Menu
Exam Questions

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.

Build a paper

Topics (none ticked: all of them)
Question types (none ticked: all of them)

Practice paper

3 questions · 8 marks

Pick again
Print
1Short recall1 markCharacter Sets Swap Remove

ASCII uses 7 bits to store each character. A system has only 6 bits available to store each character.

State the number of different characters the system can represent.

[1 mark]
Mark scheme

Award one mark for:

  • 64 (1)
  • 2^6 (1)
  • 2 × 2 × 2 × 2 × 2 × 2 (1)

Allow 64 characters / sixty-four.

Allow 2 to the power of 6 for 2^6.

Do not accept 128, which is the number of characters that can be represented using 7 bits.

Do not accept 63, the largest value that can be represented using 6 bits, rather than the number of different characters.

Do not accept 12 (2 × 6), ie the number of bits multiplied by 2.

Example answers and how they were marked
Full marks1/1

64

Why: Correct: 2^6 = 64 different characters (1).

No marks0/1

128

Why: Scores 0: 128 is the number of characters that 7 bits can represent, not the 6 bits the system has; the Do not accept line applies.

No marks0/1

63

Why: Scores 0: 63 is the largest value 6 bits can hold, not the number of different characters; the Do not accept line applies.

2Short recall1 markImages Swap Remove

Each pixel in a bitmap image is stored using a number of bits.

Define the term colour depth.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • The number of bits per pixel (1)
  • The number of bits used to represent/store the colour of each pixel (1)

Allow bit depth

Do not accept the number of colours a pixel can have on its own

Do not accept the number of pixels in the image (this is the resolution/image size)

Example answers and how they were marked
Full marks1/1

The number of bits used to store the colour of one pixel.

Why: Gives the number of bits per pixel (1)

No marks0/1

The number of colours that each pixel can use.

Why: Gives the number of colours, not the number of bits; the mark scheme does not accept this on its own

No marks0/1

The number of pixels in the image.

Why: Confuses colour depth with resolution/image size, which the mark scheme does not accept

3Discuss6 marksSound Swap Remove

A toy company is designing an electronic keyboard. The keyboard can store and play back short recorded sounds. The memory chip in the keyboard has very little space, so each sample is stored using only 3 bits.

Discuss the limitations of storing the recorded sounds using only 3 bits per sample.

Your answer should include:

  • the range and number of amplitude values that can be stored
  • the accuracy of each sample that is stored
  • how the limitation could affect what the user hears.
[6 marks]
Mark scheme

Indicative content

Range and number of values

  • With a bit depth of 3, the keyboard can store only 2^3 = 8 different amplitude values.
  • The 3-bit codes run from 000 to 111, so the loudest and quietest amplitudes the keyboard can record are fixed by those codes.
  • Because only eight levels of loudness are available, the keyboard cannot store the full variation in amplitude of the original recording.
  • Any sound in between two of the eight values cannot be stored at all, so much of the detail of the original sound has no code to represent it.

Accuracy of the stored sample

  • Each true amplitude must be rounded to the nearest of the eight available values, so the stored sample is not the same as the amplitude that was measured.
  • The difference between the true amplitude and the rounded value is the quantisation error, which makes every stored sample less accurate.
  • The eight values are far apart, so there is a large step between one stored amplitude and the next and the stored sound rises and falls in big jumps rather than following the original wave.
  • A quiet sound whose amplitude is smaller than one step may be stored with the same code as silence, so that part of the recording is lost.

Effect on the user

  • When the keyboard plays back the recording, the large steps between stored amplitudes are heard as distortion or noise rather than a smooth copy of the original sound.
  • Quiet parts of the recording may not be heard at all, because they are stored as the same value as silence.
  • The reproduced sound may not be recognisable as the instrument or voice that was recorded.

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 explain that 3 bits gives only 8 amplitude values and link the large steps between those values to the distortion or the loss of quiet sounds that the user hears; an explicit binary range of 000 to 111 is not required for Level 3.

Level 2 requires one point to be developed with a reason, e.g. eight values means each amplitude is rounded to the nearest and the quantisation error is large enough to be heard; stating 8 values, reduced accuracy and distortion as separate basic points without a reason is Level 1. Do not accept bit depth described as the number of samples taken per second, or a bare statement that the quality is worse with no explanation.

Example answers and how they were marked
Full marks6/6

With only 3 bits per sample, the keyboard can store just 2^3 = 8 different amplitude values. Each recorded amplitude has to be rounded to the nearest of these eight values, so the stored sample is not the same as the original and a quantisation error is created. The eight values are far apart, so the stored sound moves in large steps instead of following the original wave. A quiet sound smaller than one step is stored as the same code as silence, so it is lost. When the keyboard plays the recording back, the user hears these large steps as distortion and noise, and quiet parts of the music may not be heard at all, so the sound is not a faithful copy of the original.

Why: Level 3 (6 marks): explains the 8 values from 3 bits, rounding creating quantisation error, the large steps between values, lost quiet sounds and the distortion the user hears, all applied to the keyboard.

Some marks2/6

With 3 bits, there are only 8 values that can be stored, so the amplitude is rounded to the nearest value. This makes the sound less accurate than the original recording. The user might hear distortion when the keyboard plays it back.

Why: Level 1 (2 marks): gives basic points (8 values, rounding to the nearest value, less accurate, possible distortion) but states them separately, without explaining why the eight far-apart values cause a large quantisation error or why that is heard as distortion, so it does not reach Level 2.

No marks0/6

3 bits means 3 samples per second, so the keyboard cannot store much sound. The quality will be low.

Why: Level 0 (0 marks): confuses bit depth with sample rate ('3 samples per second'), which the scheme says not to accept, and 'the quality will be low' is a bare statement with no explanation, so there is no creditworthy point.

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

Build a paper on this topic 56
Character Sets 18 questions Images 19 questions Sound 19 questions

2.3 Data storage and compression

Build a paper on this topic 24
Compression 18 questions Units & Conversion 6 questions

3.1 Hardware

Build a paper on this topic 77
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

Build a paper on this topic 124
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

Build a paper on this topic 37
Low and High Level Languages 19 questions Translators 18 questions

4.1 Networks

Build a paper on this topic 138
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

Build a paper on this topic 36
E-waste 17 questions Manufacturing Technology 19 questions

5.2 Ethical and legal

Build a paper on this topic 71
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

More ways to revise Edexcel GCSE Computer Science (1CP2)

Activities Flashcards Revision notes

Teachers: build a paper, print it with the mark schemes at the end, and sign your school up to set your classes activities on every topic.

Fetch Decode Explain isn't affiliated with or endorsed by Pearson Edexcel.