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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 · 5 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 recall2 marksUnits & Conversion Swap Remove

Data storage is measured in binary multiples.

Define the term bit.

[2 marks]
Mark scheme

Award one mark for any of the following up to a maximum of two marks:

  • A binary digit (1)
  • Has the value 0 or 1 (1)
  • The smallest unit of data storage (1)
  • A single 0 or 1 (1)

Allow binary digit/binary place value for binary digit

Allow a single binary digit for a single 0 or 1

Do not accept a group of 8 bits/half a nibble of 4 bits, which describe a byte or a nibble

Do not accept a binary number/binary on its own

Example answers and how they were marked
Full marks2/2

A binary digit that can have the value 0 or 1.

Why: A binary digit (1) and has the value 0 or 1 (1).

Some marks1/2

It is the smallest unit of data storage.

Why: Smallest unit of data storage (1), but does not state that it is a binary digit or that it has the value 0 or 1.

No marks0/2

A group of 8 bits.

Why: Describes a byte, not a bit; no creditworthy point and named in the Do not accept line.

3Explain2 marksTopologies Swap Remove

A bus topology uses one main cable shared by all devices.

Explain why a bus topology can be a security risk.

[2 marks]
Mark scheme

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

  • All devices receive every data packet (1) because the main cable is shared by all nodes (1)
  • Data can be read by any device on the network (1) because there is no central switch to send it only to the destination (1)
  • A device can intercept/capture data not meant for it (1) because all transmissions travel along the same cable (1)
  • Any device can view all data on the cable (1) so data is not private/secure (1)

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

Do not accept 'it is easy to hack' without saying data can be seen/intercepted on the shared cable.

Do not accept 'the central switch can be hacked' because a bus topology has no central switch.

Example answers and how they were marked
Full marks2/2

Any device on the bus can see all the data (1) because every packet travels along the same shared cable (1).

Why: Linked point (1) and reason (1): data is visible to all devices because the cable is shared.

Some marks1/2

All devices can see the data.

Why: Awarded 1 mark for stating that all devices can see the data, but no linked reason about the shared cable is given.

No marks0/2

It is less secure because the central switch can be hacked.

Why: No credit: a bus topology has no central switch; the answer gives a misconception and no valid point about the shared cable.

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