Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• Reduces/makes the size of a file smaller (1)
• No data is lost/removed (during compression) (1)
• The original file/data can be recreated/restored exactly (1)

Allow 'the compressed file takes up less storage space' for the first mark.

The second and third bullets are two ways of making the same point: award a maximum of one mark for them, so a response that says no data is lost and that the original file can be restored, but does not say the file is smaller, scores one mark.

Do not accept descriptions of lossy compression, e.g. 'it removes data that is not needed to make the file smaller'.

Ignore reference to download/transmission times, bandwidth and streaming, as these are benefits of compression and not part of the definition.

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

• The compiler reports all syntax errors after translation has finished (1) whereas the interpreter stops at the first error it finds (1)
• The interpreter reports a syntax error as soon as it finds one (1) and does not translate/execute any more of the program (1)
• The compiler continues translating after an error (1) and reports the errors at the end (1)
• The interpreter stops translating when it reaches an error (1) but the compiler finishes translating before reporting errors (1)

Do not accept answers about fixing/correcting errors or about object code.

Do not award 'the compiler finds more errors' without saying errors are reported at the end.

Indicative content

Types of backup that could be used

• A full backup copies all of the company's project files every time it is run, so the whole set of files is held together in one backup.
• A full backup takes longer to make and needs more storage space than an incremental backup.
• An incremental backup copies only the files that have changed since the previous backup, so it is quicker to run each evening.
• Restoring from incremental backups needs the last full backup plus every incremental backup made since, which takes longer and is more complex.
• A weekly full backup with nightly incremental backups can be suitable for the company when the reason is explained using the properties of the two types.

Where and how often backups should be made

• Backups should be kept on a separate device and, ideally, at a different location, so that a fire or theft in the office cannot destroy the computer and the backups together.
• Backups should be made regularly, for example every evening, so that at most one day's design work would be lost.
• Cloud storage can hold copies off-site automatically, without the owner taking a disk home.
• An external hard disk or USB flash drive can be used as the backup medium, with a copy kept away from the office.

How the backups would be used if the hard disk failed again

• If the hard disk fails again, the backup software is used to restore the latest full backup and any later incremental backups onto a replacement disk.
• The restored project files allow the company to carry on working and meet its clients' deadlines.
• The backups should be tested by restoring a file so that the company knows the backup is usable before it is needed.
• Backup software does not repair the failed hard disk itself, so a replacement disk 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 requires all three bullets to be developed and applied, including both types of backup (or a justified combination) and a restoration sequence; a response that describes only a full backup cannot reach Level 3.

An answer that explains only one type of backup with at most a brief location or frequency point and no developed restoration is Level 1 (1–2 marks). Credit one off-site point only: cloud storage, an external disk kept elsewhere and 'a different location' are the same point. Do not accept that backup software repairs a failed hard disk or recovers files that were never backed up; an answer that only makes this claim is Level 0. An unsupported weekly-full/nightly-incremental recommendation is not credited.

Indicative content

Ease of learning, use and debug

• High-level language statements are written in English-like words and mathematical symbols, so the students can read the quiz game code and understand what each line does.
• The language is easier to learn than a low-level language, so students who are new to programming can start writing the quiz game quickly.
• Errors are easier to find and fix because the code is readable; for example, the students can check a line that updates a score against the rule they intended.
• The students do not need to know how the processor carries out each statement, so they can concentrate on the quiz questions and rules.

Data structures

• High-level languages provide lists or arrays, so the names and scores of all the players can be stored under one name and processed with a loop.
• A record can store a player's name and score as one item; in some languages a dictionary or class can be used instead, which keeps related data together.
• Using a data structure makes the code shorter and easier to understand than separate variables for every player's name and score.

Built-in functions and library routines

• High-level languages provide built-in functions such as print and input, so the students can display a question and read a player's answer without writing the underlying code.
• Library routines such as a random number generator can be used to choose quiz questions, saving the students time.
• String-handling routines can check or compare a player's answer, so the students do not have to write these routines themselves.
• Reusing tested routines reduces the amount of code the students write and can reduce errors in the quiz game.

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)

Additional guidance: Credit only points applied to the quiz game and the students; comparison with low-level languages is not required, but a correct contrast may support a point if it is applied. Do not award generic claims such as 'high-level programs run faster', 'work on any computer' or 'students do not need to learn syntax' unless they are justified for the quiz game.

Level 3 responses must cover all three bullet areas with linked reasoning that explains why the characteristic helps the students finish the game quickly with few errors; an answer covering only two bullet areas is limited to Level 2. Do not award the idea that high-level code is already machine code or is understood directly by the processor. Accept dictionaries or classes as equivalents of records.