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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 markSound Swap Remove

Identify the term used for the number of bits used to record each sample of a sound.

[1 mark]
  • AAmplitude
  • BBit depth
  • CSample interval
  • DSample rate
Mark scheme
  • B Bit depth (1)
  • The only correct answer is B. The correct answer is bit depth.
  • A is not correct because amplitude is the height of the sound wave at the point it is sampled
  • C is not correct because the sample interval is the time between each sample
  • D is not correct because the sample rate is the number of samples taken each second
Example answers and how they were marked
Full marks1/1

B Bit depth

Why: Selects the only correct option (1).

No marks0/1

D Sample rate

Why: Near miss: this is the number of samples taken each second, not the number of bits per sample (0).

No marks0/1

A Amplitude

Why: Typical confusion: amplitude is what is measured at a sample, not the number of bits used to store it (0).

2Explain2 marksSound Swap Remove

The same sound is recorded twice using different sample intervals.

Explain the effect of using a longer sample interval on the digital recording.

[2 marks]
Mark scheme

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

  • Fewer samples are taken every second (1) so less detail of the sound wave is captured (1)
  • Fewer samples are taken every second (1) so the file is smaller/uses less storage space (1)
  • The wave is measured less often (1) so parts/changes in the wave between samples are missed (1)

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

The 'fewer samples are taken/measured less often' point can only be credited once; the second mark is for a valid expansion linked to it.

Do not accept restating the question, e.g. 'the time between measurements is longer' or 'the sample interval is longer', as either the point or the expansion.

Do not accept 'the sample rate is lower' as the expansion, as this says the same thing as a longer sample interval.

Do not accept 'the sound is lower quality/less accurate' on its own without saying what is lost, e.g. less detail of the wave captured/parts of the wave missed.

Do not accept answers about using fewer bits per sample or about compression, as these do not follow from the sample interval.

Example answers and how they were marked
Full marks2/2

Fewer samples are taken every second, so less detail of the sound wave is captured and the recording is less accurate.

Why: Point (fewer samples each second) (1) with linked reason (less detail of the wave captured) (1).

Some marks1/2

Fewer samples are taken every second.

Why: Creditworthy point (1) but no linked effect on the detail or size of the recording, so only one mark.

No marks0/2

The samples are stored using fewer bits, so the sound is less accurate.

Why: Describes a smaller bit depth rather than a longer sample interval, so no mark is awarded.

3Explain2 marksImages Swap Remove

An image uses a colour depth of 2 bits per pixel. The original image contains 12 different colours.

Explain why the image cannot be represented accurately at this colour depth.

[2 marks]
Mark scheme

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

  • Only 4 colours can be represented (1) because 2 bits give 2^2 = 4 possible values (1)
  • Some of the 12 colours cannot be stored (1) so they are lost/replaced with a colour that can be represented (1)
  • The image will not match the original exactly (1) because there are fewer colour codes than the number of colours needed (1)
  • Many colours will share the same binary value (1) so the image will lose colour detail (1)

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

Allow 'four colours' or '2^2'.

Do not accept 'only two colours' (confusing the number of bits with the number of values) or 'resolution is too low'.

Example answers and how they were marked
Full marks2/2

Only four colours can be represented because two bits give four possible binary values.

Why: Linked point (1) and reason (1): 2 bits give 2^2 = 4 colour codes.

Some marks1/2

Only four colours can be represented.

Why: One mark for identifying that four colours can be represented; the linked reason about two bits giving four values is missing.

No marks0/2

Only two colours can be represented because each pixel has two bits.

Why: A common misconception: two bits give four possible values, not two, so no creditworthy point is given.

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