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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 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 markPrimary Memory Swap Remove

RAM is the main memory of a computer.

Identify the effect on the contents of RAM when the computer is switched off.

[1 mark]
  • AThey are lost
  • BThey are stored permanently
  • CThey are saved to secondary storage
  • DThey are written to ROM
Mark scheme
  • A They are lost (1)
  • The only correct answer is A. The correct answer is They are lost
  • B is not correct because RAM is volatile and its contents are lost when the power is switched off, so they are not stored permanently
  • C is not correct because RAM is volatile and its contents are lost when the power is switched off, so they are not saved to secondary storage
  • D is not correct because ROM is read-only memory that holds the start-up instructions, so the contents of RAM are not written to it
Example answers and how they were marked
Full marks1/1

A They are lost

Why: Selected the correct option. RAM is volatile, so its contents are lost when the power is switched off (1).

No marks0/1

C They are saved to secondary storage

Why: Near miss: thinks RAM contents are automatically saved, but RAM is volatile and its contents are not saved to secondary storage (0).

No marks0/1

B They are stored permanently

Why: Misconception: thinks RAM is non-volatile and keeps data permanently, but RAM is volatile and loses its contents when the power is switched off (0).

2Multiple 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.

3Explain2 marksStored Program Computers Swap Remove

A computer uses an address bus, a data bus and a control bus.

Explain the role of the data bus in the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • Carries the instruction from main memory to the CPU (1) so that it can be decoded/executed (1)
  • Carries data from main memory to the CPU/registers (1) so that it can be processed by the ALU (1)
  • Carries the result of an operation from the CPU/registers (1) back to main memory to be stored (1)
  • Carries an instruction/a data item from main memory to the CPU (1) during the fetch stage of the cycle (1)

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

Do not accept 'the data bus carries data' on its own without a linked reason such as where the data is carried to or from.

Do not accept 'carries instructions to the CPU' without a linked reason such as so that it can be decoded, or naming the fetch stage.

Do not accept 'carries memory addresses' — that is the role of the address bus.

Do not accept 'carries control signals' — that is the role of the control bus.

Example answers and how they were marked
Full marks2/2

It carries the instruction from main memory to the CPU so that it can be decoded

Why: Linked point (1) and reason (1).

Some marks1/2

It carries data from main memory to the CPU.

Why: Creditworthy point (1) but no linked reason (0).

No marks0/2

It carries the memory address of the next instruction.

Why: Misconception: carrying addresses is the role of the address bus, not the data bus.

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