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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 659 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 · 5 marks

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1Multiple choice1 markCompression Swap Remove

Identify the statement that describes lossless compression.

[1 mark]
  • AData is encrypted so that it cannot be read by others
  • BData is permanently removed to make the file smaller
  • CNo data is lost and the original file can be recreated
  • DThe file is split into packets that are sent separately
Mark scheme
  • C No data is lost and the original file can be recreated (1)
  • The only correct answer is C. The correct answer is no data is lost and the original file can be recreated.
  • A is not correct because encryption hides data and does not make the file smaller
  • B is not correct because permanently removing data is lossy compression
  • D is not correct because splitting a file into packets is part of transmission, not compression
Example answers and how they were marked
Full marks1/1

C No data is lost and the original file can be recreated

Why: Correct option (1).

No marks0/1

B Data is permanently removed to make the file smaller

Why: Near miss: this is lossy compression, not lossless, so no mark.

No marks0/1

D The file is split into packets that are sent separately

Why: Misconception that compression is packet switching; no mark.

2Multiple 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).

3Short recall1 markCompression Swap Remove

A company backs up its files to an external hard drive.

Give one reason why the company compresses the files before backing them up.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • More files/data can be stored (in the same storage space) (1)
  • The files take up less storage space (1)
  • The backup is quicker/faster to complete (1)
  • Less data needs to be transferred to the backup device (1)

Do not accept 'makes the files more secure' or 'encrypts the files'.

Example answers and how they were marked
Full marks1/1

The compressed files take up less storage space, so more files can be backed up.

Why: The files take up less storage space (1).

No marks0/1

It reduces the amount of disk fragmentation.

Why: Near-miss: compression does not reduce disk fragmentation.

No marks0/1

It encrypts the files so they are safer if the drive is stolen.

Why: Misconception: compression does not encrypt files, and security is not accepted.

4Explain2 marksCompression Swap Remove

A software company distributes its programs as compressed files.

Explain why lossless compression is used for the program files.

[2 marks]
Mark scheme

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

  • No data/instructions are removed (1) so the program still works/runs correctly after decompression (1)
  • The original file can be recreated exactly (1) so all the code/instructions are present when the program is run (1)
  • Lossy compression would permanently remove some data (1) so the program would not execute correctly/could crash (1)
  • Every instruction is needed for the program to run (1) so the code must not be changed/lost (1)

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

Allow 'no data/instructions are removed/lost' on its own as the point mark (1); the second mark needs the consequence for the program, e.g. it still works/runs correctly, or all the instructions are present.

Award credit for a contrast with lossy compression only when the loss of data is linked to the program failing/not running correctly.

Do not accept 'lossless is better quality'/keeps the quality without saying that data/instructions are not lost.

Do not accept 'it makes the file smaller'/'downloads faster'/'transmits faster' as a reason for using lossless, as both types of compression reduce file size.

Example answers and how they were marked
Full marks2/2

No instructions are removed so the program still works after it has been decompressed.

Why: No data/instructions removed (1) and linked reason that the program still works correctly (1).

Some marks1/2

Lossless compression does not lose any data.

Why: Point mark for 'no data/instructions are lost' on its own (1); no consequence for the program is given, so the second mark is not awarded.

No marks0/2

Lossless compression makes the file smaller so it downloads faster.

Why: File size and download speed apply to both types of compression, so this does not explain why lossless is used for the program files.

Questions by topic

5.3 Cybersecurity

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