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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 · 9 marks

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1Multiple choice1 markImages Swap Remove

Two images are displayed at the same physical size. Image A has a higher resolution than image B.

Identify what this means.

[1 mark]
  • AImage A has more bits per pixel
  • BImage A has more colours
  • CImage A has more pixels per inch
  • DImage A uses less storage
Mark scheme
  • C Image A has more pixels per inch (1)
  • The only correct answer is C. The correct answer is more pixels per inch.
  • A is not correct because bits per pixel is the colour depth
  • B is not correct because more colours is caused by a higher colour depth, not a higher resolution
  • D is not correct because a higher resolution usually needs more storage, not less
Example answers and how they were marked
Full marks1/1

C Image A has more pixels per inch

Why: Correct option; resolution is the concentration of pixels, such as pixels per inch (1).

No marks0/1

B Image A has more colours

Why: More colours is an effect of colour depth, not resolution; no mark.

No marks0/1

A Image A has more bits per pixel

Why: Bits per pixel is the colour depth, not the resolution; no mark.

2Describe2 marksCharacter Sets Swap Remove

A school needs to store text in several different languages.

Describe one limitation of using 7-bit ASCII to store this text.

[2 marks]
Mark scheme

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

  • 7-bit ASCII has only 128 different codes (1) so characters from languages such as Chinese cannot be stored (1)
  • 7 bits give 2^7 = 128 possible binary codes (1) so there are not enough codes to give every character in the world's languages its own code (1)
  • Only the 128 characters in the ASCII set can be stored (1) so a character outside the set, such as é or 中, cannot be represented (1)

The stated limit on its own (that ASCII can represent only 128 characters) earns 1 mark; the second mark is for linking it to characters from other languages not being storable.

Do not accept 'ASCII can only store English letters/characters' unless it refers to the 128 codes or the 7 bits.

Do not accept a statement that ASCII is 'limited' or 'old' with no link to the number of bits/codes.

Do not accept a recommendation to use Unicode instead, or that ASCII cannot store accented letters, without saying that the 7 bits/128 codes cause the limitation.

Do not accept responses that describe ASCII as a programming language.

Example answers and how they were marked
Full marks2/2

7-bit ASCII can only represent 128 characters, so it cannot store characters from languages such as Chinese.

Why: Only 128 characters/codes can be represented (1) and this is linked to characters from other languages not being storable (1).

Some marks1/2

ASCII only has 128 characters.

Why: States the limit set by the 7 bits, that only 128 characters can be represented (1), but does not link it to the text in several languages (0).

No marks0/2

ASCII can only store English letters, so the school should use Unicode to store accented letters like e with an accent.

Why: 'Only stores English letters' is not accepted without reference to the 128 codes/7 bits, and recommending Unicode is not a limitation caused by the number of available bits.

3Discuss6 marksImages Swap Remove

A school is creating a small logo to display on its website. The logo is stored as a bitmap image. Each pixel in the logo is stored as a binary value.

Discuss how the bitmap image of the logo is represented in binary.

Your answer should include:

  • pixels
  • binary values
  • the grid of pixels.
[6 marks]
Mark scheme

Indicative content

Pixels

  • A bitmap image is made up of picture elements, called pixels.
  • Each pixel is the smallest identifiable area of the image and has a single colour.
  • The logo is stored as a grid of pixels, and its width and height in pixels give its dimensions.
  • Each pixel is stored separately, so a larger grid needs more pixel values to be stored.

Binary values

  • Each pixel's colour is represented by a binary value.
  • The number of bits used for each pixel is the colour depth.
  • With n bits per pixel there are 2^n different binary values, so 2^n possible colours.
  • A black-and-white image can use one bit per pixel, with 0 for white and 1 for black.
  • More bits per pixel allow more colours to be represented in the logo.

Grid

  • The binary values are stored in order, row by row, so the computer can rebuild the grid.
  • The resolution is the number of pixels in the image, for example width × height.
  • A higher-resolution grid stores more pixels, so the logo can show more detail.
  • The image file stores the pixel values and data such as the image dimensions.

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 pixels and binary values.

Do not accept resolution as the number of colours.

Example answers and how they were marked
Full marks6/6

A bitmap is a grid of pixels. Each pixel is one small area of the logo and has a single colour. The width and height of the grid are measured in pixels, so the logo's dimensions tell us how many pixels it contains. Each pixel's colour is stored as a binary value. The number of bits used for each pixel is the colour depth, and with n bits there are 2^n possible values, so 2^n possible colours. For example, 3 bits per pixel would allow 8 colours. The binary values are stored row by row so that the computer can rebuild the grid. A larger grid stores more pixel values, but it can show more detail. More bits per pixel let the logo use more colours, such as the school's colours.

Why: Covers pixels as the smallest areas of a grid (AO1), binary values with colour depth and 2^n colours (AO1), and applies these to the logo's grid and colours (AO2). Sustained and structured, so Level 3.

Some marks4/6

A bitmap is a grid of pixels. Each pixel is a small square with one colour. Each pixel is stored as a binary value. The logo needs a binary value for every pixel, so a bigger logo has more values. More bits per pixel means more colours.

Why: Gives pixels and binary values, with a simple link to the logo's size. Points are mostly independent and not developed into a full discussion, so Level 2.

Some marks1/6

A bitmap image is a grid of pixels. Resolution is the number of colours in the image. Each pixel is stored as a letter, so the logo can use any colour.

Why: One basic point: a bitmap is a grid of pixels. The rest is incorrect: resolution is not the number of colours, and pixel values are stored as binary, not letters.

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