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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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1Short recall1 markImages Swap Remove

A bitmap image uses one bit per pixel.

State the limitation this places on the number of colours in the image.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • Only two different colours can be represented/stored (1)
  • Each pixel can only be one of two values (1)
  • The image can only be shown in black and white (1)

Allow answers that give the number of colours, e.g. two colours, 2 colours

Allow any pair of two colours, e.g. black and white, black and grey

Do not accept low resolution/poor quality/lower quality

Do not accept only one colour/can only show black

Do not accept 2 bits/2^1 without a statement about the number of colours that can be represented

Example answers and how they were marked
Full marks1/1

Only two colours can be represented, such as black and white.

Why: States that only two different colours can be represented (1)

No marks0/1

The image will have a low resolution.

Why: Confuses colour depth with resolution; low resolution is not accepted

No marks0/1

The image can only show black.

Why: One colour is all a single value can give; the limitation is that only two colours can be represented, so this is not accepted

2Short recall2 marksCharacter Sets Swap Remove

A computer uses a character set to represent text.

Define the term character set.

[2 marks]
Mark scheme

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

  • A set/collection of characters (1)
  • (Characters such as) letters, digits and symbols/punctuation (1)
  • Each character is represented by a unique code/binary value (1)
  • A standard set of characters so that text can be exchanged between computer systems (1)

Allow 'a list of characters that a computer can represent' for the first mark.

Do not accept a program/software that converts text into binary.

Do not accept 'a set of binary codes' on its own.

Example answers and how they were marked
Full marks2/2

A set of characters, such as letters, digits and punctuation, where each character is represented by a unique binary code.

Why: Set/collection of characters with examples (1) and each character has a unique code (1).

Some marks1/2

A set of letters and symbols that a computer can use to represent text.

Why: Awarded for the set/collection of characters (1); no creditworthy point saying each character has its own unique code (0).

No marks0/2

A program that converts the keys pressed on a keyboard into binary.

Why: Describes software that converts text, not a set of characters; the Do not accept line applies.

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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