IBO Level 3 Certificate in HL Computer Science Practice
Exam
**Question 1.** Which of the following best describes the purpose of a system
backup strategy in an organization?
A) To increase processing speed of the CPU
B) To ensure data can be recovered after loss or corruption
C) To reduce the number of users on a network
D) To eliminate the need for firewalls
Answer: B
Explanation: A backup strategy creates copies of data so that it can be restored if
the original is lost, corrupted, or destroyed.
**Question 2.** In the Von Neumann architecture, which component stores the
instructions that the CPU executes?
A) RAM
B) ROM
C) Cache memory
D) Hard disk drive
Answer: A
Explanation: In Von Neumann machines, both data and instructions reside in the
same memory space, typically RAM during execution.
**Question 3.** Which logic gate outputs true only when exactly one of its two
inputs is true?
, IBO Level 3 Certificate in HL Computer Science Practice
Exam
A) AND
B) OR
C) XOR
D) NAND
Answer: C
Explanation: XOR (exclusive OR) yields true when the inputs differ, i.e., exactly one
is true.
**Question 4.** Which of the following is a characteristic of an operating system’s
kernel?
A) Provides a graphical user interface
B) Manages hardware resources directly
C) Stores user documents permanently
D) Generates network traffic reports
Answer: B
Explanation: The kernel is the core part of an OS that interacts directly with
hardware to manage resources.
**Question 5.** In a star network topology, which device typically acts as the
central point of communication?
A) Hub
B) Switch
, IBO Level 3 Certificate in HL Computer Science Practice
Exam
C) Router
D) Repeater
Answer: B
Explanation: A star topology connects all nodes to a central switch (or hub), which
forwards traffic.
**Question 6.** Which protocol is primarily responsible for reliable, ordered
delivery of data over the Internet?
A) UDP
B) TCP
C) IP
D) HTTP
Answer: B
Explanation: TCP provides error checking, flow control, and ensures that data
arrives in order.
**Question 7.** Which encryption method uses the same key for both encryption
and decryption?
A) RSA
B) Diffie‑Hellman
C) AES (symmetric)
D) ECC
, IBO Level 3 Certificate in HL Computer Science Practice
Exam
Answer: C
Explanation: Symmetric encryption algorithms like AES use a single shared secret
key for both operations.
**Question 8.** Decomposing a complex problem into smaller, manageable parts
is an example of which computational thinking skill?
A) Thinking procedurally
B) Thinking abstractly
C) Thinking concurrently
D) Thinking ahead
Answer: A
Explanation: Procedural thinking involves breaking a problem down into a
sequence of steps.
**Question 9.** Which of the following pseudocode structures correctly
represents a loop that repeats while a condition is true?
A) IF condition THEN … ENDIF
B) WHILE condition DO … ENDWHILE
C) REPEAT … UNTIL condition
D) FOR i = 1 TO n DO … ENDFOR
Answer: B
Exam
**Question 1.** Which of the following best describes the purpose of a system
backup strategy in an organization?
A) To increase processing speed of the CPU
B) To ensure data can be recovered after loss or corruption
C) To reduce the number of users on a network
D) To eliminate the need for firewalls
Answer: B
Explanation: A backup strategy creates copies of data so that it can be restored if
the original is lost, corrupted, or destroyed.
**Question 2.** In the Von Neumann architecture, which component stores the
instructions that the CPU executes?
A) RAM
B) ROM
C) Cache memory
D) Hard disk drive
Answer: A
Explanation: In Von Neumann machines, both data and instructions reside in the
same memory space, typically RAM during execution.
**Question 3.** Which logic gate outputs true only when exactly one of its two
inputs is true?
, IBO Level 3 Certificate in HL Computer Science Practice
Exam
A) AND
B) OR
C) XOR
D) NAND
Answer: C
Explanation: XOR (exclusive OR) yields true when the inputs differ, i.e., exactly one
is true.
**Question 4.** Which of the following is a characteristic of an operating system’s
kernel?
A) Provides a graphical user interface
B) Manages hardware resources directly
C) Stores user documents permanently
D) Generates network traffic reports
Answer: B
Explanation: The kernel is the core part of an OS that interacts directly with
hardware to manage resources.
**Question 5.** In a star network topology, which device typically acts as the
central point of communication?
A) Hub
B) Switch
, IBO Level 3 Certificate in HL Computer Science Practice
Exam
C) Router
D) Repeater
Answer: B
Explanation: A star topology connects all nodes to a central switch (or hub), which
forwards traffic.
**Question 6.** Which protocol is primarily responsible for reliable, ordered
delivery of data over the Internet?
A) UDP
B) TCP
C) IP
D) HTTP
Answer: B
Explanation: TCP provides error checking, flow control, and ensures that data
arrives in order.
**Question 7.** Which encryption method uses the same key for both encryption
and decryption?
A) RSA
B) Diffie‑Hellman
C) AES (symmetric)
D) ECC
, IBO Level 3 Certificate in HL Computer Science Practice
Exam
Answer: C
Explanation: Symmetric encryption algorithms like AES use a single shared secret
key for both operations.
**Question 8.** Decomposing a complex problem into smaller, manageable parts
is an example of which computational thinking skill?
A) Thinking procedurally
B) Thinking abstractly
C) Thinking concurrently
D) Thinking ahead
Answer: A
Explanation: Procedural thinking involves breaking a problem down into a
sequence of steps.
**Question 9.** Which of the following pseudocode structures correctly
represents a loop that repeats while a condition is true?
A) IF condition THEN … ENDIF
B) WHILE condition DO … ENDWHILE
C) REPEAT … UNTIL condition
D) FOR i = 1 TO n DO … ENDFOR
Answer: B
