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Edexcel GCSE Computer Science (1CP2) Exam Questions

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5 questions · 14 marks

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1Short recall2 marksStored Program Computers Swap Remove

The central processing unit (CPU) contains an arithmetic logic unit (ALU).

State two types of operation carried out by the ALU.

[2 marks]
Mark scheme

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

  • An arithmetic operation, e.g. addition/subtraction/multiplication/division (1)
  • A logical operation, e.g. comparing two values (is A > B?) / using AND, OR, NOT (1)

Do not accept decoding instructions, fetching instructions or controlling the timing of the CPU, as these are carried out by the control unit.

Example answers and how they were marked
Full marks2/2

It carries out arithmetic operations such as addition and subtraction, and logical operations such as comparing two values to see if one is greater than the other.

Why: Arithmetic operation (1) and logical operation (1).

Some marks1/2

It adds numbers together and works out the result.

Why: Arithmetic operation, addition (1). No logical operation.

No marks0/2

It decodes the instructions that have been fetched from main memory.

Why: Decoding and fetching are the control unit's role; the mark scheme's do-not-accept line covers this.

2Short recall2 marksUnits & Conversion Swap Remove

Data storage is measured in binary multiples.

Define the term bit.

[2 marks]
Mark scheme

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

  • A binary digit (1)
  • Has the value 0 or 1 (1)
  • The smallest unit of data storage (1)
  • A single 0 or 1 (1)

Allow binary digit/binary place value for binary digit

Allow a single binary digit for a single 0 or 1

Do not accept a group of 8 bits/half a nibble of 4 bits, which describe a byte or a nibble

Do not accept a binary number/binary on its own

Example answers and how they were marked
Full marks2/2

A binary digit that can have the value 0 or 1.

Why: A binary digit (1) and has the value 0 or 1 (1).

Some marks1/2

It is the smallest unit of data storage.

Why: Smallest unit of data storage (1), but does not state that it is a binary digit or that it has the value 0 or 1.

No marks0/2

A group of 8 bits.

Why: Describes a byte, not a bit; no creditworthy point and named in the Do not accept line.

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.

4Describe2 marksLow and High Level Languages Swap Remove

A programmer has written a program in assembly language.

Describe why it is necessary to translate the program into machine code before it can be run.

[2 marks]
Mark scheme

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

  • The processor/CPU can only execute machine code/binary instructions (1) so the assembly instructions must be converted into machine code before the program can run (1)
  • Each assembly instruction/mnemonic matches/corresponds to one machine code instruction (1) so each line must be replaced with the machine code the processor executes (1)
  • The program is written using mnemonics (1) that must be translated into machine code for the processor to carry out the instructions (1)
  • The hardware/processor does not understand assembly language directly (1) so it must be translated into machine code that the processor can execute (1)

Do not accept 'assembly language is a low-level language'.

Do not accept 'it is hard to understand' or 'it is not English'.

Do not accept benefits, such as 'machine code runs faster' or 'the program will run more quickly'.

Do not accept 'an assembler/a translator converts it' on its own, with no reference to the processor only being able to execute machine code/binary.

Do not accept responses about high-level languages or about compilers/interpreters.

Example answers and how they were marked
Full marks2/2

The processor can only execute machine code, so the assembly instructions must be converted into machine code before the program can run.

Why: States what the processor can execute (1) and links it to converting the program's instructions into machine code (1).

Some marks1/2

Each assembly instruction matches one machine code instruction.

Why: Correct point about the one-to-one match (1) but no development saying that this is because the processor only executes machine code.

No marks0/2

Because an assembler translates assembly language into machine code.

Why: Names the translator but gives no reason tied to the processor only being able to execute machine code, so no mark; this is in the 'Do not accept' guidance.

5Discuss6 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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