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Edexcel GCSE Computer Science (1CP2) Exam Questions

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1Describe2 marksStored Program Computers Swap Remove

The CPU contains an arithmetic logic unit (ALU).

Describe the purpose of the arithmetic logic unit (ALU).

[2 marks]
Mark scheme

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

  • Carries out arithmetic operations/calculations, such as addition or subtraction (1) so that the result can be stored in a register (1)
  • Carries out logical operations, such as comparing two data items (1) to see which one is greater/larger (1)
  • Compares two data items (1) to decide whether a condition is true / which path a program takes next (1)

Allow the result of an arithmetic or logical operation being held/stored in a register, but only where the operation is named.

Do not accept answers that say the ALU stores data or results without naming an operation (registers/main memory store data).

Do not accept answers about controlling components, decoding instructions or timing (that is the control unit or the clock).

Do not award credit for 'it processes data' on its own; an arithmetic or a logical operation must be named.

An example on its own, e.g. 'it adds two numbers', does not earn a second mark; the second mark needs a linked development.

Example answers and how they were marked
Full marks2/2

The ALU carries out arithmetic operations such as addition and subtraction, and the result of the calculation is stored in a register.

Why: Linked point (1) for arithmetic operations with an example, and development (1) for the result being stored in a register.

Some marks1/2

It does all the calculations in the CPU, for example adding two numbers together.

Why: Point (1) for arithmetic operations/calculations named with an example; no linked development, so the second mark is not earned.

No marks0/2

It stores the results of calculations so that they can be used by the CPU later.

Why: Storing results with no arithmetic or logical operation named, which the 'Do not accept' line rules out, so no mark is earned.

2Explain2 marksPrimary Memory Swap Remove

A computer follows the von Neumann stored program concept. A program's instructions are stored on secondary storage before the program is run.

Explain one reason why the instructions of a program must be held in RAM before they can be executed.

[2 marks]
Mark scheme

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

  • The CPU can only fetch/read instructions from main memory/RAM (1) so the instructions of a running program must be copied/loaded into RAM before they can be executed (1)
  • RAM is faster to access than secondary storage (1) so the instructions can be fetched quickly enough for the CPU to execute them (1)
  • The CPU needs the instructions in RAM to fetch and execute them (1) because the fetch-decode-execute cycle reads each instruction from main memory/RAM (1)
  • The address of the next instruction is sent to RAM on the address bus (1) so the instruction can be transferred to the CPU/registers for decoding/execution (1)

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

Allow the point and reason in either order if they are linked.

Do not accept answers that only say the CPU needs instructions, or that RAM is faster, without linking this to fetching/executing the instructions.

Do not accept answers that only say RAM holds data and instructions without linking this to the fetch-decode-execute cycle.

Do not accept 'RAM is permanent/non-volatile storage, so the instructions are kept safe' - RAM is volatile.

The response does not need to name the address bus or the fetch stage for full marks; a linked reason that explains why instructions must be in RAM (for example, the CPU can only fetch from RAM, or RAM is faster than secondary storage) is enough.

Example answers and how they were marked
Full marks2/2

The CPU can only fetch instructions from main memory, so the instructions of a running program must be copied into RAM before they can be executed.

Why: Linked point (1) for the CPU only being able to fetch instructions from main memory/RAM, and reason (1) for instructions being copied into RAM before execution.

Some marks1/2

The CPU can only fetch instructions from main memory.

Why: Point (1) only; there is no linked reason that explains why this means the instructions must be held in RAM before execution, such as RAM being faster than secondary storage.

No marks0/2

Instructions are kept in RAM because RAM is permanent storage and does not lose the instructions when the power is turned off.

Why: Misconception: RAM is described as permanent/non-volatile, which the mark scheme's 'Do not accept' line rules out; no creditworthy linked point.

3Explain2 marksSecondary Memory Swap Remove

A memory stick uses solid state storage.

Explain how data is stored in solid state storage.

[2 marks]
Mark scheme

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

  • Data is stored as electric charges (1) which are trapped/held in the memory cells/chips (1)
  • A current forces electrons through a barrier (1) and they stay trapped on the other side until another current/'flash' is applied (1)
  • A cell that is holding trapped electrons/a charge represents a 1 (1) and a cell with no charge represents a 0 (1)

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

Allow one mark for stating that data is stored as electric charges/electrons without a linked reason.

Do not accept 'there are no moving parts' or 'it is fast/durable' - these are characteristics of solid state storage, not how data is stored.

Do not accept 'data is stored magnetically' or 'as pits and lands'.

Example answers and how they were marked
Full marks2/2

Data is stored as electric charges. A current forces electrons through a barrier and traps them, and a cell with a trapped charge represents a 1 while a cell with no charge represents a 0.

Why: Linked point (1) data stored as electric charges with reason (1) electrons forced through a barrier and trapped, and the charge representing the binary values.

Some marks1/2

Data is stored as electric charges.

Why: Allow line (1): states that data is stored as electric charges, but gives no linked reason (how the charges are trapped or how they represent 1s and 0s), so only one mark.

No marks0/2

The data is stored on the chips using tiny magnets, in the same way as a hard disk.

Why: Misconception. Do not accept 'data is stored magnetically' - solid state storage stores data as electric charges, not magnetic patterns.

Questions by topic

2.1 Binary

Build a paper on this topic 58
Adding Binary Numbers 6 questions Binary and Hexadecimal Basics 10 questions Binary Shifts 6 questions Binary to Denary Conversion 6 questions Binary to Hexadecimal Conversion 6 questions Denary to Binary Conversion 6 questions Denary to Hexadecimal Conversion 6 questions Denary to Negative Binary Conversion 6 questions Hexadecimal to Binary Conversion 6 questions

2.2 Data representation

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Character Sets 18 questions Images 19 questions Sound 19 questions

2.3 Data storage and compression

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Compression 18 questions Units & Conversion 6 questions

3.1 Hardware

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Embedded Systems 17 questions Fetch Decode Execute Cycle 15 questions Primary Memory 15 questions Secondary Memory 15 questions Stored Program Computers 15 questions

3.2 Software

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File Management 18 questions Memory Management 16 questions Peripheral Management 11 questions Process Management 12 questions Purpose & Function of Operating Systems 17 questions Software Basics 13 questions User Management 18 questions Utility Software 19 questions

3.3 Programming languages

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Low and High Level Languages 19 questions Translators 18 questions

4.1 Networks

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Addressing 16 questions LANs & WANs 16 questions Network Speed 5 questions Packet Switching 16 questions Protocols & Layers 17 questions The Internet 16 questions Topologies 17 questions Wired Connections 17 questions Wireless Connections 18 questions

4.2 Network security

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Network Security Risks 18 questions Preventing Network Security Risks 18 questions

5.1 Environmental

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E-waste 17 questions Manufacturing Technology 19 questions

5.2 Ethical and legal

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Data Protection Act 17 questions Impact of AI 18 questions Intellectual Property 18 questions Software Licences 18 questions

5.3 Cybersecurity

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Malware 18 questions Social Engineering 18 questions

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