KCSE 2015 Computer Studies Paper 1 with Marking Scheme

SECTION A (40 marks)
Answer ALL the questions in this section in the spaces provided.

1. State two circumstances under which warm booting of a computer may be necessary. (2 marks)
2. List six file manipulation activities that may be carried out using an operating system. (3 marks)
3. Figure 1 shows relationships between tables in a database.
   
   Identify two primary and two foreign keys used in the relationship. (2 marks)
4. State two advantages of using portable computers. (2 marks)
5.     
   1. Write the acronym MODEM in full. (1 mark)
   2. Explain the purpose of a modem when connecting to the internet. (2 marks)
6. Distinguish between an assembler and an interpreter as used in programming. (2 marks)
7. State three possible causes of fire outbreak in a computer laboratory. (3 marks)
8. State three benefits of using optical magnetic reader to register candidates for an examination. (3 marks)
9. List four factors to be considered when acquiring a printer. (4 marks)
10. State three circumstances under which voice input would be preferred over other methods of data capture. (3 marks)
11. A computer technician found it necessary to disable a firewall when working on a computer system. State two reasons that may have necessitated disabling of the firewall. (2 marks)
12. State two advantages of making payments through a mobile phone. (2 marks)
13. State three reasons why it is important to define datatypes of fields in a database correctly. (3 marks)
14. Explain two uses of a system documentation in system development. (4 marks)
15. Distinguish between a systems administrator and a database administrator as used in computers. (2 marks)
    

SECTION B (60 marks)
Answer Question 16 and any other THREE questions in this section in the spaces provided.

16.    
    1. List four web programming languages. (2 marks)
    2. State four ways in which a programmer can make program code easy to follow. (4 marks)
    3. Draw a program flowchart to represent the following pseudocode. (9 marks)
       Begin
       While scores exist
       initialize sum to zero
       initialize counter to zero
       input a score
       increment counter by 1
       Add score to sum
       If there are more scores to read,
       compute average as sum divided
       by counter
       Print the average
       Else
       input next score
       End if
       Else
       Print no records exist End while
       End
17.    
    1.    
       1. In the BCD number coding scheme, letter A is represented by 110001 and letter B by 110010. Determine how the word CAB is coded in BCD. (2 marks)
       2. Convert the decimal number 11.125 to its binary number system equivalent. (3 marks)
       3. Perform the binary arithmetic: 111.01 + 1011.111 - 101.011 and convert the answer to decimal notation. (3 marks)
    2. Explain the importance of each of the following in word processing:
       1. tab stops; (2 marks)
       2. section breaks. (2 marks)
       3. State three documents that are used during mail merging in word processing. (3 marks)
    3. State three functions of networking operating systems other than providing network security. (3 marks)
18.      
    1. Explain three ways in which an operating system provides data security in a computer system. (6 marks)
    2. Explain three circumstances under which observation method may be preferred during data collection. (6 marks)
19.    
    1.    
       1. List two techniques of acquiring electronic images to be used in a desktop publishing program. (1 mark)
       2. Describe two layout guides in a desktop publishing program (DTP) that assist a user to place an object in a preferred position. (4 marks)
    2. Explain three ways of ensuring that data submitted for processing is accurate. (6 marks)
    3. An engineering company requires a computer system to design roads and bridges. Explain one suitable choice for:
       1. output device; (2 marks)
       2. software (2 marks)
20.    
    1. Explain two ways in which the use of internet could make reporting of corruption easier. (4 marks)
    2. Explain two circumstances under which the use of wireless communication would be preferred in data communication. (4 marks)
    3. Figure 2 is an extract of a spreadsheet showing what the students had targeted to score and the actual score in a computer remedial class.
       

       	A	B	C	D	E
       1	NAME	TARGET SCORE	ACTUAL SCORE	PERFORMANCE FACTOR	REMARKS
       2	Abdi	40	45
       3	Alex	30	65
       4	Ben	50	60
       5	Betty	30	20
       6	Bena	45	45
       7	Sheila	70	60

       Figure 2
       A performance factor is obtained by subtracting the target score from the actual score and dividing the difference by the target score.
       Write a formula that uses cell references only that would be entered in cell:
       1. D2 to compute the performance factor. (2 marks)
       2. E2 to display the statement ‘more remedials’ if the performance factor is less than zero, 'exempted' if the factor is greater than zero and optional remedials' if otherwise. (4 marks)
       3. D8 to display the best performance factor. (1 mark)

MARKING SCHEME

SECTION A: 40 Marks

1. Reasons for warm booting a computer
   • when computer hangs
   • when a program encounters an error
   • during the installation of new software for the installation to be complete
   • during the installation of hardware so that the drivers can be activated.
     (Any 2 x 1) = 2 marks
2. File manipulation activities
   • creation of files/folders
   • deletion of files/folders
   • moving of files/folders/drop/drag/cut & paste
   • copying of files/folders
   • viewing of files/folders
   • editing of files/folders
   • sorting of files/folders
   • renaming of files/folders
   • Hiding of files/folders
     (Any 6 x ) = 3 marks
3. Primary and foreign keys
   Primary keys
   • TermID
   • StudentID
     
     Foreign keys 
   • TermCode
   • StudID
     (2 marks)
4. Advantages of portable computers
   • They have battery that powers the devices hence can be used when where is no power.
   • They can be used anywhere because they are light.
   • They require less space.
   • Technology must be qualified.
     (Any 2 x 1) = 2 marks
5.      
   1. Acronym MODEM in full
      Modulator Demodulator/modulation demodulation (1 mark)
   2. Purpose of a Modem
      Convert digital signals to analog format before transmission; and incoming signals from analog to digital before processing. (2 marks)
6. Distinguish between an assembler and interpeter
   • Assembler: Translators that convert assembly language codes into machine code. (1 mark)
   • Interpreter: Translators that convert high level language source code into machine code. (1 mark)
7. Sources of fire in a computer laboratory
   • Electrical faults;
   • Natural causes e.g lightening;
   • External attacks e.g arsonists/terrorists;
   • Inflammable material;
   • Accidents.
     (Any 3 x 1) = 3 marks
8. Benefits of using OMR
   • Helps in minimizing human errors during data input/has high accuracy;
   • It hastens capturing of candidates data /is faster;
   • Cheaper, since it reduces the need for human intervention;
   • Can be used for bulk processing.
     (Any 3 x 1) = 3 marks
9. Factors to consider when acquiring a printer
   • Initial cost;
   • Print quality (Number of pixels);
   • Running cost;
   • Speed of the printer;
   • Whether coloured or black & white;
   • Paper size;
   • Nature of work.
   • Volume of work
   • Technology involved eg. printing from storage media.
     (Any 4 x 1) = 4 marks
10. Circumstance for voice input
    • When the hands of the user are engaged;
    • When the user has physical disabilities;
    • When faster input is required;
    • When the user is not good in keying skills.
      (Any 3 x 1) = 3 marks
11. When firewall is disabled
    • Testing the communication link;
    • When upgrading the firewall;
    • When there is a need to install an application and the firewall is preventing the operation;
    • When the firewall prevents legitimate communication.
      (Any 2 x 1) = 2 marks
12. Advantages of mobile phone in payments
    • Easier payment of bills (No queuing)/saves time;
    • Cheaper (qualified);
    • Transactions over wide geographical space;
    • Relatively secure due to audit records.
      (Any 2 x 1) = 2 marks
13. Reasons for defining datatypes in databases
    • Memory use optimisation when the program is loaded;
    • Assist in trapping errors during data input;
    • So that appropriate computation can be performed;
    • Increase speed of processing.
      (Any 3 x 1) = 3 marks
14. Uses of system documentation
    • Technical manual referred to during system maintenance;
    • User training: it has details of how the system works and used hence used for training new users;
    • System progress: the document assists in the tracking of flow from one stage to the next;
    • User guide that helps a system user to solve problems since the document outlines how the system is operated and the errors that are likely to occur/installing programs.
      (Any 2 x 2) = 4 marks
15. Distinguish between systems administrator and database administrator
    • Systems administrator is responsible for all parts of computer network such as user accounts, computer accounts, domain trusts, email accounts;
    • Database administrator deals with only aspects of database such as database server and client software, (2 marks)

SECTION B : 60 Marks

16.       
    1. Web programming languages
       • HTML - Hyptertext Mark-up Language
       • Java script
       • VBScript - Visual Basic script
       • XML - Extensible Markup Language
       • PHP - Hypertext Preprocessor
       • SQL - Structured Query Language
       • Dream weaver
       • Front page
         (Any 4 x 3) = 2 marks
    2. Ways to make program code easy to follow:
       • Using modules or short blocks of program/functions/procedures;
       • Making internal documentation / comments;
       • Using meaningful variable names and user words in the program;
       • Using indent to represent nested statement;
       • Using blank lines to separate blocks of code statement;
       • Test formatting of reserved words eg. bolding(Any 4 x 1) = 4 marks
    3. Program flowchart
       
       
17.    
    1.      
       1. Cis 110011
       2. CAB is 110011 110001110010
          (2 marks)
       3. 
          

          Integer	Part
          2	11
          2	5 R1
          2	2 R1
          2	1 R0
          	0 R1

          Number 1011
          
          Decimal part
          .125 x 2 = 0.250
          250 x 2 = 0.5
          .5 x 2 = 1.0
          Number is 0.001
          
          11.125₁₀ = 1011.001₂
          (3 marks)
       4. Arithmetic operations
          111.01
          + 1011.111
          10011.001
          - 101.011  
          1101.110
          (1 x 2³) + (1 x 2²) + (0 x 2¹) + (1 x 2⁰)+(1 x 2^-1) + (1 x 2^-2)
          = 13 ³/₄ (3 marks)
    2. Importance of tab stops and section break (1)
       1. Tab stop: when tab stops are set, they allow aligning of text into columns; (2 marks)
       2. Section breaks: Allows splitting of a document into different sections so that different formatting styles can be applied to the different sections. (2 marks)
    3. Documents used during mail merge
       
       • Main document - primary/secondary data source
       • The address list - the intended recipients of the document.
       • The merged document - final document ready for printing or sending. (3 marks)
18.    
    1. Functions of network operating systems
       
       • Provide access to network resources;
       • Supporting network services like protocols;
       • Support communication;
       • Respond to requests from applications; (Any 3 x 1) = 3 marks
    2. Ways in which an operating system provides data security
       • Access control: Deals with the problem of verifying /authenticating the identity of a user before permitting access to the request resource (e.g. use of passwords, user account);
       • Encryption - Transforming data into an unreadable format so that they are safely transmitted;
       • Firewalls - Filters out unwanted data and programs/criminals/hackers/malicoius persons;
       • Log files - A means by which transactions in a computer system can be recorded thereby detering potential infiltrators;
       • Alerts - Alerting a user when he/she is about to delete a file/folder.
         (Any 3 x 2) = 6 marks
    3. Preference of observation during data collection
       
       • When the subjects that are being observed need not be made aware of the fact;
       • When there is need to directly see what subjects do rather than rely on what they tell you;
       • When there is need to collect data without interfering with the working of the subjects;
       • When nature of data can only be collected via observation e.g. traffic flow;
       • When collecting data in situation that subjects may be unwilling to give information.
         (Any 3 x 2) = 6 marks
19.    
    1.    
       1. Ways of acquiring images in DTP:
          • Scanning;
          • Picture capture via camera;
          • downloading;
          • getting from secondary storage.
            (Any 2 x ) = 1 mark
       2. Layout guides
          • Ruler guides: a ruler on the edges of the page that guides a user to position objects and resize them;
          • Margin guides: used to define page margins so that the user will be prevented from placing objects in non-printable areas of the page;
          • Column guides: Vertical lines used to divide a page into two or more columns;
          • Row guides: Lines used to divide a publication page into two or more section to help structure the layout;
          • Snap points: Positions on the screen where the object is stuck on.
            (Any 2 x 2) = 4 marks
    2. Ways of ensuring accuracy of data during data processing
       1. Data is stored in secondary storage in such a way that access to it is controlled.
       2. Encrypting of data before it is transmitted to minimize chances of it being compromised during transmission.
       3. Use of validation methods to ensure that data is correct at the point of input.
       4. Use of direct data capture methods which eliminates human errors. - Use of verification methods.
          (Any 3 x 2 ) = 6 marks
    3.    
       1. Output device: A plotter because it prints large size drawings to high precision. (2 marks)
       2. ACAD software because it facilitates in the design of engineering drawings. (2 marks)
20.      
    1. Ways in which internet makes reporting of corruption easier.
       • Interactiveness: the internet based technology enables real-time dialogue hence instantaneous reporting of cases;
       • Outreach: the technology allows the coverage of wide areas/can be reported from anywhere;
       • Social mobilisation: It is easy to use technology to create a network with people or organisations with similar concerns;
       • Anonymity: With use of the technology, it has become easy to report corruption cases without being known;
       • Security: The message sent reaches the destination with less risk of being intruded.
         (Any 2 x 2) = 4 marks
         
         
    2. Circumstances when wireless is preferred
       • When the targetted recipients are many and diverse e.g. different platforms, devices,
         geographical locations.
       • When the sender or receiver is mobile and it in practical to use wired media.
       • When there is no space or it is inconvenient to lay cables e.g in a congested town.
       • When the distance of travel is very big e.g extraterestial communication.
         (Any 2 x 2) = 4 marks
    3.      
       1. (C2 - B2)/B2 (2 marks)
       2. If (D2 <0, “More remedial”, If (D2 = 0, "Optional”, “Exempted")) remedials
          OR
          If (D2>0,"Exempted””Optional remedials”)
          Use of the IF function
          First selection & output Second selection & output Last selection & output (4 marks)
       3. = Max (D2:D7) (1 mark)