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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 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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3 questions · 10 marks

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1Describe2 marksSound Swap Remove

Sound is converted into binary using a limited bit depth.

Describe one limitation of representing a sound sample with a limited bit depth.

[2 marks]
Mark scheme

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

  • Only a fixed number of amplitude values/levels can be represented (1) so the amplitude is rounded to the nearest available value/level (1)
  • Fewer amplitude values/levels are available to choose from (1) so similar/close amplitudes cannot be stored as different values (1)
  • The exact amplitude often falls between available values/levels (1) so the stored amplitude is not exact/less accurate (1)

Answers must relate to the number of bits per sample (bit depth) and the amplitude values/levels it can represent.

Do not accept answers about the sample rate, sample interval or the number of samples taken, or that confuse bit depth with the number of samples.

Do not award 'lower quality'/'more detail'/'less detail' unless it is linked to the number of amplitude values/levels.

Do not accept 'the sound cannot be played/stored' without a linked limitation.

Example answers and how they were marked
Full marks2/2

Only a fixed number of amplitude values can be represented, so the amplitude is rounded to the nearest available value and some detail is lost.

Why: Linked points: fixed number of amplitude values (1) and rounding to the nearest available value (1).

Some marks1/2

Only a fixed number of amplitude values can be represented.

Why: Gives the first linked point only (1); it does not develop what this limitation leads to.

No marks0/2

A lower bit depth means fewer samples are taken, so parts of the sound are missed.

Why: Confuses bit depth with the number of samples/sample rate; no creditworthy point about amplitude values is given.

2Explain2 marksImages Swap Remove

Two versions of the same bitmap image are saved. The second version has a higher colour depth.

Explain why the second version may have a larger file size.

[2 marks]
Mark scheme

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

  • More binary data is stored for each pixel (1) because a higher colour depth uses more bits per pixel (1)
  • Each pixel has a longer binary code (1) so more storage is needed to hold the image (1)
  • More colours can be represented (1) so more bits are needed for each pixel (1)
  • The file contains more bits in total (1) because colour depth is the number of bits per pixel (1)

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

Allow 'more bits per pixel' for one mark.

Do not accept 'more pixels' or 'higher resolution' as the reason, because changing colour depth does not change the number of pixels.

Example answers and how they were marked
Full marks2/2

The second version stores more binary data for each pixel because a higher colour depth uses more bits per pixel.

Why: Linked point (1) and reason (1): more data per pixel because more bits per pixel.

Some marks1/2

The second version uses more bits for each pixel.

Why: One mark for identifying that more bits are stored per pixel; no linked statement about more data or file size.

No marks0/2

The second version has more pixels, so there is more data to store.

Why: A common misconception; colour depth does not change the number of pixels, so no creditworthy point is given.

3Discuss6 marksImages Swap Remove

A handheld games console displays sprites. The console stores each pixel of a sprite using 4 bits. Designers want sprites that contain many shades of green and blue.

Discuss the limitations of using 4 bits to store each pixel of a sprite on the console.

Your answer should include:

  • the number of colours that can be represented
  • the effect on the appearance of the sprite
  • how the limitation could be managed.
[6 marks]
Mark scheme

Indicative content

Number of colours

  • 4 bits give 2^4 = 16 different binary values, so at most 16 colours can be stored for each pixel.
  • The console cannot store every shade that the designers want; colours outside the 16 must be approximated or left out.
  • Adding more bits per pixel would allow more colours, but this may not be possible on the console's hardware.

Effect on appearance

  • The sprite may show banding where a smooth change from green to blue should be.
  • A sprite that needs many shades, such as a detailed landscape, will look unrealistic or have blocks of colour.
  • Simple sprites with flat colours, such as a retro character, can still look acceptable.
  • The limitation is in the number of colours, not the number of pixels; resolution is a separate issue.

Managing the limitation

  • Designers can choose a palette of 16 colours that includes the most important greens and blues for the game.
  • They can design sprites with flat colours rather than smooth gradients.
  • They can use more bits per pixel for important sprites if the console allows it.
  • They can accept that some shades will be approximated and check that the sprite still looks clear on the console's screen.

Levels

  • Level 0 (0 marks): No rewardable content.
  • Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
  • Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
  • Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Level 3 responses must cover the number of colours and the effect on appearance.

Do not accept 4 bits give 4 colours or 8 colours.

Example answers and how they were marked
Full marks6/6

4 bits per pixel gives 2^4 = 16 different binary values, so each pixel can be only one of 16 colours. The designers want many shades of green and blue, but most of these cannot be stored exactly and must be approximated or left out. This can cause banding where a smooth change from green to blue should be, so a detailed sprite may look unrealistic. A simple sprite with flat colours could still look acceptable. The designers could choose a palette of 16 colours that includes the most important greens and blues, and design sprites with flat colours instead of gradients. Using more bits per pixel would allow more colours, but the console's hardware may not support this.

Why: Explains 2^4 = 16 colours and the limitation on shades, links this to banding and realism, and gives suitable ways to manage it in the console context. Sustained reasoning, so Level 3.

Some marks4/6

4 bits can store 16 colours. This means the sprite cannot have many colours. It might look bad if it needs lots of shades of green and blue. The designers could use fewer colours in the sprite.

Why: Correctly gives 16 colours and makes a simple link to the sprite's appearance and a way to manage it. There is little development of the effect or the management, so Level 2.

Some marks1/6

4 bits can store 16 colours. This means the sprite will have a low resolution, so it will look blocky. The designers should use a higher resolution to get more shades of green and blue.

Why: One correct point: 4 bits give 16 colours. The answer then confuses colour depth with resolution; increasing resolution would not provide more shades.

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

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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

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Data Protection Act 17 questions Impact of AI 18 questions Intellectual Property 18 questions Software Licences 18 questions

5.3 Cybersecurity

Build a paper on this topic 36
Malware 18 questions Social Engineering 18 questions

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