AQA Computer Science Practice Questions With Full Answers

Practising exam-style questions is one of the most effective ways to improve performance in AQA Computer Science. Many students revise content but still lose marks because they don’t understand how questions are worded or how marks are awarded.

This guide includes realistic AQA-style practice questions, clear model answers, and examiner tips explaining what earns marks and what commonly causes students to lose them.

Why Practice Questions Matter in AQA Computer Science

AQA exams reward:

• precise terminology

• structured answers

• understanding of how and why, not just what

• 
  

Students who only read notes often struggle to apply knowledge in exam conditions. Practice questions train you to:

• interpret command words

• structure answers efficiently

• recognise common question patterns

Practice Question 1: Algorithms (Low-Mark Foundation Question)

Question

Describe what is meant by an algorithm. (2 marks)

Model Answer

An algorithm is a step-by-step set of instructions used to solve a problem or complete a task.

Examiner Tip

For definition questions:

• one clear sentence is enough

• avoid examples unless asked

• vague wording like “a program” will lose marks

Practice Question 2: Algorithms and Efficiency

Question

Explain why algorithms should be efficient. (3 marks)

Model Answer

Algorithms should be efficient so they use less processing time and less memory, allowing programs to run faster and handle larger amounts of data effectively.

Why This Scores Full Marks

• Mentions time and memory

• Explains why efficiency matters

• Uses technical language

Practice Question 3: Data Representation

Question

Describe how characters are represented in a computer system. (3 marks)

Model Answer

Characters are represented using binary codes, where each character is assigned a unique binary value. These codes are stored and processed using binary because computers only understand 0s and 1s.

Common Mistake

Students often say “letters are stored as text” — this earns 0 marks.

Practice Question 4: Programming Concepts (Trace Question)

Question

total = 0
numbers = [3, 6, 2]

for n in numbers:
    total = total + n

print(total)

State the output produced by the program. (2 marks)

Correct Answer

11

Examiner Tip

Always:

• trace code line by line

• write intermediate values on paper

• avoid mental shortcuts

Practice Question 5: Programming Logic (Explain Question)

Question

Explain how iteration is used in the program above. (3 marks)

Model Answer

Iteration is used through a loop that repeats instructions for each value in the list. The loop adds each number to the total until all values have been processed.

Why This Works

• Mentions repetition

• Refers to purpose of the loop

• Links explanation to the code

Practice Question 6: Boolean Logic

Question

State the result of the following expression:

(True AND False) OR True

(1 mark)

Correct Answer

True

Tip

Always evaluate brackets first. Boolean logic questions are easy marks but often rushed.

Practice Question 7: Computer Systems

Question

Explain the purpose of the CPU. (3 marks)

Model Answer

The CPU executes program instructions by fetching, decoding, and executing them. It processes data and controls the overall operation of the computer system.

Examiner Insight

Answers that only say “it runs programs” usually score 1 mark at most.

Practice Question 8: Networks

Question

Describe one advantage and one disadvantage of a wired network. (4 marks)

Model Answer

An advantage of a wired network is that it provides a stable and fast connection with less interference. A disadvantage is that cables can be expensive to install and restrict device mobility.

Marking Tip

Each point needs:

• a clear statement

• correct technical reasoning

Practice Question 9: Cyber Security

Question

Explain why encryption is used when sending data over a network. (4 marks)

Model Answer

Encryption is used to protect data from being intercepted by unauthorised users. It converts data into an unreadable format so that only the intended recipient with the correct key can access the original information.

Common Error

Saying “it stops hacking” is too vague and loses marks.

Practice Question 10: Extended Response Strategy

Question

Discuss the impact of cyber security threats on individuals. (6 marks)

High-Level Answer Structure

• identify threats (e.g. malware, phishing)

• explain consequences (data loss, financial harm)

• discuss real-world impact

• use technical terms

Examiner Tip

For 6-mark questions:

• write in paragraphs

• make at least 3 developed points

• avoid bullet points unless short on time

How to Use These Practice Questions Effectively

To get the most benefit:

1. Answer questions without notes

2. Time yourself

3. Mark using model answers

4. Rewrite weak responses

5. Learn common phrasing used by examiners

Passive reading does not build exam skill — active practice does.

Final Advice for AQA Computer Science Exams

• Learn command words

• Practise explaining answers, not just stating them

• Write clearly and concisely

• Don’t assume the examiner knows what you mean

Consistent practice with exam-style questions is one of the fastest ways to increase marks.

If you find certain question types consistently difficult, targeted support from an experienced Computer Science tutor can help identify gaps and improve exam technique more efficiently.