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Edexcel GCSE Computer Science (1CP2) Exam Questions

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3 questions · 9 marks

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1Short recall1 markImages Swap Remove

Each pixel in a bitmap image is stored using a number of bits.

Define the term colour depth.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • The number of bits per pixel (1)
  • The number of bits used to represent/store the colour of each pixel (1)

Allow bit depth

Do not accept the number of colours a pixel can have on its own

Do not accept the number of pixels in the image (this is the resolution/image size)

Example answers and how they were marked
Full marks1/1

The number of bits used to store the colour of one pixel.

Why: Gives the number of bits per pixel (1)

No marks0/1

The number of colours that each pixel can use.

Why: Gives the number of colours, not the number of bits; the mark scheme does not accept this on its own

No marks0/1

The number of pixels in the image.

Why: Confuses colour depth with resolution/image size, which the mark scheme does not accept

2Describe2 marksTranslators Swap Remove

A high-level program must be translated into machine code before it can be run.

Describe how a compiler and an interpreter differ in when the translated code is executed.

[2 marks]
Mark scheme

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

  • The interpreter executes each line as soon as it has been translated (1) so translation and execution happen together/at the same time (1)
  • The compiler translates the whole program first (1) and the machine code is run later/separately (1)
  • The interpreter translates the code and runs it while the program is running (1) whereas the compiler does not run the code it produces (1)
  • The compiler produces translated code that is executed only after all the translation has finished (1) but the interpreter executes each line immediately (1)

Allow 'translates one line at a time' where it is linked to executing each line immediately.

Do not accept answers that only state that a compiler is faster/an interpreter is slower, without reference to when execution happens.

Do not accept answers that only give object code, error reporting or portability, without reference to when execution happens.

Do not accept the compiler executing the program as it translates it.

Example answers and how they were marked
Full marks2/2

The compiler translates the code first and the program is executed afterwards, but the interpreter executes each line as soon as it has been translated.

Why: Compiler translates the whole program first and it is executed afterwards (1) and interpreter executes each line as soon as it is translated (1).

Some marks1/2

The interpreter executes each line immediately after translating it.

Why: Correct interpreter timing (1); no comparison with when the compiler's translated code is executed.

No marks0/2

The compiler executes the program line by line as it translates it.

Why: Reverses the two translators; a compiler does not execute the program it translates, so no mark.

3Discuss6 marksPrimary Memory Swap Remove

A school is buying new computers for its IT room. The computers the technician has ordered have 16 GB of RAM and a large hard drive.

Discuss why main memory (RAM) is needed for programs to run on these computers.

Your answer should include:

  • the role of RAM in the stored program concept
  • what happens to a program when it is opened
  • why the CPU cannot execute a program directly from secondary storage.
[6 marks]
Mark scheme

Indicative content

the role of RAM in the stored program concept

  • In the von Neumann stored program concept, a program's instructions and the data it uses are held together in main memory.
  • RAM holds the instructions and data of the program that the CPU is currently processing.
  • The CPU fetches each instruction from RAM during the fetch-decode-execute cycle, so a program must be in RAM before it can be run.
  • RAM is directly accessible by the CPU, so instructions can be fetched quickly enough for the CPU to keep working.

what happens to a program when it is opened

  • When a program is opened, a copy of its instructions and data is transferred from secondary storage, such as the hard drive, into RAM.
  • The operating system loads the program into RAM so that the CPU can start fetching and executing its instructions.
  • When the program is closed, it is removed from RAM, and the space it used is free for another program.
  • If a computer does not have enough RAM, the program may not open, or another open program has to be closed first.

why the CPU cannot execute a program directly from secondary storage

  • Secondary storage, such as a hard disk drive, is much slower to access than RAM.
  • The CPU can process instructions much faster than secondary storage can supply them, so the CPU would have to wait and would not be working at full speed.
  • RAM is fast electronic memory with no moving parts, so data can be read from it in a fraction of the time taken by a magnetic hard disk drive.
  • Running the school's programs directly from secondary storage would make the computers in the IT room very slow to use.

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 cover both the role of RAM in the stored program concept and the speed difference between RAM and secondary storage, with a reason such as the CPU having to wait for instructions.
  • Answers that make only basic, independent points, such as what RAM is, that a program is copied into RAM when it is opened, or that RAM is faster than a hard drive, without linking them to explain why the CPU would have to wait for instructions, are limited to Level 1.
  • Do not accept statements that RAM is permanent storage, that RAM replaces secondary storage, or that secondary storage is read-only.
Example answers and how they were marked
Full marks6/6

The computers need RAM because of the von Neumann stored program concept, in which the instructions of a program and the data it uses are both held in main memory. When a student opens a program on one of the new computers, the operating system copies it from the hard drive into RAM. The CPU then fetches each instruction from RAM in the fetch-decode-execute cycle, so the program must be in RAM before it can be run. The CPU cannot execute a program directly from secondary storage because a hard disk drive is much slower than RAM. It has moving parts and a much lower transfer rate, so the CPU would often have nothing to do while it waited for the next instruction. RAM is fast electronic memory that the CPU can read directly, which is why 16 GB of RAM lets the school run several programs at once and still keep the CPU working at full speed.

Why: Comprehensive understanding: the stored program concept is explained (instructions and data held in main memory), the program being opened is linked to it, and the speed difference is developed with the reason that the CPU would wait for instructions, all applied to the school's computers. Level 3.

Some marks2/6

RAM is the main memory of the computer. It stores the programs and data that are being used at the moment. When you open a program it is copied into RAM, and the CPU fetches instructions from RAM. RAM is faster than the hard drive, so a program runs better from RAM. Having 16 GB means the school can have more programs open at once.

Why: Basic, independent points only: what RAM is, that a program is copied into RAM when it is opened, that the CPU fetches instructions from RAM, and that RAM is faster than a hard drive. None is linked to the stored program concept or developed to explain why the CPU would have to wait for instructions, so Level 1, 2 marks.

No marks0/6

RAM is the permanent storage inside the computer, like a hard drive. The school needs 16 GB of RAM so that all the students' files can be saved permanently. When a program is opened, it is copied from RAM to the CPU. The CPU cannot execute from secondary storage because secondary storage is read-only.

Why: No creditworthy points. RAM is described as permanent storage, files are said to be saved permanently in RAM, a program is said to be copied from RAM to the CPU, and secondary storage is said to be read-only. All are the misconceptions listed in the Do not accept guidance, so Level 0.

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

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

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