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100+ Free A-Level Computer Science Practice Questions

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Depth-first search (DFS) of a graph is typically implemented using which data structure (whether explicit or implicit via recursion)?

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B
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D
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2026 Statistics

Key Facts: A-Level Computer Science Exam

A*-E

Grading scale

Ofqual

May-June

Exam series

AQA, Edexcel, OCR timetable

3 boards

Specifications available

AQA, Edexcel, OCR

100

Free practice questions here

OpenExamPrep

AQA, Edexcel, OCR A-Level Computer Science is assessed through linear end-of-course exam papers (Year 13). Coverage spans fundamentals of programming, data structures, algorithms, and grading uses the A*-E scale on 2026 specifications.

Sample A-Level Computer Science Practice Questions

Try these sample questions to test your A-Level Computer Science exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In object-oriented programming, which feature allows a subclass to provide a specific implementation of a method already defined in its superclass?
A.Encapsulation
B.Method overriding
C.Method overloading
D.Abstraction
Explanation: Method overriding occurs when a subclass redefines a method inherited from its superclass with the same signature, providing specialised behaviour. This is one of the mechanisms that enables polymorphism in OOP languages such as Java and Python.
2Which OOP principle is most directly violated when a class exposes its instance variables as public and allows external code to modify them freely?
A.Polymorphism
B.Inheritance
C.Encapsulation
D.Composition
Explanation: Encapsulation requires that internal state is hidden behind private fields and accessed only through controlled methods (getters/setters). Public mutable fields break this protection and allow invariants to be violated from outside the class.
3A class Shape has a method area(). Classes Circle and Rectangle both inherit from Shape and define their own area() methods. Calling shape.area() executes the correct version at run-time based on the actual object type. This is an example of which concept?
A.Static binding
B.Dynamic (run-time) polymorphism
C.Operator overloading
D.Multiple inheritance
Explanation: When the specific method invoked is determined at run-time from the object's actual class rather than the reference type, this is dynamic (run-time) polymorphism, typically implemented via virtual method tables. It is a core feature of OOP languages such as Java and C#.
4What is the relationship described when a class Car has-a Engine object as one of its fields?
A.Inheritance
B.Composition (aggregation)
C.Polymorphism
D.Encapsulation
Explanation: A has-a relationship indicates composition (or aggregation): one object contains another as a part. This is contrasted with inheritance, which is an is-a relationship. Composition is generally preferred for code reuse over deep inheritance hierarchies.
5An abstract class in Java contains at least one abstract method. Which statement about abstract classes is correct?
A.Abstract classes can be instantiated directly using the new operator
B.Abstract classes cannot contain any concrete (implemented) methods
C.Abstract classes can be subclassed, and concrete subclasses must implement all abstract methods
D.Abstract classes are identical to interfaces in every respect
Explanation: An abstract class cannot be instantiated directly; it must be extended by a concrete subclass that provides implementations for all inherited abstract methods. Abstract classes may also include concrete methods and instance state, distinguishing them from interfaces.
6Which design principle states that subclass objects should be substitutable for objects of their superclass without altering program correctness?
A.Single Responsibility Principle
B.Open/Closed Principle
C.Liskov Substitution Principle
D.Interface Segregation Principle
Explanation: The Liskov Substitution Principle (LSP), one of the SOLID principles, requires that any instance of a subclass can replace a superclass instance without breaking program behaviour. Violating LSP usually signals a flawed inheritance hierarchy.
7In a recursive algorithm, what is the purpose of the base case?
A.To make the recursion run faster on average
B.To define the smallest input for which the answer is returned without further recursion, terminating the recursion
C.To call the function once more before returning
D.To convert the recursion into an iterative loop
Explanation: A base case is the condition that returns a direct answer without further recursive calls, guaranteeing termination. Without a correct base case, recursive calls would continue indefinitely until the call stack overflows.
8Consider this Python function: fact(n): if n <= 1: return 1 return n * fact(n-1) What is fact(5)?
A.20
B.60
C.120
D.720
Explanation: Factorial 5 = 5 × 4 × 3 × 2 × 1 = 120. The recursion unwinds: fact(5) = 5 × fact(4) = 5 × 24 = 120.
9Why does deep recursion sometimes cause a stack overflow error?
A.Because recursive functions are inherently slower than iteration
B.Because each recursive call adds a new stack frame to the call stack, and the stack has a finite size
C.Because recursion does not allow local variables
D.Because compilers always reject recursive code
Explanation: Every active function call occupies a stack frame holding parameters, locals and return address. When recursion is too deep, the total frame size exceeds the operating system's stack limit and execution aborts with a stack overflow.
10Which of the following problems is most naturally expressed using recursion?
A.Computing the sum of an array of integers
B.Traversing the nodes of a binary tree
C.Finding the maximum of two numbers
D.Reading a single line from a file
Explanation: Binary trees are recursively defined data structures — each subtree is itself a binary tree — so traversal algorithms (pre-order, in-order, post-order) map onto recursion very cleanly. The other tasks are flat and iterative.

About the A-Level Computer Science Exam

A-Level Computer Science is offered by AQA, Edexcel, OCR as part of the UK A-Level qualification framework. The course covers fundamentals of programming, data structures, algorithms, theory of computation and is assessed primarily through written exam papers at the end of the two-year course.

Questions

100 scored questions

Time Limit

5-7 hours total across multiple papers

Passing Score

Grade E is the minimum pass, Grades A*-E count as a pass (A*-A-B-C-D-E)

Exam Fee

£75-£130 per subject (school-set entry fee) (AQA, Edexcel, OCR)

A-Level Computer Science Exam Content Outline

Core

Programming and Data Structures

OOP, recursion, lists, queues, stacks, trees, graphs, hash tables

Core

Algorithms and Computation

Searching, sorting, traversal, complexity (Big-O), Turing machines, computability, regular expressions

Core

Data Representation

Binary, hexadecimal, two's complement, floating-point, character encoding, images, sound, compression, encryption

Core

Computer Systems and Architecture

Hardware, operating systems, machine code, assembly, CPU pipelining, parallel processing

Core

Networks and Web

TCP/IP, layers, DNS, packet switching, HTTP/HTTPS, web technologies, network security

Core

Databases

Relational model, SQL, normalisation, transactions, ACID properties, distributed databases, NoSQL

Core

NEA Project

A substantial coding project documented across analysis, design, implementation, testing, and evaluation

How to Pass the A-Level Computer Science Exam

What You Need to Know

  • Passing score: Grade E is the minimum pass, Grades A*-E count as a pass (A*-A-B-C-D-E)
  • Exam length: 100 questions
  • Time limit: 5-7 hours total across multiple papers
  • Exam fee: £75-£130 per subject (school-set entry fee)

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

A-Level Computer Science Study Tips from Top Performers

1Use past papers from your specific exam board — questions follow the same style year on year
2Time yourself on full papers to build pacing for the long extended-response questions
3Build a clear understanding of mark schemes — examiners reward specific assessment objectives
4Review examiner reports each summer; common errors repeat

Frequently Asked Questions

What exam boards offer A-Level Computer Science?

A-Level Computer Science is offered by AQA, Edexcel, OCR. All boards follow Ofqual subject content but vary in the choice of set texts, optional topics, and paper structure.

When is the A-Level Computer Science exam taken?

Exams are written in the May-June series at the end of the two-year linear A-Level course. Most students sit the papers in Year 13.

How is A-Level Computer Science graded?

A-Levels are graded A*-E. A* is the highest grade and E is the minimum pass. UCAS tariff points are awarded for A-Level grades on most university applications.

How many papers does A-Level Computer Science have?

Most A-Level subjects have 3 written papers. The exact number, timing, and weighting depend on the chosen exam board. Some subjects also include a non-examined assessment (NEA) coursework component.