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Download Actual 2024 AQA A-LEVEL COMPUTER SCIENCE 7517/2 Paper 2 Merged Question Paper + Mark Sche and more Exams Computer Science in PDF only on Docsity!
Actual 2024 AQA A-LEVEL COMPUTER SCIENCE 7517/2 Paper 2 Merged Question Paper + Mark Scheme AQA= Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature | declare this is my own work. A-level COMPUTER SCIENCE Paper 2 Tuesday 18 June 2024 Afternoon Time allowed: 2 hours 30 minutes Materials ; For this paper you must have: RESIS * acalculator. Question | Mark Instructions 1 e Use black ink or black ball-point pen. 2 Fill in the boxes at the top of this page. 3 e Answer all questions. 4 « You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. 5 ¢ If you need extra space for your answer(s), use the lined pages at the end of 6 this book. Write the question number against your answer(s). 7 ¢ Do all rough work in this book. Cross through any work you do not want to 3 be marked. 9 Information 10 « The marks for questions are shown in brackets. " e The maximum mark for this paper is 100. TOTAL Advice e In some questions you are required to indicate your answer by completely shading a lozenge alongside the appropriate answer as shown. | e | If you want to change your answer you must cross out your original answer as shown. ¢ If you wish to return to an answer previously crossed out, ring the answer you now wish to select as shown. LL 2 Do not write itside the Answer all questions. Ok Anti-virus software and user training are measures that can be used to reduce the threat posed by viruses. Describe four other measures that can be used to reduce the threat posed by viruses. [4 marks] 4 INI IBGiJun24/7517/2, 2 [of2|[4] [o[2]{[2] 04 A digital camera takes photographs that are 4000 pixels wide by 3000 pixels tall and can contain up to 16 777 216 different colours. Calculate the size of one image in megabytes. [2 marks] Answer megabytes How many images, taken using the camera referred to in Question 02.1, could be stored on a 256 gigabyte memory card? You should assume that all of the storage space on the memory card is available to store image data. Round your answer down to the nearest whole number. [1 mark] Answer IB/G/Jun24/7517/2 Do not write outside the box Do not write outside the When a digital camera takes a photograph, an array of photosensors produces box analogue voltages representing the amount of light falling on each photosensor. An analogue-to-digital converter then converts these analogue voltages into digital values. These digital values are used to create the pixel data for the bitmap image. [o|2].[3| Explain why the voltages produced by the photosensors are considered to be analogue and why the pixel data is considered to be digital. [2 marks] Question 2 continues on the next page Turn over > 05 IB/G/Jun24/7517/2 5 Do not write outside the Figure 1 shows the organisation of part of a simple computer system. box Figure 1 H vy ty vy Main USB Interface Processor Memory (VO Controller) Keyboard Printer [0[3].[1] State the name of the bus labelled X in Figure 1. [1 mark] [o[3|.[2] The data bus inside the computer uses synchronous parallel data transmission. Describe what synchronous transmission is. [1 mark] Question 3 continues on the next page Turn over > 07 IB/G/Jun24/7517/2 7 [o[3][3] [o}3][4] 08 Do not write outside the Peripherals, such as a keyboard or printer, are connected to the computer using a box USB (Universal Serial Bus) connection. USB uses synchronous serial data transmission. Explain why serial transmission has been chosen to communicate with peripherals connected to the computer and why parallel transmission is used by the data bus inside the computer. [3 marks] The USB interface inside the computer is an example of an I/O controller. Describe the role of an I/O controller. [2 marks] IB/G/Jun24/7517/2 8 10 [1] Shade the lozenges next to all of the true statements about representing numbers [o]4|[2] 10 using fixed and floating point representations. [2 marks] A processor can usually carry out calculations on fixed point numbers f=] more quickly than calculations on floating point numbers. Fixed point numbers represent data using a mantissa and an exponent. [es] In a given number of bits, a fixed point system can represent positive [=] numbers that are closer to zero than a floating point system can. In a given number of bits, a fixed point system can represent some [=] numbers more precisely than a floating point system. In a given number of bits, a floating point system can represent a bigger f=] range of numbers than a fixed point system. Questions 04.2, 04.3 and 04.4 use a normalised floating point representation with an 8-bit mantissa and a 4-bit exponent, both stored using two’s complement. Figure 2 shows a floating point representation of a number: Figure 2 190 1}1}]1/]0/;0)]0 1] o}1)1 Mantissa Exponent Calculate the decimal equivalent of the number in Figure 2. You should show your working. [2 marks] Answer IB/G/Jun24/7517/2 Do not write outside the box 10 [o[4}{3] [o[4][4] 11 11 Do not write outside the Questions 04.2, 04.3 and 04.4 use a normalised floating point representation with an box 8-bit mantissa and a 4-bit exponent, both stored using two’s complement. The decimal number 12.765625 (which can also be expressed as 2S) cannot be represented exactly in this floating point system. Write the closest possible normalised representation of this number in the boxes below. You should show your working. [3 marks] Answer é Mantissa Exponent What is the smallest number of bits that would need to be added to the mantissa so that the decimal number 12.765625 could be represented exactly? [1 mark] Question 4 continues on the next page Turn over > IB/GiJun24/7517/2 11 13 Do not write outside the box Turn over for the next question DO NOT WRITE/ON THIS PAGE ANSWER IN THE/SPACES PROVIDED Turn over > 4) 3 IB/GiJun24/7517/2 13 14 Do not write outside the [o[5].[1| A company uses a file server that stores files on magnetic hard disk drives. These box files can be accessed by other computers through a network. Describe: ¢ how the data for a file would be stored on a magnetic hard disk and read from it by the file server ¢ how the individual layers of the TCP/IP stack in the file server would be used to transmit the file onto the network. In your response, you do not need to describe how the file would be transmitted across the network or how the TCP/IP stack would be used in the computer that has requested the file. You only need to write about how the data would be put onto the network by the file server. [12 marks] 14 IBGiJun24/7517/2, 14 16 Do not write outside the [o[5].[2| The company needs to purchase a second file server. box It is considering whether to purchase a file server with magnetic hard disk drives installed or a file server with solid-state disks (SSDs) instead. Each of the file servers has the same total storage capacity. State one advantage and one disadvantage of purchasing the file server that uses SSDs. [2 marks] Advantage Disadvantage 14 16 IBGiJun24/7517/2, 16 17 Do not write outside the box Turn over for the next question DO NOT WRITE/ON THIS PAGE ANSWER IN THE/SPACES PROVIDED Turn over > IMI IB/GiJun24/7517/2 17 19 Do not write outside the [o[6|.[3] Using the rules of Boolean algebra, simplify the following Boolean expression. box A-(B-C-D+B-C-D+B)+A+B You must show your working. [4 marks] Working Answer 9 Turn over for the next question Turn over > MU) IB/GiJun24/7517/2 19 20 Do not write outside the box There are no questions printed on this page DO NOT WRITE/ON THIS PAGE ANSWER IN THE/SPACES PROVIDED 20 IB/GiJun24/7517/2 20 
