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Q&A-KCSE Computer Studies Paper 1

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
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Maranda MOCK 2024 CRE Paper 2

b) What Simeon and Anna said about the life of Jesus during the dedication. (7mks)

Jesus would save people

He would bring glory to Israel

He would be a light to the gentiles

He would be a universal savoir

He would bring judgment to the Israelites

Many people would oppose his work

He would reveal secret thoughts of people

He would be the source of redemption for Jerusalem

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Website data is broken down into packets to be transmitted to a user. Describe the structure of a data packet.

It has a header

  • that contains the destination address
  • that contains the packet number
  • that contains the originator’s address

It has a payload

It has a trailer.

 

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Give one advantage of a star network when compared to a ring network.

if one station/cable fails, others are not affected
easier to identify faults when using star topologies
it is easier to expand this type of network
performance doesn’t deteriorate under load

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State the areas where infra-red radio waves are used      KCSE 2018

  • TV remote control communication;
  • DVD remote communication
  • Communication between peripheral devices and the computer
  • Data link over a short distance using mobile phones Radio remote control
  • Remote locking/opening doors/ devices
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What are computer networks?
A set of connected computers and other devices which share resources such as software, internet connection,printers etc
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She lost all her photographs when her computer crashed.
(i) What is meant by the term crashed?
(ii) How could she have avoided losing all her photographs?

  • the computer appears to “freeze”/”hang”
  • computer won’t respond
  • failure of hardware (stops computer normal functioning)
  • failure of software (stops computer normal functioning)
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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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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
     
     

Describe and give an example of one syntax and one logical programming error.

Syntax
An error that occurs when a command does not follow the expected syntax of the language, e.g. when a keyword is incorrectly spelt
Incorrect: IF A ADN B Then
Correct: IF A AND B Then

Logical
An error that causes a program to output an incorrect answer (that does not necessarily crash the program)
An algorithm that calculates a person’s age from their date of birth, but ends up giving negative numbers

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What is a computer virus?

A computer virus is a program designed to damage other programs or causes irregular behaviour in a computer system.

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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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The Acme company stores data for a private scientific research group. It has recently upgraded its storage capacity and needs to dispose of its existing hard drives securely. Outline two methods for the secure disposal of the data on the hard drives.

Acme company needs to ensure that if they are reselling the drives they wipe the drive (this should be done regardless of the destruction of the drive) to the DoD standard.

  • Disassemble the drive by pulling it apart the drive so that the data would not be accessed
  • Destroy the metal disk either by drilling holes so it cannot be read
  •  Encrypt drives with passwords that are not accessible
  • Degaussing the hard drives
  • Use specialized overwriting software

This would ensure that any software cannot be used to locate files.

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Why must operating system be installed in a computer before any other program

  1. Operating system manages the computer hardware thus without it the programs cannot communicate directly to the hardware
  2. Provide a user interface through which a user can give instructions to the computer. Without a user interface, it would be difficult to load or run programs
  3. other programs depend on the operating system to load them into the memory , allocate resources and schedule processor time, Without operating , there would be nothing to co-ordinate the execution of multiples programs
  4. The OS organizes data in files and directories, making it possible for programs to save, retrieve, and modify data.
  5. Without it, programs wouldn’t know where or how to store data.
  6. The OS controls access to files, memory, and devices, ensuring that one program doesn’t interfere with another.


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Many organisations provide free public access to a wireless network.
Explain three ethical, legal or data privacy issues that an organisation should be aware of when allowing this access

  • Websites any inappropriate websites ie pornography, drugs, guns,
  • terrorism etc. e.g. is it acceptable for the organisation to allow access to this
  • sort of material when you can’t control who is accessing the service?
  • Time limit amount of time, they may not want to provide indefinite access
  • or may want to charge for access after the time limit has expired.
  • Preventing file sharing and illegal sharing\use of copyrighted materials.
  • Accountability identification of users and actions on a network by
  • preventing anonymous access.
  • Prevention of illegal activities such as terrorism and fraud.
  • The responsibility to keep children safe and protected.
  • Responsibility to keep users (customers) data safe and secure.
  • Spoofing of websites, phishing. Responsibility of organisation to put some kind of protection in place, eg filtering of known fraudulent sites.
  • Recording of private messages or details if not encrypted.
  • Recording of usernames and passwords that the user may also use to access other systems.
  • Responsibility of organisation to secure their systems from possible attack.
  • Sales and marketing providing sales leads to market products.
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State advantages and disadvantages of the following system implementation strategies

Phased:
Advantages:

  • only a small part of the operation affected if new system fails
  •  no need to pay for two sets of wages

Disadvantages:

  •  time consuming (each part needs testing fully before expanding system)

Pilot:
Advantages:

  • if new system fails, only that part will be affected
  • possible to gradually train staff on pilot before whole system changes over

Disadvantages:

  •  time consuming (waiting to see how pilot works before rolling out to rest of the organisation)

Direct:
Advantages:

  •  less likely to malfunction since fully tested
  • immediate benefits/less time wasted
  •  reduced costs (only one system so no need to duplicate staff)

Disadvantages:

  • disastrous if the new systems does fail

Parallel:
Advantages:

  •  if new system goes down, there is a backup system in place
  • possible to gradually train staff/staff have time to get used to the new system

 

 

 

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State and briefly describe three program control structures

Sequence: Sequential execution of a program one line after another

Selection:  Involve the a decision between two or more options e.g  if...then...else

Loops/Repetitions: Used for looping i.e a line of code can be made to execute a given number times before terminating.

State advantages and disadvantages of Solid State Drives and Hard Disk Drives

Advantages of  of Hard Disk Drive

  • Hard disk drives are cheaper per gigabyte than solid state drives.
  • Hard disks have a longer lifespan than solid state drives

Disadvantages of Hard Disk Drives

  • Consumes more power than SDD
  • They are noisy.
  • They are slower than solid state drives.
  • They are susceptible to wear and tear as they have movable parts.

Advantages of Solid State Drives

  • Are faster than HDDs
  • It is more durable as it does not have moving parts
  • Consumes less power
  • Are not noisy

Disadvantages of SDD

  • It costs more than a conventional hard disk
  • Have fewer write/erase cycles compared to a hard disk drive
  • Lost data cannot not be recovered
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When data is transmitted it is subject to corruption. Explain how a parity check could be used to determine whether corruption has taken place.

  • Extra bit on each data-byte that
  •  Does not transmit data
  • Makes the number of ones in a byte always even or always odd
  • Error in the transmission of a bit will make the even/odd wrong
  • The problem of two errors in one byte not being found
  • Parity block
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Distinguish between one to one and one to many relationships as used in relational databases

One to one  - Each record in the parent table has exactly one related record in the child table, and vice versa.

One to Many -  Each record in the parent table can have multiple related records in the child table, but each record in the child table is related to only one record in the parent table

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