AQA GCSE COMPUTER SCIENCE PAPER COMPUTATIONAL THINKING AND PROBLEM – SOLVING QUESTION PAPER 2020

AQA GCSE COMPUTER SCIENCE PAPER COMPUTATIONAL

THINKING AND PROBLEM – SOLVING QUESTION PAPER 2020

Please write clearly in block capitals.Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work.For the multiple-choice questions, completely fill in the lozenge alongside the appropriate answer.

CORRECT METHOD WRONG METHODS

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.

GCSE

COMPUTER SCIENCE

Paper 1 Computational Thinking and Problem-Solving

Monday 11 May 2020 Morning Time allowed: 1 hour 30 minutes

Materials There are no additional materials required for this paper.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.• Unless the question states otherwise, you are free to answer questions that require a coded solution in whatever format you prefer as long as your meaning is clear and unambiguous.• You must not use a calculator.Information The total number of marks available for this paper is 80.

Advice

*jun20520101* IB/G/Jun20/E18 8520/1 For Examiner’s Use Question Mark 1–2 3 4 5 6–7 8 9 10 11 12 TOTAL

2 Do not write outside the *02* IB/G/Jun20/8520/1

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Answer all questions.

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. A bitmap image is represented as a grid of pixels.

State what is meant by the term pixel.

[1 mark]

. State the maximum number of different colours that can be used if a bitmap image has a colour depth of six bits.[1 mark]

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What is the minimum file size for an 800 pixel by 1000 pixel bitmap image that uses 20 different colours? You should give your answer in kilobytes.

You should show your working.[3 marks]

Answer

kB

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3 Do not write outside the *03* IB/G/Jun20/8520/1

• . The algorithm shown in Figure 1 converts binary data entered as a string by the user

into a representation of a black and white image.

The algorithm uses the + operator to concatenate two strings.

Characters in the string are indexed starting at zero. For example bdata[2] would access the third character of the string stored in the variable bdata

The MOD operator calculates the remainder after integer division, for example

17 MOD 5 = 2

Figure 1

bdata  USERINPUT image  '' FOR i  0 TO LEN(bdata) - 1 IF bdata[i] = '0' THEN image  image + '*' ELSE image  image + '/' ENDIF IF i MOD 3 = 2 THEN OUTPUT image image  '' ENDIF

ENDFOR

Complete the trace table for the algorithm shown in Figure 1 when the variable

bdata is given the following value from the user:

110101

You may not need to use every row in the table. The algorithm output is not required.[3 marks] i image

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