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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.

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5 questions · 19 marks

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1Short 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.

2Explain2 marksProtocols & Layers Swap Remove

A bank's website can use HTTP or HTTPS.

Explain one benefit to a customer of the bank's website using HTTPS.

[2 marks]
Mark scheme

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

  • Data is encrypted/scrambled (1) so it cannot be read/understood if it is intercepted (1)
  • The customer's bank/personal details are kept secure/private (1) because the data is encrypted/scrambled during transmission (1)
  • The customer's login details/password cannot be read by an eavesdropper (1) because HTTPS encrypts/scrambles the data sent to and from the web server (1)

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

Allow 'scrambled' as an alternative to 'encrypted'.

Do not accept 'it is more secure/safe' or 'the data is secure' on its own, without saying how it is made secure (e.g. encryption/scrambling).

Do not accept faster loading/speed, or claims that HTTPS stops viruses or always proves the website is genuine.

Example answers and how they were marked
Full marks2/2

The data is encrypted (1) so anyone intercepting it cannot read the customer's bank details (1).

Why: Linked point (1) and reason (1): encryption means intercepted data cannot be read.

Some marks1/2

The data is encrypted (1) so the website is secure.

Why: Point (1) for encryption, but 'secure' on its own is a near-miss that the mark scheme does not credit as the linked reason; it must say why, e.g. that intercepted data cannot be read.

No marks0/2

HTTPS is faster than HTTP (0) so the customer can log in more quickly.

Why: Speed is not a benefit of HTTPS and is named in a 'Do not accept' line, so no creditworthy point is given.

3Calculate3 marksAdding Binary Numbers Swap Remove

Binary patterns can represent numbers.

(a)

Complete the table to show the 8-bit result of the binary addition.

[2 marks]
1286432168421
11011011
11011100
Mark scheme

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

  • 1011 (1)
  • 0111 (1)

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

Ignore a carry shown beyond the eighth bit.

Example answers and how they were marked
Full marks2/2

1011 0111

Why: 219 + 220 = 439, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0000 0111

Why: Forgets to carry the 1s. The second nibble is correct (1); the first is not.

No marks0/2

1101 1111

Why: Never carries. Neither nibble is correct.

(b)

State the name of the error that occurs when this addition is carried out.

[1 mark]
Mark scheme

Award one mark for:

  • overflow (error) (1)
Example answers and how they were marked
Full marks1/1

Overflow

Why: The result needs more bits than are available (1).

No marks0/1

Underflow

Why: A near miss: the result is too big for 8 bits, not too small.

No marks0/1

A syntax error

Why: A syntax error is a mistake in a program's code, not in arithmetic.

4Discuss6 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.

5Discuss6 marksLow and High Level Languages Swap Remove

A school computing club is creating a quiz game. The game will be written by students who are new to programming. It will store the names and scores of players in a list. The club wants to choose a language that helps the students finish the game quickly and with few errors.

Discuss the characteristics of a high-level programming language that make it suitable for writing the quiz game.

Your answer should include:

  • how easy the language is to learn, use and debug
  • the data structures it provides for storing the players' names and scores
  • the built-in functions and library routines it provides.
[6 marks]
Mark scheme

Indicative content

Ease of learning, use and debug

  • High-level language statements are written in English-like words and mathematical symbols, so the students can read the quiz game code and understand what each line does.
  • The language is easier to learn than a low-level language, so students who are new to programming can start writing the quiz game quickly.
  • Errors are easier to find and fix because the code is readable; for example, the students can check a line that updates a score against the rule they intended.
  • The students do not need to know how the processor carries out each statement, so they can concentrate on the quiz questions and rules.

Data structures

  • High-level languages provide lists or arrays, so the names and scores of all the players can be stored under one name and processed with a loop.
  • A record can store a player's name and score as one item; in some languages a dictionary or class can be used instead, which keeps related data together.
  • Using a data structure makes the code shorter and easier to understand than separate variables for every player's name and score.

Built-in functions and library routines

  • High-level languages provide built-in functions such as print and input, so the students can display a question and read a player's answer without writing the underlying code.
  • Library routines such as a random number generator can be used to choose quiz questions, saving the students time.
  • String-handling routines can check or compare a player's answer, so the students do not have to write these routines themselves.
  • Reusing tested routines reduces the amount of code the students write and can reduce errors in the quiz game.

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: Credit only points applied to the quiz game and the students; comparison with low-level languages is not required, but a correct contrast may support a point if it is applied. Do not award generic claims such as 'high-level programs run faster', 'work on any computer' or 'students do not need to learn syntax' unless they are justified for the quiz game.

Level 3 responses must cover all three bullet areas with linked reasoning that explains why the characteristic helps the students finish the game quickly with few errors; an answer covering only two bullet areas is limited to Level 2. Do not award the idea that high-level code is already machine code or is understood directly by the processor. Accept dictionaries or classes as equivalents of records.

Example answers and how they were marked
Full marks6/6

A high-level language is suitable for the quiz game because its statements use English-like words and mathematical symbols, so students who are new to programming can read the code and see what each part of the quiz does. This also makes the game easier to debug, because the students can compare a line that updates a player's score with the rule they intended. The language gives the students lists or arrays, so all the players' names and scores can be stored under one name, and a loop can then go through the list to display the results. A record, or a dictionary in Python, can keep one player's name and score together, which is clearer than using separate variables. The language also provides built-in functions and library routines such as input, print and a random number generator, so the students do not have to write these from scratch. They can use input to ask for a player's name and print to show the score, and a random number routine to choose a question. This lets the club spend its time on the quiz questions and rules, so the students can finish the game quickly with fewer errors.

Why: Covers all three bullet areas with linked reasoning: readable English-like statements and debugging, lists/records for names and scores, and built-in input/print/random routines, all applied to helping new students finish quickly with fewer errors. This meets Level 3.

Some marks3/6

High-level languages use English words, so the students can understand the code for the quiz game and find mistakes more easily. They provide lists or arrays, so the players' names and scores can be stored together, and a loop can be used to display the scores. This makes the game easier to write for students who are new to programming.

Why: Level 2, 3 marks: covers ease of learning/use and data structures with some application to the quiz game, but gives no built-in facilities and limited development of why this helps the club finish quickly, so it is not Level 3.

No marks0/6

High-level code is already machine code, so the computer can run the quiz game without a translator. The students do not need to learn any syntax.

Why: Contains the machine-code misconception and a generic claim that the scheme does not credit; no creditworthy point is made, so Level 0.

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