Edexcel GCSE Computer Science (1CP2) exam questions

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5 questions · 17 marks

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1Multiple choice1 markSecondary Memory Swap Remove

A company stores films on optical media.

Identify the optical storage medium that can store the most data.

[1 mark]

ABlu-ray Disc
BCD
CDVD
DMagnetic tape

Mark scheme

A Blu-ray Disc (1)
The only correct answer is A. The correct answer is Blu-ray Disc.
B is not correct because a CD stores less data than a Blu-ray Disc, up to about 700 MB
C is not correct because a DVD stores less data than a Blu-ray Disc, up to about 4.7 GB (single-layer) or 8.4 GB (dual-layer)
D is not correct because magnetic tape is not an optical storage medium

Example answers and how they were marked

Full marks1/1

A Blu-ray Disc

Why: Correct option (1): a Blu-ray Disc has the greatest capacity of the optical media.

No marks0/1

C DVD

Why: Near miss scoring 0: a DVD is optical but stores less than a Blu-ray Disc (mark scheme line C). Only A is credited.

No marks0/1

D Magnetic tape

Why: Misconception scoring 0: candidates pick tape for its large capacity but magnetic tape is not an optical storage medium (mark scheme line D).

2Describe2 marksStored Program Computers Swap Remove

The CPU contains an arithmetic logic unit (ALU).

Describe the purpose of the arithmetic logic unit (ALU).

[2 marks]

Mark scheme

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

Carries out arithmetic operations/calculations, such as addition or subtraction (1) so that the result can be stored in a register (1)
Carries out logical operations, such as comparing two data items (1) to see which one is greater/larger (1)
Compares two data items (1) to decide whether a condition is true / which path a program takes next (1)

Allow the result of an arithmetic or logical operation being held/stored in a register, but only where the operation is named.

Do not accept answers that say the ALU stores data or results without naming an operation (registers/main memory store data).

Do not accept answers about controlling components, decoding instructions or timing (that is the control unit or the clock).

Do not award credit for 'it processes data' on its own; an arithmetic or a logical operation must be named.

An example on its own, e.g. 'it adds two numbers', does not earn a second mark; the second mark needs a linked development.

Example answers and how they were marked

Full marks2/2

The ALU carries out arithmetic operations such as addition and subtraction (1), and the result of the calculation is stored in a register (1).

Why: Linked point (1) for arithmetic operations with an example, and development (1) for the result being stored in a register.

Some marks1/2

It does all the calculations in the CPU, for example adding two numbers together.

Why: Point (1) for arithmetic operations/calculations named with an example; no linked development, so the second mark is not earned.

No marks0/2

It stores the results of calculations so that they can be used by the CPU later.

Why: Storing results with no arithmetic or logical operation named, which the 'Do not accept' line rules out, so no mark is earned.

3Describe2 marksStored Program Computers Swap Remove

A computer is based on the von Neumann stored program concept.

Describe how the CPU uses main memory (RAM) during the fetch-decode-execute cycle.

[2 marks]

Mark scheme

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

The program's instructions (and the data it uses) are held in main memory/RAM (1) so the CPU fetches both the instructions and the data from that one memory (1)
The CPU fetches the next instruction from main memory/RAM (1) using the address of the memory location that holds it (1)
The CPU reads/fetches data from main memory/RAM (1) when an instruction needs it and writes the result back to main memory/RAM (1)
The program's instructions are held in main memory/RAM while the program runs (1) and the CPU fetches them one at a time/one after another to be decoded and executed (1)

Allow 'memory' for main memory/RAM.

Allow 'gets' for fetches/reads.

For both marks, the development must say what the CPU does with the contents of main memory (fetches/reads/writes), not just that main memory is used.

Do not accept answers about the program being stored in secondary storage, such as on a hard drive, or about it being loaded from there.

Do not accept benefits such as the computer running faster or being easier for the user.

Do not accept naming CPU components (control unit, arithmetic logic unit, registers) or buses on their own, without saying what is stored or fetched.

Do not accept 'the computer stores data' on its own, without a link to the instructions of a program.

Example answers and how they were marked

Full marks2/2

The program's instructions and the data it uses are both held in the same main memory (RAM) (1), so the CPU can fetch the instructions and the data it needs from that one memory (1).

Why: Linked point (1) that instructions and data are stored together in main memory, with the development (1) that the CPU fetches both from the same memory.

Some marks1/2

The CPU fetches the instructions from main memory (1) so that they are processed more quickly (1).

Why: The first point earns (1) for the CPU fetching instructions from main memory. The second statement is a benefit (speed), which the 'Do not accept benefits' line rules out, so it earns nothing.

No marks0/2

The control unit decodes each instruction (1) and the ALU carries out the calculations (1).

Why: Both statements name CPU components without saying what is stored, fetched or written, which the mark scheme tells examiners not to accept, so neither earns a mark.

4Discuss6 marksFetch Decode Execute Cycle Swap Remove

A small robotics company is designing a new robot. The robot's computer uses von Neumann architecture. The engineers are explaining how programs are stored and run.

Discuss how the von Neumann stored program concept and main memory (RAM) are used during the fetch-decode-execute cycle.

Your answer should include:

what is meant by the stored program concept
the role of RAM in the cycle
why the stored program concept is useful.

[6 marks]

Mark scheme

Indicative content

Stored program concept

Instructions and data are stored together in the same main memory (RAM).
Instructions are fetched one at a time from memory and executed in sequence.
The program can be changed by loading different instructions into RAM.
The CPU can only execute instructions that are in main memory.

Role of RAM

RAM holds the program instructions and the data being used.
The address of the next instruction is held in the program counter (PC).
The instruction is fetched from RAM using the address bus.
The data bus carries the instruction from RAM to the CPU.
RAM is volatile, so programs are lost when power is off.
RAM is directly accessible by the CPU, unlike secondary storage.

Benefits

The same hardware can run many different programs.
Programs can be loaded and changed quickly.
No need to rewire the computer for a new task.
Makes general-purpose computers possible.

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)

Example answers and how they were marked

Full marks6/6

The von Neumann stored program concept means that both the program instructions and the data are stored together in the same main memory, RAM. During the fetch-decode-execute cycle, the CPU fetches an instruction from RAM, decodes it in the control unit, and then executes it. The program counter holds the address of the next instruction, and this address is sent along the address bus to RAM. RAM then returns the instruction along the data bus to the CPU. RAM is volatile, so it only holds the program while the robot is powered on. The stored program concept is useful because the robot's computer can run different programs without changing any hardware; new instructions can simply be loaded into RAM. This makes the computer general-purpose and flexible.

Why: Comprehensive understanding: defines stored program concept, explains RAM role with PC, address bus and data bus, applies to robot, and gives benefits. Sustained lines of reasoning. Level 3.

Some marks3/6

The stored program concept is when instructions and data are stored in RAM. The CPU fetches instructions from RAM. The program counter keeps the address of the next instruction. RAM holds the program. The benefit is that you can change the program without rewiring the computer.

Why: Adequate understanding: correct basic points about stored program concept and RAM, with some linkage, but little development or application to the robot's fetch-decode-execute cycle. Level 2.

Some marks1/6

The von Neumann stored program concept is that the CPU uses RAM to store the program. The fetch-decode-execute cycle fetches, decodes and executes. RAM is random access memory. The benefit is that it is fast.

Why: Basic independent points only; no real linkage or application to the robot. Level 1.

5Discuss6 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

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