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Edexcel GCSE Computer Science (1CP2) Exam Questions

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4 questions · 11 marks

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1Multiple choice1 markCharacter Sets Swap Remove

Characters are encoded using 7-bit ASCII.

Identify the number of different characters that can be represented using 7-bit ASCII.

[1 mark]
  • A64
  • B127
  • C128
  • D256
Mark scheme
  • C 128 (1)
  • The only correct answer is C. The correct answer is 128.
  • A is not correct because 6 bits give only 64 different combinations
  • B is not correct because 127 is the largest 7-bit value, not the number of characters that 7 bits can represent
  • D is not correct because 256 characters need 8 bits, as used by 8-bit extended ASCII
Example answers and how they were marked
Full marks1/1

C 128

Why: Selects the only correct option (1): 7 bits give 2 to the power of 7, which is 128 different characters.

No marks0/1

D 256

Why: Near miss scoring 0: 256 is the number of characters that 8 bits give in extended ASCII, not 7-bit ASCII.

No marks0/1

B 127

Why: Misconception scoring 0, the off-by-one error the examiners' report describes: 127 is the largest 7-bit value, but 7 bits give 128 different characters.

2Short recall1 markCompression Swap Remove

A company backs up its files to an external hard drive.

Give one reason why the company compresses the files before backing them up.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • More files/data can be stored (in the same storage space) (1)
  • The files take up less storage space (1)
  • The backup is quicker/faster to complete (1)
  • Less data needs to be transferred to the backup device (1)

Do not accept 'makes the files more secure' or 'encrypts the files'.

Example answers and how they were marked
Full marks1/1

The compressed files take up less storage space, so more files can be backed up.

Why: The files take up less storage space (1).

No marks0/1

It reduces the amount of disk fragmentation.

Why: Near-miss: compression does not reduce disk fragmentation.

No marks0/1

It encrypts the files so they are safer if the drive is stolen.

Why: Misconception: compression does not encrypt files, and security is not accepted.

3Calculate3 marksAdding Binary Numbers Swap Remove

Binary patterns can represent numbers.

(a)

Complete the table to show the 8-bit result of the binary addition.

[2 marks]
1286432168421
11011011
11011100
Mark scheme

Award one mark for each correct nibble in the correct order:

  • 1011 (1)
  • 0111 (1)

0 marks if the response is not 8-bit binary.

Ignore a carry shown beyond the eighth bit.

Example answers and how they were marked
Full marks2/2

1011 0111

Why: 219 + 220 = 439, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0000 0111

Why: Forgets to carry the 1s. The second nibble is correct (1); the first is not.

No marks0/2

1101 1111

Why: Never carries. Neither nibble is correct.

(b)

State the name of the error that occurs when this addition is carried out.

[1 mark]
Mark scheme

Award one mark for:

  • overflow (error) (1)
Example answers and how they were marked
Full marks1/1

Overflow

Why: The result needs more bits than are available (1).

No marks0/1

Underflow

Why: A near miss: the result is too big for 8 bits, not too small.

No marks0/1

A syntax error

Why: A syntax error is a mistake in a program's code, not in arithmetic.

4Discuss6 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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