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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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5 questions · 7 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 markUnits & Conversion Swap Remove

A computer stores data in binary.

Identify the number of bits in one kibibyte.

[1 mark]
  • A1024
  • B8000
  • C8192
  • D8 388 608
Mark scheme
  • C 8192 (1)
  • The only correct answer is C. The correct answer is 8192.
  • A is not correct because 1024 is the number of bytes in a kibibyte
  • B is not correct because 8000 is the number of bits in 1000 bytes
  • D is not correct because 8 388 608 is the number of bits in a mebibyte
Example answers and how they were marked
Full marks1/1

C 8192

Why: Correct: one kibibyte is 1024 bytes and 1024 × 8 = 8192 bits (1).

No marks0/1

A 1024

Why: Near miss: 1024 is the number of bytes in a kibibyte, not the number of bits (0).

No marks0/1

B 8000

Why: Typical misconception: uses 1000 bytes for a kibibyte, giving 1000 × 8 = 8000 bits (0).

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.

4Short recall2 marksUnits & Conversion Swap Remove

A solid state drive has a capacity of 5 gibibytes.

Give an expression to calculate the number of bits in 5 gibibytes. You do not need to do the calculation.

[2 marks]
Mark scheme

Award one mark for each of:

  • 5 × 1024^3 / 5 × 1024 × 1024 × 1024 / 5 × 2^30, for the number of bytes (1)
  • A fully correct expression with × 8 to convert bytes to bits, in any order, e.g. 5 × 1024^3 × 8, 8 × 5 × 2^30 (1)

Accept 5 × 1 073 741 824 × 8.

Accept 5 × 2^33 or 42 949 672 960 as a fully correct expression (2 marks).

Do not accept 5 × 1000^3 × 8, which uses decimal multiples.

Do not accept ÷ 8, which converts bits to bytes.

Example answers and how they were marked
Full marks2/2

8 × 5 × 2^30

Why: 5 × 2^30 is the number of bytes (1) and × 8 converts bytes to bits (1).

Some marks1/2

5 × 2^30

Why: Correct number of bytes using the binary multiple 2^30 (1), but no conversion to bits.

No marks0/2

5 × 1000^3 × 8

Why: Uses decimal 1000^3 instead of binary 1024^3, so the expression is not fully correct; no creditworthy point.

5Explain2 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.

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