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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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4 questions · 6 marks

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1Multiple choice1 markCharacter Sets Swap Remove

A text file stores each character using 7-bit ASCII.

Identify the denary ASCII code for the space character.

[1 mark]
  • A32
  • B33
  • C48
  • D65
Mark scheme
  • A 32 (1)
  • The only correct answer is A. The correct answer is 32.
  • B is not correct because 33 is the ASCII code for the exclamation mark (!)
  • C is not correct because 48 is the ASCII code for the character 0
  • D is not correct because 65 is the ASCII code for the uppercase letter A
Example answers and how they were marked
Full marks1/1

A 32

Why: Correct option: the space character has the ASCII code 32 (1).

No marks0/1

C 48

Why: Near miss scoring 0: 48 is the ASCII code for the character 0, not the space character.

No marks0/1

D 65

Why: Misconception scoring 0: 65 is the ASCII code for the uppercase letter A, so a well-known code is given but not the code for a space.

2Short recall1 markSound Swap Remove

A digital sound representation is created by sampling an analogue sound wave.

State one way the accuracy of this representation can be increased.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • Increase the sample rate / take more samples per second (1)
  • Increase the bit depth/sample resolution / use more bits per sample (1)
  • Decrease the sample interval (1)

Do not accept increase the amplitude/volume

Do not accept decrease the sample rate / increase the sample interval

Example answers and how they were marked
Full marks1/1

Increase the sample rate.

Why: Creditworthy point: increase the sample rate (1).

No marks0/1

Decrease the sample rate.

Why: Near-miss: decreasing the sample rate reduces accuracy, so no mark; the mark scheme's do-not-accept line covers this (0).

No marks0/1

Increase the volume of the sound.

Why: Misconception: loudness/amplitude is not a way to increase sampling accuracy; do not accept increase amplitude/volume (0).

3Explain2 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.

4Explain2 marksCharacter Sets Swap Remove

ASCII uses a fixed number of bits to represent each character.

Explain one reason why ASCII uses 7 bits to represent each character.

[2 marks]
Mark scheme

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

  • 7 bits give 128 different codes/combinations (1) which is enough to represent all the characters on a keyboard (1)
  • 7 bits allow 128 unique characters (1) so uppercase and lowercase letters, digits and punctuation can all be represented (1)
  • 6 bits give only 64 combinations (1) which is not enough for the number of characters on a keyboard (1)
  • A keyboard needs to represent more than 64 different characters (1) so 7 bits are needed to give the 128 combinations required (1)
  • A fixed number of 7 bits gives 128 possible codes (1) which is enough for the characters ASCII represents, so more bits are not needed (1)

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

Do not accept 'because ASCII is 7-bit' or 'because 7 bits is enough' as these repeat the question without giving the number of combinations or saying what they allow.

Do not accept '7 bits give 256 characters'; 256 combinations come from 8 bits (extended ASCII).

Allow 'ASCII has 128 characters/codes' for the 128 point.

Example answers and how they were marked
Full marks2/2

7 bits give 128 different codes, which is enough for every letter, digit and punctuation symbol on a keyboard.

Why: Gives the point that 7 bits give 128 codes (1) and links it to the reason that this is enough for all the characters on a keyboard (1).

Some marks1/2

7 bits give 128 different combinations.

Why: Gives the point that 7 bits give 128 combinations (1) but does not say what this number of combinations allows, so the linked reason (1) is not earned.

No marks0/2

Because ASCII uses 7 bits so it can store 256 characters.

Why: Repeats the question and gives the wrong number of characters (256 is 8-bit extended ASCII), so there is no creditworthy point.

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