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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 631 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 markUnits & Conversion Swap Remove

Units of data storage can be binary or decimal.

Identify the unit of storage that is equivalent to 1024 gibibytes.

[1 mark]
  • AGibibyte
  • BMebibyte
  • CTebibyte
  • DTerabyte
Mark scheme
  • C Tebibyte (1)
  • The only correct answer is C. The correct answer is tebibyte.
  • A is not correct because a gibibyte is 1024 mebibytes
  • B is not correct because a mebibyte is 1024 kibibytes
  • D is not correct because a terabyte is 1000 gigabytes
Example answers and how they were marked
Full marks1/1

C Tebibyte

Why: Correct: 1024 gibibytes make one tebibyte (1).

No marks0/1

A Gibibyte

Why: Near miss: a gibibyte is 1024 mebibytes, not 1024 gibibytes (0).

No marks0/1

D Terabyte

Why: Typical misconception: uses the decimal terabyte (1000 gigabytes) instead of the binary tebibyte (0).

2Multiple choice1 markCompression Swap Remove

Identify one reason for using data compression.

[1 mark]
  • ATo increase the number of packets sent
  • BTo reduce the time taken to transmit a file
  • CTo improve the quality of the file
  • DTo make the file harder to open
Mark scheme
  • B To reduce the time taken to transmit a file (1)
  • The only correct answer is B. The correct answer is to reduce the time taken to transmit a file.
  • A is not correct because compression reduces file size, which can reduce the number of packets sent
  • C is not correct because lossy compression can reduce the quality of a file
  • D is not correct because encryption, not compression, can make a file harder to open
Example answers and how they were marked
Full marks1/1

B To reduce the time taken to transmit a file

Why: Correct option (1).

No marks0/1

A To increase the number of packets sent

Why: Near miss: compression reduces the number of packets sent, so no mark.

No marks0/1

C To improve the quality of the file

Why: Misconception that compression improves quality; no mark.

3Short recall2 marksCompression Swap Remove

Files can be compressed before they are stored.

Define the term lossless compression.

[2 marks]
Mark scheme

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

  • Reduces/makes the size of a file smaller (1)
  • No data is lost/removed (during compression) (1)
  • The original file/data can be recreated/restored exactly (1)

Allow 'the compressed file takes up less storage space' for the first mark.

The second and third bullets are two ways of making the same point: award a maximum of one mark for them, so a response that says no data is lost and that the original file can be restored, but does not say the file is smaller, scores one mark.

Do not accept descriptions of lossy compression, e.g. 'it removes data that is not needed to make the file smaller'.

Ignore reference to download/transmission times, bandwidth and streaming, as these are benefits of compression and not part of the definition.

Example answers and how they were marked
Full marks2/2

Lossless compression reduces the size of a file without permanently removing any data, so the original file can be restored exactly.

Why: Reduces the size of a file (1) and no data is lost, so the original can be restored exactly (1); maximum of two marks reached.

Some marks1/2

It makes a file smaller so it downloads more quickly.

Why: Reduces the size of a file (1); the faster download is ignored as a benefit, not part of the definition.

No marks0/2

It removes data that is not needed to make the file smaller.

Why: Describes lossy compression, which the do-not-accept line rules out, so the mention of making the file smaller is not credited.

4Describe2 marksCompression Swap Remove

Photographs are often saved as JPG files.

Describe how lossy compression reduces the size of a photograph.

[2 marks]
Mark scheme

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

  • Some data is removed permanently (1) choosing detail that people are least likely to notice (1)
  • Small changes in colour/shade are discarded (1) so fewer different values need to be stored (1)
  • Similar pixels are stored as one value (1) so there are fewer values in the file (1)
  • Fine detail is removed (1) so fewer bits are needed to store each area (1)

Do not accept answers that say repeated patterns are stored once / no data is lost.

Example answers and how they were marked
Full marks2/2

It permanently removes some of the pixel data that the human eye is unlikely to notice, such as small colour changes.

Why: Linked point: data removed permanently (1) and development: detail least noticeable (1).

Some marks1/2

Some of the data in the photograph is removed permanently.

Why: States permanent removal of data (1); no linked development is given (1).

No marks0/2

It finds repeated pixels and stores them once, so no data is lost.

Why: Describes lossless compression, not lossy; no credit.

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