Published on February 20th 2025 | 31 mins , 6158 words
COMPUTER STUDIES
PAPER 1
MARKING SCHEME
1. The development of computers can be traced to the time when historical non-electronic computing devices were invented, like the abacus. Name four other such devices. (2 marks)
- Napier bones
- Analytical Engine
- Wearing loom
- La pascaline machine
- Punch card
ii. Using illustration differentiate between analogue and digital signals. (1 mark)
2. State any two devices that can work as both input and output devices. (1 mark)
- Smart board
- Touch screen
- Digitizer
- Digital camera
ii. State factors that determine the speed of a computer. (3 marks)
- Processor speed / computer system clock
- Bus bandwidth
- Memory size
3. The diagram below represents the essential features of a computer system. Study the diagram and answer the questions that follow:
(i) Name the following components. (2 marks)
A Input device
B Control unit
C Arithmetic Logic Unit
D Main memory
(ii) On the diagram above, indicate the direction of data flow using arrows. (1 mark)
4. (i) Differentiate between the two types of Ram. (2 marks)
| | STATIC RAM | DYNAMIC RAM
| a | Does not require refreshment since it does not discharge | Require refreshment since it keeps on discharging
| b | Faster to access data | Slower in data access
| c | Expensive to acquire | Cheap to acquire
ii) Differentiate between LPT port and RS232 port. (2 marks)
| | LPT PORT | RS232 PORT
| a | Allows for transmission of group of bits at the same time | Allow for transmission of data single bit at a time
| b | Faster in data transmission | Slower in data transmission
| c | Preferred for short distance transmission | Preferred for long distance transmission
iii) Explain why gas plasma display are preferable compared to LCD monitors in entertaining places or social places. (1 mark)
- In case the monitor is inverted the l.c.d images suffers from Angle distortion whereas inverting the gas plasma has no effect on the images
5. State four problems that may occur during printing and how to solve them. (2 marks)
- lack of two way communication due to poor installation - install new drivers
- paper jams due to poor paper quality or paper folds - use high/good paper quality
- poor quality print due to poor ink / toner - use good quality ink/toner
6. Highlight three acts of parliament or laws that govern the use of ICT in Kenya. (3 marks)
- The Kenya Science and Technology Act Cap 250 of 1977
- The Kenya Broadcasting Corporation Act of 1988
- The Kenya Communication Act of 1998
7. List 3 types of job opportunities that are available in the field of computer hardware. (3 mks)
- Network Administrator
- Computer Technician
- Computer Engineer
8. Suggest two ways of enhancing data integrity. (2 marks)
- Backing up of data on external storage media
- Password to restrict access to data
- Use of direct capture method to input data
- Design user interfaces to minimize chances of invalid data entry
- Using error detection / correction software when transmitting data
9. Explain the following data control measures against computer crime. (2 marks)
Audit trail - is a record that shows who accessed the computer system and what operations on which at what time
Audit trail - Monitoring the system to identify weak points and reinforce them to improve the security
Audit trail - is a register of every actions, event or activity that a user or a system did with your data
Data encryption - Mixing up of data in form that only the sender and the receiver are aware of the Algorithm to use to get the original message
Log files - Creating of account with username and password to allow one access the system and monitor what the user does while in the system until they log off.
Passwords - Combination of characters to be used to restrict access to a certain system
10. Highlight four features of user friendly program (2 marks)
- Rapid access
- Ease of update
- Economy of storage
- Simplicity of maintenance
- reliability
11. Using place value method, convert the following to denary. (2 marks)
76CD16 A 10
B11
163 162 161 160 c12
76 C D16 = 7 x 163 + 6 x 162 + 12 x 161 + 13 x 1 D13
= 28672 + 1536 + 192 + 13
= 3041310
1238
82 81 80
1 2 38 = 1 x 82 + 2 x 81 + 3 x 80
= 64 + 16 + 3
= 8310
12. Identify four application areas of Artificial Intelligence. (3 marks)
- Artificial neural networks
- Robotics
- Expert systems
- Natural language processing
13. Distinguish between baseband and broadband. (2 marks)
-Baseband - A digital signal that is generated and applied to the transmission medium directly without modulation
- Broadband - An analog signal is sent over the transmission medium using a particular frequency.
- many signals can be sent together using different frequencies
14. State the purpose of the following field properties in DBMS. (2 marks)
Input mask - It determines how data is displayed during data entry and editing
Validation rule - A condition or restriction written to test data entered in a field
- It ensures that data entered meets a certain criteria
15. Name four data management tools used in spreadsheets. (2 marks)
- Filtering
- Sorting
- Input validation
- Subtotals
- Data entry forms
16. Study the following pseudo code and answer the questions below.
X = 10 X Y R Q (i)
Y = 5 10 5 15 10
R = X + Y
INPU Q R = 10 – 5 = 5
IF Q IS GREATER OR EQUAL TO R Y = 5 + 10 = 15
Y = R - Y
X = R + Y
ELSE
R = X – Y X Y R Q (ii)
Y = R + X 10 5 15 23
ENDIF Y = 15 - 5 = 10
PRINT R, Y, X X = 15 + 5 = 20
- i. Give the output if: (4 marks)
Q = 10
R = 5 Y = 15 X = 10
Q = 23
R = 15 Y = 10 X = 20
ii. Draw a flow chart for the above pseudo code. (6 marks)
- List three iteration control structures. (3 marks)
- Repeat - Until
- While - loop
- For - loop
- Differentiate between source code and object code. (2 marks)
- Source Code - program statements written in a programming language before being translated into machine code equivalent
- Object code - A translated source code / program statements already translated into machine code equivalent
17. a. Factors to consider when choosing DTP software. (4 marks)
- Availability in the market
- Initial and maintenance cost
- User friendliness
- Compatibility
- User needs
b. Differentiate between kerning and tracking. (2 marks)
- Kerning - Changing the spacing between two specific text characters
- Tracking - changing the spacing between all text characters, by either reducing or increasing the spaces
c. Differentiate between a logical file and physical file. (2 marks)
- Logical File - when you view a file in terms of what it contains and what processing activities can be carried out on the data
- Physical file - viewing a file in terms of how data has been arranged and how data processing activities have been made possible
d. Define the term accreditation as used in education. (1 mark)
- It is the action or process of officially recognizing an education centre to meet government standards and international standards
e. A school intends to setup an email, list four activities likely to be provided by the email facility (2 marks)
- Compose mail
- Send mail
- Forward mail
- Reply mail
- Attachment mail
- Contact management
f. Define the following terms as used in internet (2 marks)
Internet blog - a website that contains personal information which can easily be updated
Web portal - a website page that offers specialized services such as searching, email, sports, updates, financial, news and links to selected websites
g. Kenya Publishing and Printing Company wants to employ and ICT professional to assist in making publications. State the suitable ICT professional the company would employ. (1mk)
- Graphic designer
h. Define cyber terrorism. (1 mark)
- These are illegal computer crimes or operations done with or on an information system
18. a. One of the functions of an operating system is job scheduling. Explain what is meant by job scheduling. (2 marks)
- It refers to allocating each job waiting for execution processor time at each given interval
b. List and explain three types of user interface. (6 marks)
i) Command line - lets the user type command at a command prompt. The computer
reads the typed commands from the command line and executes it.
ii) Menu driven Interface - provides the user with a list of options to choose from
iii) Graphical user interface - makes the use of rectangular work area called windows,
graphical objects called icons and commands are executed using a pointing device
c. Describe the following categories of software. (4 marks)
(i) Firmware - it is a combination of both soft ware and hardware recorded permanently on electronic chip
(ii) Proprietary Software - Are those software whose source code is hidden from users
d. A new company ABC intends to go into business of desktop publishing.
Advice the company on three computer hardware specification features to consider as a measure of enhancing performance. (3 marks)
i) Ram capacity / memory
ii) Processor speed
iii) Hard disk capacity
iv) Monitor graphic adaptor
19. a. State when the following maintenance approaches are carried on in system development life cycle. (2 marks)
(i) Corrective maintenance - This involves making changes on the system in order to get rid of errors that have been identified after the system has been implemented.
(ii) Perfective maintenance - It aims at improving performances of the system. This may include adding of functions and making it more user friendly, faster and secure
(iii) Adaptive maintenance - It is carried out to enable the system to respond to changes in the operating environment and internal organizational policies e.g changes in legal requirement
b. Describe the following changeover strategies. (4 marks)
(i) Pilot - This is implementing one phase of a system for testing purposes before it is implementing. If it performs satisfactory, it is then implemented in the entire organisation
(ii) Phased - A new system is implemented in stages e.g the education system can be changed from the old to the new curriculum each year atleast one class level changes over to the new syllabus
(iii) Direct - The old system is stopped and discarded and new system started immediately
(iv) Parallel - Both the old and new system are run parallel to each other for some time until users have confidence in the new system then the old system is phased out.
c. Study the spreadsheet below and answer the questions that follow. (4 marks)
| | A | B | C | D
| 1 | WESTLINK COMPUTER BOOKS CENTER
| 2 | TITLE | PRICE | NO. SOLD | COST
| 3 | Computer longhorn book 2 | 320 | 25 |
| 4 | Visual Basic (6) turbo | 820 | 21 |
| 5 | Computer longhorn book 4 | 350 | 100 |
| 6 | Computer Science | 900 | 12 |
| 7 | Computer application | 845 | 36 |
| 8 | Computer hardware | 1250 | 10 |
| 9 | Computer software | 1250 | 27 |
| 10 | | | |
(i) Write down the formula used to find the price of the cheapest book. (1 mark)
= min (B3:B9)
(ii) Write down the formula used to determine the total sales for the book titled computer application. (1 mark)
= B7*C7
(iii) Write down the formula used to determine the average price of all the books (1 mark)
= (B3 + B4 + B5 + B6 + B7 + B8 + B9) /7
(iv) State four advantages of using an electronic spread sheet compared to traditional spreadsheet (2 marks)
- Automated tasks
- Inbuilt formula and functions
- Chart facility
- Data management tools
- Special formatting features inbuilt templates
(v) Differentiate between a column chart and a bar chart as used in spreadsheets (2 marks)
| | Column chart | Bar chart
| a | Represents data as a cluster of columns comparing values across categories | Data values arranged horizontally as clustered bars
(vi) Define the word gutter in relation to column settling in DTP. (1 mark)
Space reserved for binding in a publication. It is found outside the margin
20. a. What is the hexadecimal equivalent to 7478. (3 marks)
7 4 7 0111 1110
7 1 4 0
3 1 2 0
1 1 = 111 1 0
0 1 0 1 = 17 F16
b. Use one’s compliment to solve the following 710-510. (2 marks)
7 1 5 1
3 1 2 0
1 = 111 1 1 = 101 111
0 1 0 010 + 010
001
1
010 = 010
c. State two reasons for using binary system in digital technology. (2 marks)
- It is easier to construct electrical circuits based on binary
- Digital devices are more reliable than analog devices
- Digital devices are smaller in size than analog devices
- Digital devices use less energy that analog devices
d. Explain the term attenuation as used in networking. (2 marks)
- The decrease in magnitude and energy as a signal progressively moves along a transmission medium
e. Explain the following terms as used in fibre optic cables. (4 marks)
(i) Single mode
- It has a very narrow core therefore transmission can only be done through one path.
- Very low attenuation rate, so preferred for long distance transmission
(ii) Multi-mode
- Has a thick centre core
- Allows several light rays to be transmitted at an angle
- High attenuation rate, used for shorter distances
f. Convert 7.12510 to its binary equivalent. (2 marks)
7 Rem 0.125 x 2 = 0.250
3 1 0.25 x 2 = 0.50
1 1 = 111 0.5 x 2 = 1.0
0 1 = 111.0012