S.P.4 KCSE COMPUTER STUDIES PAPER 1 PAST QUESTIONS AND ANSWERS

SAMPLE PAPER 4

COMPUTER STUDIES PAPER 1

451/1

SECTION A (40 marks)

Answer All Questions In This Section.

1. Name TWO computer crimes. (1mk)

2. Give an example of the following:

1. Keying device (1mk)
   
2. Pointing device (1mk)
   
3. Scanning device. (1mk)
   

3. Give TWO reasons why operating systems were developed. (2mks)

4. List THREE things which accompany newly purchased software. (3mks)

5. A printer fails to work as expected when a document is sent to be printed. The user has checked that the on-line light of the printer is on and the printing paper is correctly inserted. Give TWO other possible reasons why the printing process failed. (2mks)

6. Explain the difference between serial and parallel data transmission. (2mks)

7. Programmers use programming languages to write programs. Based on this statement, distinguish between the following terms as applied in programming.

 a). Source code and an object code. (1mk)

 b). Machine language and assembly language. (1mk)

8. Computer hardware components consists of control unit(CU), main memory(MM), arithmetic and logic unit(ALU), secondary storage devices, input and output devices. Study the diagram below and answer the question that follow.

 Name the parts labelled A, B, C and D. (2mks)

9. Assuming that data is being transmitted using odd parity ASCII system, what could you deduce if each of the following bits are received?

 a). 10100101 (1mk)

 b). 10111001 (1mk)

10. a). What is a secondary storage device? (1mk)

b). Give THREE reasons why DVD’s are increasingly being used today. (3mks)

11. a). Explain the following features as used in word processing.

 i). Word wrap (1mk)

 ii). Thesaurus (1mk)

b). The first column in the table below contains the formula stored in cell C10 of a spreadsheet. Enter the formulae as they would appear when copied to cell F15 of the same spreadsheet.

(3mks)

12. Give THREE responsibilities of a systems analyst. (3mks)

13. a). What is meant by the term tele-working? (1mk)

b). An organization intends to install tele-working in its operations. List THREE disadvantages that are likely to be encountered. (3mks)

14. a). Name the stage of systems development life cycle where an interview is used. (1mk)

b). State TWO advantages and TWO disadvantages of using interviews at the stage in 14(a) above.

 Advantages (1mk)

Disadvantages (1mk)

15. a). Give TWO examples of desktop publishing software. (1mk)

b). A computer teacher at St. Joseph’s Girls High School tells students to always ensure that computers are connected to uninterrupted power supply. List TWO reasons why it’s necessary to have this device in a computer lab. (1mk)

SECTION B (60 marks)

Answer Question 16 and any other three questions from this section.

16. A programmer uses program design tools to design a program that can list the odd numbers between

0 and 100.

a). (i). Write a pseudo code for this problem. (5mks)

ii). Draw a flow chart for the pseudo code in 16 a) (i) above. (6mks)

b). Name FOUR data types used in structured programming. (4mks)

17. a). (i) Define the term information system. (1mk)

(ii) Differentiate between a closed system and an open system in relation to system boundary.

(2mks)

iii). Outline the stages of systems development life cycle in their logical sequence briefly describing what takes place at each stage. (7mks)

b). i). A user wishing to access the internet may use a modem or an ISDN connection. What is the purpose of a modem? (1mk)

 ii). Explain why using an ISDN connection to the internet eliminates the need for a modem.

(1mk)

 iii). State THREE forms of communication that can be transmitted by an ISDN line. (3mks)

18. a). (i) What is data privacy? (1mk)

 ii). Give FOUR provisions of the Data Protection Act of 1984 regarding personal data. (4mks)

 b). List FOUR factors to be considered when choosing a data processing mode. (2mks)

 c). (i) What is an expert system? (1mk)

 ii). State TWO advantages and TWO disadvantages of using expert systems.

 Advantages (2mks)

 Disadvantages (2mks)

 d). Explain the following terms as applied in internet communication.

 i). Search Engine. (1mk)

 ii). Uniform Resource Locator (URL) (1mk)

 iii) Domain name (1mk)

19. a). List TWO characteristics of good information. (2mks)

 b). (i). What is a database management system? (1mk)

 ii). State and explain THREE database models. (3mks)

c). Describe the following types of files.

 i). Master file. (2mks)

 ii). Backup file. (2mks)

 iii). Transaction file. (2mks)

 d). Explain the file organization methods given below.

 i). Serial. (1mk)

ii). Indexed sequential. (1mk)

iii). Random. (1mk)

20. a). Explain what is achieved by the following Dos commands. (2mks)

i). C:\>TYPE Class.dat

ii). C:\>DEL *.Doc

iii). A:\>COPY *.* C:\PRACTICE

 iv). D:\>DIR M*.EXE

b). (i). Identify and explain TWO types of network topologies and for each, give TWO advantages it has for its users. (6mks) ii). Convert 39.75₁₀ to binary. (4mks)

 c). State and explain THREE types of program translators. (3mks)

MARKING SCHEME

SAMPLE PAPER 4

451/1

SECTION A

1. Fraud, Trespass, Hacking, Piracy, Sabotage, Theft of data ( ½ x2 marks)
   

 2. a) Keyboard, Key- to- disk, Key- to- tape (1×1=1)

b) Mouse, Light pen, Joy stick (1×1=1)

c) Scanners, Wand, Mick, OCR, OMR (1×1=1)

 3. – To increase through put

– To improve communication between the user and the computer

– To decrease down time by displaying error messages

– To decrease job set up time

(1×2=2)

 4. – License agreement

– Warranty

– User manual

– Reference guide

– Quick reference guide (1×3=3)

 5. – The printer not being set to default

– A problem with the picking of papers

– Configuration of the printer to a wrong port (1×2=2)

1. In serial transmission, bits are send one at a time over a single transmission line from source to destination while in parallel, a group of bits are send at once over separate lines (1×2=2)
   

7. a) Source code refers to the program in its original language either assembly or high

level while object code is the machine code equivalent ( ½ x2=1)

1. Machine language represents data and instruction in binary codes while assembly language uses mnemonic codes to represent a computer operation

 ( ½ x2=1)

 8. A- Secondary storage device

B- Control Unit ( ½ mark each )

C- Input Device

D- Output device

 9. a) An error occurred during transmission as the total number of ones received are an

even number (1mk)

1. Transmission had no errors since the total number of ones form an odd number (1mk)

 10. a) – An external storage device not part of the computers CPU

– A device that stores data permanently off the computer (1×1=1)

b) – Prices have come down

– Larger storage capacities

– Affordable prices for DVD drives (1×3=3)

11. a) i) Word wrap is a feature which enables text to automatically flow to the next line if the end of the current one is reached (1mk)

1. Thesaurus is a feature used to find synonymns and antonymns( 1mk)
   

b)

 12. – Design a new system

– Teams up with programmers to ensure smooth coding

– Guides users on how to use the new system

– Carries out system review and maintenance (1×3=3)

 13. a) Employees working from home through interlinked computers other than going to

office

(1mk)

b) – Management may fear difficulties of controlling a work force that is not in

 office

– It is difficult to ensure that the involved staff fully understands the goals of the organization and be loyal to it

– Employees may feel isolated and miss the social working environment

– It is difficult for employees to work in teams or even find help

– Some teleworkers may find it difficult to separate home from work (1×3=3)

 14. a) – Investigations and fact finding (1mk)

• Advantages
  
  • Information collected is reliable and accurate
  • It is a good method for intensive investigation
  • Questions can be rephrased instantly for clarification
  • Non- verbal communication like facial expressions can be used and observed

    ( ½ x 2=1)
    

Disadvantages

• Requires a lot of expenses and time
• The interviewee may be reluctant to answer some questions
• Interviews are difficult to prepare and organize ( ½ x 2=1)
  

 15. a) – Corel draw, Adobe page maker, Ms publisher ( ½ x2=1)

b) – To act as a power backup

– Acts as a surge protector

– Enables computer users to save their work and close down the computer

correctly in the event of power break down ( ½ x2=1)

SECTION B

 16. a) i) Start Marks award

 Odd=1 * Start/ stop – 1 mk

 Repeat Repeat/ until -1 mk

 Write odd correct statements -3 mks

 Odd= Odd+2 *Also accept use of other control statements

 Until odd =99 such as while…DO

 Stop

ii)

NO

YES

1 mark for each correct symbol and procedure in the symbol (1x 6=6)

 b) – integer, Real, Char, String, Boolean

(1x 4=4)

17. a) i) An integration of both manual and computer based processes that

produce information to support decision making (1mk)

1. A closed system is one that is isolated from its environment and therefore

   does not interact with it while an open system is one connected to and interacting with its environment (1x 2=2)
   

2. Stage I
   Preliminary survey/ study

   Stage during which a problem is recognized, defined and a feasibility study initiated

   Stage II Investigation and fact finding
   

   A comprehensive study is undertaken to establish facts which relate to the proposed system

   Stage III Analysis
   

   A stage during which detailed requirements for the new system are identified by the system analysts

Stage IV System Design

At this stage, the proposed system is designed using design trols such as flow charts

Stage V System Construction &Testing

Programs are coded and tested together with the other system components

Stage VI System implementation

This is the stage at which the new system is put to use

Stage VII Maintenance and review

During this stage, repairs, modifications and corrections are done to the implemented system to keep it functional

(For each stage, ½ mk for identification ½ for explanation

b) i) To convert digital signals to analog signals and vice versa during data transmission

( 1mk)

ii) An ISDN line is capable of automatically accepting and converting digital signals to analoge before transmission ( 1mk)

iii) Voice, sound, pictures, text (1×3=3)

18. a) i) The act of making individual data accessible only to its owners and those permitted (1mk)

ii) – Should be obtained and processed fairly and lawfully

– Personal data should be held for specified purposes

– Should not be used for any other reason other than the original purpose

– Personal data should be relevant and adequate

– Should not be kept longer than necessary (1×4=4)

 b) – Time when information is required

– Costs involved in implementing the processing method

– Nature of business

– Size of business ( ½ x4=2)

c) i) A computer program which performs tasks that would otherwise require skills of

a human expert if done by people (1mk)
Advantages

– The knowledge is always available

– It works faster

– Its decisions are based on logic and issues of emotions does not arise (1x 2=2)

Disadvantages

– It is flexible as it may not take into account exceptional circumstances

– Human experts using it may tend to be over reliant on it

– Expensive to buy, install and maintain (1×2=2)

d) i) A program that enables one to search for particular information on the internet (1mk)

ii) Specifies standard addresses for web pages or other devices on the web or internet

 (1mk)

iii) Specifies the name of the file server on which the web resource is held(1mk)

19. a) – Relevant to its purposes

– From reliable source

– Correct, accurate and complete

– Communicated to the right person and at the correct time (1×2=2)

1. i) A program that manages the storage, manipulation and access data from the data base (1mk)

   ii) Network: Data is represented as a collection of records and relationships joined by links

Hierarchical: Data and relationships among data are represented by linked records which

are organized as a collection of trees

Relational: Data is held as a collection of tables

Files: Data items are stored sequentially in one large file (1×3=3)

 ( Stating ½ mk

 ( Explaining ½ mk

c) i) A file that holds permanent data in an organization against which transactions are

processed (2mks)

ii) A file created from existing master files to store duplicate copies that can be used

to restore the original file in the event of loss or damage (2mks)

iii) A file that holds temporary incoming and outgoing data in an organization for a given

period of time (2mks)

d) i) Records are written onto the disk in the order in which they come with no

regard for sequence (1mk)

1. Records are arranged on disk in sequence with an index added for easier access

   (1mk)
   

iii) Records are arranged on disk randomly with no obvious relationships among them (1mk)

 20. a) i) Displays contents of the file class data on the screen

ii) Deletes all files with Doc extension from drive C

1. Copies all files from drive A irrespective of their file extensions to a directory in drive C called PRACTICE
2. Displays all files in drive D whose names begin with M and have extension EXE ( ½ x4=2)
   

b) i) Choose any two from the following

Star topology: Individual work stations are connected by point-to-point link to a central computer (1mk)

Advantages

– If a cable for one computer fails, it does not affect the rest

– Performance is consistent even if the network is being heavily used

– Easier to add new work stations

– Passing of messages within the network is more

– Secure (1×2=2)

Bus topology: All work stations on the network share the same transmission medium called a bus (1mk)

Advantages

– Relatively cheaper and easier to install as it requires the least amount of cable

– Easier to add new work stations without disrupting the network

– Failure of one computer does not affect the others on the network

(1×2=2mks)

Ring topology: A series of computers are connected together by point-to-point links in a closed loop (1mk)

Advantages

– There is no dependence on a central server

– Transmission of messages is simple as they move in one direction

– Very high transmission rates are possible

– Signal degradation is minimal due to the use of repeaters (1×2=2)

ii) Conversion of 39₁₀ -100111₂ (1mk)

 Conversion of 0.75 -0.11 (2mks)

 Correct answer 100111.11₂ (1mk)

c) Compiler: Translates a program written in a high level language to its machine code equivalent

Assembler: Translates a program written in assembly language to its equivalent machine code

Interpreter: Translates and executes high level language statements immediately they

are encountered (1×3=3)