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Edexcel GCSE Computer Science (1CP2) Exam Questions

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3 questions · 9 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the component of the CPU that carries out arithmetic and logical operations.

[1 mark]
  • AArithmetic logic unit
  • BControl unit
  • CMain memory
  • DRegister
Mark scheme
  • A Arithmetic logic unit (1)
  • The only correct answer is A. The correct answer is arithmetic logic unit.
  • B is not correct because the control unit decodes instructions and controls the CPU
  • C is not correct because main memory is not part of the CPU and stores data and instructions
  • D is not correct because a register stores small amounts of data within the CPU
Example answers and how they were marked
Full marks1/1

A Arithmetic logic unit

Why: Correct option: the arithmetic logic unit carries out arithmetic and logical operations (1).

No marks0/1

B Control unit

Why: Control unit is a CPU component but its role is to decode and control, not perform arithmetic or logical operations, so no mark.

No marks0/1

D Register

Why: Register stores data but does not carry out operations; a common misconception that any CPU component performs calculations, so no mark.

2Explain2 marksFetch Decode Execute Cycle Swap Remove

The CPU carries out the fetch-decode-execute cycle.

Explain one reason why the address bus is used in the fetch stage of the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • The address bus carries the address of the next instruction (1) so the CPU can locate/fetch it from main memory/RAM (1)
  • The address bus carries the address of the memory location to be read (1) so the instruction/data stored there can be located/accessed (1)
  • The CPU needs to know where the next instruction is stored (1) so the address bus sends the address to main memory/RAM (1)

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

Allow 'from the program counter/PC' as part of the point for one mark, e.g. the address bus carries the address from the program counter (1), but the second mark needs the destination or purpose (e.g. to locate/fetch the instruction in main memory/RAM).

Do not award the second mark for naming the program counter/PC alone.

Do not accept answers that say the address bus carries data/instructions from main memory to the CPU, as these travel on the data bus.

Do not accept answers that say the address bus stores the address.

Do not allow an answer that only restates that the address bus carries addresses without saying which address or why it is needed.

Example answers and how they were marked
Full marks2/2

The address bus carries the address of the next instruction from the program counter to main memory, so that the CPU can locate the instruction that is to be fetched.

Why: Linked point (1) and reason (1).

Some marks1/2

The address bus carries the address of the next instruction from the program counter.

Why: Point only (1); the second mark is not awarded because the destination/purpose of locating or fetching the instruction is missing.

No marks0/2

It carries the instruction from main memory back to the CPU so that it can be decoded.

Why: Misconception: instructions travel on the data bus, which the mark scheme's Do not accept line covers.

3Discuss6 marksPrimary Memory Swap Remove

A video production company edits films for its clients. The editors use computers to work on 4K video, and they say the computers have become slow. One editor wants to replace the CPU, but a colleague thinks adding more RAM would be better.

Discuss whether adding more RAM will improve the performance of the computers used to edit 4K video. (6)

Your answer should include:

  • how RAM is used when editing video
  • why too little RAM causes poor performance
  • why adding more RAM may not always improve performance.
[6 marks]
Mark scheme

Indicative content

How RAM is used when editing video

  • The editing software and the video project being worked on are loaded into RAM so that the CPU can access them quickly.
  • RAM holds the frames, effects and timeline data that the CPU is processing as part of the fetch-decode-execute cycle.
  • The CPU fetches the instructions and the video data it needs from RAM, which is much faster than fetching them from secondary storage.
  • Having more RAM means that more of the 4K video project and its effects can be held in memory at the same time.
  • RAM is also used by the operating system and any other open software, so not all of the RAM is available to the editing software.

Why too little RAM causes poor performance

  • If there is not enough RAM, the operating system uses virtual memory on secondary storage for data that will not fit in RAM.
  • Virtual memory is much slower than RAM, so the editor waits longer for 4K video to load and for effects to be applied.
  • Data has to be swapped between RAM and virtual memory, which is extra work that slows the computer down.
  • The editing software may freeze or close if it runs out of memory while working on the 4K video.
  • Playback of the 4K video is not smooth because the frames cannot all be held in RAM ready for the CPU.

Why adding more RAM may not always improve performance

  • If the computer already has enough RAM for the editing software, the extra RAM will not be used and performance will hardly change.
  • The clock speed and the number of cores of the CPU decide how quickly instructions are processed, so a slow CPU will still limit how quickly the video is edited.
  • A slow secondary storage drive will still limit how quickly the 4K video files can be loaded into RAM.
  • Adding RAM only improves performance if a shortage of RAM was the reason for the computer being slow.

Levels

  • Level 0 (0 marks): No rewardable content.
  • Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
  • Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
  • Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Additional guidance

  • Level 3 responses must explain how RAM is used when editing video and give a developed reason why adding more RAM may not always improve performance; responses that only explain how RAM is used, or only why too little RAM causes poor performance, are limited to Level 2.
  • Accept 'paging' or 'swap file' as equivalent to virtual memory, but do not accept 'cache' or 'ROM'; do not credit statements that adding RAM increases the CPU clock speed or makes the CPU faster, or that 'RAM is volatile' explains poor performance, as these are not linked to the question asked.
Example answers and how they were marked
Full marks6/6

RAM holds the editing software and the 4K video project that is being worked on, so the CPU can fetch the frames and the effects it needs much faster than from the hard drive. If there is not enough RAM, the operating system has to use virtual memory on secondary storage instead, and this is much slower than RAM, so the editors have to wait for video to load and the playback is not smooth. Adding more RAM can help because more of the 4K project and its effects can be held in memory at once. However, it will not always improve performance. If the computer already has enough RAM the extra memory will not be used, and if the CPU has a low clock speed or too few cores it will still take longer to process each frame. A slow hard drive will also limit how quickly the 4K files can be loaded into RAM, so adding RAM only solves the problem if the computer was short of memory.

Why: Level 3: explains how RAM is used when editing video and applies it to the frames and effects (AO1/AO2), gives a developed reason for poor performance using virtual memory and its slowness, and gives developed reasons why extra RAM may not help, namely a CPU bottleneck (clock speed and cores) and a slow drive, applied to the company's 4K editing.

Some marks2/6

RAM is used to store the video while it is being edited. If you don't have enough RAM, the computer will be slow because it has to use the hard drive instead. Adding more RAM will make the computer faster because it can store more video. The CPU also matters because it does the processing.

Why: Level 1, top end (2 marks). A basic relevant use of RAM, storing the video being edited, and a basic point that the hard drive is used when RAM is short; the extra RAM point is asserted with no reasoning and the single CPU statement is not linked to why adding RAM may not help, so there is little development and the answer does not reach Level 2.

No marks0/6

RAM is the same as the CPU, so adding more RAM makes the CPU faster. The video editor should add more RAM to increase the clock speed. 4K video is slow because RAM is volatile.

Why: No creditworthy content: treating RAM as the CPU and saying adding RAM increases the clock speed are the misconceptions named in the guidance, and 'RAM is volatile' is not linked to performance, so it earns nothing.

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

Build a paper on this topic 77
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

Build a paper on this topic 36
Malware 18 questions Social Engineering 18 questions

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