Edexcel GCSE Computer Science (1CP2) exam questions

Build a practice paper from 514 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

Practice paper

6 questions · 19 marks

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1Short recall1 markSecondary Memory Swap Remove

Data is stored on optical discs as pits and lands.

Name the component in an optical disc drive that reads this data.

[1 mark]

Mark scheme

Award one mark for:

Laser (1)

Allow laser beam

Do not accept read/write head

Do not accept pits

Do not accept lands

Do not accept reflective surface

Do not accept magnet/magnetic

Example answers and how they were marked

Full marks1/1

Laser

Why: Laser is the creditworthy answer (1).

No marks0/1

A read/write head

Why: Read/write head is not accepted by the mark scheme; it reads magnetic media, not optical discs, so no marks are awarded.

No marks0/1

Pits and lands

Why: Pits and lands are what the laser reads, not the component that reads the data, so the mark scheme does not accept them.

2Short recall2 marksUnits & Conversion Swap Remove

Data storage is measured in binary multiples.

Define the term bit.

[2 marks]

Mark scheme

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

A binary digit (1)
Has the value 0 or 1 (1)
The smallest unit of data storage (1)
A single 0 or 1 (1)

Allow binary digit/binary place value for binary digit

Allow a single binary digit for a single 0 or 1

Do not accept a group of 8 bits/half a nibble of 4 bits, which describe a byte or a nibble

Do not accept a binary number/binary on its own

Example answers and how they were marked

Full marks2/2

A binary digit that can have the value 0 or 1.

Why: A binary digit (1) and has the value 0 or 1 (1).

Some marks1/2

It is the smallest unit of data storage.

Why: Smallest unit of data storage (1), but does not state that it is a binary digit or that it has the value 0 or 1.

No marks0/2

A group of 8 bits.

Why: Describes a byte, not a bit; no creditworthy point and named in the Do not accept line.

3Explain2 marksPacket Switching Swap Remove

A file is sent across the internet in packets.

Explain why packets from the same file may take different routes.

[2 marks]

Mark scheme

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

Each router chooses the best route at the time (1) so when a route becomes busy/congested or fails, later packets are forwarded along a different path (1)
Routers forward each packet separately (1) so the path a packet takes depends on the traffic conditions when that packet arrives (1)
A router may send a packet to a different next router (1) if its routing table shows a better/less congested route for that packet (1)
Traffic on the internet changes (1) so no single path is kept for the file and each packet can use whichever route is best when it is sent (1)

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

Allow reference to a routing table, or to how a router decides the route, as part of the linked reason.

Do not accept 'the packets have different IP addresses' because all packets from the same file have the same destination IP address, even though their routes can differ.

Do not accept 'the internet is busy' or 'there is a lot of traffic' on its own without linking this to the router choosing a different route.

Do not accept 'different routers send the packets' on its own without a reason why a different router/route is chosen.

Do not accept an answer that only says the packets take different routes without explaining why.

Example answers and how they were marked

Full marks2/2

Each router chooses the best route at the time, so if one route becomes busy or fails, later packets are sent a different way.

Why: Linked point (1) that each router chooses the best route at the time and reason (1) that a busy or failed route means later packets take a different path.

Some marks1/2

Routers send packets along the least congested route.

Why: States that a router chooses the least congested route (1) but gives no linked reason why this makes the packets from the file take different routes.

No marks0/2

Because each packet is given a different IP address so they go to different places.

Why: Misconception named in the mark scheme: all packets from the same file share the same destination IP address, even though their routes can differ.

4Calculate2 marksBinary Shifts Swap Remove

Computers manipulate binary patterns.

Complete the table with the result of applying the shift to the binary pattern.

[2 marks]

Binary pattern	Shift	8-bit binary result
1000 0001	Logical shift right by 1

Mark scheme

Award one mark for each correct nibble in the correct order:

0100 (1)
0000 (1)

0 marks if the response is not 8-bit binary.

Example answers and how they were marked

Full marks2/2

0100 0000

Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).

Some marks1/2

0100 0001

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

0000 0010

Why: Shifts the bits the wrong way. Neither nibble is correct.

5Discuss6 marksPurpose & Function of Operating Systems Swap Remove

A home computer is used to stream music, edit a video and download files at the same time.

Discuss how the operating system manages the processes running on the computer.

Your answer should include:

how the CPU is shared between processes
the states a process can be in
how the operating system responds when a process needs attention

[6 marks]

Mark scheme

Indicative content

How the CPU is shared between processes

The operating system uses multitasking to give each process a short time slice on the CPU, so the music, video editor and download appear to run at the same time.
The operating system decides which ready process will run next, so one program cannot keep the CPU to itself.
The operating system can stop a running process and move it back to ready when its time slice ends, so all processes make progress.

The states a process can be in

When a program is opened, the operating system creates a process and moves its instructions into RAM so it is ready.
The operating system moves a ready process to running when the CPU is free.
A running process becomes blocked when it is waiting for input or data, such as the download waiting for data to arrive.
When the process finishes, the operating system terminates it and releases the resources it was using.

How the operating system responds when a process needs attention

An interrupt is a signal to the CPU that needs immediate attention, so the operating system suspends the current process and runs the interrupt handler.
A hardware interrupt could be a printer out of paper, and a software interrupt could be an error in a program.
After the interrupt has been handled, the operating system can return the interrupted process to the CPU.

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 at least two of scheduling, process states and interrupts.
A response that only states that the OS 'manages processes' or gives a program a turn, without expansion, is limited to Level 1.

Example answers and how they were marked

Full marks6/6

The OS uses multitasking to share the CPU. It gives each process, such as the music player and the video editor, a small time slice so they appear to run at the same time. It decides which ready process is next and how long it runs. When the video editor is opened, the OS creates a process and moves its instructions into RAM so it is ready; when the CPU is free it moves it to running. If the download is waiting for data, the OS marks it blocked so the CPU is not wasted. If the printer runs out of paper, a hardware interrupt tells the CPU to stop and run the interrupt handler; afterwards the OS returns to the process.

Why: Covers scheduling with time slices, process states (ready, running, blocked) and interrupts, with sustained application to the music, video editor and download. Level 3.

Some marks4/6

The operating system uses multitasking so the music and video editor can run at the same time. It gives each program a small amount of time on the CPU. When a program is opened it creates a process and puts it in RAM. If a process is waiting for input it is blocked.

Why: Covers CPU sharing and process states, with some application, but says nothing about interrupts. Level 2.

Some marks1/6

The operating system manages processes by giving each program a turn on the CPU. This stops the computer crashing when too many programs are open.

Why: Gives only a basic, undeveloped point about giving each program a turn, with no linkage or application. Level 1.

6Discuss6 marksTranslators Swap Remove

A company writes a photo editing program in a high-level language. The company will sell the finished program to customers. Each customer will install the program on their own computer and run it many times.

Discuss whether the company should use a compiler or an interpreter to translate the program before it is sold.

Your answer should include:

the output of each type of translator
whether the program has to be translated each time it is run
what the customer needs on their computer to run the program.

[6 marks]

Mark scheme

Indicative content

The output of each type of translator

A compiler translates the whole program in one go and produces object code.
The object code is saved as an executable file, which is already in machine code so the processor can run it directly.
An interpreter does not produce object code, so no translated file exists for the company to save and sell.
An interpreter translates one line at a time and executes it immediately, but that translation is not kept.

Whether the program has to be translated each time it is run

Compiled code is translated once, so the executable can be run as many times as the customer likes without being translated again.
If the source code is edited, the whole program has to be compiled again to produce a new executable.
An interpreted program is translated again every time it is run, so a customer who runs the program often waits for translation at every run.
An executable runs faster than interpreted code because it is already in machine code.

What the customer needs on their computer to run the program

A customer who installs the executable needs no compiler on their computer, so the program will run straight away.
If the company supplied the source code instead, the customer would need an interpreter installed, and it would have to be an interpreter for their type of computer.
A customer given only the executable does not have the source code, so cannot change the program.

Conclusion

A compiler is the better choice for this company, because the executable can be sold and the customer runs it without it being translated again and without being given the source code.
Using an interpreter would mean supplying the source code to customers and translating the program on every run.

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 all three bullets for this company's program, including translating once rather than on every run, and reach a conclusion.

Do not accept 'a compiler fixes errors' (a compiler reports syntax errors at the end of translation, it does not fix them) or 'a compiler is easier to use' with no link to output, translation or the customer. Do not accept answers about translating to assembly language.

Example answers and how they were marked

Full marks6/6

The company should use a compiler. A compiler translates the whole program in one go and produces object code, which is saved as an executable file. This executable is already in machine code, so the customer's processor can run it directly. The program is translated only once, so a customer who runs the program many times does not wait for it to be translated again, and it runs faster than interpreted code would. An interpreter produces no object code, so the company would have nothing to sell as an executable. The customer would have to be given the source code and would need an interpreter installed on their computer, and the program would be translated again every time it was run.

Why: Level 3. Covers the output of both translators (executable from the compiler, no object code from the interpreter), the effect of translating once rather than on every run, and what the customer needs on their computer, all applied to the company selling the program, with a clear conclusion.

Some marks3/6

A compiler produces an executable file, which the company can save and sell to its customers. An interpreter does not produce an executable file, so the customer would need the source code and an interpreter installed on their computer to run the program. This means a compiler is better for the company, because customers can just run the file they are given.

Why: Level 2. Gives the output of both translators and links this to what the customer needs, with a conclusion, but never says the compiled program is translated once while an interpreted one is translated on every run, so the reasoning is not developed enough for Level 3.

No marks0/6

The company should use a compiler because it is easier to write programs with a compiler and it fixes the errors in the program before the customers get it.

Why: Level 0. No creditworthy point: 'easier to write programs' is not linked to the output, the translation each run or the customer, and 'fixes the errors' is a misconception, as the mark scheme's guidance says a compiler only reports errors at the end of translation.

Edexcel GCSE Computer Science (1CP2) Exam Questions

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Questions by topic

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

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