AQA GCSE COMPUTER SCIENCE 8525/1A, 8525/1B, 8525/1C Paper 1 Computational thinking and programming skills Version: Final 1.0 *Jun2385251A01* IB/G/Jun23/E11 8525/1AQUESTION PAPER & MARKING SCHEME/ [MERGED] Marl( scheme June 2023

GCSE COMPUTER SCIENCE 8525/1A, 8525/1B, 8525/1C Paper 1 Computational thinking and programming skills Version: Final 1.0 *Jun2385251A01* IB/G/Jun23/E11 8525/1A For Examiner’s Use Question Mark 1 2–3 4–5 6–7 8–9 10–11 12 13–14 15 16 TOTAL Friday 19 May 2023 Afternoon Time allowed: 2 hours Materials • There are no additional materials required for this paper. • You must not use a calculator. Instructions • Use black ink or black ball-point pen. Use pencil only for drawing. • Answer all questions. • You must answer the questions in the spaces provided. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Do all rough work in this book. Cross through any work you do not want to be marked. • Questions that require a coded solution must be answered in C#. • You should assume that all indexing in code starts at 0 unless stated otherwise. Information The total number of marks available for this paper is 90. Advice For the multiple-choice questions, completely fill in the lozenge alongside the appropriate answer. 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. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. GCSE COMPUTER SCIENCE Paper 1 Computational thinking and programming skills – C# CORRECT METHOD WRONG METHODS 2 *02* IB/G/Jun23/8525/1A Do not write outside the Answer all questions. box 0 1 Figure 1 shows an algorithm, represented using pseudo-code, which assigns a different value to four variables. Figure 1 country  'United States of America' state  'California' city  'San Francisco' landmark  'Alcatraz Island' 0 1 . 1 Define the term algorithm. [2 marks] 0 1 . 2 The variable x is assigned a value using the statement: x  LEN(state) Using Figure 1, what is the value of x? Shade one lozenge. [1 mark] A 1 B 5 C 10 D 12 3 *03* Turn over ► IB/G/Jun23/8525/1A Do not write outside the 0 1 . 3 What is the result of concatenating the contents of the variables city and box landmark in Figure 1? Shade one lozenge. [1 mark] A San Francisco Alcatraz Island B San Francisco,Alcatraz Island C San Francisco, Alcatraz Island D San FranciscoAlcatraz Island 0 1 . 4 The subroutine SUBSTRING extracts characters from a given string. For example, SUBSTRING(3, 5, 'Computing') would return put The variable y is assigned a value using the statement: y  SUBSTRING(4, 7, landmark) Using Figure 1, what is the value of y? Shade one lozenge. [1 mark] A Alca B Atra C land D traz Question 1 continues on the next page 4 *04* IB/G/Jun23/8525/1A Do not write outside the Figure 1 has been included again below. box Figure 1 country  'United States of America' state  'California' city  'San Francisco' landmark  'Alcatraz Island' 0 1 . 5 The subroutine POSITION finds the first position of a character in a string. For example, POSITION('Computing', 'p') would return 3 The variable z is assigned a value using the statement: z  POSITION(landmark, 't') Using Figure 1, what value is assigned to z? Shade one lozenge. [1 mark] A –1 B 3 C 4 D 5 6 5 *05* Turn over ► IB/G/Jun23/8525/1A Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 6 *06* IB/G/Jun23/8525/1A Do not write outside the 0 2 Figure 2 box shows an algorithm that uses integer division which has been represented using pseudo-code. • Line numbers are included but are not part of the algorithm. Figure 2 1 again  True 2 WHILE again = True 3 a  USERINPUT 4 IF a > 0 THEN 5 counter  0 6 WHILE a > 0 7 a  a DIV 3 8 counter  counter + 1 9 ENDWHILE 10 ELSE 11 again  False 12 ENDIF 13 OUTPUT a 14 ENDWHILE Integer division is the number of times one integer divides into another, with the remainder ignored. For example: • 14 DIV 5 evaluates to 2 • 25 DIV 3 evaluates to 8 0 2 . 1 Where is iteration first used in the algorithm in Figure 2? Shade one lozenge. [1 mark] A Line number 2 B Line number 4 C Line number 6 D Line number 11 7 *07* Turn over ► IB/G/Jun23/8525/1A Do not write outside the 0 2 . 2 In the algorithm in Figure 2, what will be output when the user input is 10? box Shade one lozenge. [1 mark] A 0 B 1 C 2 D 4 0 2 . 3 In the algorithm in Figure 2, what is the largest possible value of the variable counter when the user input is 36? Shade one lozenge. [1 mark] A 0 B 2 C 4 D 5 0 3 Explain one advantage of the structured approach to programming. [2 marks] 5 8 *08* IB/G/Jun23/8525/1A Do not write outside the 0 4 Figure 3 box shows a program written in C# that calculates the area of a rectangle or the volume of a box from the user inputs. Figure 3 public static int calculate(int width, int length, int height) { if (height == -1) { return width * length; } else { return width * length * height; } } public static void Main() { int numOne, numTwo, numThree, answer; Console.Write("Enter width: "); numOne = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter length: "); numTwo = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter height, -1 to ignore: "); numThree = Convert.ToInt32(Console.ReadLine()); answer = calculate(numOne, numTwo, numThree); if (numThree == -1) { Console.WriteLine($"Area {answer}"); } else { Console.WriteLine($"Volume {answer}"); } } 0 4 . 1 Complete the trace table using the program in Figure 3. [3 marks] numOne numTwo numThree Final output 5 6 –1 10 4 0 3 5 10 9 *09* Turn over ► IB/G/Jun23/8525/1A Do not write outside the 0 4 . 2 Describe one way that the program in Figure 3 could be made more robust. box [1 mark] Turn over for the next question 10 *10* IB/G/Jun23/8525/1A Do not write outside the 0 5 Figure 4 box shows an algorithm presented as a flowchart. Figure 4 Complete the trace table for the algorithm in Figure 4. You may not need to use all the rows in the table. [3 marks] a b c 7 11 *11* Turn over ► IB/G/Jun23/8525/1A Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 12 *12* IB/G/Jun23/8525/1A Do not write outside the 0 6 Figure 5 box shows an algorithm represented using pseudo-code. The algorithm is for a simple authentication routine. The pseudo-code uses a subroutine getPassword to check a username: • If the username exists, the subroutine returns the password stored for that user. • If the username does not exist, the subroutine returns an empty string. Parts of the algorithm are missing and have been replaced with t