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KCSE 2025 Computer Studies Paper High Quality Prediction

COMPUTER STUDIES -

451//1 (THEORY)

JUNE 2024 – 2 ½ HOURS

MARKING SCHEME

Answerall the questions in this section in the spaces provided

List any THREE examples of Database packages popularly in use today. (3 marks)

MySQL

Microsoft Access

SQL server

FileMaker Pro

Oracle

dBASE

List any TWO functions of the Control Unit (2 marks)

Fetching instructions

Decoding instructions

Generating control signals

Managing execution

Coordinating data flow

Handling interrupts

Managing instruction cycle

Synchronizing operations

Mobile devices such as Smartphones and Tablets use an operating system.List any THREE types of operating system found in mobile devices. (3 marks)

Android

iOS

Symbian OS

iPhone OS

RIMs Blackberry

Windows Mobile

Palm Web OS.

A group of students are producing a class newsletter which they will email to parents of students in the class. The students have decided to use a smartphone. Data for the newsletter will be input, stored and output by the smartphone.

Identify any TWO devices that are part of the smartphone that could be used to input the data for the newsletter.(2marks)

Camera

Microphone

Touch screen

Many books contain a gutter margin. Explain gutter margin as used in word processing.(2marks)

Used as an extra margin

Adds extra space to the inside / top margin

Helps to ensure the text is not obscured by the binding

a)Distinguish between General Purpose computers and Special Purpose Computers (2 marks)

General purpose computers are computers that are able to perform a variety of tasks while Special purpose computers are computers that only do a specific task.Distinguishing 2 marks

b)Define toggle keys found on a standard keyboard, giving any TWO examples(2 marks)

Toggle keys are keys on a keyboard that switch between two functions each time they are pressed.

Common examples include the Caps Lock, Num Lock, and Scroll Lock keys

Ujuzi High School is about to set up a computer Laboratory. Advise them on three measures to take in order to ensure proper ventilation in the Room.

(3 marks)

Install Adequate Air Conditioning Systems:

Use of Windows

Proper Arrangement of Lab Equipment to allow air flow

Use of ventilation Grills

a) Define Virtual Memory.

Virtual memory is a memory management technique that extends the apparent capacity of physical RAM by using a portion of the hard drive as additional memory, allowing programs to operate as if there is more memory available than what is physically installed.

This enables efficient multitasking and handling of larger applications by swapping data between physical memory and disk storage as needed.

b)Name any ONE place where virtual memory may be found in a computer. (2 marks)

-hard disk

List any THREE differences between Cathode Ray Tube Monitors and Flat Panel Monitors (3 marks)

CATHODE RAY TUBE FLAT PANELS
Bell shaped Flat shaped
Has a poor resolution Has a high resolution
Heavier, hence less portable Light, hence more portable
Occupies more space Occupies less space
Cheaper Expensive
Produce a high amount of radiation Produces a low amount of radiation
Consumes more power Consumes less power

a)One of the factors to consider when purchasing computer hardware is warranty. List any TWO contents of a warranty.(2 marks)

scope of cover

callout response and liability agreement

preventive maintenance.

b)Distinguish between portability and compatibility as used in computer hardware.(2 marks)

Portability: Refers to the ease with which hardware can be physically moved and used in different location.

Compatibility: Refers to the ability of a piece of hardware to work with other hardware without requiring special adaptations or modifications.

Distinguishing 2 marks

A computer studies student is creating a movie, in school, for a project. He needs to take the movie home to edit it. The student decided to use solid-state memory card (SSD card) to transport the movie files. The student is unable to save the work on the memory card.

Give any TWO error messages that may appear when attempting to save the work(2marks)

Any two from:

Medium is full

Corrupt card

Write error

Card error

Card not initialized

Virus found on the card

Device not recognized

Mention any TWO advantages of serial cables over parallel cables for data transmission. (2 marks)

Cost less than other cables

Supports long-distance communication between devices.

Have fewer wires

Reliable for transferring data to long distances.

List any TWO ways that text can be made to fit in a text box in desktop publishing software(2marks)

Best fit

Shrink text on overflow

Grow textbox to fit

List any TWO application areas of artificial intelligence (2 marks)

Expert systems

Natural language processing

Robotics

Artificial neural networks

a)State any TWO functions of system software(2marks)

Booting the computer to ensure all hardware elements are working properly

Helps in storing and retrieving files

Perform various system utility functions

b)Differentiate between freeware and shareware with reference to software.(2marks)

Freeware software is provided to its users for free of cost while shareware software is provided to its users for a limited period of time after which the software is paid for.

SECTION B(60 Marks)

Answer question 16 and any other three questions in this section in the spaces provided

a)State any TWO differences between syntax error and logical error as used in programming.(4 marks)

Syntax error

Logical error

Result from improper use of language rules.

Result from improper sequence of events or formula

Detected by the language translator

Not detected by the language translator

b)The Figure below shows flowchart used to find the sum of even numbers in the first 10 natural numbers. Study it and use it to answer questions that follow.

Determine the output from the flowchart. Show your working.(4 marks)

Count Sum
1 0
2 2
3 2
4 6
5 6
6 12
7 12
8 20
9 20
10 30

Output = 30

Even number = 4 x ½ = 2

Ans = 30 (1 mark)

i)Write a pseudo code for the flowchart above.(7 marks)

Start
Sum = 0
Count = 1
Repeat
  If count = even number then
    Sum = sum + count
  End if
  Count = count + 1
Until count = 20
Output sum
Stop

a) List any TWO reasons why binary systems are used in computers.(2 marks)

Digital devices are smaller

Digital computers are reliable

Human language is complex for the computer to understand

Digital computers are power efficient

b)i) Convert 93CADF16 to its binary equivalent(2 marks)

9 – 1001 A – 1010 3 – 0011 C-1100 D – 1101 F – 1111 (1 mark)

93CADF – 1001 0011 1100 1010 1101 1111 2 (1 mark)

ii) Use the two’s compliment to solve: -3710 + 5110 (4 marks)

+37 = 00100111 (1 mark)

-37 = 11011000 (0ne’s Complement) (1 mark)

-37 = 11011000 + 1 = 11011001 (Two’s Complement) (1 mark)

11011001 + 00110011 = 00001100 2 (1 mark)

iii)Convert 10111111.011112 to its Octal equivalent(2 marks)

010-111-111.011-1102 (1 mark)

=277.368 (1 mark)

c) Give any TWO characteristics of a good system analyst.(2 marks)

Must have technical knowledge

Must have good communication skills

Must be good in problem solving

Must be business oriented

2 points for 1 mark each

d)Describe the THREE components of an expert system (3 marks)

Knowledge base Acts as the repository of expertise and provides the foundational data that the system uses to make decisions

Inference Engine: Interprets the data from the knowledge base to provide solutions or recommendations. It simulates the reasoning process of a human expert by drawing inferences based on the input data.

User Interface: Facilitates the input of queries or problems from the user and presents the system’s conclusions, solutions, or recommendations in a comprehensible manner. It ensures the user can effectively communicate with the system and understand its outputs.

Lawino opened her flash disk in one of the school’s computers using drive F. she had saved her work in a folder named “MINE”. This folder has subfolders for PICTURES, PERSONAL and AUDIO. In PERSONAL subfolder, there are files such as MyDocs.xlt and FamilyDocs.pff, while in PICTURES there are subfolders such as OFFICE and CHURCH.

a) i)Draw a directory tree structure for Lawino.(2 marks)

ii)In CHURCH subfolder there is a file named OldPicture.jpg. Write a path to this file. (2 marks)

F:\MINE\PICTURES\CHURCH\OldPicture.jpg

ii)She opened the file OldPicture.jpg, then decided to delete it. Explain what would happen. (2 marks)

She will receive a message saying “The action can’t be completed because the file is open in Paint. Close the file and try again”

b) i) One classification of operating systems according to user-interface is menu driven. Explain menu driven. (2 marks)

A menu-driven interface is a type of user interface where users interact with a program or system through a series of menus. These menus present options or commands that the user can select, typically through the use of a pointer, keyboard, or touchscreen, simplifying the interaction with the system.

ii)Describe, with the help of an example, transcription errors. (3 marks)

Transcription errors Are errors that occur during data entry caused by either misreading or mistyping of data. (2 marks)

They are caused by incorrect reading of the source documents by the user and hence entering of the wrong text or digits. E.g.Misread 589 and write S89 i.e. misread ‘5’ for ‘S’

Or

When two digits or letters are swapped around. i. putting them in the wrong order. e.g entering 396 instead of 369.

c) In the academic office of our school, there is a master file and a reference file.

i) Distinguish between a master file and a reference file. (2 marks)

A master file isthe main that contains relatively permanent records about particular items or entries. While

A reference fileis mainly used for reference or look-up purposes. Look-up information is that information that is stored in a separate file but is required during processing.

ii) For each of the files above (i), name any TWO pieces of information that can be held in each of them in relation to school.(2 marks).

An example of a master file is a student file containing details of a student such as student ID, name, Date of Admission and contact address.

An example of a reference file is school grading list,mark range of students in the school, etc.

A mark for two examples of each. (1 mark)

(a)(i) The formula B2+$C$2 was entered in cell D2 then copied to cell F2. Show the new formula in cell F2 and give a reason for your answer.(2 marks)

B2: This is a relative reference. When copied to cell F2, it will adjust two columns to the right, becoming D2.

$C$2: This is an absolute reference. It will remain unchanged.

Therefore, the new formula in cell F2 should be: D2+$C$2.

(ii)State the meaning of each of the following terms as used in spreadsheets:

Countif ( ) (2 marks)

Counts number of cells within a specified range that meets a given condition or criteria.

(B) Max ( ) (2 marks)

Returns the highest value in a set of values

(b)(i)Explain two types of documentation produced when developing a system by a system analyst.(2 marks)

User–oriented documentation – assist users learn how to use the system.

Technical–oriented documentation – assist programmer and system analyst during maintenance of system.

(c)Nosim has developed a computerized system for a school and currently in its change over stage, where the new system is introduced in a department then tested to ascertain its effectiveness and once its performance is satisfactory it is implemented in the entire organization.

(i)Identify the changeover strategy used.(1 mark)

Piloting

(ii) Explain any two advantages of the changeover strategy identified in (i)above.(4 marks)

Reduces risks of data loss

System tested thoroughly

Provide platform to train all the employees of the organisation

Cheaper to train employees

Arosy bought a smartphone. Smartphones can be connected using wired or wireless methods.

a)i)Give two disadvantages, to Arosy, of using a wired method to connect to the smartphone. (2marks)

Cannot move around (while transferring data)

Have to waste time finding/connecting cables

Cost of cables / more expensive

Health and safety issues (trailing wires).

ii)Give two disadvantages to Arosy of using a wireless method to connect to the smartphone.(2marks)

Slower / lower bandwidth / higher latency

Shorter range

Less stable connection

Interference (e.g. dropped packets, loss of data) / Affected by obstructions

Less secure

Requires a password

Increased demand on battery life.

b) The diagram shows how a network is connected to the internet.

i) Identify the hardware device labelled A on the diagram.

Device A (1 mark)

Router / gateway / modem

ii) Identify any TWO types of connections that can be used to connect the company network to the internet.(2marks)

Broadband

Dialup

VPN

Wi-fi

Satellite

c) i) What is an ISP? (2 Marks)

An internet service provider (ISP) is a company that provides access to the internet. ISPs can provide this access through multiple means, including dial-up, DSL, cable, wireless and fiber-optic connections.

ii) Give four examples of ISPs found in Kenya.(2 Marks)

Safaricom.

Faiba.

Zuku.

Telkom.

Airtel.

d)Security solutions prevent read and write access to data, which provides very strong protection against tampering and unauthorized access.

Explain the following terminology as used in data security (4 Marks)

i) Cypher text

Ciphertext is encrypted text transformed from plaintext using an encryption algorithm. Ciphertext can’t be read until it has been converted into plaintext

ii). Piracy

Software, information ; data are protected by copyright laws. Piracy means making illegal copies of copyrighted software, data, or information either for personal use or for re-sale.

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