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Form 4 Computer Studies Paper 1 (Theory) Question Paper

Form 4 Computer Studies Paper 1 (Theory)

Course:Computer Studies

Exam Year:2017

451/1
Computer Studies
Paper 1
(THEORY)
2 ½ Hours

COMPREHENSIVE REVISION SET

SECTION A (40 Marks)
1. Give TWO reasons why Powder type fire extinguishers are not recommended to be used in a computer laboratory.
i. Powder based fire extinguishers may react with some electrical components hence changing their electrical characteristics
ii. Powder based fire extinguishers has abbrasive particles that may cause corrosion to moving parts of the computer
Or any other correct responce
Reason @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks

2. State the purpose of each of the following memories in a computer system.
(i) ROM
It stores the firmware that is required frequently to perform specialised functions on the computer ie to control the booting process
Or
It is used to permanently hold information that can only be accessed but not modified or erased by the user

(ii) RAM
Temporarily holding
a. User data
b. Running programs
c. Input storage shortly before processing
d. Output storage shortly after processing
Or any other correct responce
Purpose @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks

3. State two factors that one would consider when selecting data entry method in computing.
i. Type of data
ii. Speed of input device

Or any other correct responce
Factor @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks
4. Describe the following types of printers and state one application area of each.
(a) Dot matrix
A dot-matrix printer is an impact printer that produces printed images with a print head striking mechanism. The print head of a dot matrix printer is implemented in an array of pins arranged in rows and columns. To print a character, the required sets of pins are activated and sruck against an inked ribbon leaving the image on paper. Application – in banks for printing bank slips

(b) Thermal printer.
It is a non impact printer that uses a chemically treated paper that changes color to form characters when subjected to heat. Application – in photo studios to print pictures
Description @ 1 Mark
Application Area @ ½ Mark
Total = (2 X 1 Mark) + (2 X ½ Mark)
= 3 Marks

5. Differentiate between in-house software and freeware.
These are programs developed and designed to solve specific user problems. They are developed for a specific person/ organisation and therefore they cannot be used by anyone else except the owners of the software who have all the rights over the software while freeware software are software products that are freely made available to the user. Most freeware software are distributed freely over the internet where the user can download a program of choice.
Difference @ 2 Marks

6. Give two importance of feedback mechanism in systems
i. The feedback mechanism helps in evaluating the system output to determine whether a system is moving toward the achievement of its goal
ii. The feedback mechanism helps in monitoring the performance of the system

Or any other correct responce
Importance @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks

7. With an aid of a diagram, explain one-to-one database relationship.

A one-to-one relationship is created if and only if the relating field in both tables are primary keys
Diagram @ 1 Mark
Explanation @ 1 Mark
Total = (1 X 1 Mark) + (1X 1 Mark)
= 2 Marks

8. KASSU Secondary School intends to set up internet connection in their school for e-learning purposes. Advise the school management on four internet connectivity requirements that is required for them to be able to access internet.
i. Network interface card
ii. Internet service provider
iii. Computer
iv. Communication media
Or any other correct responce
Connectivity requirement @ ½ Mark
Total = 4 X ½ Mark
= 2 Marks

9. The figure below shows an extract of an e-mail application.

What is meant by each of the following terms:
(a) Trash
Acts as a dust bin for your e-mail account where all deleted mails are stored before being permanently removed from the account

(b) Spam
This is a folder in your account where all junk and suspicious mails received are stored

(c) Inbox
This is a folder in your account where all genuine mails received are stored
Meanimg @ 1 Mark
Total = 3 X 1 Mark
= 3 Marks

10. State two ways in which users in an organization can be a security threat to data in an information system.
i. Through accidental access to files they are not supposed to access
ii. By using confidential data for their own personal gain
iii. Through intentional access to unauthorised data
Or any other correct responce
Threat @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks

11. State three negative impact of information communication technology on the Environment.
i. The huge garbage dumps of dead computer parts, printers, ink toners, cartridges, monitors and other accessories are deposited in land fills causing pollution.
ii. Disposal of Nickel-Cadmium laptop batteries which contain toxic cadmium are buried in a land fill can leak into underground water table and catchment areas.
iii. Massive extraction of natural resourses such as mining of iron ore and other metals for the costruction of computer parts
Or any other correct responce
Threat @ 1 Mark
Total = 3 X 1 Mark
= 3 Marks

12. In a computer based information system, state the purpose of the following files and give one example where such a file may be required in a school.
a. Report file.
A report file is used to extract records from the masterfile or generated after processing. It stores a copy of the generated reports by the system.

b. Sort file.
A sort file is used where data is to be processed sequetially to first arrange the records in the order of the master file before updating it. Example students exams marks entered in a class list
Function @ 2 Marks
Total = 2 X 2 Mark
= 2 Marks

13. State three responsibility of a Database administrator in an organization.
i. Selection of hardware and software
ii. Managing data security and privacy
iii. Managing Data Integrity
iv. Data backup
v. Database recovery
vi. Tuning database performance
vii. Improving query processing performance

Any three correct responce
Responsibility @ 1 Mark
Total = 3 X 1 Mark
= 3 Marks

14. With an example for each, describe how computers are used in the following areas of education;
a. Simulation
This is whereby the compters are designed to resemble the actual enviroment for the users to learn instead of going to the actual environment which might be very expensive or risky for them. Example used for training pilots instead of using the actual planes

b. Tutorial
These are learning materials provided in soft copy for the learners to read for knowledge. Example: e – books

Description @ 1 Mark
Example @ ½ Mark
Total = (2 X 1 Mark) + (2 X ½ Mark)
= 3 Marks

15. a. Dan a computer student noticed that every time a person enters the computer lab the computer screen flickers. Identify three reasons why the monitor might be flickering
i. There may be a loose connection to his computer hence flckering when touched
ii. Cables may be laid on the path way hence flickering when stepped on
iii. Electronic Interference - External factors can also cause monitor flicker, it is possible that additional electronic devices, emitting their own waves, could be interacting with the monitor screen, causing a flicker. Generally, any strong magnetic force or device that sends out signals such as mobile phones could cause it.
Or any other correct responce
Reason @ 1 Mark
Total = 3 X 1 Mark
= 3 Marks

b. State two ways in which the problem can be solved
i. Proper insulation of cables
ii. Laying the cables in trunks away from busy pathways
Or any other correct responce
Solution @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks

SECTION B (60 Marks)
16. a. State two advantages and two disadvantages of high level programming language
Advantages of high level programming
(i) High level languages are machine independent hence portable
(ii) High level languages are user friendly
(iii) They are easy to learn
(iv) High level language programs are easy to debug
(v) They are more flexible hence they enhance the creativity of the programmer thus increasing productivity

Disadvantages of high level programming
(i) High level languages are executed much slower than low level programming languages
(ii) High level languages have to be translated into machine code before execution
(iii) One instruction translates into several machine code instruction hence requires more storage space.
(iv) They do not make efficient use of computer memory and the processor
Or any other correct responce
Advantage @ ½ Mark
Disadvantage @ ½ Mark
Total = (2 X ½ Mark) + (2 X ½ Mark)
= 2 Marks

c. State three situations when REPEAT .. UNTIL structure can be used in writing a program
i. When the instructions are to be executed atleast once
ii. When the number of loops is not known at the beginning of the program
iii. When the instructions are to be executed if the condition is false
Or any other correct responce
Situation @ 1 Mark
Total = 3 X 1 Mark
= 3 Marks

d. The roots of the equation ax2 + bx + c = 0 are given by the formula

i. Write a pseudocode for the above program
BEGIN
INPUT A, B, C
D= (B*B)-(4*A*C)
IF D<0 THEN
X1=INVALID
X2=INVALID
ELSE
IF D=0 THEN
X1= -B/(2*A)
X2=X1
ELSE
IF D>0 THEN
X1= (- B + SQRT(D))/(2*A)
X2= (- B - SQRT(D))/(2*A)
END IF
END IF
END IF
PRINT X1, X2
STOP

Start/ stop @ ½ Mark
Input @ ½ Mark
Evalute D @ ½ Mark
Condition/ Construct @ 1 Mark
Process @ 1 Mark
Logic @ 1 Mark
Output @ ½ Mark

Total = ½ + ½ + ½ + 1 + 1 + 1 + ½
= 5 Marks

ii. Draw a flow chart for the above pseudocode

Start/ stop @ ½ Mark
Input @ ½ Mark
Evalute D @ ½ Mark
2 decisions @ 1 Mark
Process @ 1 Mark
Logic @ 1 Mark
Output @ ½ Mark

Total = ½ + ½ + ½ + 1 + 1 + 1 + ½
= 5 Marks

17. (a) (i) The figure below shows a picture tool bar

Name and state the functions of the features marked A, B and C:
(i) A
Name: Cropping tool
Function: Used to trim the unwanted parts of graphics
Name @ ½ Mark
Function @ ½ Mark
Total = ½ + 1 Mark
= 1 Mark
(ii) B
Name: Rotate left 900
Function: Used to rotate objects through an angle of 900 to the left
Name @ ½ Mark
Function @ ½ Mark
Total = ½ + 1 Mark
= 1 Mark

(iii) C
Name: Text wrap tool
Function: Used to place text arround graphics
Name @ ½ Mark
Function @ ½ Mark
Total = ½ + 1 Mark
= 1 Mark

(b) State the importance of Column breaks as used in word processor.
It is used to enforce an end of a column to start/ move the cursor at the beginning of the next paragraph.
Importance @ 1 Mark

(c) Change case is where a user applies so that the text can have some contrast in size. Write the word
(i) Title case
Digital Signal
Title case @ 1 Mark
(ii) Toggle case
dIGITAL signal
Toggle case @ 1 mark
(d) Define the following terms as used in charts.
(i) Legend
The Legend is a chart object that identifies the patterns or colors that are assigned to the data series or categories in the chart.

(ii) Data range
The data range is the area of the worksheet that you want to chart. It includes any numeric data that you want to chart and can include the titles for the data.
Definition @ 1 Mark
Total = 2 X 1 Mark
= 2 Marks

(e) The table below shows how a kiosk owner uses a spread sheet to keep records in a shop.
A B C D E F
1 ITEM NAME NUMBER OF ITEMS UNIT COST TOTAL BUYING PRICE TOTAL SELLING PRICE PROFIT
2 Blue band 150 120 3600
3 Toss 135 50 1350
4 Cow boy 120 120 2880
5 Panga soap 118 50 1180

(I) Write a function to calculate the total buying price.
=product(B2:C2) or =product(B2,C2)
Function @ 2 Marks

(II) Write a formula to calculate the Profit.
=E2-D2
Formula @ 2 Marks

(III) The total buying prices of all items was increased by 12% and the value 12% is placed in cell B6. Using cell addresses with absolute referencing, write a formula to calculate the Total Selling Price in cell E2.
=($B$6/100)*D2
Formula @ 2 Marks

(IV) State the output of the expression =SUMIF(F2:F5,"<1 500")would return.
2530
Output @ 1 Mark

18. a. Describe the term prefixing an extra sign bit as used in data representation.
This is a technique used to represent both positive and negative numbers using an extra sign bit as its most significant bit where a 1 represents a negative number and a 0 represents a positive number.
Description @ 2 Marks

b. Convert each of the following numbers system.
(i) to binary
0.78125 X 2 = 1.5625
0.2625 X 2 = 1.125
0.125 X 2 = 0.25
0.25 X 2 = 0.5
0.5 X 2 = 1.0
= 0.110012
Conversion @ 2 Marks

(ii) to Octal (2 Marks)
Convertion to binary
3 - 00112
A – 10102
9 – 10012
=0011101010012
Convertion to octal
001/110/101/0012 = 16518
Hex to binary/decimal @ 1 Mark
Binary/ decimal @ 1 Mark
Total = 1 Mark + 1 Mark
= 2 Marks

c. Perform the following binary operation.

1010.112
111.102
10010.012
101.112
1010.102
Operation @ 3 Marks

d. Using one’s complement, perform the following binary arithmetic leaving the answer decimal notation.
Conversion to binary
1710 –10001 00010001
4510 – 101101 00101101

Convert to 1c
11010010
Add the two numbers
00010001
11010010
11100011

Reconvert to 1c
00011100

Conversion decimal
-28
Calculation @ 1 Mark each step
Total = 6 Marks

19. a. Distinguish between the following terms as used in data communication
i. Guided transmission medium and unguided transmission media
Guided transmission medium is a transmission medium that transmits data to its destination using a physical medium such as cables while unguided transmission media is one that transmits data though free space. There is no physical connection between the communicating devices.
ii. Multiplexing and demultiplexing
Multiplexing Is the process of sending multiple data signals over a single medium along a communication channel. While demultiplexing is the process of separating the multiplexed signals at the receiving end of a channel back to the number of transmmission chansmission channels multiplexed.
iii. Logical and physical Topology
The physical topology of a network refers to the physical arrangement of cables, computers, and other peripheral devices on a network.
Logical topology is the method used to pass information between computers on a network.
Difference @ 2 Mark
Total = 3 X 2 Mark
= 6 Marks

b. Below is a diagram of a network topology.

i. Name the above topology
Tree topology
Name @ 1 Mark
ii. State two advantages and two disadvantages of using the topology named above (4 Marks)
Advantages of Tree topology
• It allows for Point-to-point wiring for individual segments.
• It is supported by several hardware and software vendors.

Disadvantages Tree topology
• Overall length of each segment is limited by the type of cabling used.
• If the backbone line breaks, the entire segment goes down.
• It is more difficult to configure and wire than other topologies.

Or any other correct responce
Advantage/ disadvactage @ 1 Mark
Total = 4 X 1 Mark
= 4 Marks

c. List and explain the two data transmission techniques
Packet switching
This is a data transmission technique which involves transmitting and routing of data as packet segments sent rapidly and sequentially over a communication channel.
It involves breaking the data into individual segments known as packets which are transmitted individually and then re-assembled when they reach the destination computer. The packets are labeled to show where they come from and where they are to go. Packets are forwarded from one computer to another until they arrive at their destination. If any are lost, they are re-sent by the originator. The recipient computer acknowledges receipt of packets to eliminate unnecessary re-transmissions.
Circuit switching
A method of communicating in which a dedicated communications path referred to as a circuit or channel is established between two devices through one or more intermediate switching nodes before communication between the devices takes place. Unlike packet switching, digital data is sent as a continuous stream of bits on a circuit.
Each circuit that is dedicated cannot be used by others on the network until the circuit is released and a new connection is set up.
Listing @ ½ Mark
Explanation @ 1 ½ Marks
Total = (2 X ½ Mark) + (2 X 1 ½ Mark)
= 4 Marks
20. a. Distinguish between a computer drive and computer driver
A computer drive is a hardware component that facilitates storage and retreval of data on a removable storage device while a computer driver is sets of instructions installed/ incorporated to the operating system the controlls the functionality of their specific peripheral devices.
Difference @ 2 Mark

b. State any four factors to consider when selecting an operating system
i. The hardware configuration of a computer e.g. memory capacity, processor speed and hard disk capacity.
ii. The type of computer in terms of size and make. For example, some earlier Apple computers would not run on Microsoft Operating systems
iii. The application software intended for the computer
iv. User – friendliness of the operating system
v. The documentation available
vi. The cost of the operating system
vii. Reliability and security provided by the operating system
viii. The number of processors and hardware it can support
ix. The number of users it can support.
Or any other correct responce
Factor @ 1 Mark
Total = 4 X 1 Mark
= 4 Marks
c. Explain any four factors that dictates how the operating system organizes data in a computer
i. Rapid access: The organization method should allow quick access to stored data
ii. Ease of update: - The organization method should allow ease of update and the operating system must be able to keep a record of the date of modification
iii. Economy of storage : - the organization method should use the least storage possible because memory is a scarce resource
iv. Simplicity of maintenance: - The organization method should enable quick navigation through the file system and make it easy for it to be maintained.
v. Reliability: - the file organization method must be reliable.

Or any other correct responce
Factors @ 1 Mark
Total = 4 X 1 Mark
= 4 Marks

d. Define the term file in relation to the operating system
This is the smallest unit of data storage in a computer. Every user document in a computer is stored in files of specified formats depending on the program used to create it.
Files can also be defined as a collection of related data items given unique name for ease of access, manipulation and storage.
Definition @ 1 Mark

e. The operating system stores details of a file for easy identification and retrieval of files. Explain any four file details the operating system uses to search and identify a file
i. A unique name and an optional extension; the name and extension are separated by a period (.).
ii. The file size
iii. The date and time the file was created or modified.
iv. The file type

Detail @ 1 Mark
Total = 4 X 1 Mark
= 4 Marks

f. Distinguish between a menu driven operating system and graphical user interface operating system
MENU DRIVEN INTERFACE
A menu driven operating system provide the user with a list of options that represent computer commands for the user to choose from.

THE GRAPHICAL USER INTERFACE (GUI)

GUI make use of rectangular work areas called windows, graphical objects (icons) to represent computer files and folders, most commands are executed using a pointing device as well as menus.

Difference @ 2 Marks

Form 4 Computer Studies Paper 1 (Theory) Question Paper

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