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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 659 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

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4 questions · 8 marks

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1Short recall2 marksImages Swap Remove

Bitmap images are stored as a grid of pixels.

Define the term pixel.

[2 marks]
Mark scheme

Award one mark for any of the following up to a maximum of two marks:

  • The smallest element/area of a bitmap image (1)
  • The smallest identifiable part of an image (1)
  • Stores/represents a single colour as a binary value (1)
  • Stores/represents a single colour using a number of bits/colour depth (1)

Allow 'picture element' for element/part in the first two bullets, but not on its own

Allow 'bit depth' for colour depth

Do not accept 'picture element'/'pixel' on its own

Do not accept 'a group of pixels' or 'a dot' on its own; allow 'dot' only when it is described as the smallest element/area of the image

Do not accept 'single colour' on its own for the second mark; it must be linked to a binary value/number of bits

Do not accept 'lots of coloured dots' (it contradicts a single colour)

Example answers and how they were marked
Full marks2/2

The smallest identifiable area of a bitmap image, which has one colour stored as a binary value.

Why: Smallest identifiable area (1) and single colour stored as a binary value (1)

Some marks1/2

The smallest part of a bitmap image, made of one colour.

Why: Smallest part (1); no credit for the second mark because the single colour is not linked to a binary value or number of bits

No marks0/2

A picture element made from lots of coloured dots.

Why: 'Picture element' on its own is not accepted and 'lots of coloured dots' contradicts a single colour

2Describe2 marksCharacter Sets Swap Remove

Uppercase letters are represented in a computer using 7-bit ASCII codes.

Describe how the ASCII codes for the uppercase letters A to Z are arranged.

[2 marks]
Mark scheme

Award up to two marks for a linked description such as:

  • The codes run in alphabetical order/consecutively (1) so each letter has a code one more than the letter before it (1)
  • A has the code 65 and Z has the code 90 (1) so the codes for the letters in between increase by 1 each time (1)
  • The letters are stored in sequence (1) so B is A + 1, C is B + 1 and so on (1)

Accept the codes given in denary (65, 90) or as 7-bit binary (1000001, 1011010).

Do not accept 'the codes go up' or 'the codes are in order' on its own, as neither gives the step of 1 or links one letter to the next.

Do not accept 'each uppercase letter has a different code' on its own, as this does not describe the arrangement.

Example answers and how they were marked
Full marks2/2

The codes are in alphabetical order, so B is one more than A and C is one more than B.

Why: Codes are consecutive/in order (1) with the linked step of one more for each letter (1).

Some marks1/2

A is 65 and Z is 90.

Why: Gives the first half of the linked pair, the start and end codes (1), but does not give the linked development, the increase of 1 between letters (0).

No marks0/2

The ASCII codes for uppercase letters go up.

Why: 'Codes go up' on its own gives no step of 1 and no link to the next letter, so it is not creditworthy (0) under the 'Do not accept' line.

3Explain2 marksImages Swap Remove

An image uses a colour depth of 2 bits per pixel. The original image contains 12 different colours.

Explain why the image cannot be represented accurately at this colour depth.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • Only 4 colours can be represented (1) because 2 bits give 2^2 = 4 possible values (1)
  • Some of the 12 colours cannot be stored (1) so they are lost/replaced with a colour that can be represented (1)
  • The image will not match the original exactly (1) because there are fewer colour codes than the number of colours needed (1)
  • Many colours will share the same binary value (1) so the image will lose colour detail (1)

For both marks, the expansion must follow/associate with the statement.

Allow 'four colours' or '2^2'.

Do not accept 'only two colours' (confusing the number of bits with the number of values) or 'resolution is too low'.

Example answers and how they were marked
Full marks2/2

Only four colours can be represented because two bits give four possible binary values.

Why: Linked point (1) and reason (1): 2 bits give 2^2 = 4 colour codes.

Some marks1/2

Only four colours can be represented.

Why: One mark for identifying that four colours can be represented; the linked reason about two bits giving four values is missing.

No marks0/2

Only two colours can be represented because each pixel has two bits.

Why: A common misconception: two bits give four possible values, not two, so no creditworthy point is given.

4Explain2 marksSound Swap Remove

Each sample of a sound wave is stored in binary using a fixed number of bits.

Explain one limitation of representing an analogue sound wave in binary when only a small number of bits is available for each sample.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • Only a limited number of different amplitude values can be stored (1) so each sample is rounded to the nearest available value and the digital wave does not match the analogue wave exactly (1)
  • The wave is continuous but only a limited set of values can be represented (1) so amplitude detail/accuracy is lost (1)
  • Quiet and loud parts of the sound may be stored as the same value (1) because there are too few values to tell them apart (1)
  • The range of amplitudes that can be represented is limited (1) so the loudest/quietest parts of the sound cannot be stored accurately (1)

For both marks, the expansion must follow/associate with the statement.

Do not award marks for answers that say the sound cannot be stored or heard at all.

Do not award answers about the number of samples taken/sample rate, as the number of bits limits the amplitude values, not how often the wave is sampled.

Do not accept 'lower quality'/'less accurate'/'less detail' on its own without a link to the amplitude values that can be stored/the number of bit combinations.

Do not accept 'the file size is smaller' without a link to the accuracy or the range of values that can be stored.

Example answers and how they were marked
Full marks2/2

Only a small number of amplitude values can be stored, so each sample is rounded to the nearest value and does not match the original wave exactly.

Why: Point (limited number of amplitude values) (1) with linked reason (samples are rounded and the wave is not exact) (1).

Some marks1/2

Only a small number of amplitude values can be stored.

Why: Creditworthy point (1) but no linked limitation such as rounding or lost accuracy, so only one mark.

No marks0/2

The sound cannot be stored at all because there are not enough bits to hold every sample.

Why: Misconception: the sound can still be stored, just less accurately, so no mark is awarded.

Questions by topic

2.1 Binary

Build a paper on this topic 58
Adding Binary Numbers 6 questions Binary and Hexadecimal Basics 10 questions Binary Shifts 6 questions Binary to Denary Conversion 6 questions Binary to Hexadecimal Conversion 6 questions Denary to Binary Conversion 6 questions Denary to Hexadecimal Conversion 6 questions Denary to Negative Binary Conversion 6 questions Hexadecimal to Binary Conversion 6 questions

2.2 Data representation

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Character Sets 18 questions Images 19 questions Sound 19 questions

2.3 Data storage and compression

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Compression 18 questions Units & Conversion 6 questions

3.1 Hardware

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Embedded Systems 17 questions Fetch Decode Execute Cycle 15 questions Primary Memory 15 questions Secondary Memory 15 questions Stored Program Computers 15 questions

3.2 Software

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File Management 18 questions Memory Management 16 questions Peripheral Management 11 questions Process Management 12 questions Purpose & Function of Operating Systems 17 questions Software Basics 13 questions User Management 18 questions Utility Software 19 questions

3.3 Programming languages

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Low and High Level Languages 19 questions Translators 18 questions

4.1 Networks

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Addressing 16 questions LANs & WANs 16 questions Network Speed 5 questions Packet Switching 16 questions Protocols & Layers 17 questions The Internet 16 questions Topologies 17 questions Wired Connections 17 questions Wireless Connections 18 questions

4.2 Network security

Build a paper on this topic 36
Network Security Risks 18 questions Preventing Network Security Risks 18 questions

5.1 Environmental

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E-waste 17 questions Manufacturing Technology 19 questions

5.2 Ethical and legal

Build a paper on this topic 65
Data Protection Act 17 questions Impact of AI 18 questions Intellectual Property 18 questions Software Licences 12 questions

5.3 Cybersecurity

Malware 8 questions

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