Edexcel GCSE Computer Science (1CP2) exam questions

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4 questions · 16 marks

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1Describe2 marksSecondary Memory Swap Remove

A laptop uses a solid state drive (SSD) for secondary storage.

Describe how data is stored on a solid state drive.

[2 marks]

Mark scheme

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

Data is stored on (flash) memory chips/cells (1) as a pattern of electrical charges (1)
A current/voltage forces electrons through a barrier (1) so that they are trapped (or not trapped) to hold/represent a value (1)
Cells with a trapped charge and cells with no trapped charge (1) represent 1s and 0s/binary (1)
The trapped charge remains when the power is turned off (1) so the data is not lost/it is non-volatile (1)

Do not accept responses that describe magnetic storage, e.g. magnetised platters, spinning disks or read/write heads, or optical storage, e.g. lasers, pits and lands.

Do not award a mark for 'it is solid state' or 'it has no moving parts' without a description of how the data is stored.

Do not award a mark for restating the stem, e.g. 'a laptop uses an SSD' or 'an SSD uses flash memory'.

'Data is stored as electrical charges' on its own, with no reference to memory chips/cells or to how the charge is held, earns a maximum of one mark (1).

A response that only describes electrons being trapped, with no link to how the value/data is represented, earns one mark (1). The second mark needs a link such as trapped and not trapped charge representing 1s and 0s, or the trapped charge being kept so the data is not lost.

Example answers and how they were marked

Full marks2/2

A current is used to force electrons through a barrier so that they become trapped, and a cell with a trapped charge or a cell with no trapped charge represents a 1 or a 0.

Why: Linked description: a current forces electrons through a barrier (1) and trapped/not trapped charge represents 1s and 0s (1).

Some marks1/2

The data is stored in flash memory chips.

Why: Gives the creditworthy point that data is stored on flash memory chips (1) but does not develop it, e.g. by saying the data is held as electrical charges or by describing trapped electrons.

No marks0/2

The data is stored as magnetised areas on a spinning platter.

Why: This describes magnetic storage, which the mark scheme says not to accept for a solid state drive.

2Describe2 marksStored Program Computers Swap Remove

The control unit (CU) is a component inside the CPU.

Describe the role of the control unit in the fetch-decode-execute cycle.

[2 marks]

Mark scheme

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

Decodes each (fetched) instruction (1) to work out which operation is needed / which components should carry it out (1)
Coordinates/directs the other components (1) by sending control signals along the control bus (1)
Fetches the next instruction (1) by sending its address to main memory along the address bus (1)
Sends a read/write control signal to main memory (1) so that the instruction or data is transferred during the fetch/execute stage (1)

Do not accept answers about synchronising the CPU or timing the cycles (that is the role of the clock).

Do not accept answers about carrying out arithmetic or logical operations (that is the ALU).

Do not accept answers about holding data or the results of instructions (that is registers/main memory).

Do not accept generic answers that only say the CU controls the CPU or processes instructions, with no linked development.

Only award one mark for a response that only repeats that the CU sends control signals; the second mark needs a linked outcome such as coordination, a memory read/write, or fetching an instruction.

Do not accept 'during the decode stage' as the development for the decoding point, as it restates the question.

Example answers and how they were marked

Full marks2/2

It decodes the instruction that has been fetched so that it knows which operation the CPU must carry out and which components should do it.

Why: Decoding named with the acceptable wording 'each (fetched) instruction' (1), plus the linked development that this identifies the operation and components (1).

Some marks1/2

It decodes each instruction during the decode stage of the cycle.

Why: Earns (1) for decoding the instruction. 'During the decode stage' restates the question and is not accepted as a development, so the second mark is not earned.

No marks0/2

It carries out the calculations and comparisons when the instruction is executed.

Why: Calculations and comparisons are the ALU's role, which the 'Do not accept' line rules out, so no mark is earned.

3Discuss6 marksPrimary Memory Swap Remove

A video production company edits films for its clients. The editors use computers to work on 4K video, and they say the computers have become slow. One editor wants to replace the CPU, but a colleague thinks adding more RAM would be better.

Discuss whether adding more RAM will improve the performance of the computers used to edit 4K video. (6)

Your answer should include:

how RAM is used when editing video
why too little RAM causes poor performance
why adding more RAM may not always improve performance.

[6 marks]

Mark scheme

Indicative content

How RAM is used when editing video

The editing software and the video project being worked on are loaded into RAM so that the CPU can access them quickly.
RAM holds the frames, effects and timeline data that the CPU is processing as part of the fetch-decode-execute cycle.
The CPU fetches the instructions and the video data it needs from RAM, which is much faster than fetching them from secondary storage.
Having more RAM means that more of the 4K video project and its effects can be held in memory at the same time.
RAM is also used by the operating system and any other open software, so not all of the RAM is available to the editing software.

Why too little RAM causes poor performance

If there is not enough RAM, the operating system uses virtual memory on secondary storage for data that will not fit in RAM.
Virtual memory is much slower than RAM, so the editor waits longer for 4K video to load and for effects to be applied.
Data has to be swapped between RAM and virtual memory, which is extra work that slows the computer down.
The editing software may freeze or close if it runs out of memory while working on the 4K video.
Playback of the 4K video is not smooth because the frames cannot all be held in RAM ready for the CPU.

Why adding more RAM may not always improve performance

If the computer already has enough RAM for the editing software, the extra RAM will not be used and performance will hardly change.
The clock speed and the number of cores of the CPU decide how quickly instructions are processed, so a slow CPU will still limit how quickly the video is edited.
A slow secondary storage drive will still limit how quickly the 4K video files can be loaded into RAM.
Adding RAM only improves performance if a shortage of RAM was the reason for the computer being slow.

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 explain how RAM is used when editing video and give a developed reason why adding more RAM may not always improve performance; responses that only explain how RAM is used, or only why too little RAM causes poor performance, are limited to Level 2.
Accept 'paging' or 'swap file' as equivalent to virtual memory, but do not accept 'cache' or 'ROM'; do not credit statements that adding RAM increases the CPU clock speed or makes the CPU faster, or that 'RAM is volatile' explains poor performance, as these are not linked to the question asked.

Example answers and how they were marked

Full marks6/6

RAM holds the editing software and the 4K video project that is being worked on, so the CPU can fetch the frames and the effects it needs much faster than from the hard drive. If there is not enough RAM, the operating system has to use virtual memory on secondary storage instead, and this is much slower than RAM, so the editors have to wait for video to load and the playback is not smooth. Adding more RAM can help because more of the 4K project and its effects can be held in memory at once. However, it will not always improve performance. If the computer already has enough RAM the extra memory will not be used, and if the CPU has a low clock speed or too few cores it will still take longer to process each frame. A slow hard drive will also limit how quickly the 4K files can be loaded into RAM, so adding RAM only solves the problem if the computer was short of memory.

Why: Level 3: explains how RAM is used when editing video and applies it to the frames and effects (AO1/AO2), gives a developed reason for poor performance using virtual memory and its slowness, and gives developed reasons why extra RAM may not help, namely a CPU bottleneck (clock speed and cores) and a slow drive, applied to the company's 4K editing.

Some marks2/6

RAM is used to store the video while it is being edited. If you don't have enough RAM, the computer will be slow because it has to use the hard drive instead. Adding more RAM will make the computer faster because it can store more video. The CPU also matters because it does the processing.

Why: Level 1, top end (2 marks). A basic relevant use of RAM, storing the video being edited, and a basic point that the hard drive is used when RAM is short; the extra RAM point is asserted with no reasoning and the single CPU statement is not linked to why adding RAM may not help, so there is little development and the answer does not reach Level 2.

No marks0/6

RAM is the same as the CPU, so adding more RAM makes the CPU faster. The video editor should add more RAM to increase the clock speed. 4K video is slow because RAM is volatile.

Why: No creditworthy content: treating RAM as the CPU and saying adding RAM increases the clock speed are the misconceptions named in the guidance, and 'RAM is volatile' is not linked to performance, so it earns nothing.

4Discuss6 marksEmbedded Systems Swap Remove

A technology company is developing a new fitness tracker. The tracker is worn on the wrist and monitors the wearer's heart rate, the number of steps taken and their sleep. It has a rechargeable battery and a touch screen.

Discuss the use of embedded systems in the fitness tracker.

Your answer should include:

what an embedded system is.
the functions embedded systems perform in the tracker.
why an embedded system is suitable for this device.

[6 marks]

Mark scheme

Indicative content

What an embedded system is

An embedded system is a computer system that forms part of a larger device, such as the fitness tracker.
It performs a single, dedicated or specific task rather than being a general purpose computer.
It is often built around a microcontroller, which contains the processor, RAM and ROM on a single chip.
Its software is held in ROM so the tracker can run its program as soon as it is switched on.

Functions in the tracker

Monitoring the heart rate using a sensor and processing the readings so that they can be displayed on the screen.
Counting steps using an accelerometer and using the count to calculate the distance walked or the calories burned.
Tracking sleep by monitoring the wearer's movement during the night.
Controlling the touch screen so that the user can move between displays.
Managing the battery, for example stopping the charging when the battery is full and saving power when the tracker is idle.
Sending the collected data to a smartphone using Bluetooth so that it can be viewed in an app. Accept any other specific function of the fitness tracker that an embedded system could control.

Why an embedded system is suitable for this device

It has low power consumption, so the battery lasts longer between charges, which matters for a device that is worn all day.
It is small and light, so it can be fitted into a wristband.
Its dedicated function means it does not need a full operating system, so it is reliable and does not need restarting.
The program is small and stored in ROM, so the tracker needs only a small amount of memory.
It can be optimised for its specific tasks, so it responds quickly to the readings from its sensors.
The low cost per unit keeps the tracker affordable for the customer.

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 what an embedded system is, the functions it performs in the tracker and why it is suitable for the tracker.
Do not award installing new software/apps, functions the tracker does not perform (such as playing music) or 'it is like a phone'.

Example answers and how they were marked

Full marks6/6

An embedded system is a computer system that forms part of a larger device and performs a single, dedicated task. In the tracker it is built around a microcontroller, which has the processor, RAM and ROM on one chip, and its program is stored in ROM so it runs as soon as the tracker is switched on. The embedded system monitors the heart rate using a sensor and processes the readings before showing them on the screen. Another function counts the steps using an accelerometer and uses that count to work out the distance walked and the calories burned, and further functions monitor movement at night to track sleep and send the data to a smartphone by Bluetooth. The embedded system also controls the touch screen and manages the battery so that charging stops when it is full and power is saved when the tracker is idle. An embedded system is suitable because it has low power consumption, so the battery lasts longer between charges, which matters for a device that is worn all day and cannot be charged constantly. It is also small and light, so it fits into a wristband, and because it is dedicated to a few tasks it does not need a full operating system, so it is reliable and can be optimised to respond quickly to its sensors. Keeping the cost low also makes the tracker affordable for the customer.

Why: Comprehensive definition including the microcontroller and ROM (AO1), a range of functions each applied to the tracker (heart rate, steps, sleep, Bluetooth, touch screen, battery), and suitability points developed with reasons (low power for a device worn all day, small size for a wristband, dedicated design for reliability and quick response). Sustained lines of reasoning, all three bullets covered: Level 3 (5-6) clearly met.

Some marks2/6

An embedded system is a small computer inside a device. In a fitness tracker it can monitor your heart rate and count your steps. It is suitable because it is small and does not use much power.

Why: Basic independent points only: a basic definition, two functions and one basic suitability point, with no development and almost no application to the tracker (no explanation of why small size or low power matter). Level 1 (1-2 marks), upper end because there are several independent correct points, but no linkage or reasoning for Level 2.

No marks0/6

An embedded system is a computer that you can install apps on. The fitness tracker uses it to play music and send texts. It is suitable because it is like a phone.

Why: The definition is the opposite of an embedded system (it cannot install new software), the functions are ones the tracker does not perform and 'it is like a phone' is not a suitability point. No rewardable content: Level 0 (0 marks).

Edexcel GCSE Computer Science (1CP2) Exam Questions

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2.1 Binary

2.2 Data representation

2.3 Data storage and compression

3.1 Hardware

3.2 Software

3.3 Programming languages

4.1 Networks

4.2 Network security

5.1 Environmental

5.2 Ethical and legal

5.3 Cybersecurity

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