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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 604 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 · 4 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the function of the control unit in the fetch-decode-execute cycle.

[1 mark]
  • ADecodes instructions
  • BPerforms arithmetic operations
  • CStores data and instructions
  • DTemporarily stores data being processed
Mark scheme
  • A Decodes instructions (1)
  • The only correct answer is A. The correct answer is Decodes instructions.
  • B is not correct because the arithmetic logic unit performs arithmetic operations
  • C is not correct because main memory stores data and instructions
  • D is not correct because registers temporarily store data being processed
Example answers and how they were marked
Full marks1/1

A Decodes instructions

Why: Correct option: the control unit decodes instructions during the fetch-decode-execute cycle (1).

No marks0/1

C Stores data and instructions

Why: Main memory stores data and instructions, not the control unit; this is a common distractor, so no mark.

No marks0/1

B Performs arithmetic operations

Why: Arithmetic operations are performed by the ALU, not the control unit; a common confusion between CPU components, so no mark.

2Short 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.

3Describe2 marksTranslators Swap Remove

Source code can contain syntax errors.

Describe how a compiler and an interpreter differ in the way they deal with syntax errors.

[2 marks]
Mark scheme

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

  • The compiler reports all syntax errors after translation has finished (1) whereas the interpreter stops at the first error it finds (1)
  • The interpreter reports a syntax error as soon as it finds one (1) and does not translate/execute any more of the program (1)
  • The compiler continues translating after an error (1) and reports the errors at the end (1)
  • The interpreter stops translating when it reaches an error (1) but the compiler finishes translating before reporting errors (1)

Do not accept answers about fixing/correcting errors or about object code.

Do not award 'the compiler finds more errors' without saying errors are reported at the end.

Example answers and how they were marked
Full marks2/2

A compiler reports all the syntax errors at the end of translation, whereas an interpreter stops and reports the error as soon as it finds one.

Why: Compiler reports errors at the end (1) and interpreter stops/reports at the first error (1).

Some marks1/2

An interpreter stops translating when it finds a syntax error.

Why: Interpreter stops at the first error (1); no comparison with when the compiler reports errors.

No marks0/2

A compiler reports a syntax error immediately, before translating the rest of the program.

Why: Reverses the compiler's behaviour; it finishes translating before reporting errors.

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