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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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4 questions · 11 marks

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1Short 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

2Explain2 marksCharacter Sets Swap Remove

The ASCII code for the uppercase letter A is 65, which is stored as the 7-bit pattern 1000001.

Explain why the lowercase letter a is stored using a different 7-bit pattern.

[2 marks]
Mark scheme

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

  • The computer needs to tell/distinguish the uppercase A from the lowercase a (1) because each different character has its own unique 7-bit code/pattern (1)
  • A and a are different characters (1) so each needs a different 7-bit pattern to be stored and displayed correctly (1)
  • If A and a had the same 7-bit pattern (1) the computer could not tell which character to display (1)

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

Do not accept 'because they are different letters/cases' without saying they need different/unique codes or that the computer must tell them apart.

Do not accept 'because A is a capital letter' on its own.

Do not accept 'because the codes are different numbers' or '65 is not 97' without linking to the need to tell the characters apart or to unique codes.

Example answers and how they were marked
Full marks2/2

Each character needs its own unique code, so the computer can tell that A and a are different characters and display the right one.

Why: Gives the point that the computer must tell A and a apart (1) and links it to the reason that each character needs its own unique code (1).

Some marks1/2

The computer must be able to tell the difference between uppercase and lowercase letters.

Why: Gives the point that the computer must tell the two characters apart (1) but gives no linked reason about unique codes or different 7-bit patterns.

No marks0/2

Because A is a capital letter and a is lowercase.

Why: Only states that the letters are different cases, which the mark scheme says is not accepted without saying they need unique codes or that the computer must tell them apart.

3Explain2 marksSound Swap Remove

Analogue sound is converted to binary by sampling at regular intervals.

Explain one reason why increasing the sample rate improves the quality of a digitised sound.

[2 marks]
Mark scheme

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

  • More samples are taken every second / the sample rate is higher (1) so the digital wave follows the shape of the analogue wave more closely (1)
  • The amplitude is measured more often / at shorter intervals (1) so fewer changes in the sound are missed between measurements (1)
  • The sample interval is shorter (1) so less of the sound wave is lost/goes unrecorded between samples (1)
  • More data points are recorded for the same length of sound (1) so the digital representation is a closer copy of the original sound (1)

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

Do not accept 'the quality is better/higher' or 'the sound is clearer' as a point on its own without a reason such as more samples or more detail.

Do not accept 'the samples are more accurate' or 'more data is collected' without saying what becomes more accurate or what the extra data records.

Do not accept 'the file size is larger' as a reason for improved quality.

Do not accept answers about using more bits per sample, as these describe bit depth, not the sample rate.

Example answers and how they were marked
Full marks2/2

More samples are taken every second, so the digital representation follows the shape of the analogue wave more closely.

Why: Point (more samples each second) (1) with linked reason (follows the analogue wave more closely) (1).

Some marks1/2

More samples are taken every second.

Why: Creditworthy point (1) but no linked reason about what the extra samples achieve, so stays on one mark.

No marks0/2

Each sample is stored using more bits, so every measurement is more accurate.

Why: This describes bit depth, not the sample rate, so neither mark is awarded.

4Discuss6 marksImages Swap Remove

A wildlife photographer takes a photograph for a magazine. The photograph can be printed across a full page or used as a small thumbnail on the magazine's website.

Discuss how the resolution of the photograph affects its use in the magazine and on the website.

Your answer should include:

  • what resolution means
  • the effect of resolution on the detail shown
  • the effect of resolution on the file size.
[6 marks]
Mark scheme

Indicative content

What resolution means

  • Resolution is the number of pixels in the image, or the number of pixels per inch.
  • A photograph that is 6000 × 4000 pixels has a higher resolution than one that is 600 × 400 pixels.
  • Resolution is not the same as colour depth or the number of colours.

Effect on detail

  • A higher-resolution photograph has more pixels in the same area, so it can show more detail.
  • A low-resolution photograph printed across a full page will look blocky or pixelated because each pixel is enlarged.
  • A small website thumbnail uses fewer pixels on screen, so a lower-resolution version may still look sharp.
  • A high-resolution original can be cropped and still contain enough pixels for a full-page print.

Effect on file size

  • More pixels means more binary values must be stored, so the file is larger.
  • A large file takes more storage and is slower to upload or download, which matters for visitors to the website.
  • The photographer could make a lower-resolution copy for the website and keep the high-resolution original for print.
  • File size also depends on the colour depth and the file format or compression used.

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 both detail and file size.

Do not accept resolution as the number of colours.

Example answers and how they were marked
Full marks6/6

Resolution is the number of pixels in the photograph, for example 6000 × 4000 pixels. A high-resolution photograph has more pixels, so it can show fine detail such as the animal's fur. This is important for the full-page magazine print because a low-resolution image would look blocky when enlarged. The small website thumbnail uses fewer pixels on screen, so a lower-resolution copy would still look sharp and would be suitable. A high-resolution file contains more pixel values, so it takes up more storage space. It would also be slower to download for people viewing the website. The photographer could keep the high-resolution original for print and make a lower-resolution copy for the website.

Why: Defines resolution accurately, links detail to the print use, links file size to storage and download for the website, and gives a sensible recommendation. Sustained application, so Level 3.

Some marks4/6

Resolution means how many pixels are in the image. A higher resolution means the photograph has more pixels, so it can show more detail. This is good for the full-page print because it will not look pixelated. A lower resolution might be enough for the small website thumbnail because it is shown smaller.

Why: Covers what resolution means and its effect on detail, with some application to print and the website. It does not discuss the effect on file size, so it is limited to Level 2.

Some marks1/6

Resolution is the number of pixels in the image. The photograph will have a higher resolution if it has more colours, so it will look sharper in the magazine. The file size is bigger when the resolution is higher, so the website will load faster.

Why: Only the definition of resolution is creditworthy. The answer wrongly links resolution to the number of colours and says a larger file will make the website load faster.

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