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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 · 5 marks

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1Multiple choice1 markImages Swap Remove

Identify the smallest identifiable area of a bitmap image.

[1 mark]
  • AColour depth
  • BFile size
  • CPixel
  • DResolution
Mark scheme
  • C Pixel (1)
  • The only correct answer is C. The correct answer is pixel.
  • A is not correct because colour depth is the number of bits used to store the colour of each pixel
  • B is not correct because file size is the amount of storage an image takes up, not an area of the image
  • D is not correct because resolution is a measure of the number of pixels in an image (such as its width × height), not the smallest identifiable area
Example answers and how they were marked
Full marks1/1

C Pixel

Why: Correct option; a pixel is the smallest identifiable area of a bitmap image (1).

No marks0/1

D Resolution

Why: Resolution is a measure of the number of pixels in an image, not the smallest identifiable area; no mark.

No marks0/1

A Colour depth

Why: Colour depth is the number of bits used to store each pixel's colour, not the smallest identifiable area; 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.

3Explain2 marksSound Swap Remove

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

Explain how increasing the bit depth affects the representation of a sound wave.

[2 marks]
Mark scheme

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

  • Each sample is stored using more bits (1) so the amplitude can be recorded more precisely (1)
  • More different amplitude values can be represented (1) because each extra bit doubles the number of possible values (1)
  • The height of the wave at each sample point is measured more accurately (1) so the digital wave is closer to the analogue wave (1)
  • The gap between the true amplitude and the stored value is smaller (1) because there are more values for the sample to be rounded to (1)

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

Do not accept 'the sound is sampled more often' or 'more samples are taken per second', as these describe the sample rate, not the bit depth.

Do not accept 'the file size increases' on its own as an effect on the representation of the sound.

Example answers and how they were marked
Full marks2/2

Each sample is stored using more bits, so the amplitude at each sample point can be recorded more precisely.

Why: Point (more bits per sample) (1) with linked reason (amplitude recorded more precisely) (1).

Some marks1/2

Each sample is stored using more bits.

Why: Creditworthy point (1) but no linked effect on the accuracy of the representation, so only one mark.

No marks0/2

It takes more samples every second, so the wave is stored in more detail.

Why: Confuses bit depth with sample rate, so no mark is awarded.

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