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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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4 questions · 7 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.

2Describe2 marksLow and High Level Languages Swap Remove

A programmer has written a program in assembly language.

Describe why it is necessary to translate the program into machine code before it can be run.

[2 marks]
Mark scheme

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

  • The processor/CPU can only execute machine code/binary instructions (1) so the assembly instructions must be converted into machine code before the program can run (1)
  • Each assembly instruction/mnemonic matches/corresponds to one machine code instruction (1) so each line must be replaced with the machine code the processor executes (1)
  • The program is written using mnemonics (1) that must be translated into machine code for the processor to carry out the instructions (1)
  • The hardware/processor does not understand assembly language directly (1) so it must be translated into machine code that the processor can execute (1)

Do not accept 'assembly language is a low-level language'.

Do not accept 'it is hard to understand' or 'it is not English'.

Do not accept benefits, such as 'machine code runs faster' or 'the program will run more quickly'.

Do not accept 'an assembler/a translator converts it' on its own, with no reference to the processor only being able to execute machine code/binary.

Do not accept responses about high-level languages or about compilers/interpreters.

Example answers and how they were marked
Full marks2/2

The processor can only execute machine code, so the assembly instructions must be converted into machine code before the program can run.

Why: States what the processor can execute (1) and links it to converting the program's instructions into machine code (1).

Some marks1/2

Each assembly instruction matches one machine code instruction.

Why: Correct point about the one-to-one match (1) but no development saying that this is because the processor only executes machine code.

No marks0/2

Because an assembler translates assembly language into machine code.

Why: Names the translator but gives no reason tied to the processor only being able to execute machine code, so no mark; this is in the 'Do not accept' guidance.

3Explain2 marksTopologies Swap Remove

A mesh topology has many connections between devices.

Explain one reason why a mesh topology is resilient.

[2 marks]
Mark scheme

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

  • There is no single point of failure (1) because there is no central device that all the other devices depend on (1)
  • If one device/connection fails, the network can still communicate/work (1) because data can be sent along another route between devices (1)
  • A faulty device/connection can be bypassed (1) because each device is connected to more than one other device (1)

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

Allow one mark for a correct point without a linked reason.

Allow 'the network can still communicate/work' as the outcome point and 'if one cable/connection breaks' as the failure point.

Allow 'reliable'/'robust' only when expanded with a reason, such as multiple routes or no single point of failure.

Do not accept 'it has many connections' on its own without saying why this makes the network resilient.

Do not accept 'mesh is faster' or 'data is backed up' as these do not explain resilience.

Do not accept 'it uses a central switch/device' as part of the explanation.

Example answers and how they were marked
Full marks2/2

There is no single point of failure (1) because each device is connected to several others, so data can take another route if one connection fails (1).

Why: Linked point (1) and reason (1): no single point of failure is explained by multiple connections and alternative routes.

Some marks1/2

If one device fails, the network still works.

Why: Awarded 1 mark for the correct outcome point; no linked reason about multiple routes or connections is given.

No marks0/2

It is resilient because a central switch redirects data around a broken cable.

Why: No credit: the mark scheme does not accept a central switch in a mesh explanation, and no valid point about multiple routes is given.

4Calculate2 marksBinary Shifts Swap Remove

Computers manipulate binary patterns.

Complete the table with the result of applying the shift to the binary pattern.

[2 marks]
Binary patternShift8-bit binary result
1000 0001Logical shift right by 1
Mark scheme

Award one mark for each correct nibble in the correct order:

  • 0100 (1)
  • 0000 (1)

0 marks if the response is not 8-bit binary.

Example answers and how they were marked
Full marks2/2

0100 0000

Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).

Some marks1/2

0100 0001

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

0000 0010

Why: Shifts the bits the wrong way. Neither nibble is correct.

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