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Edexcel GCSE Computer Science (1CP2) Exam Questions

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5 questions · 12 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the function of the control unit in the fetch-decode-execute cycle.

[1 mark]
  • ADecodes instructions
  • BPerforms arithmetic operations
  • CStores data and instructions
  • DTemporarily stores data being processed
Mark scheme
  • A Decodes instructions (1)
  • The only correct answer is A. The correct answer is Decodes instructions.
  • B is not correct because the arithmetic logic unit performs arithmetic operations
  • C is not correct because main memory stores data and instructions
  • D is not correct because registers temporarily store data being processed
Example answers and how they were marked
Full marks1/1

A Decodes instructions

Why: Correct option: the control unit decodes instructions during the fetch-decode-execute cycle (1).

No marks0/1

C Stores data and instructions

Why: Main memory stores data and instructions, not the control unit; this is a common distractor, so no mark.

No marks0/1

B Performs arithmetic operations

Why: Arithmetic operations are performed by the ALU, not the control unit; a common confusion between CPU components, so no mark.

2Multiple choice1 markCharacter Sets Swap Remove

ASCII is a character set used for representing text.

Identify the number of bits used to encode each character in ASCII.

[1 mark]
  • A6
  • B7
  • C8
  • D16
Mark scheme
  • B 7 (1)
  • The only correct answer is B. The correct answer is 7 bits.
  • A is not correct because 6 bits give only 64 different characters
  • C is not correct because 8 bits are used by extended ASCII to give 256 characters
  • D is not correct because 16 bits give 65 536 different characters, which is far more than the 128 in ASCII
Example answers and how they were marked
Full marks1/1

B 7

Why: B is the only correct answer: each ASCII character is encoded using 7 bits (1).

No marks0/1

C 8

Why: Near miss scoring 0: 8 bits is extended ASCII, and the scheme's C line says extended ASCII, not ASCII, is not the answer.

No marks0/1

A 6

Why: Misconception scoring 0: 6 bits give only 64 different characters, so it cannot be ASCII.

3Describe2 marksUtility Software Swap Remove

A student has a large number of photographs stored on a computer.

Describe the purpose of data compression software.

[2 marks]
Mark scheme

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

  • Makes a file/files smaller (1) so less storage space is needed on the disk (1)
  • Reduces the size of the data (1) so it takes less time to upload/download/transfer the file (1)
  • Compresses files/folders into a single file (1) so an attachment is under the size limit for email (1)
  • Reduces the size of the files (1) so more of them fit onto a storage device/backup media (1)

Do not accept 'it compresses the files' on its own, as this repeats the question.

Do not accept responses about protecting files from malware/viruses or about deleting files.

Example answers and how they were marked
Full marks2/2

It makes the files smaller (1) so that they use less storage space on the computer and more of them fit on the disk (1).

Why: The point (1) and a linked development giving the benefit (1).

Some marks1/2

It makes files smaller.

Why: This is the point (1) but there is no development of what the smaller size leads to, so only one mark.

No marks0/2

It protects the files from viruses so that they cannot be damaged.

Why: This describes anti-malware software, which the mark scheme does not accept; no creditworthy point is made.

4Calculate2 marksBinary Shifts Swap Remove

Computers manipulate binary patterns.

Complete the table with the result of applying the shift to the binary pattern.

[2 marks]
Binary patternShift8-bit binary result
1000 0001Logical shift right by 1
Mark scheme

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

  • 0100 (1)
  • 0000 (1)

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

Example answers and how they were marked
Full marks2/2

0100 0000

Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).

Some marks1/2

0100 0001

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

0000 0010

Why: Shifts the bits the wrong way. Neither nibble is correct.

5Discuss6 marksFile Management Swap Remove

A small business has one computer with a single hard disk. Two employees save documents and photographs to it every day. The operating system manages the disk.

Discuss why the operating system needs to manage where files are stored on the disk.

Your answer should include:

  • how the operating system allocates disk space when a file is saved
  • how the operating system keeps track of each file
  • what could happen if the operating system did not manage files
[6 marks]
Mark scheme

Indicative content

Allocating space

  • The operating system checks that there is enough free space before a file is saved, so a large photograph does not make the save fail.
  • The operating system finds free space on the disk and allocates it to the new file, so the file's data has somewhere to be written.
  • Disk space is allocated so that a file is not written on top of data that already belongs to another file.
  • When a file is deleted, the operating system marks its space as free so it can be used again by the next document that is saved.

Keeping track

  • The operating system keeps a record of the name, size and location of every file, so it knows where each file is stored.
  • The record is updated whenever a file is saved, renamed or deleted, so it still matches what is on the disk.
  • The operating system uses this record to find a file again, so an employee can open a document or photograph that was saved earlier.
  • The record lets the operating system tell the two employees' documents and photographs apart, even though they are all on the same disk.

Without this management

  • Two files could be given the same space, so one document would overwrite another and the work would be lost.
  • The operating system would not know where a file is stored, so a saved document could not be found and opened again.
  • Space used by deleted files might never be freed, so the disk would fill up and new files could not be saved.

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 both the allocation of space and the tracking of files, with at least one consequence of no management linked to its cause. Reference to a file being split across blocks that are not next to each other, or to the record holding the location of each block, is Level 3 detail and is not required.

Basic, unlinked points with no application to the business's documents or photographs, and a consequence such as 'files would be lost' with no cause given, are limited to Level 1; to reach Level 2 a point must be linked to a reason (for example, the record is kept so a document can be found again) and be applied to the context. Do not accept defragmentation, process scheduling, user management, peripheral management, or backup and antivirus scanning, as file management.

Example answers and how they were marked
Full marks6/6

Before a document is saved, the operating system checks that there is enough free space on the single disk, so a large photograph cannot make the save fail. It then finds free space and allocates it to the new file, making sure it does not write over data that already belongs to another file. The operating system keeps a record of the name, size and location of every file and updates it whenever a file is saved or deleted. It uses this record to find a file again, so an employee can open a document that was saved earlier. Without this, the two employees could be given the same space, so one document would overwrite the other, or the operating system would not know where a file is stored and the business could not find its work again.

Why: Covers both allocation (free space check, free space given to the file, no overwriting) and tracking (record of name, size and location, updated on save, used to find the file), applies it to the business's single disk and its two employees' documents and photographs, and links the consequences of no management to their causes: Level 3.

Some marks2/6

The operating system decides where on the disk a file is saved. It also keeps a record of where each file is stored. Without this, files would be lost.

Why: Two basic points are made: space is allocated when a file is saved, and a record of where each file is stored is kept. Neither is linked to a reason, there is no application to the business's documents and photographs, and 'files would be lost' is given with no cause: Level 1, top of the level.

Some marks1/6

The operating system puts files in the right place so the disk does not get full. It also defragments the disk to make the files smaller.

Why: One basic point about the operating system placing files on the disk so it does not fill up (Level 1). Defragmentation is not file management and does not make files smaller, so it is not credited: Level 1.

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