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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 · 4 marks

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1Multiple choice1 markCharacter Sets Swap Remove

Characters are encoded using 7-bit ASCII.

Identify the number of different characters that can be represented using 7-bit ASCII.

[1 mark]
  • A64
  • B127
  • C128
  • D256
Mark scheme
  • C 128 (1)
  • The only correct answer is C. The correct answer is 128.
  • A is not correct because 6 bits give only 64 different combinations
  • B is not correct because 127 is the largest 7-bit value, not the number of characters that 7 bits can represent
  • D is not correct because 256 characters need 8 bits, as used by 8-bit extended ASCII
Example answers and how they were marked
Full marks1/1

C 128

Why: Selects the only correct option (1): 7 bits give 2 to the power of 7, which is 128 different characters.

No marks0/1

D 256

Why: Near miss scoring 0: 256 is the number of characters that 8 bits give in extended ASCII, not 7-bit ASCII.

No marks0/1

B 127

Why: Misconception scoring 0, the off-by-one error the examiners' report describes: 127 is the largest 7-bit value, but 7 bits give 128 different characters.

2Short recall1 markImages Swap Remove

A bitmap image has a resolution.

State what is meant by the resolution of an image.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • The concentration/density of pixels in an area (1)
  • The number of pixels per inch (PPI) / pixels per unit area (1)
  • The width and height/dimensions of the image in pixels (1)

Do not accept the number of pixels in the image on its own, without dimensions or an area, e.g. 'the total number of pixels'

Do not accept colour depth / the number of bits used per pixel / the number of colours

Do not accept file size in bytes / the amount of storage the image uses / screen size / image quality

Example answers and how they were marked
Full marks1/1

The concentration of pixels in an area, such as the number of pixels per inch.

Why: Gives the density/concentration of pixels in an area, and pixels per inch (1)

No marks0/1

The number of pixels in the image.

Why: A bare total pixel count is not accepted without dimensions or an area

No marks0/1

The number of bits used to store each pixel's colour.

Why: Describes colour depth, not resolution, and colour depth is not accepted

3Describe2 marksImages Swap Remove

A bitmap image can use different colour depths.

Describe what is meant by the colour depth of a bitmap image.

[2 marks]
Mark scheme

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

  • The number of bits used to store/represent each pixel (1) which determines how many colours/shades it can have (1)
  • The number of binary values/combinations available for each pixel (1) so a greater colour depth gives a wider range of colours/a larger colour palette (1)
  • More bits are stored for each pixel (1) so each pixel can be one of more possible colours/shades (1)

Do not award 'the number of colours' alone, as it does not say that colour depth is the number of bits per pixel.

Do not accept responses about image resolution or the number of pixels.

Example answers and how they were marked
Full marks2/2

The number of bits used to store each pixel; more bits means more colours can be represented.

Why: Point (1) that colour depth is the number of bits used to store each pixel and linked development (1) that more bits means more colours can be represented.

Some marks1/2

The number of bits used for each pixel.

Why: Point (1) that colour depth is the number of bits per pixel, but no linked development about the number of colours.

No marks0/2

The number of pixels across the image.

Why: No credit: this describes resolution, and responses about the number of pixels are not accepted.

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