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:

• Keeps a record/index of where each file is stored on the disk (1) so the file can be found and opened later (1)
• Allocates space on the disk for each file (1) so files are stored without overwriting each other (1)
• Provides facilities to name file(s) and organise them into folder(s)/directories (1) so the user can find and manage their files (1)

Do not accept responses about process management, peripheral management or user management.

Do not accept bare statements of storing/saving, e.g. 'it stores files', 'it saves files' or 'it keeps files safe', with no development.

Do not award a mark for responses that repeat the question, e.g. 'it manages files', with no development.

Indicative content

How malware could affect the charity's computers

• A virus could damage or delete the charity's files, such as its records of donations.
• Spyware could record keystrokes and send staff passwords or personal data to a hacker.
• A Trojan horse could hide malicious code inside a useful-looking program that a volunteer downloads, so it is installed without the user knowing.
• Malware could spread from one laptop to another through files shared on the charity's network, so more laptops become infected and more files are lost.

How anti-malware software finds and deals with malware

• It scans files and compares their code with a database of known malware patterns (signatures) to identify a match.
• It can apply rules (heuristics) to decide whether a program is behaving suspiciously.
• A suspicious file can be run in a sandbox to see whether its behaviour is malicious.
• When malware is found, the file is quarantined so that it cannot run, and it can be deleted.
• Downloads and email attachments can be scanned before a member of staff opens them.

What else the charity must do for the anti-malware software to be effective

• The database of malware definitions must be kept up to date, or new malware will not be recognised.
• Staff and volunteers should be trained not to open unexpected attachments or download from unreliable sites.
• Backups are still needed, because anti-malware cannot repair files that malware has already damaged.
• Scheduled scans must be allowed to run on all 15 laptops, so that malware is found even if no one opens the file.

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 malware could affect the computers and how anti-malware software finds or deals with it; a brief deal-with point and an unexplained update point, with no identification method and no effect on the charity's files, are Level 1.

Do not accept anti-malware software described as a firewall, or 'scans files'/'finds viruses' on its own as a method of identifying malware.

Indicative content

Machine independence

• A high-level language is machine independent, so the same source code can be run on different types of computer with few or no changes.
• The company can write the program once and sell it to users with different computers, without rewriting the code for each type of computer.
• Only one version of the program needs to be written and maintained, so development takes the company less time.

Processor specificity

• A low-level language is processor-specific, so a program written for one processor will not run on a different processor without being rewritten.
• Assembly language instructions depend on the instruction set of the particular processor, so the company would need a separate version of the program for each type of computer.
• Writing a separate low-level version for every type of computer would take the company much longer than writing one high-level program.
• Low-level code gives direct control of the hardware of one processor, so it is better suited to device drivers than to a program that must run on many different computers.

Translation

• High-level source code is translated for each type of computer by a compiler or an interpreter, so one version of the source code is enough for all the users.
• Assembly language is translated into machine code by an assembler, and the assembler produces machine code for one specific processor only.
• Machine code is already in a form that one particular processor can execute directly, but the same machine code will not run on a different processor.
• Each high-level statement translates into several machine code instructions, so the programmer does not need to know the instruction set of the processor.

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

• Level 3 responses must cover both high-level machine independence and low-level processor specificity, with the effect on the company's decision.
• Do not award low-level language, assembly language or machine code as portable, or 'high-level languages are written in English/like English' as a reason for machine independence.