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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 514 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 · 3 marks

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1Multiple choice1 markCompression Swap Remove

Identify the definition of lossy compression.

[1 mark]
  • AData is removed only while the file is being transmitted
  • BData is permanently removed to reduce the file size
  • CData is restored exactly when it is decompressed
  • DData is stored using a dictionary of repeated patterns
Mark scheme
  • B Data is permanently removed to reduce the file size (1)
  • The only correct answer is B. The correct answer is data is permanently removed to reduce the file size.
  • A is not correct because the data removed by a lossy algorithm is not restored after transmission
  • C is not correct because that describes lossless compression, where the original file is rebuilt exactly
  • D is not correct because dictionary encoding is a lossless method that records repeated patterns once
Example answers and how they were marked
Full marks1/1

B Data is permanently removed to reduce the file size

Why: Correct option (1).

No marks0/1

C Data is restored exactly when it is decompressed

Why: Near miss: this describes lossless compression, so no mark.

No marks0/1

A Data is removed only while the file is being transmitted

Why: Misconception that compression only applies during transmission; the data is removed permanently, so no mark.

2Multiple choice1 markCompression Swap Remove

A student downloads a compressed music file and then decompresses it.

Identify what is meant by decompression.

[1 mark]
  • AData is encrypted so that it cannot be read
  • BData is permanently removed to reduce the file size
  • CData is restored to its original format
  • DData is stored using fewer bits
Mark scheme
  • C Data is restored to its original format (1)
  • The only correct answer is C. The correct answer is data is restored to its original format.
  • A is not correct because encryption changes data so that it cannot be read without a key; it does not restore the data
  • B is not correct because permanently removing data to reduce the file size is lossy compression, not decompression
  • D is not correct because storing data using fewer bits is compression, not decompression
Example answers and how they were marked
Full marks1/1

C Data is restored to its original format

Why: Correct option (1).

No marks0/1

D Data is stored using fewer bits

Why: Near miss: this describes compression, not decompression.

No marks0/1

B Data is permanently removed to reduce the file size

Why: Misconception: this describes lossy compression, not decompression.

3Short recall1 markUnits & Conversion Swap Remove

A file has a size of 2 kibibytes.

State the number of bytes in the file.

[1 mark]
Mark scheme

Award one mark for:

  • 2048 (1)
  • 2 × 1024 (1)
  • 2^11 (1)

Allow 2048 bytes.

Do not accept 2000, which is the number of bytes in two decimal kilobytes.

Do not accept 1024, which is the number of bytes in one kibibyte.

Do not accept 16, which is the number of bits in two bytes.

Example answers and how they were marked
Full marks1/1

2048

Why: 2048 is 2 × 1024, the number of bytes in 2 kibibytes (1).

No marks0/1

2000

Why: 2000 uses the decimal kilobyte, not the binary kibibyte; the mark scheme does not accept it.

No marks0/1

16

Why: 16 is the number of bits in two bytes, confusing bits with bytes; the mark scheme does not accept it.

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