AQA GCSE Computer Science sample questions and answers (8525)
Guide overview All 8 topics Sample questions Papers and weighting Look inside Questions and answers
40 sample questions and answers
Taken from every topic of AQA GCSE Computer Science, specification 8525. The full guide has 664.
Paper 1
Algorithms
75 questions in the guide, across 5 subtopics. More from this topic
-
Algorithms, decomposition and abstraction
Why must each step of an algorithm be unambiguous?
Show the answer
A step with only one meaning gives the same result whoever follows it. A computer cannot guess what a vague instruction was meant to say. -
Algorithms, decomposition and abstraction
Why is abstraction useful in programming?
Show the answer
Abstraction makes a problem simpler to understand and to solve. A program that models only the relevant details is quicker to write and to run. -
Pseudo-code, flowcharts and trace tables
What do a rounded rectangle and a plain rectangle show in a flowchart?
Show the answer
A rounded rectangle, called a terminal, marks the start or the end. A plain rectangle shows a process such as a calculation. -
Pseudo-code, flowcharts and trace tables
An algorithm reads side ← USERINPUT, then area ← side * side, then OUTPUT area. Which line is the processing?
Show the answer
The line area ← side * side is the processing. The first line is the input and the last line is the output. -
Efficiency of algorithms
Why does efficiency matter more as the amount of data grows?
Show the answer
A small difference in steps per item becomes a huge difference over millions of items. An inefficient algorithm can become too slow to use on large data sets.
Paper 1
Programming
124 questions in the guide, across 8 subtopics. More from this topic
-
Data types
What is the character data type?
Show the answer
A character is a single letter, digit, symbol or space. Examples of characters are 'A', '7' and '#'. -
Variables, constants and assignment
Why is a named constant safer than typing the same value throughout a program?
Show the answer
A constant cannot be changed by mistake while the program runs. The risk of mistyping the value in one of many places is also removed. -
Sequence, selection and iteration
What is indefinite iteration?
Show the answer
Indefinite iteration repeats a block until a condition is met, so the number of repetitions is not known in advance. Indefinite iteration is also called condition-controlled iteration. -
Arithmetic, relational and Boolean operators
What does 3 + 4 * 2 give?
Show the answer
The expression gives 11. Multiplication is carried out before addition, so 4 * 2 is worked out first. -
Arrays and records
How is one item in an array changed?
Show the answer
An item is changed by assigning a new value to its index, as in scores[1] ← 10. The value 10 replaces whatever index 1 held before.
Paper 2
Data Representation
143 questions in the guide, across 9 subtopics. More from this topic
-
Number bases and why hexadecimal is used
State the decimal values of the hexadecimal digits A to F.
Show the answer
A is 10, B is 11 and C is 12. D is 13, E is 14 and F is 15. -
Converting between binary, decimal and hexadecimal
How can you check a decimal-to-binary conversion?
Show the answer
Add up the place values of every column that holds a 1. The total should equal the decimal number you started with. -
Units of information: bits, bytes and prefixes
How many megabytes make one gigabyte?
Show the answer
One gigabyte, written 1 GB, is 1,000 megabytes. A gigabyte is therefore 1,000,000,000 bytes. -
Binary addition and binary shifts
How can you check the answer to a binary addition?
Show the answer
Convert each number to decimal and add them. The decimal total should match the binary answer converted to decimal. -
Character encoding: ASCII and Unicode
The ASCII code for a lower-case a is 97. Which character has the code 100?
Show the answer
The code 100 stands for the lower-case letter d. The lower-case letters run in order from 97 upwards.
Paper 2
Computer Systems
95 questions in the guide, across 6 subtopics. More from this topic
-
Hardware, software and the operating system
Give two examples of system software.
Show the answer
An operating system such as Windows is one example of system software. A utility program such as backup software is also system software. -
Hardware, software and the operating system
How does an operating system manage applications?
Show the answer
The OS loads applications into memory and starts them running. The OS also closes applications and handles their requests for resources such as files. -
Logic gates, truth tables and Boolean expressions
Which symbols represent AND, OR, XOR and NOT in a Boolean expression?
Show the answer
A dot (written . or ·) represents AND and a plus sign represents OR. The symbol ⊕ represents XOR, and a bar over a term represents NOT. -
Logic gates, truth tables and Boolean expressions
How many rows does a truth table need for a circuit with three inputs?
Show the answer
A truth table for three inputs needs 8 rows. Each extra input doubles the number of rows, as 2³ = 8. -
Programming languages and translators
What is assembly language?
Show the answer
Assembly language is a low-level language that uses short mnemonics such as ADD and SUB. Each mnemonic stands for one machine code instruction.
Paper 2
Computer Networks
76 questions in the guide, across 5 subtopics. More from this topic
-
Network types and topologies
What is a Local Area Network (LAN)?
Show the answer
A LAN connects devices across a small geographical area such as a school, office or home. A LAN is usually owned and managed by one person or organisation. -
Network types and topologies
What are the advantages of a star topology?
Show the answer
A fault in one cable only affects the device on that cable. Performance stays good under heavy traffic because each device has its own link. -
Wired and wireless networks
When would fibre optic cable be the appropriate choice?
Show the answer
Fibre suits long links, such as between buildings or across a country. Fibre also suits backbone cables carrying heavy traffic and places with electrical interference. -
Wired and wireless networks
Why would a video editing computer be connected by cable rather than wirelessly?
Show the answer
A cable gives a faster and more stable connection. Large video files transfer quickly without dropouts. -
Network protocols
What does UDP (User Datagram Protocol) do?
Show the answer
UDP sends packets without setting up a connection or checking they arrive. UDP is faster than TCP but less reliable.
Paper 2
Cyber Security
55 questions in the guide, across 4 subtopics. More from this topic
-
Cyber security, common threats and penetration testing
What are misconfigured access rights?
Show the answer
Misconfigured access rights give users more access than they need, or leave data open to anyone. An ordinary user might be able to read or delete sensitive files. -
Cyber security, common threats and penetration testing
Why do organisations use penetration testing?
Show the answer
Penetration testing reveals security weaknesses so they can be fixed. The results show how well the organisation's defences would hold up. -
Social engineering: blagging, phishing and shouldering
What is phishing?
Show the answer
Phishing is fraudulently obtaining private information, usually by email or text message. The message pretends to come from a trusted organisation such as a bank. -
Social engineering: blagging, phishing and shouldering
How can organisations protect against social engineering?
Show the answer
Organisations can train staff to recognise and report social engineering attempts. Clear rules, such as never giving passwords over the phone, also help. -
Malware: viruses, trojans and spyware
How does a trojan differ from a virus?
Show the answer
A trojan relies on the user being tricked into installing it. A virus copies itself into other files to spread.
Paper 2
Relational Databases and Sql
48 questions in the guide, across 3 subtopics. More from this topic
-
Relational databases and keys
What is a data type in a database?
Show the answer
A data type sets what kind of value a field can hold. Common data types are integer, real, text, Boolean and date/time. -
Relational databases and keys
What is data redundancy?
Show the answer
Data redundancy is the same data being stored more than once without need. Redundant copies waste storage space. -
SQL SELECT queries
What does ORDER BY do in an SQL query, and what do ASC and DESC mean?
Show the answer
The ORDER BY clause sorts the results by a chosen field. ASC sorts in ascending order and DESC sorts in descending order. -
SQL SELECT queries
A table Film has fields FilmID, Title, Year and Rating. What does SELECT Title FROM Film WHERE Year > 2010 AND Rating = 'PG' return?
Show the answer
The query returns the titles of PG films released after 2010. A film must meet both conditions to appear. -
SQL INSERT, UPDATE and DELETE
What happens if an INSERT INTO command gives a new record the same primary key value as an existing record?
Show the answer
The database rejects the new record. A primary key value must be unique within its table.
Paper 2
Ethical, Legal and Environmental Impacts of Digital Technology
48 questions in the guide, across 3 subtopics. More from this topic
-
Ethical issues in digital technology
What are computer-based implants?
Show the answer
Computer-based implants are devices containing a computer that are placed inside the body. Examples include pacemakers, cochlear implants and brain-computer interfaces. -
Ethical issues in digital technology
What is the difference between malicious hacking and ethical hacking?
Show the answer
Malicious hacking is gaining unauthorised access to a computer system to steal, damage or disrupt. An ethical hacker has the owner's permission to find weaknesses so they can be fixed. -
Legal issues, privacy and surveillance
What does the Computer Misuse Act 1990 make illegal?
Show the answer
The Computer Misuse Act 1990 makes unauthorised access to computer material a crime. The Act also covers access with intent to commit further crimes, and impairing a computer's operation. -
Legal issues, privacy and surveillance
How do governments argue that access to private data keeps citizens safe?
Show the answer
Security services argue that monitoring communications helps them stop terrorist attacks and serious crime. Access to messages and browsing records can reveal plots before they happen. -
Environmental impacts of digital technology
Why does the short lifespan of mobile phones matter for the environment?
Show the answer
Many people replace their phone every two or three years, even if it still works. Each replacement means more mining, more manufacturing energy and more e-waste.
AQA GCSE Computer Science Active Recall Guide
The other 624 questions, with the answers printed after each section.