What Comes Up Every Year in AQA GCSE Computer Science — Exam Predictions 2025/26

Every AQA GCSE Computer Science paper tests the same core topics. The questions change but the underlying knowledge being assessed stays remarkably consistent from year to year. This guide identifies what has appeared on multiple past papers and is therefore highly likely to appear on yours.

This is not guesswork — it is pattern analysis across AQA 8525 mark schemes from multiple series.

Paper 1 — Computer Systems: what always appears

1. The fetch-decode-execute cycle (3–4 marks)

This appears on virtually every Paper 1, usually as a 3–4 mark describe or explain question. The mark scheme consistently rewards:

The address in the PC is copied to the MAR
The instruction at that address is fetched from memory into the MDR
The instruction is copied from the MDR to the CIR
The PC is incremented to point to the next instruction
The Control Unit decodes the instruction in the CIR
The ALU executes the operation; result to ACC

Know all five register names (PC, MAR, MDR, CIR, ACC) and what each holds. Not knowing these loses guaranteed marks.

2. Binary/hex/denary conversion (2–4 marks)

Every paper. Usually two sub-questions:

Convert X from denary to binary
Convert Y from binary to hexadecimal

Sometimes with a file size calculation as a third part. No calculators permitted. Practice these until they take under 60 seconds.

3. Network security — threats and defences (4–6 marks)

Common formats: “describe two threats and a suitable defence for each” or “explain how [specific attack] works”. The mark scheme specifically wants:

Named threat with an explanation of how it works (not just what it does)
A specific, matching defence (not just “install antivirus” for all threats)

Common pairings that score marks:

Phishing → user education / email filtering
Brute force → account lockout / strong passwords / two-factor authentication
Malware → antivirus software / not opening unknown attachments
SQL injection → parameterised queries / input validation

4. RAM vs ROM / types of storage (2–3 marks)

This comes up every year. The key distinction: RAM is volatile (data lost without power); ROM is non-volatile. A second question usually compares HDD vs SSD or asks about the purpose of cache memory.

5. Network topology (2–3 marks)

Star topology advantages/disadvantages. Sometimes a comparison with mesh or bus. The reliable points:

Star: switch failure = whole network down; cable failure = one device affected
Mesh: no single point of failure; more cables needed; more expensive

6. Operating system functions (2–3 marks)

“State two functions of an operating system” appears frequently. The five functions: process management, memory management, I/O management, file management, security management. Know at least three with a brief explanation.

Paper 2 — Computational Thinking: what always appears

7. Bubble sort trace table (4–5 marks)

Every Paper 2. The mark scheme awards one mark per correct pass state. Common mistake: only showing swaps and skipping no-swap comparisons. You must show every comparison — including ones where nothing changes.

Also: examiners consistently give a mark for identifying early termination (“if a complete pass produces no swaps, the algorithm terminates”).

8. Binary search trace (4 marks)

Every Paper 2. Show low, mid and high at each step. Calculate mid as ⌊(low + high) / 2⌋. State when the target is found and which index it is at.

9. Write a Python program (4–6 marks)

Typically worth 4–6 marks and appears on every paper. Common tasks:

Calculate the total/average of a list of numbers
Find the highest or lowest value
Count items matching a condition
Validate input with a loop

The mark scheme awards marks for: correct structure (loop/if), correct syntax, correct output. A program that does most things correctly but has one small error typically scores 3/4 marks. A completely missing component (e.g. no loop at all) scores 0 for that aspect.

10. Boolean logic (3–4 marks)

Complete a truth table for a given circuit, or draw a circuit from a Boolean expression. Know AND, OR, NOT, NAND, NOR and XOR truth tables. For NAND: inverted AND. For NOR: inverted OR. For XOR: output is 1 when inputs are DIFFERENT.

11. Trace a given algorithm (3–4 marks)

A segment of code is given (usually a loop or nested loop). You must trace it and show the value of each variable at each step. Common mistakes: incorrect loop bounds (range(5) = 0 to 4, not 1 to 5) and forgetting to update variables inside a while loop.

Topics that appear most years but not every year

File handling in Python
Compression (lossy vs lossless)
CPU performance factors (clock speed, cores, cache)
SQL SELECT queries with WHERE/ORDER BY
Subroutines (functions and procedures), parameter passing
Data types and type conversion

Topics that are lower frequency but high marks when they appear

Two’s complement / signed binary
Normalised floating point
Stages of compilation
Sorting algorithm comparison (bubble vs merge, advantages/disadvantages)

The five-minute pre-exam checklist

Before you go into the exam, make sure you can do the following without looking anything up:

☐ Convert 127 to binary (answer: 01111111)
☐ Convert 11001010 to denary (answer: 202)
☐ Convert B4 hex to denary (answer: 180)
☐ Write out the five FDE registers and what each does
☐ Write the AND, OR, NOT and NAND truth tables
☐ Write bubble sort in Python from memory
☐ State two functions of an operating system
☐ State what volatile memory means

If you can do all eight in under five minutes, you are ready.

Where to practise

AQA GCSE revision page — topics, tools and questions for spec 8525
Question bank — exam-style questions with mark schemes across all topics
Algorithm visualiser — watch and trace bubble sort and binary search
Binary converter — practise number conversions with immediate feedback
Logic gate simulator — build circuits and check truth tables