Edexcel GCSE Computer Science (1CP2) Exam Questions

• D Time slice (1)
• The only correct answer is D. The correct answer is time slice.
• A is not correct because a process is a program that is being run
• B is not correct because round robin is a scheduling method that takes turns, not the period of CPU time itself
• C is not correct because a scheduler decides which process runs next

• C WAN (1)
• The only correct answer is C. The correct answer is WAN, which connects networks over a large geographical area.
• A is not correct because a LAN covers a limited area such as one building or site
• B is not correct because a PAN connects devices around one person
• D is not correct because a WLAN is a LAN that uses wireless connections and is still local

• D Replacement cycle (1)
• The only correct answer is D. The correct answer is replacement cycle.
• A is not correct because disposal is getting rid of devices at the end of their life
• B is not correct because energy consumption is the amount of energy devices use
• C is not correct because manufacture is making devices

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

• A higher sample rate means more samples are taken each second (1) so more binary values are stored to represent the sound (1)
• A higher sample rate records the wave more frequently (1) so the binary representation follows the shape of the analogue wave more closely/is more accurate (1)
• A lower sample rate records fewer samples (1) so the binary representation is less detailed/less accurate (1)

A statement about the effect of sample rate on sampling (e.g. more/fewer samples) without a link to the binary representation scores a maximum of one mark.

A definition of sample rate on its own, with no effect on sampling, scores no marks.

Accept 'more accurate' for the second mark only when linked to more samples or binary values being stored, for example by 'so', 'which means' or 'because'.

Do not accept responses that describe sample interval or bit depth instead of sample rate.

Do not accept 'a higher sample rate means more bits per sample' or 'higher resolution', as these describe bit depth.

Do not accept a larger file size unless it is linked to more samples/binary values being stored.

For both marks, the expansion must follow/associate with the statement.

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

• The door stays locked until the correct PIN/code is entered (1) so people without the code cannot get into the server room (1)
• The PIN/code is given only to authorised staff (1) so other people cannot reach the servers (1)
• The code can be changed when staff leave (1) so former staff cannot get physical access to the servers (1)
• Too many wrong codes make the keypad lock/stop accepting codes (1) so the code cannot be guessed by someone trying (1)

Do not accept responses that say the keypad stops hackers from logging on to the network without describing physical access.

Do not accept 'stops theft' or 'stops damage' unless it is linked to preventing unauthorised access to the room/servers.

Do not accept 'it keeps the room safe' without saying how access is controlled.

Do not accept responses about firewalls or anti-malware.

Do not accept passwords used to log on to the network.

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

• The instructions/program instructions and data are stored together in main memory/RAM (1) so the CPU can fetch each instruction (from its address) and execute it (1)
• The instructions/program instructions are held in main memory/RAM (1) rather than being built into/part of the hardware, so the computer does not need to be rewired/rebuilt to run a different program (1)
• The next instruction to be executed/instruction is held in main memory/RAM (1) so the CPU can fetch it using its address before it is decoded and executed (1)

For both marks, the expansion must follow/associate with the statement.

A point/statement on its own can only earn one mark.

Do not accept a response that only refers to data being stored in main memory/RAM without referring to the instructions/program instructions.

Do not accept instructions/programs being stored on the hard disk/backing store.

Do not accept 'the program is stored in memory' without saying that it is the instructions/program instructions that are stored there.

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

• The programmer can control/manipulate the hardware directly (1) because low-level instructions can access registers/memory addresses/hardware features (1)
• The code can be made to work efficiently with a specific device (1) because low-level languages are processor/chipset specific, so the instructions match that hardware (1)
• The code produced is fast to execute (1) because it is optimised for the specific processor/uses few instructions (1)
• The code produced is small (1) so it fits in the limited memory/ROM available in the device (1)

For both marks, the expansion must follow/associate with the statement.

Fast execution and small code size are typical advantages of low-level languages; award them only where the linked reason relates to the device.

Do not accept 'it is easier to write/learn/understand' or 'it is faster to write' as a point or as the expansion, because low-level languages are not easier for these.

Do not accept 'it is close to the hardware' or 'it works with hardware' without expansion of what that allows the program to do.

Do not accept 'because it is low-level' as the expansion; the answer must say what the language/hardware allows.

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

• The training data may not represent all customers (1) because it contains more examples of one type of customer than another, so the system favours that type of customer (1)
• The system learns from the bank's past decisions (1) which may reflect past discrimination against some groups of customers (1)
• The people who build the system may pass on their own prejudice (1) because they choose the training data/rules the system learns from, which can unfairly treat some customers (1)

For both marks, the expansion must follow/associate with the statement and must say how the decisions are biased/unfair (e.g. some customers are more likely to be refused a loan).

A statement about the training data on its own earns 1 mark only.

Accept 'past decisions were unfair/discriminatory' as the expansion for the past-decisions point.

Do not accept 'the system/algorithm is biased' without a reason why.

Do not accept 'the training data is too small' or 'the system uses too much data' unless it is linked to how this leads to biased/unfair decisions.

Do not accept answers that only say the system is inaccurate/makes mistakes, as this is not the same as being biased.

Award one mark for each correct digit in the correct position:

• E (1)
• 4 (1)

Answer: E4

Indicative content

Secondary storage

• Compressed lesson videos take up less space on the school's file server, so more recordings can be stored.
• The cloud backup service has a fixed amount of storage, so compressing the files means more of them can be backed up within it.
• Video files are very large, so without compression a much bigger hard disk would be needed to keep them all.

Sending data over a network

• A compressed video is split into fewer packets, so it takes less time for a student to download it at home.
• Less data is transferred, so the school's internet connection is not used up as quickly and other users are not slowed down.
• A smaller file can be sent as an email attachment, where there is a limit on the size of an attachment.
• Compressed video can be streamed, because the data can be sent as fast as it is played, which reduces buffering.

Drawbacks of compressing the files

• The file has to be compressed before it is stored and decompressed before it is played, which takes time and processing power.
• Lossy compression permanently removes data, so the quality of the lesson recording is reduced and it cannot be restored exactly.
• Lossless compression keeps all of the data, but it does not make the files as small as lossy compression does.

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 secondary storage and sending data over a network.

Do not accept the idea that compression makes the files more secure.