KCSE 2017 Computer Studies Paper 1 with Marking scheme

Instructions to candidates

• This paper consists of two sections: A and B
• Answer all questions in section A.
• Answer question 16 and any other three questions from section B.
• Candidates should answer the questions in English

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

1. State the meaning of the term computer software. (2 marks)
2. State three features of fifth generation computers.  (3 marks)
3. Differentiate between home page and web page as used in the Internet.  (2 marks)
4. State three characteristics of mainframe computers.  (3 marks)
5. The management of an organisation intends to purchase a printer. State three factors that they should consider during the purchase  (3 marks)
6. Describe each of the following computer cables:
   1. Parallel cable;  (2 marks)
   2. Serial cable;  (2 marks)
7. A computer technician has observed a lot of dust on computers in the computer laboratory. State three precautions that need to be put in place to avoid this.  (3 marks)
8. Explain the term proofreading as used in word processing. (2 marks)
9. State the function of each of the following computer keyboard keys when using a word processor:
   1. End (1 mark)
   2. Insert  (1 mark)
   3. Backspace.   (1 mark)
10. Explain two problems associated with the computer hard disk.   (4 marks)
11. State the spreadsheet function that can be used to obtain each of the following values in a worksheet:
    1. Number of cells with values in a column.   (1 mark)
    2. Mean of values in a range of cells.  (1 mark)
12. A school intends to install wireless media in their communication system. State three advantages of this mode of communication media.   (3 marks)
13. State two ways in which one can create a password which cannot be easily accessed by hackers.   (2 marks)
14. State two ways through which a computer user can minimise Repetitive Strain Injuries (RSI) associated with the use of a computer.  (2 marks)
15. Identify four tasks that can be achieved using a Desktop Publishing programme from the following list of tasks.
    (2 marks)
    1. Managing students records in a school
    2. Creating a calendar
    3. Designing a building structure
    4. Creating a banner
    5. Creating a book cover
    6. Processing of examination results
    7. Creating business cards

SECTION B
Answer question 16 and any other three questions from this section.

16.  
    1. State two qualities of a good pseudocode.    (2 marks)
    2. With the aid of flowchart diagrams, describe each of the following programme control structures:
       1. Sequence    (3 marks)
       2. Selection   (3 marks)
    3. Draw a programme flowchart that would accept three numbers and find their sum. If the sum ids greater than 20, it adds 30 to the sum, otherwise subtracts 20 from the sum. The programme should then display the results.   (7 marks)
17.  
    1. Describe three arithmetic errors that may occur during computerised data processing. (6 marks)
    2. Arnold a programmer intends to create a user input interface screen for a system. State three factors that he should consider.   (3 marks)
    3. With the aid of an example in each case describe the following types of maintenance.
       1. adaptive;   (2 marks)
       2. perfective;  (2 marks)
       3. corrective.   (2 marks)
18.  
    1. Distinguish between a microwave transmission and a radio transmission.  (4 marks)
    2. Figure 1 shows a computer, network topology. Use it to answer the questions that follow.
       
       1. Identify the type of topology.   (1 mark)
       2. State the function of each of the parts labelled A and B. (4 marks)
    3. A computer laboratory experiences power supply problems. Describe three power related problems that should be addressed.   (6 marks)
19.  
    1. A school has been advised to employ a database administrator. State three responsibilities of this personnel in the school.  (3 marks)
    2. Explain two ways in which computers can be used in the transport industry.  (4 marks)
    3. Mary was advised to partition a hard disk for her computer. Explain two reasons that may have necessitated this.(4 marks)
    4. Explain a reason for conducting each of the following studies in systems development:
       1. Schedule feasibility:  (2 marks)
       2. Technical feasibility.   (2 marks)
20.  
    1. Explain three functions of an information system in an organisation  (6 marks)
    2. Explain two benefits that a company would gain from using batch processing method for data processing.
       (4 marks)
    3.  
       1. Convert the number 11101.11₂ to its decimal equivalent.    (3 marks)
       2. Perform the following binary operation 11011₂ + 101₂  (2 marks)

MARKING SCHEME

1. Computer software
   • It is a set of programs written in a computer language to direct a computer on how to perform a particular task or behave in a certain way.
2. Features of fifth generation computers
   • Use of expert system
   • Support the use of natural language
   • Support distributed computing
   • Support artificial intelligence and voice recognition
   • Support parallel processing
   • Small in size/ portable
   • Superior hardware and software
   • consume less power
     (First 3 @ 1 mark)
3. Difference between Home page and web page
   • Home Page - It's the first page that opens when a site is opened using the when the domain name.
   • Web Page - It is web document in a website! Any page on a web.
4. Characteristics of mainframe
   • They have bigger memory capacity. 
   • Have high processing power.
   • It supports multiprocessing.
   • Supports large number of users at the same time/ Supports several peripheral devices.
   • Runs so many applications at the same time.
   • (First 3 @ 1 mark)
5. Factors to consider when purchasing a printer
   • Volume of work to be printed.
   • Maintenance cost below e.g. consumables like toners should be affordable.
   • Speed of printing.
   • Type of work to be printed; type of paper, paper size/user needs /range of capability.
   • Type of printout whether colour is required or not.
   • Compatibility with the existing hardware
   • Initial cost
   • availability of in the market
   • Portability / physical size
     (First 3 @ 1 mark)
6. Description of computer cables
   1. Parallel cable
      • It is a communication cable which has high speed of transmission and transmits several bits at the same time. 
   2. Serial cable
      • It is a communication cable which has low speed of transmission and bits follow one another in sequence or are transmitted one at a time.
7. Precautions to be put in place in the lab to avoid dust 
   • Fit ventilating / air conditioning system to allow free circulation of air. 
   • Fit curtains on the windows / add a curtain net to reduce dust entry into the laboratory
   • Regularly use of a blower or vacuum cleaner/mob to blow dust from the computer parts.
   • Avoid entering the laboratory with materials that may have dust such as shoes.
     (First 3 @ 1 mark) 
8. Meaning of proofreading
   • It is the process of using appropriate proofing reading like spelling and grammar checkers and autocorrect features to check whether the document has typographical or grammatical errors.
9.  
   1. End
      • Used for moving the cursor to the end of the line been typed or already typed.
   2. Insert key
      • Used for changing typing mode from insert mode to type over and vice versa (Accept the description of type over and insertion)
   3. Backspace
      • Used to delete a character to left of the cursor position, 
10. Problems of computer hard disk
    • Excessive shock like dropping it on the hard surface may cause the platters to dislocate hence reading may be a problem
    • Contact with strong magnetic fields or static electricity may affect the device since data is saved magnetically.
    • If the case containing the platters is opened, dust may get into it causing disk crash.
    • Some viruses may create virtual tasks which will eventual cause the disk to be overwork hence causing it to crash
    • Sporadic power failure may cause the disk to crash.
      (First 2@ 2 marks)
11.  
    1. =Count()
    2. =Average
       NB Accept the any range given
12. Three advantages of wireless media to the schoo
    • The school will find it easy to add or remove modes on the system.
    • Incase of new building is put up, there will be no need of interfering with the communication media.
    • Users will find it safer to move around as there are no wires around the rooms.
    • Students will be able to roam as they access the network.
      (First 3@ 1 mark)
13. Password which cannot be hacked.
    • By including many characters in a password 
    • By combining different characters in a password 
    • Use password generator manager.
      (Any 2@ 1 mark) 
14. Ways of minimizing repetitive strain injuries.
    • Taking regular break intervals when using a computer
    • Use an ergonomic keyboard to avoid stress.
    • Support wrist with wrist rest pad when using a mouse.
    • Use of standard furniture/proper sitting posture.
      (First 2@ 1 mark)
15. Tasks achieved using DTP
    • Creating a calendar.
    • Creating a banner.
    • Creating a book cover.
    • Creating business cards
      (First 4 @ ½ mark)
16.  
    1. Qualities of a good pseudo code.
       • should be short and clear/ precise
       • should have start and end clearly shown.
       • Statements should be clearly defined.
       • should depict the logical flow of solving the problem.
       • should not be ambiguous.
       • it should be indented /neat / legibility
         (First 2 @ 1 mark)
    2.  
       1. Sequence
          Program statements are executed on after the other in the order in which they appear.
          Flow chart
          
       2. Selectiion
          Flow of a program is determined by a choice of one of two or more options based on a condition given.
          
    3. The flow chart
       
17.  
    1. Arithmetic errors
       • Truncation error
         Results due to shortening or leaving out part of a number or a word.
       • Rounding off error
         Arising by approximating a number by replacing it with a number that has fewer significant digits or one with zeros for its ending digits.
       • Overflow error
         Occurs when the results of a computation is larger than the allocated memory space.
       • Underflow error
         Type of error occurs when the output is low small to be represented in the chosen format.
         (First 3 @ 2 marks)
    2. User interface design considerations
       • Should be user friendly.
       • Colour, fonts and layout should be appealing to the user.
       • Consider a consistent layout in the entire system.
       • Should prompt user clearly. 
       • Should capture the same number of items of date as indicated in the manual data capture form.
         (First 3 @ 1 mark)
    3. Types of maintenance
       1. Adaptive
          Type of maintenance that is done to make the system to adopt the changing technology e.g. changing the system because to new o/s
       2. Perfective
          Type of maintenance done to make the system better in its operation e.g. adding a module in a system.
       3. Corrective
          Type of maintenance done to correct an error in the system e.g. wrong results during addition.
          (3 @ 2 marks)
18.  
    1. Distinction between microwave transmission and radio transmission Microwave
       

       Microwave	Radio Waves
       Microwave is a type of transmission  that propagates its signals in one direction at a time	radio transmission is a type of transmission that start from a central point and spread outwards over the covered area hence they travelling in all the directions from the source.

    2.  
       1. Bus topology
       2.  
          • A - The Bus cable
            It is a core section of the bus topology network which has all the nodes connected to it and data pass through it.
          • B - Terminator
            It destroys data that does not reach its destination so that it doesn't cause echo back.
    3. Problems related to power that should be addressed
       • Blackout: This is unexpected discontinuation of power supply in the laboratory
       • Power sage: Sudden drop of voltage levels that lasts less than a second
       • Transients/ surge: High voltage flowing.
       • Brownout: Partial blackout where there's low voltage flow.
       • Short circuit: live wires touching each other's 
       • Loose connection, which may cause tripping or total power failure
         (First 3 @ 2 marks)
19.  
    1. Possible responsibilities of a database admin in a school
       • Carrying out school database backups.
       • Recovering of lost school data incase of system failure.
       • Ensuring the security and integrity of the school system.
       • Adding new users to the school system and managing the user's accounts.
       • Designing and developing database application for the school.
       • Updating or maintaining database for the school.
         (First 3 @ 1 mark) 
    2. Ways in which computers can be used in a transport industry.
       • Use of GPS to track vehicles, flights etc.
       • Bookings to different destinations can be done through the use of computers (online booking).
       • The computers can also be used to reduce the speed of vehicles and bring sanity in the industry. O
       • Managing human resource involved in the industry.
         (First 2 @ 2 marks)
    3. Reasons for partitioning hard disk
       • For security purposes, incase one partition fails the second partition remains functional.
       • If she requires backup copies to be stored in the same hard disk.
       • If she intends to install more than one operating system.
         (First 2 @2.marks)
    4.  
       1. Schedule feasibility
          • To determine if the proposed solution can be developed within the required time. 
       2. Technical feasibility
          • To determine if the system can be supported by the available technology.
            (2 @ 2 marks)
20.  
    1. Functions of information system in an organization.
       • Process data in an organization according to the policies and objectives.
       • Decision making by providing information that helps with strategic planning within the organization.
       • Means of communication and flow of information to various sections of an organization / enable sharing of information.
       • Improving quality of production, through the use of feedback mechanisms for counter checking the production with expected results.
         (First 3 @ 2 marks)
    2. Benefits of using batch processing.
       • Output is increased because the processor work is uninterrupted. 
       • Low cost of operation since the tasks are processed as a group. 
       • Requires little supervision since the processing runs automatically as long as the instructions are given.
       • Less labour required since the process is automatic.
       • Efficient use of computer resources due to no idle time.
       • Gives company opportunity to check any error before processing begins.
         (First 2 @ 2 marks)
    3.  
       1. Decimal equivalent
          

          Bits	1	1	1	0	1	.	1	1
          Place value	16	8	4	2	1	.	0.5	0.25
          Values	16	8	4	0	1	.	0.5	0.25	29.75

          = 29.75₁₀  @1
       2. Binary operation
          11011₂ + 101₂