer systems. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2] (b) Identify and describe two software-based security methods that the company can use to protect their computer systems and data. Method 1 ................................................................................................................................... Description ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Method 2 ................................................................................................................................... Description ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [6] 9 © OCR 2022 Turn over (c) Tick (3) one box on each row to identify the legislation that would cover each of the given events. Event The Data Protection Act (2018) Computer Misuse Act (1990) Copyright Designs and Patents Act (1988) A company transmits personal data to another company without the individual’s permission. A school accidentally publishes their students’ addresses on the school website. The interface for a piece of software is replicated by a rival company. A user leaves a computer logged on and another person leaves them a message on their desktop. A student guesses their teacher’s password and accesses their computer account. [5] 10 © OCR 2022 6 A student is creating a range of documents for a school project. (a) The student records a podcast about computer science. (i) Describe how an analogue sound wave is converted into digital form. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3] (ii) Tick (3) one or more boxes on each row to identify the effect(s) that each change will have on the sound file. Change File size increases File size decreases Accuracy increases Accuracy decreases Duration changes from 10 minutes to 20 minutes Sample rate changes from 44 kilohertz to 8 kilohertz Bit depth changes from 8 bits to 16 bits [3] (b) The student writes a report about volcanoes. (i) The computer stores text using the ASCII character set. Part of the ASCII character set is shown: Character ASCII denary code M 77 N 78 O 79 P 80 Q 81 Identify the character that will be represented by the ASCII denary code 84. ...................................................................................................................................... [1] 11 © OCR 2022 Turn over (ii) Identify a second character set. ...................................................................................................................................... [1] (c) The student takes a photograph of their science experiment. The image file includes metadata. Identify three pieces of metadata that is often stored with an image. 1 ................................................................................................................................................ 2 ................................................................................................................................................ 3 ................................................................................................................................................ [3] (d) The student compresses all their documents before emailing them to their teacher. (i) Give two benefits of compressing the data before it is emailed. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... [2] (ii) Explain why lossy compression may not be appropriat [Show More]

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