SECTION A – 6 MARKS EACH

Question 1

In the space provided below, draw the circuit diagram for the following system only using the AND, OR and NOT logic gate symbols.

(A OR B) AND NOT (C AND D)

Solution

To implement this expression, two sub-circuits must first be created. The expression (A OR B) requires an OR gate with inputs A and B. The expression (C AND D) requires an AND gate with inputs C and D. The output of this AND gate must then pass through a NOT gate to create NOT (C AND D).

The final step is to connect the output of the OR gate and the output of the NOT gate into a final AND gate. The output of this final gate represents the complete expression.

Marks: 6

Question 2

Explain why the result of the following binary subtraction is impossible to represent using standard binary notation.

00001100₂  

- 00011001₂

Solution

Converting both numbers to decimal shows the problem clearly.
00001100₂ = 12₁₀ and 00011001₂ = 25₁₀. The calculation is therefore 12 – 25 which equals –13.

Standard binary notation is unsigned and can only represent positive integers. It does not include a method to store negative values. Because the result of this subtraction is negative, it cannot be represented without using a signed system such as two’s complement.

Marks: 6

Question 3

Examine the Python code below and complete the trace table underneath for each iteration of the loop.

x = 1

k = 0

while x <= 6:

    if x % 2 == 1:

        k += x*2

    x += 1

Solution

The loop begins with x = 1 and k = 0. The condition checks if x is odd. Only odd values of x update k. When x is 1, k becomes 2. When x is 3, k becomes 8. When x is 5, k becomes 18. Even values of x do not change k. The loop finishes when x becomes 7.

Marks: 6

Question 4

Answer the following in the context of databases.
(a) What is meant by the term ‘primary key’?
(b) State one reason why a school database might use a foreign key.

Solution

A primary key is a field that uniquely identifies each record in a table. No two records can share the same primary key value and it cannot be null.

A foreign key is used to create a relationship between two tables. In a school database, a StudentID in an Attendance table could act as a foreign key linking attendance records to the main Student table.

Marks: 6

Question 5

Give two specific design features that would support users with additional needs in an online banking app. Explain how each improves accessibility.

Solution

One useful feature is screen-reader compatibility. This allows visually impaired users to navigate the app using audio descriptions of buttons and text.

Another feature is high-contrast mode with large scalable fonts. This supports users with visual difficulties by making text easier to read and interface elements easier to identify.

Marks: 6

Question 6

HTML and JavaScript can both be used to develop websites. Using examples, describe the strengths and weaknesses of both HTML and JavaScript.

Solution

HTML is strong for structuring content such as headings, paragraphs and images. It is simple and supported by all browsers, but it is static and cannot perform calculations or respond to user actions.

JavaScript allows interactivity such as form validation and dynamic content updates. However, it is more complex than HTML and can behave differently across browsers if not coded carefully.

Marks: 6

Question 7

(a) What is the main purpose of the Hypertext Transfer Protocol (HTTP)?
(b) Give one reason why HTTP is important for computer communication.

Solution

HTTP is the protocol used to transfer web pages and related resources from a web server to a client browser.

HTTP is important because it provides a standard method for communication on the World Wide Web, allowing different devices and operating systems to exchange information reliably.

Marks: 6

Question 8

A school wants to know what time of day students borrow books most often.
(a) Name a suitable data field to collect.
(b) Suggest a graph type that would be suitable to show a trend.

Solution

A suitable data field would be a timestamp such as Borrow_Time or Hour_Of_Day.

A line graph would be appropriate to show how borrowing changes across the day, as it clearly displays trends over time.

Marks: 6

Question 9

Draw a flowchart to:
• Input a number
• Use a loop to display every number from 1 to that number
• Count how many even numbers occur
• Output the count

Solution

The flowchart should begin with an input symbol for n. A counter variable should be set to zero. A loop from 1 to n should test each number using “number mod 2 = 0”. If true, the counter increases by one. After the loop, the counter value is output.

Marks: 6

Question 10

State the purpose of:
(a) Functional testing
(b) System testing

Solution

Functional testing checks whether each individual feature meets the specified requirements.

System testing checks the entire integrated system to ensure all components work together correctly.

Marks: 6

Question 11

Describe two advantages of using a digital signal rather than an analogue signal.

Solution

Digital signals are less affected by noise and interference, so data remains more accurate over long distances.

Digital signals can use error detection and correction methods, making communication more reliable.

Marks: 6

Question 12

State the function of each component and give one application.
• Transistor
• Capacitor

Solution

A transistor acts as a switch or amplifier. It is used in processors to represent binary 1s and 0s.

A capacitor stores electrical charge and releases it when needed. It is used in power supplies to smooth voltage.

Marks: 6

SECTION B – 38 MARKS EACH

Question 13

(a)(i) What is meant by the term Machine Learning?
(ii) State an everyday example.

Solution

Machine Learning refers to computer systems that improve their performance by learning from data rather than following only explicit instructions. The system identifies patterns and makes predictions based on previous examples.

An everyday example is a streaming service recommending movies based on a user’s viewing history.

Marks: 8

(b)(i) Outline one consequence of algorithmic bias.

Solution

Algorithmic bias can reinforce stereotypes and unfair treatment. For example, if an AI mainly shows men when prompted with “engineer”, it may influence society to view engineering as a male profession, reducing diversity.

Marks: 6

(b)(ii) Two benefits of teachers using AI.

Solution

AI can assist teachers by generating differentiated resources quickly, saving preparation time. It can also help with assessment by automatically marking quizzes and identifying student misconceptions.

Marks: 8

(b)(iii) Two risks of AI in education.

Solution

Over-reliance on AI may reduce teacher professional judgement. Data privacy is another risk, as student information may be processed by external systems.

Marks: 8

(c) Apply Quicksort to:
32, 15, 7, 45, 23, 5, 12

Solution

Using 32 as pivot:
Left: 15,7,23,5,12
Right: 45

Sorting left recursively produces:
5,7,12,15,23

Final sorted list:
5,7,12,15,23,32,45

Quicksort is faster than bubble sort on large lists because it divides the problem into smaller partitions rather than repeatedly swapping adjacent values.

Best case complexity is O(n log n) when partitions are balanced.
Worst case is O(n²) when pivots create very uneven partitions.

Marks: 16

(d) Shortest path A → M

Solution

Applying Bellman’s principle, the best path is built from optimal subpaths. Tracing through the graph gives:

A–C–F–I–J–L–M
Cost = 2 + 3 + 1 + 2 + 1 + 1 = 10

Marks: 12

Question 14

(a)(i) Rewrite the code

def sum_even(L):

    total = 0

    for i in range(len(L)):

        if L[i] % 2 == 0:

            total += L[i]

    return total

Marks: 8

(a)(ii) Unit test

print(sum_even([2,5,6,9]))   # Expected 8

Marks: 6

(a)(iii) Importance of testing

Solution

Testing ensures that software behaves as intended, finds defects early, and prevents errors from reaching users.

Marks: 4

(b) Abstraction & Full Adder

Solution

Abstraction means hiding internal complexity and showing only necessary details.

A full adder adds two input bits and a carry-in bit to produce a sum and carry-out.

Marks: 10

(c) Definitions

Solution

Concatenation joins data such as strings.
Iteration repeats instructions using loops.
Recursion occurs when a function calls itself.

Marks: 6

(d) Logic expression

Solution

The required expression is:
(A AND B AND NOT C) OR D

Marks: 4

Question 15

(a) Data errors

Solution

The table contains inconsistent date formats, duplicate student IDs, spelling errors such as “absnt”, and inconsistent capitalisation. These problems make analysis unreliable.

Marks: 10

(b) Ethics

Solution

Poor management could lead to a data breach exposing student information. Good practices include strong access control and encryption of personal data.

Marks: 8

(c) Storage & TCP/IP

Solution

Primary storage such as RAM is fast and temporary. Secondary storage such as SSD is permanent.

TCP stands for Transmission Control Protocol and ensures reliable delivery of data. IP provides addressing so devices can locate each other.

Marks: 12

(d) Base 60 conversion

Solution

324₆₀
= 3×60² + 2×60 + 4
= 10800 + 120 + 4
= 10924₁₀

Marks: 8

Yes — I’ve gone through Section C (Question 16 Parts A & B) in your uploaded paper and extracted the exact coding concepts being assessed.

I checked each task from the screenshots (ratings list, averages, filtering, categories, bar chart, function, etc.) and grouped them into clear curriculum-style concepts you can paste directly into a Google Site revision page .

Below is a clean, student-friendly format, ready to paste.

💻 Section C – Programming Concepts Assessed

Question 16 (Higher Level)

🔹 Part A – Ratings Tracker Program

📘 Core Coding Concepts Tested

1. User Input

• Using input() to collect data from the user

• Converting strings to integers using int()

2. Lists (Arrays)

• Creating an empty list

• Appending values using .append()

• Storing multiple values

• Iterating through list elements

3. Loops

• for loops (repeat fixed number of times)

• while loops (sentinel-controlled loops)

• Looping until a stop value (–1)

4. Variables & Counters

• Running totals (sum of ratings)

• Counting specific values (number of 5-star ratings)

• Accumulator patterns

5. Arithmetic Operations

• Calculating totals

• Finding averages

• Division

• Rounding to 2 decimal places using round()

6. Conditional Statements

• if, elif, else

• Range checking (1–5 only)

• Detecting invalid input

7. Data Validation

• Checking values are within bounds

• Removing invalid list entries

• Preventing bad data from affecting calculations

8. List Processing Without Built-ins

• Manual counting instead of .count()

• Manual filtering instead of shortcuts

• Writing algorithms yourself

(very common LC exam skill)

9. Sorting

• Sorting a list

• Descending order (reverse=True)

10. Output Formatting

• Printing formatted results

• Displaying clean summaries

✅ Skills Summary (Part A)

Students must demonstrate ability to:

• Collect data

• Store data

• Process data

• Validate data

• Summarise data

👉 This is essentially “Data Processing with Lists”

🔹 Part B – Categorised Feedback System

📘 Core Coding Concepts Tested

1. Multiple Lists

• Creating and managing two separate lists

• Grouping data into categories (positive/negative)

2. Classification Using Conditionals

• Decision logic

if rating >= 4:

• Assigning items to correct category

3. Sentinel-Controlled Loops

• Looping until user types "done"

• String comparison in loops

4. Comparing Values

• Comparing list lengths

• Determining greater/less than

• Producing different outputs based on comparison

5. Percentages & Calculations

• Percentage formula

• Decimal formatting

• Numeric precision

6. Frequency Counting

• Counting occurrences of each rating (1–5)

• Building a simple histogram

7. Text-Based Visualisation

• Creating a horizontal bar chart using *

• Repetition with loops

print("*" * count)

8. Functions

• Writing reusable functions

• Defining with def

• Calling functions

• Separating logic into modules

(very important LC higher-level skill)

9. Program Structure & Decomposition

• Breaking solution into parts

• Organising code logically

• Improving readability