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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 term for the number of bits used to store the colour of each pixel.

[1 mark]
  • AColour depth
  • BImage size
  • CResolution
  • DStorage size
Mark scheme
  • A Colour depth (1)
  • The only correct answer is A. The correct answer is colour depth.
  • B is not correct because image size is the width and height of the image in pixels
  • C is not correct because resolution is the number of pixels per unit length, such as pixels per inch
  • D is not correct because storage size is the amount of storage the image file uses
Example answers and how they were marked
Full marks1/1

A Colour depth

Why: Correct option; colour depth is the number of bits used to store the colour of each pixel (1).

No marks0/1

B Image size

Why: Image size is the width and height of the image in pixels, not the number of bits used per pixel; no mark.

No marks0/1

D Storage size

Why: Storage size is the amount of storage the image file uses, not the colour depth; no mark.

2Short recall2 marksSound Swap Remove

A sound wave is sampled and the amplitude of each sample is stored using a small number of bits.

Give two limitations of storing the sound in binary when only a small number of bits is available for each sample.

[2 marks]
Mark scheme

Award one mark for any of the following up to a maximum of two marks:

  • Only a limited/fixed number of amplitude values can be stored (1)
  • The amplitude of each sample is rounded/approximated to the nearest value that can be stored (1)
  • The recording is less accurate than the original analogue sound/does not match the analogue wave exactly (1)
  • Sounds louder than the highest amplitude that can be stored are clipped/distorted (1)
  • Sounds quieter than the lowest amplitude that can be stored cannot be represented/are lost (1)

Allow quantisation error/noise for the amplitude being rounded to the nearest value that can be stored, but do not award a second mark for the same idea

Allow a stated consequence as a separate mark only when it is a different point from the list, e.g. fewer amplitude values can be stored (1) so very quiet sounds are lost (1)

Do not accept 'lower quality'/'poorer sound' on its own; the answer must say the recording is less accurate than the original/does not match the analogue wave

Do not accept sample rate/sample interval/number of channels (stereo/mono), as these are not limited by the number of bits available for each sample

Do not accept remedies such as 'a larger bit depth would make it more accurate', as these do not describe a limitation

Do not accept answers about file size, compression or playback method

Do not accept a statement that repeats the stem, e.g. 'the sound is stored in binary using a fixed number of bits'

Example answers and how they were marked
Full marks2/2

The amplitude of each sample has to be rounded to the nearest value that can be stored, and very quiet sounds cannot be represented.

Why: Amplitude rounded to the nearest stored value (1) and quiet sounds cannot be represented (1): two different points from the list.

Some marks1/2

The recording is less accurate than the original sound.

Why: The recording is less accurate than the original analogue sound (1); a second, different limitation is not given.

No marks0/2

The sample rate is too low, so parts of the wave are missed.

Why: Sample rate is not limited by the number of bits per sample, so it is not accepted.

3Describe2 marksImages Swap Remove

The resolution of a bitmap image can be measured.

Describe what is meant by the resolution of a bitmap image.

[2 marks]
Mark scheme

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

  • The number of pixels in a given area/inch (1) so a higher resolution has more pixels in the same area (1)
  • The width and height of the image in pixels (1) which gives the total number of pixels (1)
  • The concentration/density of pixels (1) which determines the detail/sharpness of the image (1)
  • A larger number of pixels across the width and height (1) so more detail can be shown (1)

Do not accept 'how clear the image is' alone.

Do not accept the number of colours.

Do not award responses about file size.

Example answers and how they were marked
Full marks2/2

The number of pixels per inch. A higher resolution means more pixels in the same area.

Why: Point (1) that resolution is the number of pixels in a given area and development (1) that a higher resolution has more pixels in the same area.

Some marks1/2

The number of pixels across the width and height of the image.

Why: Point (1) that resolution is the width and height in pixels, but no linked development about the total number of pixels or detail.

No marks0/2

How many colours the image can show.

Why: No credit: the number of colours is not accepted as the meaning of resolution.

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