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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 markEmbedded Systems Swap Remove

Modern cars contain many embedded systems.

Identify what the embedded system that controls the cruise control does.

[1 mark]
  • AIt controls the interior lights
  • BIt displays a map for the driver
  • CIt keeps the car at a constant speed
  • DIt sounds an alarm if the car is broken into
Mark scheme
  • C It keeps the car at a constant speed (1)
  • The only correct answer is C. The correct answer is it keeps the car at a constant speed.
  • A is not correct because controlling the interior lights is done by a different embedded system in the car
  • B is not correct because displaying a map for the driver is done by the satellite navigation system
  • D is not correct because sounding an alarm is done by a different embedded system in the car
Example answers and how they were marked
Full marks1/1

C It keeps the car at a constant speed

Why: Correct option: this is the function of the embedded system that controls the cruise control (1).

No marks0/1

B It displays a map for the driver

Why: Near miss: displaying a map is the function of the satellite navigation system, which the mark scheme says is not correct, so no mark.

No marks0/1

A It controls the interior lights

Why: Misconception: the interior lights are controlled by a different embedded system, so no mark.

3Explain2 marksFetch Decode Execute Cycle Swap Remove

The control unit is part of the CPU.

Explain the role of the control unit in the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • Decodes/interprets/translates the instruction (1) to work out what the instruction is/what operation is required (1)
  • Sends control signals to the other components (1) so that the correct component carries out the instruction (1), e.g. the ALU/main memory
  • Controls the fetch of the instruction from main memory (1) because the address of the next instruction is sent via the address bus (1)
  • Controls the fetch of the next instruction from main memory (1) by sending a control signal/read signal to main memory (1)

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

For the decode point, 'decodes the instruction' alone gains 1 mark; a second mark needs the purpose of decoding, i.e. working out what the instruction is/what operation is required.

Do not accept 'it controls the CPU' on its own, without naming a task in the cycle.

Do not accept 'it fetches the instruction from memory' on its own, as this describes the fetch step rather than the control unit's role; credit only if linked to controlling/signalling the fetch.

Do not accept carrying out arithmetic/logical operations, as these are carried out by the ALU, or holding the address of the next instruction, as this is the program counter.

Do not accept storing the instruction in a register (e.g. MAR/MDR), as this is not the role of the control unit.

Example answers and how they were marked
Full marks2/2

The control unit decodes each instruction, working out what it means, so that the CPU knows which component should carry it out.

Why: Linked point (1) and reason (1): decodes/interprets the instruction, and works out what it is/what operation is required.

Some marks1/2

It decodes the instruction that has been fetched from main memory.

Why: Decode point only (1); it does not explain the purpose of decoding, i.e. working out what the instruction is/what operation is required.

No marks0/2

It adds the two numbers together and stores the result in a register.

Why: Misconception: arithmetic is carried out by the ALU, which the mark scheme's Do not accept line covers.

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