Basic components of a computer system

Correct answer: C. Uninterruptible power supply

Explanation: The governing concept is short-term power backup. An uninterruptible power supply, or UPS, contains a battery and changes to battery power when the main supply fails, allowing the computer to continue briefly and giving the user time to save work and shut down safely. A joystick controls games, a webcam captures video, and a graphics card processes images; none supplies backup electricity. Therefore, option C is correct.

Correct answer: D. Expansion slots

Explanation: The governing concept is motherboard expansion. Expansion slots are electrical connectors on the motherboard designed to accept add-on cards, such as graphics, sound, network, or other interface cards. They allow a computer to gain new capabilities or be upgraded. File extensions describe file types, memory sectors refer to storage organization, and audio ports connect sound devices rather than internal cards. Thus option D is correct.

Correct answer: A. Receiving data and instructions

Explanation: The governing concept is the input-process-output cycle. The input unit receives raw data and instructions from a user or an input device, such as a keyboard, mouse, or scanner, and passes them to the computer for processing. Printing results belongs to the output unit, permanent file storage belongs to secondary storage, and supplying electricity is the power supply's role. Therefore, option A is correct.

Correct answer: B. Output unit

Explanation: The governing concept is the output stage of the input-process-output cycle. After the CPU processes data, the output unit communicates the resulting information to the user in a usable form. A monitor displays it, speakers produce sound, and a printer makes a paper copy. Storage keeps data, the control unit directs operations, and the power unit supplies electricity; therefore option B is correct.

Correct answer: C. Arithmetic and Logic Unit

Explanation: The governing concept is the internal organization of the CPU. The Arithmetic and Logic Unit, abbreviated ALU, performs numerical operations such as addition and subtraction and logical operations such as comparisons. The memory unit stores data and instructions, the input unit accepts data, and the power supply provides electricity rather than processing values. Hence option C is the only correct answer.

Correct answer: D. Coordinating the activities of other units

Explanation: The governing concept is CPU coordination. The control unit fetches and interprets instructions, then sends control signals so the arithmetic-logic unit, memory, input, and output units act in the proper sequence. It does not itself serve as a sound player, printer, or long-term file store. Those choices describe peripheral or storage functions, whereas coordination is the control unit's central role. Therefore option D is correct.

Correct answer: A. Registers

Explanation: The governing concept is the CPU memory hierarchy. Registers are tiny storage locations inside the processor that hold operands, instructions, addresses, or intermediate results needed immediately. They provide faster access than cache, RAM, or secondary storage, although their capacity is very small. A hard disk, pen drive, and optical disc are non-volatile storage devices outside the CPU and are much slower. Thus option A is correct.

Correct answer: B. RAM

Explanation: The governing concept is volatility. RAM is volatile primary memory: it temporarily holds programs and data currently being used, but its electronic contents generally disappear when electrical power is removed. ROM, a solid-state drive, and a hard disk are non-volatile, so they retain stored information without continuous power. Although SSDs use memory chips, they preserve data; therefore option B, RAM, is correct.

Correct answer: D. Cache memory

Explanation: The governing concept is the memory hierarchy. Cache memory is a small, high-speed memory located close to or within the CPU and used to keep frequently needed data and instructions. By serving these requests faster than RAM, it reduces CPU waiting time. A hard disk, pen drive, and optical disc are slower secondary-storage devices and are not the fast intermediary described. Therefore option D is correct.

Correct answer: B. Heat sink

Explanation: The governing concept is thermal management of the processor. A heat sink is a metal component, commonly made from aluminium or copper, that draws heat away from the CPU and spreads it through fins over a larger surface area. This allows heat to dissipate, so option B is correct. A fan moves air across the heat sink and improves cooling, but it is not the metal heat-spreading component itself. RAM and a modem perform different functions.

Correct answer: D. Graphics card

Explanation: The governing concept is specialized processing by expansion cards. A graphics card contains a graphics processing unit, or GPU, that handles visual calculations and prepares images and video frames for display. Thus option D is correct. A network card manages data communication, a sound card processes audio signals, and a modem converts signals for network access. Although the CPU can also process graphics tasks, the graphics card is the dedicated visual-processing expansion card.

Correct answer: C. Solid-state drive

Explanation: The governing concept is non-volatile internal storage. A solid-state drive, or SSD, stores data on flash memory and generally retains it when the computer is switched off, so option C is correct. RAM, registers, and cache are volatile working-storage areas used during processing; their contents are normally lost when power is removed. An internal SSD is therefore a suitable example of permanent or secondary storage.

Correct answer: A. Magnetic Ink Character Recognition

Explanation: The governing concept is specialised character-recognition technology. Magnetic Ink Character Recognition, or MICR, reads the specially printed magnetic-ink characters along the lower part of bank cheques, so option A is correct. OMR detects filled marks on forms, OCR recognises ordinary printed characters, and barcode recognition decodes patterned bars. The banking and cheque context specifically identifies MICR.

Correct answer: D. Biometric input device

Explanation: The governing concept is biometric authentication, in which a computer captures a measurable and distinctive human characteristic. A fingerprint or face scanner collects this feature as input and compares it with stored reference data, so option D is correct. An output device presents results, a storage device saves data, and a cooling device controls temperature. Those categories do not describe identity capture.

Correct answer: C. Laser printer

Explanation: The governing concept is matching printer technology with workload. A laser printer uses a laser, imaging drum, and toner to produce pages rapidly and with relatively little operating noise, making option C correct for high-volume document printing. Dot matrix printers are impact-based and noisy, inkjet printers are better suited to moderate jobs and colour detail, and plotters are designed for large technical drawings rather than routine page volumes.

Correct answer: A. Keeping the system clock and basic settings

Explanation: The motherboard battery, commonly called the CMOS or RTC battery, supplies a small amount of power when the computer is switched off. It helps preserve the real-time clock and certain firmware settings, such as basic configuration information. It does not power the monitor, operate a printer, or increase RAM. Therefore, option A correctly describes its main purpose.

Correct answer: D. Bus

Explanation: In computer architecture, a bus is a set of communication pathways that carries data, addresses, and control signals between components such as the processor, memory, and input-output devices. A folder organizes files, a shortcut points to a resource, and a cursor indicates a position on the screen. These do not provide internal data communication. Hence, option D is correct.

Correct answer: B. Primary memory supports active work while secondary storage keeps data for long-term use

Explanation: Primary memory, especially RAM, gives the processor fast access to programs and data currently in use. It is generally volatile, so its contents are lost when power is removed. Secondary storage, such as an SSD, hard drive, or pen drive, is intended to retain files for long-term use. Therefore, option B is accurate; the other statements confuse device roles or permanence.

Correct answer: C. When the computer slows while many programs run together

Explanation: RAM is fast temporary memory used to hold active programs and the data they need. When several applications run at once, insufficient RAM may cause the operating system to move information to slower storage, making switching and multitasking sluggish. Adding RAM can reduce this pressure when the system supports an upgrade. Dust, missing printer paper, and mouse-pad size do not determine RAM capacity, so option C is correct.

Correct answer: D. Monitor and video cable

Explanation: When the computer appears to run but the screen is blank, the first practical checks are whether the monitor has power, the correct input is selected, and the video cable is firmly connected at both ends. These checks target the visual-output path directly and are simple and safe. A microphone, printer, or speaker cannot display the computer image. Thus, option D is the most appropriate first check.

Correct answer: B. Hardware, software, data, and user

Explanation: A computer system is more than its physical parts. Hardware provides the equipment, software supplies instructions, data is the information being processed, and the user gives commands or uses the results. These elements work together to perform useful tasks. Hardware alone cannot operate meaningfully, and internet, modem, monitor, or printer combinations are incomplete. Therefore, option B gives the most accurate combination.

Correct answer: A. Motherboard battery

Explanation: The governing concept is that the motherboard, or CMOS/RTC, battery supplies a small amount of power to the real-time clock even when the computer is switched off. If this battery is weak or exhausted, the stored date and time may reset or become inaccurate after shutdown. Therefore, option A is correct. A graphics card processes display images, while a speaker and scanner handle sound output and image input; none maintains the system clock.

Correct answer: B. Expansion slot

Explanation: The governing concept is hardware expansion: a graphics card is an add-on circuit board that communicates with the computer through a compatible expansion slot, commonly a PCI Express slot on modern motherboards. Thus, option B is correct. A memory slot is designed for RAM modules, the processor socket holds the CPU, and an audio port connects sound equipment. Those parts cannot provide the proper interface for installing a graphics card.

Correct answer: A. Fetch, then Decode, then Execute

Explanation: The governing concept is the CPU instruction cycle. First, the control unit fetches the next instruction from memory; second, it decodes the instruction to determine the required operation and operands; third, the CPU executes it through the appropriate unit. Therefore, option A gives the correct Fetch–Decode–Execute sequence. The other choices either place stages in the wrong order or include printing, scanning, storing, or deleting, which are not the standard three stages.

Correct answer: B. Direct and coordinate instruction execution

Explanation: The governing concept is the control unit’s coordinating role within the CPU. It fetches and decodes instructions, then sends timing and control signals so the arithmetic logic unit, registers, memory, and input/output devices perform their parts in the proper order. Therefore, option B is correct. Permanent image storage belongs to storage devices, printing belongs to an output device, and sound generation belongs to audio hardware rather than the control unit.