WGU D386 Hardware and Operating Systems Essentials Object
Assessment (OA) Exam Study Guide | Complete Practice Exam
Questions with Verified Answers and Detailed Rationales
(100% Correct Solutions) | Latest Update 2026/2027
Question 1
Which CPU component is primarily responsible for performing arithmetic and
logical operations?
A. Control Unit
B. Arithmetic Logic Unit (ALU)
C. Register
D. Cache
Correct Answer: B. Arithmetic Logic Unit (ALU)
Rationale: The ALU performs arithmetic operations such as addition and
subtraction and logical operations such as AND, OR, and comparisons. The
Control Unit coordinates instruction execution, registers provide very fast
temporary storage, and cache stores frequently accessed instructions and
data.
Question 2
Which sequence correctly represents the basic CPU instruction cycle?
A. Decode → Execute → Fetch
B. Execute → Fetch → Decode
C. Fetch → Decode → Execute
D. Fetch → Execute → Decode
Correct Answer: C. Fetch → Decode → Execute
Rationale: During the fetch stage, the CPU retrieves an instruction from
memory. During decode, the instruction is interpreted so the CPU knows
what operation is required. During execute, the CPU performs the requested
pg. 1
,operation. Remembering this sequence is important when questions
distinguish CPU processing stages.
Question 3
Which type of memory is volatile and normally loses its contents when
electrical power is removed?
A. ROM
B. RAM
C. SSD
D. Flash memory
Correct Answer: B. RAM
Rationale: Random Access Memory (RAM) is volatile memory, meaning its
stored information depends on continuous electrical power. It temporarily
holds programs and data that the CPU is actively using. ROM, SSDs, and flash
memory are nonvolatile, so their contents remain stored after power is
removed.
Question 4
A computer frequently accesses the same instructions and data repeatedly.
Which hardware component can reduce the time required for the CPU to
access this frequently used information?
A. Cache
B. Optical drive
C. Power supply
D. Expansion slot
Correct Answer: A. Cache
Rationale: CPU cache is high-speed memory designed to store frequently
accessed instructions and data close to the processor. By reducing the need to
pg. 2
,repeatedly access slower main memory, cache can improve processing
performance. Cache is generally much smaller but faster than RAM.
Question 5
Which CPU component controls and coordinates the execution of
instructions?
A. ALU
B. Control Unit
C. Hard disk
D. RAM
Correct Answer: B. Control Unit
Rationale: The Control Unit directs CPU operations by interpreting
instructions and coordinating the activities required to execute them. The ALU
performs arithmetic and logical operations, while RAM and storage provide
locations for data and instructions rather than directly coordinating CPU
execution.
Question 6
Which storage technology has no moving mechanical parts and generally
provides faster access than a traditional hard disk drive?
A. HDD
B. SSD
C. Magnetic tape
D. Optical disc
Correct Answer: B. SSD
Rationale: A solid-state drive (SSD) uses flash-based storage and has no
spinning platters or mechanical read/write heads. This allows SSDs to provide
fast access times and generally better resistance to physical shock than
traditional HDDs.
pg. 3
, Question 7
What is the primary purpose of an operating system?
A. To replace the CPU
B. To manage hardware and software resources
C. To permanently store all user files
D. To increase the physical capacity of RAM
Correct Answer: B. To manage hardware and software resources
Rationale: An operating system acts as an intermediary between applications,
users, and computer hardware. It manages resources such as CPU time,
memory, storage, files, devices, and processes. It does not replace physical
hardware or permanently store every user file.
Question 8
Which operating-system function determines which process receives CPU
time?
A. Process management
B. File compression
C. Disk formatting
D. Device manufacturing
Correct Answer: A. Process management
Rationale: Process management includes controlling processes and
determining when they run. The operating system uses scheduling
mechanisms to allocate CPU time among processes. File compression, disk
formatting, and hardware manufacturing are not primary process-
management functions.
Question 9
pg. 4
Assessment (OA) Exam Study Guide | Complete Practice Exam
Questions with Verified Answers and Detailed Rationales
(100% Correct Solutions) | Latest Update 2026/2027
Question 1
Which CPU component is primarily responsible for performing arithmetic and
logical operations?
A. Control Unit
B. Arithmetic Logic Unit (ALU)
C. Register
D. Cache
Correct Answer: B. Arithmetic Logic Unit (ALU)
Rationale: The ALU performs arithmetic operations such as addition and
subtraction and logical operations such as AND, OR, and comparisons. The
Control Unit coordinates instruction execution, registers provide very fast
temporary storage, and cache stores frequently accessed instructions and
data.
Question 2
Which sequence correctly represents the basic CPU instruction cycle?
A. Decode → Execute → Fetch
B. Execute → Fetch → Decode
C. Fetch → Decode → Execute
D. Fetch → Execute → Decode
Correct Answer: C. Fetch → Decode → Execute
Rationale: During the fetch stage, the CPU retrieves an instruction from
memory. During decode, the instruction is interpreted so the CPU knows
what operation is required. During execute, the CPU performs the requested
pg. 1
,operation. Remembering this sequence is important when questions
distinguish CPU processing stages.
Question 3
Which type of memory is volatile and normally loses its contents when
electrical power is removed?
A. ROM
B. RAM
C. SSD
D. Flash memory
Correct Answer: B. RAM
Rationale: Random Access Memory (RAM) is volatile memory, meaning its
stored information depends on continuous electrical power. It temporarily
holds programs and data that the CPU is actively using. ROM, SSDs, and flash
memory are nonvolatile, so their contents remain stored after power is
removed.
Question 4
A computer frequently accesses the same instructions and data repeatedly.
Which hardware component can reduce the time required for the CPU to
access this frequently used information?
A. Cache
B. Optical drive
C. Power supply
D. Expansion slot
Correct Answer: A. Cache
Rationale: CPU cache is high-speed memory designed to store frequently
accessed instructions and data close to the processor. By reducing the need to
pg. 2
,repeatedly access slower main memory, cache can improve processing
performance. Cache is generally much smaller but faster than RAM.
Question 5
Which CPU component controls and coordinates the execution of
instructions?
A. ALU
B. Control Unit
C. Hard disk
D. RAM
Correct Answer: B. Control Unit
Rationale: The Control Unit directs CPU operations by interpreting
instructions and coordinating the activities required to execute them. The ALU
performs arithmetic and logical operations, while RAM and storage provide
locations for data and instructions rather than directly coordinating CPU
execution.
Question 6
Which storage technology has no moving mechanical parts and generally
provides faster access than a traditional hard disk drive?
A. HDD
B. SSD
C. Magnetic tape
D. Optical disc
Correct Answer: B. SSD
Rationale: A solid-state drive (SSD) uses flash-based storage and has no
spinning platters or mechanical read/write heads. This allows SSDs to provide
fast access times and generally better resistance to physical shock than
traditional HDDs.
pg. 3
, Question 7
What is the primary purpose of an operating system?
A. To replace the CPU
B. To manage hardware and software resources
C. To permanently store all user files
D. To increase the physical capacity of RAM
Correct Answer: B. To manage hardware and software resources
Rationale: An operating system acts as an intermediary between applications,
users, and computer hardware. It manages resources such as CPU time,
memory, storage, files, devices, and processes. It does not replace physical
hardware or permanently store every user file.
Question 8
Which operating-system function determines which process receives CPU
time?
A. Process management
B. File compression
C. Disk formatting
D. Device manufacturing
Correct Answer: A. Process management
Rationale: Process management includes controlling processes and
determining when they run. The operating system uses scheduling
mechanisms to allocate CPU time among processes. File compression, disk
formatting, and hardware manufacturing are not primary process-
management functions.
Question 9
pg. 4
