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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

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.

2Short recall2 marksFetch Decode Execute Cycle Swap Remove

The control unit is one component of the CPU.

Give two roles of the control unit during the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • Decodes the instruction / works out what the instruction is (1)
  • Sends control signals to the other components (of the CPU) (1)
  • Coordinates/controls the activities of the CPU (1)
  • Directs the timing of the other components / controls when each component acts (1)

Do not accept carrying out arithmetic or logical operations, as this is the role of the ALU.

Do not accept holding/storing the data or instructions, as this is the role of the registers/main memory.

Example answers and how they were marked
Full marks2/2

It decodes each instruction and sends control signals to the other components to tell them what to do.

Why: Decodes the instruction (1) and sends control signals to the other components (1).

Some marks1/2

It decodes the instructions and carries out the calculations.

Why: Decoding the instruction (1); the calculations are carried out by the ALU, so the second part earns nothing.

No marks0/2

It stores the data that the CPU is working on.

Why: Storing data is the role of the registers/main memory, not the control unit, so no point is creditworthy.

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.

4Discuss6 marksUtility Software Swap Remove

A college has a room of older desktop computers. Each computer has a magnetic hard disk that is almost full. Staff have noticed that files on these computers take a long time to open because the disks have become fragmented.

Discuss the use of disk defragmentation software on these computers.

Your answer should include:

  • how files become fragmented
  • what defragmentation software does
  • the benefits and drawbacks of running it.
[6 marks]
Mark scheme

Indicative content

How files become fragmented

  • A file is saved into free blocks on the disk, so as files are deleted and new ones saved, one file can end up split across blocks in different places.
  • Large files are more likely to become fragmented because they may not fit into one free space.
  • The more the disks are used, the more fragmented they become, so the read/write head has to move to more locations to read all the parts of a file.
  • Fragmentation is the reason that files on the college's computers take a long time to open.

What defragmentation software does

  • It reorganises the blocks of each file so that they are stored together (contiguously) on the disk.
  • It collects the free space into one block so that new files are written in one piece and are less likely to be fragmented.
  • It is a housekeeping utility that is often supplied with the operating system, and it reorganises data that is already on the disk.
  • It does not change the contents of any file, it only changes where the blocks of the file are stored.

Benefits of running it

  • Files and programs open faster because the read/write head makes fewer movements, so the older computers feel quicker without the college buying new hardware.
  • Free space in one block means new files are written in one piece, so the improvement lasts for a while.
  • Running it may mean the college can keep using the older computers for longer instead of replacing them.

Drawbacks of running it

  • It can take a long time to run, so it should be scheduled for when the room is not in use, such as overnight or at weekends.
  • It causes a lot of disk activity, so running it too often puts unnecessary strain on the disks.
  • It does not free up any space, as no files are deleted, so the disks will still be almost full.
  • It only reorganises files that are intact, so it cannot recover a corrupted file, and a backup is still needed.

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 how files become fragmented and what defragmentation software does, with at least one benefit or drawback applied to the college's computers. An answer that only states what the software does and one benefit, with no explanation of how files became fragmented and no drawback, is Level 1 (2 marks).

Do not accept: defragmentation software compresses files, frees up storage space, deletes unused files, repairs corrupted files, or speeds up the processor or internet connection.

Example answers and how they were marked
Full marks6/6

As files are deleted and new ones saved, a file can be split into blocks in different places on the disk, especially a large file that will not fit into one free space. This means the read/write head has to move to more locations to read the file, which is why the files on these computers are slow to open. Defragmentation software reorganises the blocks so that each file is stored together, and it moves the free space into one block, so new files are written in one piece. Staff would find that files and programs open faster because the head makes fewer movements, so the older computers feel quicker without the college buying new ones. It can take a long time, so the college should schedule it overnight or at the weekend when the room is empty, and it should not be run too often because of the strain on the disks. It will not free up space, as nothing is deleted, so the disks will still be almost full and a backup is still needed.

Why: Level 3: fragmentation, the extra head movements and what the software does are explained accurately (AO1) and applied to the college's own computers, with a benefit and drawbacks including a sensible schedule (AO2).

Some marks2/6

Defragmentation software rearranges the files so that the parts of each file are stored together. This means files open faster, which will help on these computers. It should be run regularly.

Why: Level 1: two basic, independent points, namely that the software stores the parts of a file together and that files then open faster, with little linkage and no explanation of how the files became fragmented and no drawback, so Level 2 is not reached.

Some marks1/6

Defragmentation software compresses the files so they take up less space on the nearly full disks. If the parts of a file are stored together it opens faster.

Why: Level 1: only the basic point that storing the parts of a file together makes it open faster is creditworthy; the claim that defragmentation compresses files is a misconception on the do-not-accept line and is not credited.

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