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Edexcel GCSE Computer Science (1CP2) Exam Questions

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3 questions · 10 marks

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1Short 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 each 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.

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 marksUser Management Swap Remove

A small design company has 18 employees who use a network with a shared file server. Some employees are company directors and need to manage the system. Designers need to work on shared project folders, but salary files must be kept private.

Discuss how the operating system's user management can give employees the access they need while protecting the company's files.

Your answer should include:

  • administrator accounts
  • standard user accounts
  • file permissions.
[6 marks]
Mark scheme

Indicative content

Administrator accounts

  • An administrator account can create new user accounts for new employees and delete accounts when employees leave.
  • The administrator can reset a forgotten password, so an employee can get back to work without sharing another person's account.
  • The administrator can set the access rights for each user or group, so designers get access to project folders and only directors can open salary files.
  • Administrator privileges should be given to only a few trusted employees, as administrators can change any settings on the system.

Standard user accounts

  • Designers should use standard user accounts, so they cannot install unauthorised software or change system settings.
  • A standard user can be given permission to read and write files in the project folder that their team uses.
  • Standard users should not be able to change other users' permissions, so the access rules cannot be removed by accident.
  • If a standard user tries to open a file without permission, the operating system denies access.

File permissions

  • Each file or folder can have permissions that allow a user to read, write or delete it.
  • Project folders can be set so all designers can read and write the files inside them.
  • Salary files can be set so only directors can read them, and other users are denied access.
  • Permissions can be set for a group of users, such as all designers, which is quicker than setting them for each person.
  • A file can be made read-only for standard users, so they can view it but cannot change it.

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)

Level 3 responses must cover administrator accounts, standard user accounts and file permissions, and apply them to the design company.

Do not accept general operating system functions such as managing the processor or memory unless they are explicitly linked to controlling what a user can access.

Example answers and how they were marked
Full marks6/6

The directors should have administrator accounts so they can create accounts for new designers, delete accounts when staff leave, and set permissions on the file server. Ordinary designers should have standard user accounts so they cannot install software or change permissions. The administrator can give the designers read and write permission on the shared project folders, but only the directors can read the salary files. This means the designers can work together on projects, while confidential salary information stays private. If a designer leaves, the administrator can disable their account so they can no longer open company files.

Why: Level 3. It covers administrator accounts, standard accounts and file permissions, with coherent application to project folders and salary files.

Some marks4/6

The administrator can add and delete users and set their permissions. Normal users can only access the files they are allowed to. The salary files can be made private so only the administrator can see them.

Why: Level 2. Administrator accounts and file permissions are described with some application, but standard user accounts are not developed and the explanation lacks sustained reasoning.

No marks0/6

The administrator is the person who uses the computer most often, so the operating system gives them more memory and a faster processor. This means they can manage the users.

Why: Level 0. It confuses administrator privileges with extra memory and processor speed, which is process management, not user management.

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