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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 markCharacter Sets Swap Remove

A new character set must be able to represent 70 different characters.

Identify the minimum number of bits needed to represent each character.

[1 mark]
  • A6
  • B7
  • C8
  • D70
Mark scheme
  • B 7 (1)
  • The only correct answer is B. The correct answer is 7.
  • A is not correct because 6 bits give only 64 combinations, which is not enough for 70 characters
  • C is not correct because 7 bits already give 128 combinations, so 8 bits is not the minimum needed
  • D is not correct because 70 is the number of characters needed, not a number of bits
Example answers and how they were marked
Full marks1/1

B 7

Why: The only correct answer: 7 bits give 128 combinations, enough for 70 characters, and it is the smallest number of bits that does (1).

No marks0/1

C 8

Why: Distractor, no credit: a single-tick item has no partial credit, and 8 bits is not the minimum because 7 bits already give 128 combinations, so the scheme's C line gives no mark.

No marks0/1

A 6

Why: Misconception, no credit: 6 bits give only 64 combinations, which cannot represent 70 different characters, so the scheme's A line gives no mark.

2Describe2 marksSound Swap Remove

A computer stores a digitised sound.

Describe how the sample rate affects the accuracy of the binary representation of a sound.

[2 marks]
Mark scheme

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

  • A higher sample rate means more samples are taken each second (1) so more binary values are stored to represent the sound (1)
  • A higher sample rate records the wave more frequently (1) so the binary representation follows the shape of the analogue wave more closely/is more accurate (1)
  • A lower sample rate records fewer samples (1) so the binary representation is less detailed/less accurate (1)

A statement about the effect of sample rate on sampling (e.g. more/fewer samples) without a link to the binary representation scores a maximum of one mark.

A definition of sample rate on its own, with no effect on sampling, scores no marks.

Accept 'more accurate' for the second mark only when linked to more samples or binary values being stored, for example by 'so', 'which means' or 'because'.

Do not accept responses that describe sample interval or bit depth instead of sample rate.

Do not accept 'a higher sample rate means more bits per sample' or 'higher resolution', as these describe bit depth.

Do not accept a larger file size unless it is linked to more samples/binary values being stored.

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

Example answers and how they were marked
Full marks2/2

A higher sample rate takes more samples each second, so more binary values are stored and the digital representation is more accurate.

Why: Linked points: more samples each second (1) leading to more binary values and a more accurate representation (1).

Some marks1/2

A higher sample rate records the wave more often.

Why: Correct statement about the effect on sampling (1) but no link to the binary representation.

No marks0/2

A higher sample rate uses more bits for each sample, so each sample is more accurate.

Why: Confuses sample rate with bit depth; 'more bits per sample' is not accepted.

3Explain2 marksImages Swap Remove

Two versions of the same photograph are displayed at the same size on a screen. Version A is 800 × 600 pixels. Version B is 1600 × 1200 pixels.

Explain why Version B can show more detail.

[2 marks]
Mark scheme

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

  • Version B has more pixels in the same area (1) so each pixel represents a smaller part of the image (1)
  • Version B has a higher pixel density (1) so finer detail can be represented (1)
  • The pixels in Version B are smaller (1) so more detail can be captured in the same space (1)
  • Version B has a higher resolution (1) because there are more pixels per unit of area (1)

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

Do not accept 'more pixels' on its own without saying same area/pixel density/smaller pixels.

Do not accept higher colour depth or more colours.

Example answers and how they were marked
Full marks2/2

Version B has more pixels in the same area so each pixel represents a smaller part of the image.

Why: Linked point (1) and reason (1): more pixels in the same area means smaller pixels and more detail.

Some marks1/2

Version B has more pixels in the same area.

Why: One mark for the point about pixel density; the linked reason about smaller pixels or finer detail is missing.

No marks0/2

Version B has a higher colour depth, so it can display more colours.

Why: Colour depth is not the reason for more detail here; this is the common misconception that colour depth increases resolution.

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