Virus / trojan / worm / malware

• Piece of software/code/a program that replicates itself  or causes damage e.g. editing/deleting files

Prevention

• Running anti-virus/anti-malware software 
• don’t download from unknown sources
• don’t click on unknown links

Spyware / malware / keylogger

• Piece of software/code/a program that records actions/key presses and sends this data to a third party analysis

Prevention

•  Running anti-spyware/anti-malware software/firewall

Data interception / passive

• Data is sent to another device and is intercepted by a third party

Prevention

• Encryption

Phishing

• An e-mail has a link that when clicked directs the user to a fake website that collects personal data

Prevention

• Network policy // firewall

Pharming

• A piece of code installed that redirects user to fake website that collects personal data

Prevention

• Anti-malware or firewall

Hacker

• Person attempting to gain unauthorised access to the network/computers/ data/files 
• unauthorised access and then deleting/editing data/files

Prevention

• Firewall
• strong password 
• biometrics
• penetration testing

• A laser printer makes use of powdered ink and static electricity to print
• Unlike inkjet printers which print line-by-line, laser printers print the whole page in one go

Steps

• The data from the  file to be printed is sent to a printer driver
• The printer driver checks that the data is in an understandable format
• The printer driver checks if the printer is able to carry out the print job
• The data is sent to the printer and is stored in a printer buffer
• A printing drum in the printer is given a positve charge. A laser beam removes the positive charge in some areas. This leaves negatively charged areas which matches the characters/images to be printed
•  

• It refers to a computer that controls other computers in a network and monitors user's access to the shared resources.

SECTION A (40 MKS)

Answer all the questions in this section in the spaces provided.

1.Describe the computer booting process.    (2 mks)

2. State the functions of the following keys on the computer keyboard   (2 mks)

  a) Backspace

  b)Insert (ins)

3. Jane has noticed the following problems with her computer keyboard    (2mks)

• It is taking a longer time to start-up;
• It is often hanging;
• Applications are taking longer to load.

 State three possible causes of these problems and how they can be solved (3mks)

4 a)Define authenticity as used in software selection  (1mk)

  b) List four ways of acquiring software in an organization     (2mks)

5 some of the storage disk available are:  zip disks, 3 ½ inch floppy disks, DVDs and 5 ¼ inch floppy disks. Arrange these devices in ascending order of storage capacity.    (2mks)

6.You have been asked to change your computer password. State a precaution you need to take in order to avoid each of the following:           

a) Forgetting the password     (1mk)

b) Hacking       (1mk)              

7.State four benefits of using a computer in a school library   (2 mks)

8. Using six bits, find the two’s complement of -2310.     (4 mks)

9. Explain data series, axis and legends as used in spreadsheet charts.  (3mks)

• Data

• Axis

• Legend                       

10. a) Describe the term data integrity.                                            (2 mks)

     b) State four situations in which data may lose integrity.           (2mks)

11.State the function of each of the following:

            a)Network interface card                                                           (1 mk)

            b)Network protocol                                                                    (1 mk)

           c)Hub                                                                                         (1mk)  

12. List four types of publications that can be designed by using desktop publishing software.   (2mks)

13. Differentiate between the following pair of terms as used in database design:

    a)  Input mask and design.                                                           (2 mks)

    b) Table and query                                                                      ( 2mks)

14. List four factors to be considered when purchasing an operating system.     (2mks)

15   Write an algorithm to compute the area of a triangle.   (2mks)

SECTION B (60 MARKS)

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

16. Study the flowchart below and answer the questions that follow

i) Name the control structures used in the flowchart                 (2mks)

ii) Determine the values of M, N, P and Q.                                ( 4 mks)

M………………………….. N………………………..

P ………………………….. Q ………………………

  iii) Write the pseudo code for the flowchart   (7mks)

 b)  List four functions of an assembler    (2 mks)

17. Define the following web related terms:       

 i)  Web browser   (1mk)

 ii)  Hyperlink      (1mk)

iii) Hypertext document                (1mk)

b)  List six activities performed on the web      (3mks)

c) An institution has ten stand alone computers

i)  Suggest with reasons the most appropriate topology required to inter-connect the computers.   (3mks)

ii) State the necessary steps required to connect the computers to the  internet.      (4mks)

d) Below is an email address:

Name the parts labeled:

                        i)

                        ii)

                        iii)

18.A computer C directory has folders for form 1, form 2, Form 3 and form 4.  Each class has student’s folders labeled according to their number.  The students create their own folder for the subject the are studying based on the table shown below

a)Assuming there is one student per class, draw the corresponding directory tree structure.  (6 mks)

b) i)  a form four student wants to create a folder to store her project. State the path for that project folder.(2 mks)

ii)Suggest how the student can ensure that:

                        1.         Work is not lost in case the hard disk fails.                (1mk)

                        2.         The project is not copied by other students.               (1mk)

c) i).  Other than I/O devices, list other three devices under the control of the operating system.                                                  (3mks)

 ii)Explain any one of the devices named in C (i) above            (1mk)

d)Define the term trouble shooting    (1mk)

19. A manager wishes to replace the current manual system with a computerized one

 a)Describe three main areas that must be evaluated to justify the  replacement   (6mks)

b) List the three areas that would be considered in the requirements specifications.      (3mks)

c)State and explain three ways that can be followed to replace the current system    (6mks)

20. a)  A head teacher keeps the following student details in a database:  Name, Address, Town, Date of Birth, Marks scored, Fees paid.

i)Name the most appropriate primary key. Give a reason      (2mks)

ii)For each item in the student’s details above, indicate its most appropriate data type as used in the database.           (3mks)

iii)Explain why input screens are better data entry designs than entering data directly to a table.        (2mks)

b)List two career opportunities associated with databases.       (2mks)

c)Distinguish between:

i) A table in a word-processing application and a table in a database application (2mks)

ii)Mouse pointer and insertion point.    (2mks)

d)Outline the steps to be followed in order to merge cells in a word processing table.    (2mks)

State the characteristics of each of the following network topologies (KCSE COMPUTER STUDIES 2021 )

i) Mesh Topology  (2mks)

• a host/node is connected to one or multiple hosts
• a   host/node in point to point connection with every other host or a few hosts
• hosts/nodes in mesh topology also work as relays for other hosts which do not have point-to-point links

(ii) Ring Topology (2mks)

• each host/node connects exactly to two other hosts
• data travels around the ring in one direction through all intermediate hosts
• failure of any host results in the failure of the whole ring

High level languages are used in situations when:

1. Speed of execution is not a critical factor, such as in office applications.
2. a programmer needs to use complex commands that perform complex tasks.
3. A programmer wants to make use of standardised library / sub routines.

Low level languages are used in situations when:

1. a program must execute quickly such as real time applications
2. a programmer needs to write code that interacts directly with the hardware, such as device drivers
3. a programmer needs to perform a specific command not available in a HL language.

1. Availability in the market
2. Initial and maintenance cost
3. User friendliness
4. Compatibility
5. User needs

Taking a four-digit 0  binary number i.e (0000)2

In ones complement this is  1111

In twos complement this becomes 1111+1= 0000

So, It is clear that 0 and negative zero is the same in twos complement while in ones complement they are two different values

• Refers to the scrambling of data into unreadable form before transmission over a telecommunication media  OR
• transformation of data from plaintext to ciphertext

Advantages

• no wires
• fast/high-speed wireless Internet access
• WLAN is faster than a modem or mobile
• WLAN for working at home one day a week/teleworkers
• see internet content away on the move
• create and send multimedia messages to mobiles or e-mail
• picture messaging - send photos/pictures text/sound/recorded
• greetings from mobiles to mobiles/PCs
• instant transmission - no busy signals/no searching for phone jacks
• download e-mail and file attachments on mobile
• watch live webcast on mobile/hotspot
• listen to streaming video on mobile/hotspot
• news/weather/sport/games while on the move
• access information from mobile anytime
• send/receive/delete e-mail while on the move
• wireless Inbox on mobile - to contacts and calendar
• view business appointments while out of the office on mobile
• send corporate e-mail while out of the office - even behind a firewall on mobile
• wireless internet connection from chat rooms for discussions with colleagues while on the move
• give visual demonstrations from mobile and colleagues watch back at the office

 disadvantages e.g.

• WLAN speeds are slower than Net access at work/narrow band width
• any one within the WLAN nodes range with an appropriate device can use your WLAN and broad band link
• any one who walks past your house or WLAN linked into a corporate system can access sensitive information or credit card details
• 3G phones not compatible with 2G phones
• Blue tooth - has limited range
• blocked signal/distorted signal/weak signal/lag
• health problems from microwaves

• More RAM will improve the performance of the computer 
• More RAM will speed up the access to data
• Excessive use of VM can cause disk thrashing which decreases performance
• VM is slower to access than RAM direct (because it has to go back to RAM first)
• Moving data between RAM and VM takes processor time

Branch of computer science based on enabling computers to
behave like humans/mimic aspects of human intelligence
• AI is implemented in software.
• Combines psychology, biology, linguistics, mathematics, neuroscience,
and philosophy (ethics)
• AI is not the same as the general intelligence of human beings

Uses – Any of the following:
• Game playing (chess, quiz, video games)
• Analytics (analyse buying patterns, predicting behaviours, predictive
text, financial markets)
• Image processing (recognising objects/patterns)
• Logistics (scheduling, order fulfilment)
• Control systems (cars, manufacturing, weapons, navigation)
• Expert systems (medical, mechanical, electrical diagnosis)
• Neural networks (simulating neuron behaviours as in brains)
• Natural languages processing (chatterbots, chatbots, speech
recognition)
• Robotics (dangerous situations, help aged or disabled)

Ethical issues – Any of the following:
• Take the work of humans, thereby affecting employment rates
• Is a computer to be trusted to make decisions (life-death)?

• If a computer discovers something that humans can’t prove, should it be
accepted as truth?
• Do AI machines have rights?
• Will people be comfortable interacting with machines that are
considered intelligent?