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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 · 6 marks

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1Explain2 marksPacket Switching Swap Remove

Data is split into packets before it is sent across the internet.

Explain why each packet has a packet number in its header.

[2 marks]
Mark scheme

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

  • The receiver can put the packets back into the correct order (1) because packets may arrive out of order/take different routes (1)
  • The receiver can see if a packet is missing (1) because the sequence of numbers shows a gap (1)
  • The receiver knows when the whole file has arrived (1) because the total number of packets/last packet number is known (1)

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

Allow 'so the packets can be put back in the correct order/reassembled' for the first mark, but the second mark needs the reason, i.e. packets may arrive out of order/take different routes.

Do not accept 'so the packets can be identified' without stating what the number is used for, e.g. reordering or spotting a missing packet.

Do not accept 'so the router knows where to send it' - the router uses the destination IP address, not the packet number.

Example answers and how they were marked
Full marks2/2

The receiver can put the packets back in the correct order because they may arrive out of order.

Why: Linked point (1) and reason (1): the packet number allows reordering because packets can arrive out of order.

Some marks1/2

It shows the receiver the order of the packets.

Why: The point is given (1) but there is no linked reason, such as packets arriving out of order.

No marks0/2

So the router knows which route to use.

Why: Routers use the destination IP address, not the packet number, so this earns nothing; it is named in the mark scheme as a 'Do not accept'.

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 because each device is connected to several others, so data can take another route if one connection fails.

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.

3Explain2 marksWireless Connections Swap Remove

A student plays an online game using a laptop connected to the school Wi-Fi.

Explain one reason why an online game can respond more slowly over a wireless connection than over a wired connection.

[2 marks]
Mark scheme

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

  • Wireless signals can be blocked or absorbed by walls (1) so the data must be re-sent, which adds delay (1)
  • A device further from the access point has a weaker signal (1) so data must be re-sent/transmitted at a lower rate, adding delay (1)
  • Devices on a wireless network share a channel (1) so a device must wait its turn to transmit, which adds delay (1)
  • Interference from other devices affects the radio signal (1) so data must be re-sent, adding delay (1)

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

Allow 'waiting to send' or 'collisions' as the delay caused by devices sharing a channel.

Do not accept 'wireless is slower than wired' on its own, as this repeats the question.

Do not accept a reason that only affects download speed/bandwidth (e.g. 'files take longer to download') without a link to delay.

Example answers and how they were marked
Full marks2/2

Interference from other devices affects the radio signal, so the data has to be re-sent and this adds delay before the player's action appears.

Why: Linked point (1): interference affects the signal; reason (1): re-sending the data adds delay (latency).

Some marks1/2

Walls can block the wireless signal.

Why: Point only (1): walls block the signal. No linked reason saying that this means data must be re-sent, which adds delay.

No marks0/2

Wireless has less bandwidth than wired, so a game update takes longer to download.

Why: Confuses latency with bandwidth/download speed; the mark scheme says not to accept this without a link to delay.

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