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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 631 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 · 6 marks

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1Multiple choice1 markCharacter Sets Swap Remove

A text file stores each character using 7-bit ASCII.

Identify the denary ASCII code for the space character.

[1 mark]
  • A32
  • B33
  • C48
  • D65
Mark scheme
  • A 32 (1)
  • The only correct answer is A. The correct answer is 32.
  • B is not correct because 33 is the ASCII code for the exclamation mark (!)
  • C is not correct because 48 is the ASCII code for the character 0
  • D is not correct because 65 is the ASCII code for the uppercase letter A
Example answers and how they were marked
Full marks1/1

A 32

Why: Correct option: the space character has the ASCII code 32 (1).

No marks0/1

C 48

Why: Near miss scoring 0: 48 is the ASCII code for the character 0, not the space character.

No marks0/1

D 65

Why: Misconception scoring 0: 65 is the ASCII code for the uppercase letter A, so a well-known code is given but not the code for a space.

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 marksSound Swap Remove

Each sample of a sound is stored as a binary number.

Describe how bit depth affects the stored value of a sound sample.

[2 marks]
Mark scheme

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

  • The bit depth is the number of bits used to store each sample/measurement (1) so a higher bit depth gives more possible/discrete values for the amplitude (1)
  • A higher bit depth records the amplitude more accurately (1) because the stored value can be closer to the actual height of the wave (1)
  • A low bit depth gives fewer possible amplitude values (1) so the amplitude is rounded to the nearest value, making the recording less accurate (1)

Do not accept sample rate/sample interval (number of samples per second) in place of bit depth.

Do not accept 'more bits gives better quality' or 'more accurate' on its own, without a development linked to the number of values or the amplitude stored.

Do not accept file size on its own, and a file size point cannot earn the second mark, as it does not describe the stored value.

Example answers and how they were marked
Full marks2/2

The bit depth is the number of bits used to store each sample, so a higher bit depth gives more possible values for the amplitude that can be stored.

Why: First point, the number of bits per sample (1), then the linked development, more possible values for the amplitude (1).

Some marks1/2

The bit depth is the number of bits used to store one sample.

Why: Gives the first point, the number of bits per sample (1), but does not develop how this affects the value that is stored.

No marks0/2

A higher bit depth makes the sound better quality and more accurate.

Why: Near-miss: 'better quality' and 'more accurate' on their own, with no development linked to the number of values or the amplitude, so no mark is awarded.

4Explain2 marksImages Swap Remove

A bitmap image uses a colour depth of 8 bits. Each pixel is stored as a binary value.

Explain how the colour of a pixel is represented in a bitmap image.

[2 marks]
Mark scheme

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

  • Each pixel is stored as a binary value/code (1) which represents/maps to a colour (1)
  • The binary value is used to look up a colour in a palette (1) so the pixel can be displayed in that colour (1)
  • A bit pattern is assigned to each colour (1) and each pixel stores the bit pattern for its colour (1)
  • The number of bits per pixel sets how many different colour codes exist (1) so each code can represent a different colour (1)

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

Do not accept 'pixels are binary' or 'the image is made of 1s and 0s' without saying a pixel's colour is represented by a binary value.

Do not accept RGB values stored as denary or hexadecimal.

Example answers and how they were marked
Full marks2/2

Each pixel stores a binary value (1); this value is used to look up the pixel's colour in a palette (1).

Why: Linked point (1) and reason (1): a binary value is stored for each pixel and maps to a colour.

Some marks1/2

A bit pattern is assigned to each colour.

Why: One mark for stating that colours have bit patterns; it does not say that each pixel stores the pattern for its colour.

No marks0/2

Each pixel stores the RGB colour as denary numbers between 0 and 255.

Why: Bitmap pixels are stored in binary, not as denary values; this common misconception earns no mark.

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