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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 markCompression Swap Remove

Identify the definition of lossy compression.

[1 mark]
  • AData is removed only while the file is being transmitted
  • BData is permanently removed to reduce the file size
  • CData is restored exactly when it is decompressed
  • DData is stored using a dictionary of repeated patterns
Mark scheme
  • B Data is permanently removed to reduce the file size (1)
  • The only correct answer is B. The correct answer is data is permanently removed to reduce the file size.
  • A is not correct because the data removed by a lossy algorithm is not restored after transmission
  • C is not correct because that describes lossless compression, where the original file is rebuilt exactly
  • D is not correct because dictionary encoding is a lossless method that records repeated patterns once
Example answers and how they were marked
Full marks1/1

B Data is permanently removed to reduce the file size

Why: Correct option (1).

No marks0/1

C Data is restored exactly when it is decompressed

Why: Near miss: this describes lossless compression, so no mark.

No marks0/1

A Data is removed only while the file is being transmitted

Why: Misconception that compression only applies during transmission; the data is removed permanently, so no mark.

2Short recall2 marksCompression Swap Remove

Images and sound can be stored using lossy compression.

Define the term lossy compression.

[2 marks]
Mark scheme

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

  • Reduces the size of a file (1)
  • Permanently removes/loses some data (1)
  • The original file cannot be recreated/restored exactly (1)

Allow 'some data is deleted/discarded and cannot be recovered' for the second mark.

Do not award the first mark where the response also states that no data is lost.

Do not accept 'removes repeated data' (this describes lossless compression).

Example answers and how they were marked
Full marks2/2

Lossy compression reduces the size of a file by permanently removing some data, so the original cannot be restored exactly.

Why: Reduces the size of a file (1); permanently removes some data (1); maximum two marks awarded.

Some marks1/2

It makes a file smaller.

Why: Reduces the size of a file (1); no reference to data being permanently lost.

No marks0/2

It makes a file smaller without losing any of the data.

Why: States that no data is lost, which describes lossless compression; the first mark is not awarded.

3Discuss6 marksPrimary Memory Swap Remove

An employee is writing a report on a laptop. There is a power cut and the laptop turns off. When power is restored, the employee cannot find the report file.

Discuss the role of RAM in this situation.

Your answer should include:

  • why the report was lost
  • the difference between RAM and secondary storage
  • how the employee could prevent this in future.
[6 marks]
Mark scheme

Indicative content

Why the report was lost

  • The report was being created and edited in RAM, which is volatile.
  • Volatile memory loses its contents when the power supply is removed.
  • The power cut removed the power, so the data in RAM was lost.
  • The report had not been saved to secondary storage before the power cut.
  • Only data that had been saved to secondary storage would remain after the power cut.

The difference between RAM and secondary storage

  • RAM is volatile and holds data temporarily while the computer is on.
  • Secondary storage is non-volatile and keeps data permanently when the power is off.
  • RAM is directly accessible by the CPU and is much faster than secondary storage.
  • Secondary storage has a larger capacity and is cheaper per gigabyte than RAM.
  • RAM holds the programs and data currently in use; secondary storage holds files for long-term storage.

How the employee could prevent this in future

  • The employee should save the report regularly to secondary storage, such as the hard drive or a USB flash drive.
  • The employee could enable autosave or autosave/recovery features in the word processor.
  • The employee could use cloud storage that saves changes automatically.
  • The employee could use an uninterruptible power supply (UPS) or battery to keep the laptop on during a power cut.
  • The employee should not rely on RAM to keep work permanently.

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 that RAM is volatile and contrast this with non-volatile secondary storage.
  • Do not award marks for stating that the report was lost from secondary storage unless it had been saved there.
Example answers and how they were marked
Full marks6/6

The report was lost because it was being held in RAM, which is volatile memory. RAM only keeps its contents while the computer has power. When the power cut happened, the laptop turned off and everything in RAM was lost, including the unsaved report. RAM is different from secondary storage because secondary storage is non-volatile and keeps data permanently even when the power is off. For example, the hard drive would still contain the report if it had been saved. RAM is also much faster than secondary storage and is used for programs and data currently in use. To prevent this in future, the employee should save the report regularly to the hard drive or use autosave. They could also save to cloud storage, which saves automatically, or use a UPS to keep the laptop running during a power cut.

Why: Comprehensive understanding of RAM volatility, clear contrast with non-volatile secondary storage, and well-linked prevention methods applied to the employee's situation.

Some marks4/6

The report was lost because it was in RAM. RAM is temporary memory and it loses data when the power goes off. Secondary storage is permanent, so if the employee had saved the report it would still be there. RAM is faster than secondary storage. To prevent it, they should save their work.

Why: Adequate understanding shown through the volatility of RAM and the difference from permanent secondary storage, but the answer lacks detail about why the report was specifically lost and gives only a brief prevention method.

No marks0/6

The report was lost from the hard drive because the power cut erased it. RAM is permanent storage, so the report should have been saved there. The employee should buy more RAM to stop this happening again.

Why: No creditworthy points. The answer wrongly says the report was lost from the hard drive and that RAM is permanent storage, and it suggests more RAM will prevent power-loss data loss. These are misconceptions.

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