KCSE Revision Resources

Define the following

(a) Cookies

(b) Spyware

(c) Phishing

(d)Spam

(e) Pharming

(a) Cookies

Information that a website stores about a user on their hard disk; this enables
the website to remember details about the user when they next visit the website.

(b) Spyware

Program installed on a PC to gather information about the user. It monitors
every key press and relays the information back to the home base

(c) Phishing

Sending an email that claims to be from a legitimate company; the recipient is then directed to a bogus website where their personal details will be collected

(d)Spam

Junk/ (unsolicited) electronic mail advertising products and services sent to a general mailing list.

(e) Pharming

Malicious code installed on a PC or on a server. This code directs users to a
a fraudulent website without their knowledge.

How many hard disks are required to implement RAID 10?

4 (four)

A school opted to use direct changeover approach when installing a new system. Explain three challenges that the school may face as a result of this approach (KCSE 2019)

The users may not have gained enough confidence to run the new system

It may be very inconveniencing in case the new system fails or faces problems

The weaknesses of the old system may not be corrected or may still be transferred to the new system

Name two other input/output devices used at the POS terminal apart from keyboard and barcode reader and give a use for each device.

device: beeper/loud speaker
use: to indicate barcode correctly read/error in reading barcode
device: (LCD) screen/monitor
use: to show prices and other information about goods
device: touch screen
use: to show prices and other information about goods/to select items that need to be
weighed/identified
device: weighing machine
use: to find weight of loose items (e.g. fruit) to enable pricing
device: (magnetic) card reader/CHIP and PIN reader
use: to read customer’s debit/credit card/enable customer to pay for goods using a
credit or debit card
device: printer
use: to print receipts

Differentiate between object code and source code

Object code refers to a program in machine language while source code to a program in a high level language that must be translated to object code for it to be machine readable

One characteristic of a robot is its mechanical structure.
State two other characteristics of a robot

It has electrical components.

It is programmable.

Aeroplanes now use Global Positioning Systems (GPS) to determine their location.

Describe how the computer on board the aeroplane uses GPS to find its exact location

Give two benefits of using GPS in this application

Describe how the computer on board the aeroplane uses GPS to find its exact location

– satellites transmit signals to onboard computers
– computers receive/interpret these signals
– system depends on very accurate timing/use of atomic clocks
– each satellite transmits data indicating location and time
– computer in aeroplane calculates location based on at least three satellites
– at least 24 satellites in operation at any one time
– position accurate to within one metre
– can also calculate altitude of aeroplane
– ref to “triangulation”:

Give two benefits of using GPS in this application

– safer as the known location is exact/more accurate
– reduces the possibility of pilot error
– allows accurate estimation of arrival time
– display and guide the pilot to the nearest airport in case of emergency

Explain the Fetch – Execute cycle and provide an example of a Central Processing Unit (CPU) component for each stage of the cycle

The Fetch – Execute cycle is a sequence of actions, performed by the processor as it fetches
a program instruction from its memory, determines what the instruction wants to do and
carries out those actions. The stages of the cycle are provided below.

Fetch the instruction – the processor fetches the instruction from a memory address stored in a program counter and transfers the instruction, via a data bus, to an instruction register. At the end of the fetch operation, the counter points to the next instruction that will be read in the next cycle.
Decode the instruction – the processor decodes the instruction stored in the instruction register, including getting any operands required to complete the instruction.
Execute the instruction – the decoded instruction is executed.
Store the result – the result generated by the execute phase is stored in the main memory, and/or sent to an output device. The program counter is updated with feedback from the arithmetic logic unit (ALU), to a different address from which the next instruction will be fetched.

A workshop has a lot of heavy machinery operating throughout the day and requires a cable to connect a workstation to a switch. Which of the following, unshielded twisted pair (UTP) or shielded twisted pair (STP) cable, would be the more suitable? Justify your response.

Shielded twisted pair cable:
A twisted pair cable is made up of four pairs of twisted copper wires, a shielded twisted pair cable applies a shield to each one of the pairs on a cable or to all of the pairs together. This shield can reduce EMI (electromagnetic interference), which would be emitted from heavy machinery. This increased data transmission quality in the workshop. STP can also reduce crosstalk.

List three types of errors that are likely to exist in a program (3 marks)

Syntax errors-Incorrect use of programming language

Logical errors- The program do not give the expected output

Runtime errors- Premature end of a program

Internet and E-mail Questions

Define the term internet 1mk

The global interconnection of computer networks for purpose of communication and resource sharing

Explain the term web page 1mk

A hypertext page prepared to display the content on the web

Explain the following internet address http://www.google.co.us in reference to the structure of a URL 3mks

HTTP- hypertext transfer protocol or simply protocol
WWW – subdomain
google – the name of the computer with the web content/domain name
.co – top level domain for commercial organization
.us- a TLD extension for the country US

What is the world wide web 1mk

A virtual space on the internet that allows web pages and sites to be accessed

Define the term browser 1mk

A software that used viewing of web content

Explain the meaning of the word hyperlink 1mk

A text or picture that is a link to another webpage on the internet

What is a search engine? 1mk

Is a special program that collects and stores links to information websites allowing users to search its database for them
A specialized web-based application that help the user to search for specific information on the internet.

Explain the meaning of the term internet service provider 1mk

A company that offers internet services to end-users

Identify three elements apart from a computer that is required for one to be connected to the internet 3mk

Modem
Internet software
Internet service provider
Telecommunication lines
TCP/IP protocols

Define the term modem 1mk

Stands for modulator-demodulator
A device that enables telecommunication to use telephone lines

What is a protocol? Write the following in full: TCP/IP, HTML, HTTP and FTP 5mks

Protocols – are special communication rules that govern sending and receiving of messages by computers on a network
Html – hypertext markup language
Hypertext transfer protocol
Transmission Control Protocol
Internet Protocol
File Transfer Protocol

What would you do if a website refused to load on the browser within the first attempt? 1mk

Click the refresh button on the toolbar

State three internet services 3mks

Instant messaging
E-mails
E-commerce
Social media and networks
E-learning

Define the term internet telephony 1mk

Transmission of voice data over the internet

State three benefits of the internet in our society

Provides a platform for conducting business and marketing
Provides many platforms such as social media through which people can contact each other
Cost saving
Efficient communication

Define Data Security

Is the protection of programs and data in computers and communications systems against unauthorized modification, access or disclosure

State three types of optical disks

compact disks

DVDs

Blue Ray

Explain the term proofreading as used in word processing (2mks) [kcse 2017 Paper 1]

It is the use of proofing tools like spelling and grammar checkers and autocorrects to check whether a document has typographical or grammatical errors

Give any three advantages of computer networks

Enable resource sharing
Facilitate remote communication
Enable distributed processing
Provide better data security and management

State the difference between radio waves and microwave transmission

Radiowaves are omnidirectional while microwaves propagate in one direction at a time(unidirectional)

Radiowaves can be propagated over long distances through sky mode while microwaves require a relay satellite to amplify and retransmit the microwaves signals to the receiver earth station

What is a source code as used in computer programming?

It is a program written in a high level langauage

Data integrity in a database can be divided into three categories: referential integrity, domain integrity and entity integrity.

(a)Outline the meaning of each of the following.

(i) Referential integrity

(ii) Entity integrity

(b) Describe how data integrity can improve the process of database management. (2 marks)

(i) Referential integrity

Two entities that are related require that a foreign key must have a matching primary key

(ii) Entity integrity

Entity integrity specifies that the Primary Keys on every instance of an entity must be kept, must be unique and must have values other than NULL

(b) Describe how data integrity can improve the process of database management. (2 marks)

Data integrity is the maintenance of, and the assurance of, data accuracy and consistency over its entire life-cycle and is a critical aspect to the design, implementation, and usage of any system that stores, processes, or retrieves data
The overall intent of any data integrity technique is the same: ensure data is recorded exactly as intended (such as a database correctly rejecting mutually exclusive possibilities)

IT technicians are setting up a new file server for a school. Describe the benefits and drawbacks of using a command line interface (CLI) rather than a graphical user interface (GUI) to set up a new file server. (4marks)

Benefits

The user is not restricted to the predetermined options//the GUI uses icons and set menus
The user has more control over the computer settings//in GUI computer settings are protected from the user
Uses less memory than GUI
Requires less processing power for the interface
More processing power is made available for the task

Drawbacks

The commands used have to be learnt
The commands used have to be remembered
The commands used have to be typed in/entered exactly
Have to remember the exact path/correct name of application
More prone to errors on data entry Commands have to be typed in//in a GUI can use touchscreens/mice
Tends to be used by specialist people//GUI is more user-friendly and can be used by non-experts

Describe four features of the operating system when providing a graphical user interface on a personal computer. Give a suitable example of each feature.

Windows for example a word processing application and a spreadsheet

Menus, for example, allow the user to perform operations or run applications such as right-click to create a new folder

Icons for example a picture of linked computers for networking

Pointers(mouse or touchscreen) for example to select items/trigger events

Shortcuts for example to frequently used applications for example having a shortcut to your mail client on your desktop

File navigation for example when searching the hard disc for a file/folder using a browser

copying / deleting / moving/sorting/naming/searching of files or folders for example copying of a file from the hard drive to a USB pen drive (File handling)

Desktop customisation for example changing the colours and background image

Copy and paste for example between applications e.g. copying a graph from a spreadsheet to a word processor

Error messages for example provide users with error/warning/help messages for example ‘printer out of paper’

Q&A-KCSE Computer Studies Paper 1

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