Download SOTIK DISTRICT JOINT EVALUATION TEST

SOTIK DISTRICT JOINT EVALUATION TEST-2015
451/1
COMPUTER STUDIES
PAPER 1
(THEORY)
MARKING SCHEME
SECTION A
1.
a
This is a type of computer storage that is directly accessed by the
processor/control unit
b
Static Random Access Memory
Dynamic Random Access Memory
0.5 x 2=1
2
a
Computer Aided Design
b
No need for scaling since all drawing is done full size
The screen drawing area can be set to any size with click of a button
All tools needed are supplied by the program
Absolute accuracy can be maintained
Production details can be extracted directly from the drawing
Easily be erased and changed
Can be copied and pasted many times
Can be sent elsewhere quickly since it in electronic form
Can easily produce mass identical products. Any 2 x 1 = 2marks
3
a
Data security includes all measures that are taken to detect, document and
counter the threats to data and information while data privacy involves
securing confidential data from unauthorized access
b
A hacker is a person who gains unauthorized access to a computer network
for profit, criminal mischief; or personal gain.
4.
a
Modem
Router
0.5 x 2=1
Reject gateway
b
Use of Internet filtering software/blocking inappropriate sites using
suitable firewalls
Use of software that monitors the sites visited by the employees
conducting awareness programme for employees in which they are
briefed
2 x 1=2marks
5
a
Disk compression reduces the amount of space used by all the files and
folders in the disk hence creating more free space
Do not award a mark if a student defines instead of stating the
significance
b
Disk clean up ensures that additional free space is created by removing
rarely used files and programs that take unnecessary space without reducing
the drive performance
Do not award a mark f a student defines instead of stating the
significance
6
a
Develops system and application software
Developing user and technical documentation for the new system
Maintaining the software to meet day-to-day requirements while
overcoming the challenges
Any 2 x 1=2marks
Computer Studies 451/1
Marking Scheme
1
1 mark
1 mark
1 mark
2 marks
1 mark
1 mark
1 mark
2 mark
1 mark
2marks
b
7
a
b
8
a
b
9
10
a
a
b
Develop in-house application programs or system programs
Customize commercial applications packages to suit the organizations
needs
Install, test, debug and maintain programs developed or customized for
the organization
Any 2x1=2marks
A special-purpose computer is designed to handle/accomplish a particular
specific task only e.g. robot, electronic calculator, mobile phone while an
embedded computer is a computer that is within another device or system
but is not accessed directly. e.g., there are embedded computers
operating within Petrol pumps, Watches, Cameras and Video
recorders.
Award 1 mark for difference; do not award if the difference is not clear
Award 0.5 mark for each correct example >>0.5 x 2=1mark
The media used is highly portable hence convenient to carry around
They have high access speeds since they do not have moveable parts
Most are easily transferrable between computers
Award 0.5 mark for any 2 correct answers >>>0.5. x 2=1mark
=B4*$B$1
No mark if the formula does not start with an equal sign
=((B4*$B$1)+B4)*5
Check for BODMAS- if brackets are absent, wrong result will be yielded
Presenting three dimensional objects or ideas that are either real or
abstract
Entertainment
Training
Design evaluation
Simulation and assembly of sequences
Assistance to physically challenged
Any 2 x 0.5 = 1
Repetitive strain injury
Eye strain and headaches/Computer Vision Syndrome
Electromagnetic emissions
Any 2 x 0.5 = 1
Repetitive strain
 Fixing breaks during sessions
 Ensuring users sit in relaxed positions
 Enlightening users on various typing techniques they may adopt
Electromagnetic emissions
Provide low emission devices
Providing frequent breaks
Eye strain and headaches
Provide monitors of good resolution
Provide antiglare screens for CRT displays
 Ensuring users adjust brightness of the monitor to comfortable
Level
Any suitable TWO answers x 1=2marks
Computer Studies 451/1
Marking Scheme
2
2 marks
2 marks
1marks
1 mark
2marks
1 mark
1 mark
2 marks
11
a
b
c
12
a
b
13
In real time processing the computer receives and processes the incoming
data as soon as it occurs, updates the transaction file, and gives an
immediate response that would affect the events as they happen.
Or
A data processing mode where processing happens so quickly such that the
results (output) produced are able to influence, control, or affect the
outcome of the activity or process currently taking place.
Airline reservation systems:
Theatre (cinema) booking.
Hotel reservations.
Banking systems for making enquiries about customers’ accounts.
Police enquiry systems.
Chemical processing plants:
In Missile control systems
In Hospitals to monitor the progress of a patient.
Any 2 x 0.5=1
Timing of the information (reports) is not a necessity.
Cost of processing is limited
Level of training for the personnel required to setup the data processing
system is low
Any 2 x 0.5 =1
UPS/Power stabilizer
Voltage regulator
Power backup devices
Any 2 x 0.5=1
UPS
V It regulates power from an unstable power source to the required clean
stable voltage.
 It prevents power surges and brownouts that might destroy the computer.
It temporarily provides power to the computer in case of the main power
failure. This allows the user to save his/her work and shutdown the
computer using the correct procedure.
 Alerts the user of any power loss (by beeping).
Voltage regulator
It regulates power from an unstable power source to the required clean
stable voltage.
Power backup devices
 It provides power to the computer in case of the main power failure.
Any 2 x0.5=1
A Window is a rectangular portion! area of the screen that Windows sets
aside for a specific task.
A Window is a rectangular area on a display screen in which text and
graphical images may be displayed.
Example
An application window
Pointer— a graphical feature that enables the user to select objects on the
Computer Studies 451/1
Marking Scheme
3
1 mark
1 mark
1 mark
1 mark
1 mark
4 marks
14
15
display screen and is controlled by a pointing device e.g. arrow shaped
pointer, hour glass pointer
Icons — small graphical pictures that represent commands, files, or
applications e.g. a folder, my computer icon, recycle bin icon etc
Menus — this is a list of choices that let the user execute commands by
selecting them e,g start menu, file menu etc Award a s follows
 Correct explanation 0.5 mark >>> 0.5 x 4= 2
 Correct example drawn from any OS 0.5 >>>0.5 x 4 = 2
Total score 4
Select text and then open the replace dialog box
Type MS in the Find what box and Microsoft in the Replace With
box
Click Replace all button
1 mark x 3 steps = 3
To check for syntactical errors
To carryout program linking
Convert source code into object code
To let the compiler identify the proper order of processing, so as to
execute the process as fast as possible & minimize the storage space
required in memory.
To allocate space in memory for the storage locations defined in the
program to be executed.
To combine the program (machine) code generated with the
appropriate subroutines from the library.
produce a listing of the program, indicating errors, if any.
Any 2 x 1=2
SECTION B
Computer Studies 451/1
Marking Scheme
4
3 marks
2 marks.
15
a
Award only if the program will execute to this point.
NB
1. award for correct use of the IF... THEN control using same scheme
2. DENY mark for processing if the student writes the expression:
a. Having denominator and numerator instead of using the slash
b. Writes M2 instead of M
2
3. Check that correct symbols have been used in each case. DO NOT
award where incorrect symbol has been used
4. INPUT/ENTER/READ or such phrases should be used iii the input
box to score. If a student just writes M without indicating it is an
input should not score
5. OUTPUT/PRINT or such phrases should be used iii the output box
to score. If a student just writes K without indicating it is (ill output
should not score
b
START
0.5 marks for start
INPUT M
0.5 marks for input of M
IF M<>O THEN
0.5 mark for correct condition
K (M + 1)/M”2
0.5 mark for processing
OUTPUT K
0.5 mark for outputting K
ELSE
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Marking Scheme
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c
d
17
a
PRINT “Invalid Value of M”
0.5 marks for alternative
ENDIF 0.5 mark for ENDIF T
STOP 0.5 mark jf program executes to I/ic end
NB
The pseudocode should be the actual representation of the jiowachart.
DO NOT award marks f the pseodocode is different from the flowchart
i A pseudocode is a method of documenting a program logic in which
English-like statements are used to describe the processing steps.
or
 These are structured English-like phrases that indicate the program
steps to be followed to solve a given problem.
ii An Algorithm is a limited (finite) number of logical steps that a
program follows in order to solve a problem.
or
A step-by-step (a set of) instructions which when followed will
produce a solution to a given problem.
It is flexible.
 Structured programs are easier to read.
 Programs are easy to modify because; a programmer can change the
details of a section without affecting the rest of the program.
 It is easier to document specific tasks.
 Use of modules that contain standard procedures throughout the
program saves development time.
Modules can be named in such a way that, they are consistent and
easy to find in documentation.
 Debugging is easier because; each module can be designed, coded & tested
independently
i
Taking the integral part
2410= 110002
Taking the fractional part:
1mark
Integral part
0.35x2=0.7
0
0.7x21.4
1
0.40x2=0.8
0
0.80x2=1.6
1
0.60x2=1.2
1
0.20x2=0.4
0
0.40x20.8
0
0.80x2= 1.6
0 >0.3510=0.0101102
1 mark
Hence 24.3510 = 110002 +0.0101102 = 11000. 0101102
1 mark
Student at liberty to use long division or place value method for the
whole number
Computer Studies 451/1
Marking Scheme
6
ii
iii
b
6ABH = (6 x162)x (Ax 161)+(B x 16°)
But
A= 10
B = 11
16°= 1
Hence
6ABH=(6x162)x(Ax161) +(Bx160)
6ABH=(6x256)x(10x16)+(11x1)
=1536+160+11
170710
7468 in binary:
78= 1112
48= 1002
68= 1102
=> 7468 = 111100 1102
Putting in groups of 4
1
11
We have:
12=1
11102=14
0110=6
But
1410= EH
Hence
7468 = 1E6H
1 mark
1 mark
10
0110
1 mark for deriving these values
1mark
36 10
=> 3610 = 1001002
2510
1 mark
=> 2510 = 1001002
Hence 3610 — 2510 1001002 - 110012
= 1001002-0110012
1 mark for making numbers of bits equal
Computer Studies 451/1
Marking Scheme
7
c
18.
a
b
c
= 1001002 +(NOT(0110012)+1)
= 1001002 +(100110+ 1)2
=1001002+ 1001112
1 mark for 2’s complement
= 10010112
=0010 1 12
1 mark for correct answer
=>25= 110012 1 mark
11101.110
111.011+
100101.001
Award 2 marks for correct answer
Field
Data type
MemberlD
Text/string
PostCode
text/string reject number because of prefix 00..
FeePaid
Yes/No (Boolean)
DateJoined
Date/Time
1 mark x 4 correct data types = 4
MemberiD
1 mark for correct field
Reason:
It is unique for each member hence can be used to uniquely identify the
member records in the database
I mark for reason
i It is not possible that one is a member with full fees paid on a date that is yet
to occur i.e. the member has joined but at a future date
ii The mistake can be prevented during data entry by introducing a validation
rule with an accompanying validation text
1 mark
The validation rule should be set to restrict entries that are greater than
current date
I mark
d
e
f
19.
a
b
Correct fields as in the question paper 1 mark
Correct condition 2 marks
Relational since the records are held in a table
Award 2 marks — 1 mark for relational and 1 mark for proof.
Do not award if there is no proof or if proof is incorrect
An application software that facilitates the creation and maintenance of
databases ________
Problem identification recognition
 Information gathering
 Requirements specification.
System Construction (coding).
System Testing and Implementation.
 System Review and Maintenance
Any 3 x 1 =3 marks
Ascertaining strengths and limitations of current system
 Determination of the task to be undertaken
Reviewing the current system
Computer Studies 451/1
Marking Scheme
8
c
e
20
a
 Determination of the objectives and scope of proposed system
 Feasibility study
Any3xl =3 marks
System flowchart is a tool that can be used for analysing processes. It
allows one to break a process down into individual events/activities, and also
display these events in a short form showing the sequential or logical
relationships between them.
Procedure flowcharts is a special type of flowchart that allows the developer
to provide details of individual processes in the system
based on the system flowchart
 Entity relationship diagrams is a tool that shows the various entities/objects
in the system and how they associate with each other
Program flowcharts is a tool used to show the processing logic of a program
in diagrammatic form
Any three tools correctly described x 1 = 3 marks
NB: do not award for stating
Use the high-level structured languages, e.g., Pascal, COBOL, etc
Use the 4th generation languages, e.g., Visual Basic, Visual COBOL,
Delphi Pascal, etc
Customise and use a ready-made standard package such as a database
software, financial package or enterprise management system.
3 x 1 =3 marks
i Changeover refers to moving from the current system to the new system
ii Direct (straight) changeover:
The users have a very high level of confidence with the system.
The new system bears little resemblance to the old.
 The system is relatively small.
 Personal resources are unavailable for any other method.
Parallel running:
 It promotes user confidence since it allows the results of the old & new
system to be compiled side-by-side.
 It is reliable because it enables thorough testing.
 The users are given time to familiarize themselves with the new system.
Phased changeover:
It ensures slow but sure changeover, and also tends to prolong the
implementation period. In this case, users/analysts are able to learn from their
mistakes.
Pilot running:
Pilot running offers gradual change to the overall new system. During this
time, the staff gains enough experience & confidence.
Citing correct reason
1 mark
Strategy selected correctly qualified : 1 mark
NB:
There is no particular changeover strategy fitting the exam processing
situation since it depends on various factors. Let the student’s argument
support particular strategy identified. Award only if the reason qualifies
the strategy
A LAN is a computer network that is formed whenever computers are
connected together in a relatively small geographical area. e.g.. in one
Computer Studies 451/1
Marking Scheme
9
b
c
d
e
f
g
i
building or a school.
Or
LAN is the smallest size of network that normally covers an area within the
radius of l0m — 3 Km.
 Mail server
 Database server
 Print sever
DNS server
Any 2xl=2marks
 Hard disks have very large storage capacities
 They also have fast access rates
 They are well protected from environmental elements
 They are reliable
Any 3 x 1 = 3 marks
When sending a common mail to all the clients of the firm/employees of the
firm
 When sending a common mail to all the employees of the finn
 When sending a common mail to various parties having different addresses
Any 1 x1=1mark
Standard dictionary will contain standard English words and cannot be
customized to contain non English word
 Custom dictionary will allow the user to add non-English word or word not
found in standard English
Each salient feature correctly identified x 1 = 2 marks
 Dot matrix printers produce inferior quality output
Dot matrix printers are noisy during operation
Dot matrix are relatively slow during operation especially if the higher
resolution printing is to be achieved
Any2xl=2marks
ii  Laser printers are expensive to purchase
Laser printers are not capable of producing multiple copies
2x1=2marks ____
Star Network
I mark
Advantages
- Central management of network through a switch/hub
- Node failure does not affect the network
- Easy addition and removal of nodes Disadvantages
Disadvantages
- Failure of central switch brings down the whole network
- Expensive in terms of cabling as each node has its own
independent cable to the switch.
Any 1 disadvantage x 0.5= 0.5 marks
Any_1_advantage_x_0.5_=_0.5_marks
Computer Studies 451/1
Marking Scheme
10