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Q&A-KCSE Computer Studies Paper 1

There are security concerns associated with cloud storage.
(a) State one way in which providers of cloud storage could prevent security breaches by their own employees

 (b) Explain why data on networks is encrypted

(a) One from:

  • Background checks
  • Access control
  • Physical security
  • User policies

(b) To prevent unauthorised access (1) so that data remains confidential (1) by making it unintelligible (1) because it is scrambled (1)

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Joe plays online games using the world wide web. A sequence of processes is required to open a web page. Describe this sequence of processes

  • URL is clicked/typed into a web browser address bar. The page is requested (by the web browser) so HTML and files are fetched from a web server and the browser collates the page, which is then displayed on the monitor.
  • OR
    URL is clicked/typed into a web browser address bar (1). The browser locates the IP address either in cache or using a DNS server and the browser sends a request to the web server with that IP address web server uses HTTP to send back the requested web page and the browser displays the content of the page .
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List three other types of software license.

  • Network
  • Commercial
  • Enterprise
  • Proprietary
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Explain the Fetch – Execute cycle and provide an example of a Central Processing Unit (CPU) component for each stage of the cycle

The Fetch – Execute cycle is a sequence of actions, performed by the processor as it fetches
a program instruction from its memory, determines what the instruction wants to do and
carries out those actions. The stages of the cycle are provided below.

  • Fetch the instruction – the processor fetches the instruction from a memory address stored in a program counter and transfers the instruction, via a data bus, to an instruction register. At the end of the fetch operation, the counter points to the next instruction that will be read in the next cycle.
  • Decode the instruction – the processor decodes the instruction stored in the instruction register, including getting any operands required to complete the instruction.
  • Execute the instruction – the decoded instruction is executed.
  • Store the result – the result generated by the execute phase is stored in the main memory, and/or sent to an output device. The program counter is updated with feedback from the arithmetic logic unit (ALU), to a different address from which the next instruction will be fetched.
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List three types of errors that are likely to exist in a program                             (3 marks)

Syntax errors-Incorrect use of programming language

Logical errors- The program do not give the expected output

Runtime errors- Premature end of a program

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The introduction of a new system involves evaluation and maintenance once the system is
implemented.
Describe the evaluation and maintenance stage of the systems development life cycle (SDLC)
and provide one example of an activity undertaken in this stage.

  • Continually monitoring, evaluating and updating the system once it is operational. Activities include rectifying bugs, requesting changes, updating aspects, finding errors, maintaining code etc.
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What is an Operating System?

  • It refers to a system software that provides a platform for installation and execution of an application software and also manages the computer hardware
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State the seven layers of the OSI model

  1. Application
  2. Presentation
  3. Session
  4. Transport
  5. Network
  6. Data link
  7. Physical

An organisation that supplies audiobooks over the internet is moving into a new office building.
 (a) One reason for networking devices is to provide access to the internet.
  (i) Give two other reasons for connecting devices to networks.
 

  • Share peripherals/devices (e.g. printers, scanners)
  • Communicate (e.g. email, instant messaging, play games)
  • Share data (e.g. files/music/videos/backups on servers)
  • Deploy/update applications
     
     

List three electronic data processing modes used in computers

  • Realtime processing
  • Batch processing
  • Timesharing
  • multiprogramming
  • Online
  • Batch
  • Distributed
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Aeroplanes now use Global Positioning Systems (GPS) to determine their location.

Describe how the computer on board the aeroplane uses GPS to find its exact location

Give two benefits of using GPS in this application

Describe how the computer on board the aeroplane uses GPS to find its exact location

– satellites transmit signals to onboard computers
– computers receive/interpret these signals
– system depends on very accurate timing/use of atomic clocks
– each satellite transmits data indicating location and time
– computer in aeroplane calculates location based on at least three satellites
– at least 24 satellites in operation at any one time
– position accurate to within one metre
– can also calculate altitude of aeroplane
– ref to “triangulation”:

Give two benefits of using GPS in this application

– safer as the known location is exact/more accurate
– reduces the possibility of pilot error
– allows accurate estimation of arrival time
– display and guide the pilot to the nearest airport in case of emergency

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In reference to word processing, define the following terms

Word wrap

Justification

Drop cap

Word wrap - Is a word processing feature in which a word that does not fit in the current line is automatically moved at the start of the next line

Justification - refers to aligning text on both left and right margins

Drop cap - Make the first character of a paragraph occupy more than one line below it

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Which files are backed up in an incremental backup scheme?

  • Any new or changed files since the last backup
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Describe the purpose of the control unit (CU) within this computer.

  • It sends control signals that manage the transfer of data and instructions within the CPU
  • It decodes an instruction using an instruction set
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State three factors to consider when selecting an operating system to install in a computer        (3 marks)

  • Ease of installation and use
  • Application software intended for use in the computer
  • Processor type. Some processors do not support all operating systems
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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)
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Give a reason why HMTL is not regarded as a programming language

  •  It does not have declaration part
  • It does not  have control structures
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State a circumstance under which dry-run testing is performed when developing a program (2mks)

  • To detect and remove errors
  • To confirm if the program produces the expected output
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 Lucy wrote: “I should validate the input into my database by typing in the same data twice”.Why was her statement incorrect?

  • she had actually described verification
  • data could be incorrect, therefore same incorrect data typed in twice
  • accept description of validation process e.g. range check
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Explain the term website as used in the internet

  • A collection of related webpages under the same domain name
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