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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 · 7 marks

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1Short recall2 marksCompression Swap Remove

Files can be compressed before they are stored.

Define the term lossless compression.

[2 marks]
Mark scheme

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

  • Reduces/makes the size of a file smaller (1)
  • No data is lost/removed (during compression) (1)
  • The original file/data can be recreated/restored exactly (1)

Allow 'the compressed file takes up less storage space' for the first mark.

The second and third bullets are two ways of making the same point: award a maximum of one mark for them, so a response that says no data is lost and that the original file can be restored, but does not say the file is smaller, scores one mark.

Do not accept descriptions of lossy compression, e.g. 'it removes data that is not needed to make the file smaller'.

Ignore reference to download/transmission times, bandwidth and streaming, as these are benefits of compression and not part of the definition.

Example answers and how they were marked
Full marks2/2

Lossless compression reduces the size of a file without permanently removing any data, so the original file can be restored exactly.

Why: Reduces the size of a file (1) and no data is lost, so the original can be restored exactly (1); maximum of two marks reached.

Some marks1/2

It makes a file smaller so it downloads more quickly.

Why: Reduces the size of a file (1); the faster download is ignored as a benefit, not part of the definition.

No marks0/2

It removes data that is not needed to make the file smaller.

Why: Describes lossy compression, which the do-not-accept line rules out, so the mention of making the file smaller is not credited.

2Explain2 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.

3Calculate3 marksAdding Binary Numbers Swap Remove

Binary patterns can represent numbers.

(a)

Complete the table to show the 8-bit result of the binary addition.

[2 marks]
1286432168421
11011011
11011100
Mark scheme

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

  • 1011 (1)
  • 0111 (1)

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

Ignore a carry shown beyond the eighth bit.

Example answers and how they were marked
Full marks2/2

1011 0111

Why: 219 + 220 = 439, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0000 0111

Why: Forgets to carry the 1s. The second nibble is correct (1); the first is not.

No marks0/2

1101 1111

Why: Never carries. Neither nibble is correct.

(b)

State the name of the error that occurs when this addition is carried out.

[1 mark]
Mark scheme

Award one mark for:

  • overflow (error) (1)
Example answers and how they were marked
Full marks1/1

Overflow

Why: The result needs more bits than are available (1).

No marks0/1

Underflow

Why: A near miss: the result is too big for 8 bits, not too small.

No marks0/1

A syntax error

Why: A syntax error is a mistake in a program's code, not in arithmetic.

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