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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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2 questions · 3 marks

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1Short recall1 markProtocols & Layers Swap Remove

TCP is a protocol in the transport layer of the TCP/IP model.

State one role of TCP when data is transmitted over a network.

[1 mark]
Mark scheme

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

  • Breaks messages/data into packets (1)
  • Reassembles packets (at the destination) (1)
  • Detects errors (1)
  • Resends lost/missing packets/requests retransmission of lost packets (1)
  • Creates/establishes a connection between two computers/hosts/sets up a connection before data is sent (1)

Do not accept routing packets or using IP addresses, which is the role of IP.

Do not accept encrypting data or providing security.

Do not accept vague answers such as 'transmits data' or 'sends data' without saying how TCP does this.

Example answers and how they were marked
Full marks1/1

It splits data into packets.

Why: States that TCP breaks data into packets.

No marks0/1

It routes packets between IP addresses.

Why: Near-miss: routing packets is the role of IP, not TCP.

No marks0/1

It encrypts data so it is secure.

Why: Encryption is not a role of TCP, so no creditworthy point.

2Describe2 marksFetch Decode Execute Cycle Swap Remove

The control unit is one component of the CPU.

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

[2 marks]
Mark scheme

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

  • Decodes instructions (1) to determine what action/operation is required (1)
  • Sends control signals (1) along the control bus to coordinate/control the actions of other components (1)
  • Controls the fetch stage (1) by causing the next instruction to be fetched from main memory/RAM (1)
  • Controls the execute stage (1) by telling the ALU/other components when to carry out the required operation (1)

Do not accept responses relating to how the control unit affects performance, such as increasing clock speed.

Do not accept responses that describe the role of the ALU, registers or clock instead of the control unit.

Do not accept responses about the ALU performing calculations unless the control unit controlling the ALU is also stated.

Example answers and how they were marked
Full marks2/2

The control unit decodes instructions to determine what action is required.

Why: Linked point (1) and development (1): decodes instructions and determines the required action.

Some marks1/2

The control unit controls the fetch stage of the cycle.

Why: Point only (1): controls the fetch stage, but no linked development.

No marks0/2

The control unit carries out arithmetic and logical operations on data.

Why: No creditworthy point: describes the role of the ALU, which the mark scheme rejects.

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