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Q&A-KCSE Computer Studies Paper 1

Data integrity in a database can be divided into three categories: referential integrity, domain integrity and entity integrity.

(a)Outline the meaning of each of the following.

(i) Referential integrity

(ii) Entity integrity

(b) Describe how data integrity can improve the process of database management. (2 marks)

(i) Referential integrity

  • Two entities that are related require that a foreign key must have a matching primary key

(ii) Entity integrity

  • Entity integrity specifies that the Primary Keys on every instance of an entity must be kept, must be unique and must have values other than NULL

(b) Describe how data integrity can improve the process of database management. (2 marks)

  • Data integrity is the maintenance of, and the assurance of, data accuracy and consistency over its entire life-cycle and is a critical aspect to the design, implementation, and usage of any system that stores, processes, or retrieves data
  • The overall intent of any data integrity technique is the same: ensure data is recorded exactly as intended (such as a database correctly rejecting mutually exclusive possibilities)

Distinguish between a file and a folder

A file is a collection of related data given a unique name while a folder is named storage location on a storage media that contains related files

1. State two ways in which a computer may be used in a healthcare  sector other than record keeping

  • Patient monitoring
  • Used to control medical equipment e.g ultra sound
  • medical research and studies
  • communication and telemedicine

Give two other uses of hexadecimal in computer science.

  • colour codes // colour in HTML/CSS
  • error messages
  • locations in memory
  • memory dump // debugging 
  • IP(v6) address
  • ASCII // Unicode
  • assembly language
  • URL.

 

State two effects of a computer virus

  • memory used up/slows down computer/alters setting/systems failure
  • erases files/erases data/corrupts data/data needs restoring
  • infects other computers on the network
  • production loss/financial loss

Differentiate between Physical and logical topologies

  • Physical topology deals with the placement of nodes
  • Logical topology deals with the data flow  in the network

5 Artificial intelligence is an emerging trend in computer science.
(a) Discuss the use of artificial intelligence by describing some of its characteristics, the ways in which it may be used and the ethical issues associated with its use.
 

Branch of computer science based on enabling computers to
behave like humans/mimic aspects of human intelligence
AI is implemented in software.
Combines psychology, biology, linguistics, mathematics, neuroscience,
and philosophy (ethics)
AI is not the same as the general intelligence of human beings

 

Uses – Any of the following:
Game playing (chess, quiz, video games)
Analytics (analyse buying patterns, predicting behaviours, predictive
text, financial markets)
Image processing (recognising objects/patterns)
Logistics (scheduling, order fulfilment)
Control systems (cars, manufacturing, weapons, navigation)
Expert systems (medical, mechanical, electrical diagnosis)
Neural networks (simulating neuron behaviours as in brains)
Natural languages processing (chatterbots, chatbots, speech
recognition)
Robotics (dangerous situations, help aged or disabled)

 

Ethical issues – Any of the following:
Take the work of humans, thereby affecting employment rates
Is a computer to be trusted to make decisions (life-death)?

If a computer discovers something that humans can’t prove, should it be
accepted as truth?
Do AI machines have rights?
Will people be comfortable interacting with machines that are
considered intelligent?

Students are using their wireless notebooks to complete their work in a classroom. They will need to connect wirelessly to a printer to print their answers at the end of the lesson.
Describe how CSMA/CA (Carrier-sense multiple access with collision avoidance) operates in the above scenario.

  • All nodes ‘listen’ for traffic to sense when the network is idle.
  • When a node wishes to transmit, it transmits a ‘request to send’ frame’ (RTS)
  • The intended receiving device will transmit a ‘clear to send’ (CTS) frame if it is available.
  • All other nodes ‘sense’ the network is busy and wait a random amount of time before trying to transmit

Describe the following features of a graphical user interface:

(a) Pointer

(b) Desktop

(a) Pointer

  •  A graphical object on a computer screen that responds to move movement and allows the computer user to select and execute commands in graphical user interface operating systems

(b) Desktop

  • It Is a special folder in the file system that is displayed when no other windows are open

Apart from the user interface, name three other components that make up a typical expert system.

– knowledge base
– rule(s) base
– inference engine
– explanation system
– (expert system) shell

State the function of a switch in a computer network

  • It transfers data signals from one node directly to another in the network without broadcasting

Give three examples of how data can be damaged accidentally

  • Power surge/loss (damages hardware)
  •  Use a UPS
  • Water can be spilt on the device
  • Don’t have water near the device
  • Keep the device in a waterproof box when not is use
  • Fire can destroy the device
  • Use electrics safety
  • Keep the device in a fireproof box when not in use
  • Data is accidentally deleted
  •  Add verification method for data deletion
  •  Set access levels for data to limit who can delete the data
  • Incorrect use of storage device
  • Making sure the device is ejected before removing
  •  Physical damage to hardware // hardware failure
  •  Correct care and maintenance of hardware
  •  Software failure 
  • Making sure it is always up to date // enable automatic updates

 

A supermarket uses point of sale (POS) terminals at the checkout for scanning barcodes on the products.

(a) State two items of data that are stored on the barcode.

(b) Describe how the computer system checks that the barcode has been read correctly.

(c) State the type of file access that is used to get the price from the central computer.

(d) Explain how the system updates the file when an item has been sold.

(a) State two items of data that are stored on the barcode.

  • check digit
  • product number/item number/code
  • country of origin
  • manufacturers number/code
  • weight
  • price

(b) Describe how the computer system checks that the barcode has been read correctly.

  • check digit calculation is performed on the check digit, remainder = 0 if the barcode has been read correctly
  • weights and modulus 11 and use remainder
  • or subtractions and addition and use answer


(c) State the type of file access that is used to get the price from the central computer.

  • random/direct/online

(d) Explain how the system updates the file when an item has been sold.

  • search file/master file using barcode number/product code and decrease number in stock/increase quantity sold

State the functions of the following:

  1. Hub
  2. Router
  3. Switch
  4. Bridge

Bridge: Joins together two networks that use the same base protocols.

Hub: Copies all packets of data to all devices on the network.

Router: Stores the addresses of computers on the network and transfers data between devices.

Switch : Analyses each data packet and sends it to the computer it was intended for.

Computer Studies KCSE 2006 Paper 1

SECTION A (40 MARKS)

1.What is meant by

    a)Analogue data

     b)Digital data                           (4 mks)

2. Distinguish between transcription and transposition types of errors and give an example of each  (4mks)

3. a)What are peripheral devices?  (1mk)

   b)Give two examples of peripheral devices  (1mk)

4a)What meant by the term user-friendly as used in software development? (1mk)

  b)Distinguish between the terms single-tasking and multi-user as used in operating systems  (2mks)

5.What actions should be taken in case of a fire outbreak in the computer laboratory?  (4mks)

6a) What is an Internet Service Provider?    (1mk)

  b) An employee in a business company is charged with the responsibility of putting the company advertisements on the Internet.

 i) State the professional title of the employee. (1mk)

ii) Give an example of software used by this employee to carry out the above task.    (1mk)

7.Differentiate between COM ports and LPT ports     (2mks)

8.Explain two ways in which ICT can enhance commerce.  (2mks)

9. Explain the following software terms:

    a) Portability       (1 mk)

    b) Modularity      (1 mk)

10. a) State two application areas of desktop publishing software. (2mks)

     b) Explain the following graphic terms:                                                                                     

     i) Rotate (1 mk)

    ii) Crop  (1mk)

12. a)List two arithmetic operations that can be performed on a row of numeric data in a word processing table.    (1 mk)

     b) In each case of (a) above, write the expression used.  (2mks)

13. List two methods of gathering information during the system development process   (2mks)

14.Name three types of optical disks.(3mks)

15.The diagram below shows a formatted plate surface of a storage disk.

 

 

 

            Shade and label:

            a)         one sector                                                                                ( 1mk)

            b)         One block                                                                                (1mk)

SECTION B (60 MKS)

Answer question 16 and any other three questions from this section in the  space provided

16 a) List two examples of:

       i) Third generation languages    (2mks)

       ii) Object oriented languages    (2 mks)

b) Draw a flowchart to compare three non-equal numeric values A, B, C and prints the largest of the three. (11 mks)

17 a) One of the functions of an operating system is job scheduling.  Explain what is meant by job scheduling.   (1mk)

    b)List and explain three types of user interfaces.                      (6 mks)

    c)Describe the following categories of software:

       i) Firmware                 (1mk)

       ii) Proprietary software  (1mk)

     d) a new company XYZ intends to go into the business of desktop publishing. Advise the company on three computer hardware system specification features to consider as a measure of enhancing performance. (6 mks)

18. a) distinguish between the following sets of terms as used in spreadsheets.        (2mks)

     i)Worksheet and workbook

     ii) Filtering and sorting

     b) State one way in which a user may reverse the last action taken in a spreadsheet package.        (1 mk)

     c)The following is a sample of a payroll. The worksheet row and column headings are marked  1, 2, 3, .  and A, B, C.  respectively

 

One facility of a Software Development Environment is to convert source code to machine code.  Name and briefly describe four other facilities commonly found in a Software Development Environment.

  • Editor: this allows a programmer to enter and edit source code
  • Automatic formatting:  Correctly indents code
  • Automatic colour coding:  Changes key words, literals and annotation to different colours
  • Linker: this is a program which allows previously compiled code, from software libraries, to be linked together
  • Loader: this is a program which loads previously compiled code into memory.
  • Debugger: this is a program which helps locate, identify and rectify errors in a program
  • Syntax error detection:  Highlighting syntax errors before code is translated
  • Trace: this is a facility which displays the order in which the lines of a program are executed, and possibly the values of variables as the program is being run
  • Break point: this is a facility which interrupts a program on a specific line of code, allowing the programmer to compare the values of variables against expected values.  The program code can then usually be executed one line at a time.  This is called single-stepping
  • Variable watch: this is a facility which displays the current value of any variable.  The value can be 'watched' as the program code is single-stepped to see the effects of the code on the variable.  Alternatively a variable watch may be set, which will interrupt the program flow if the watched variable reaches a specified value
  • Memory inspector: this is a facility which will display the contents of a section of memory
  • Error diagnostics: these are used when a program fails to compile or to run.  Error messages are displayed to help the programmer diagnose what has gone wrong
  • Emulator: will provide and emulator to run the code/app so no physical device required
  • Context sensitive menu:  SDE suggests available options
  • Statement completion:  SDE will complete a statement such as adding an ‘end if’ to an ‘if’ statement GUI creation:  Allows programmer to create a GUI by dragging and dropping controls (buttons, etc...) onto a form.
  • Publisher: facility to package up and deploy program as an easy to install package

 Describe four features of the operating system when providing a graphical user interface on a personal computer. Give a suitable example of each feature.

Windows for example a word processing application and a spreadsheet
 
Menus, for example, allow the user to perform operations or run applications such as right-click to create a new folder  
 
Icons for example a picture of linked computers for networking
 
Pointers(mouse or touchscreen)  for example to select items/trigger events  
 
Shortcuts for example to frequently used applications for example having a shortcut to your mail client on your desktop
 
File navigation for example when searching the hard disc for a file/folder using a browser
 
copying / deleting / moving/sorting/naming/searching of files or folders for example copying of a file from the hard drive to a USB pen drive (File handling)
 
Desktop customisation for example changing the colours and background image
 
Copy and paste for example between applications e.g. copying a graph from a spreadsheet to a word processor
 
Error messages for example provide users with error/warning/help messages for example ‘printer out of paper’ 

451/1

COMPUTER STUDIES

PAPER 1

THEORY

DECEMBER 2021

TIME: 2 HOURS

 

FORM TWO END OF TERM TWO 2O21 EXAM

451/1

COMPUTER STUDIES

PAPER 1

THEORY

TIME: 2½ HOURS

 

INSTRUCTIONS TO CANDIDATES:

  • Write your name and ADMISSION number in the spaces provided above.
  • Write the date of examination and sign in the spaces provided.
  • This paper consists of two sections.
  • Answer all the questions in section A.
  • Choose one topic to answer in section B
  • All answers must be written in the spaces provided in this question paper.

  1. SECTION A
  2.  Answer all questions in this section
  3. What is a computer?                                                                                                            1mks
  4. State three physical components that make up a computer                                                 3mks
  5. State the hardware technological differences between the second generation and third generation computers                                                                                                          2mks
  6. State and explain three characteristics of a computer                                                         3mks
  7. State the functions of the following special memories in a computer                                3mks
  8. Buffers
  9.  
  10. Registers
  11. Cache
  12.  
  13. Define the following as used in data representation in a computer                                  (5mks)
  14. Bit
  15.  
  16.  
  17. Byte
  18.  
  19.  
  20. Nibble
  21.  
  22.  
  23.  
  24. Word
  25.  
  26.  
  27.  
  28. Word-length
  29.  
  30.  
  31. State two reasons why a DVD is superior to a typical compact disk                               (2mks)
  32. State three advantages of flat panel monitors over cathode ray tube monitors                   3mks
  33. Explain the following terms as used in word processing                                                  3mks
  34. Section breaks
  35. Thesaurus
  36. Superscript
  37. State two advantages of  impact printers                                                                             2mks
  38. State the function of the following keys on the computer keyboard                                  3mks
  39. Enter key
  40. Insert key
  41. Delete key
  42. State the technology used by the following secondary devices to store data                      3mks
  43. Magnetic storage devices
  44. Solid state storage devices
  45. Optical storage devices
  46. State three reasons why an operating system is important in a computer                         3mks
  47. A typical computer’s main memory consists of both volatile and non-volatile memory.
  48. i)  Explain what is meant by the term volatile memory                                          (1mark)
  49. ii) What is normally stored in the non-volatile part of a computer’s main memory (1mark)
  50. Explain why having cache memory can improve the performance of the CPU         (2mks)
  51. What is a computer system?                                                                                           (1mk
  52. Give two differences between a solid state drive (SSD) and a hard disk drive (HDD)   2mks
  53. State three categories of software classified according User license agreement              (3mks)
  54. State two disadvantages of Random Access Memory                                                       (1mk)
  55.  
  56.  
  57. a) Explain the functions performed by the following components of a processor   (2 marks)
  58. Control unit

What is a defragmentation software

  • It is a utility software that places file data in adjacent sectors to free up space for more data and reduce access time for files stored

Describe two differences between a switch and a repeater

  • a repeater is a two-port device that amplifies a signal from one port to another
  • a switch is a multiport device that uses a table of addresses to send a signal through the correct port