Information Technology 9626/12 May/June 2021: question paper and mark scheme

Mark scheme

1(a) 1 It returns an error message if a data item is not in a lookup list. It checks to make sure a data item is within an upper limit and a lower limit. It checks that a data item consists of a set number of characters, Π not more or less. It is only used to check numbers. 1(b) 1 It is used to check that the data in two fields correspond. It checks the number of digits. It is the digit added to the end of a long number after a calculation Π has been performed. It checks that a number is above a certain limit. 1(c) Eight from: 8 Examples: A type check checks that all data items are of the same type of character… …either letters or numbers A type check on the Weight could be carried out as the data must be numeric A type check on the Year patented could be carried out as the data must be numeric… …there are no letters in the Weight/Year patented fields A type check would not prevent numbers out of range/incorrect numbers being entered for Weight… A type check would not prevent numbers out of range/incorrect numbers being entered for Year patented… A format check checks that a string follows a certain pattern… …such as dd/mm/yyyy for somebody’s date of birth A format check could be carried out on the Product number as it must be two letters followed by three numbers A format check would not pick up a non-existent/incorrect Product number …as long as it was two letters followed by a three numbers… A format check could possibly be carried out on Weight as it has to be a digit followed by one single decimal number A format check could possibly be carried out on Year patented as it has to be four digits… …but it would still accept an out of range/incorrect year… Must be a proper analysis to gain full marks Max. six marks if bullets/list of points Must have expansions to be a proper analysis

Mark scheme

2(a) 1 Readings from sensors are not processed before being output. A sound sensor is the sensor most frequently used in a weather station. Rainfall is measured using a computerised measuring stick. Graphs can be produced automatically from a weather monitoring Π system. 2(b) 1 An actuator is the most important input device in such a system. The timing sequence of the traffic lights is randomly generated. An induction loop is used to detect the presence of an automobile. Π Traffic light systems use moisture sensors to detect the presence of pedestrians. 2(c) Six from: 6 The start time of the cooking is set using buttons/switches/remote control The required temperature is set using buttons/switches/remote control The length of cooking time/end time is set using buttons/switches/remote control The start time/cooking time/end time/temperature are stored as preset values The microprocessor continuously checks the start time against its internal clock/timer If the start time is equal to the internal clock time, the microprocessor sends a message to an actuator… …The actuator switches on the heater (and fan) If the start time is not equal to the internal clock time, the microprocessor takes no action The temperature sensor reads the temperature inside/of oven… … ADC converts analogue data from sensor to digital data… …and sends/inputs temperature of oven to microprocessor The microprocessor continuously compares the temperature of the oven against the required temperature/preset value If the temperature of the oven is equal to/greater than the required temperature, the microprocessor sends a message to an actuator… … the actuator switches off the heater (and fan) If the temperature of the oven is not greater than the required temperature and the heater (and fan) is/are off, the microprocessor sends a message to an actuator… …the actuator switches on the heater (and fan) The end time can be calculated by adding the length of the cooking time to the start time The microprocessor continuously checks the end time against its internal clock/timer If the end time is equal to the internal clock time, the microprocessor sends a message to an actuator… …The actuator switches off the heater (and fan) The time/temperature output goes to the (LED) display

Mark scheme

3(a) Three from: 3 It is quicker to type/input coded data (e.g. G) than it is to type uncoded data (e.g. Light green) Codes such as S require less storage space than shirt Fewer mistakes will be made when entering data such as S instead of 25–30 When data has been coded it makes it easier to use validation such as for A or D or U or G than typing in Astio or Dasiap or Utap or Gumho 3(b) Three from: 3 Light and dark green are both coded as G, so it is difficult to know which shade of green is being referred to Shirt and skirt are both coded as S, so it is difficult to know which type of garment is being referred to Coding can obscure the meaning of the data, e.g. S in size is difficult to judge waist size/range is quite large There may be other brands beginning with A, D, etc. so it may be difficult to convert the coded data back into uncoded data The size codes use different lengths of code, e.g. S is 1 character, but XXL is 3 characters 3(c) Two from: 2 Use the second letter in addition to the first to code the Colour/Type of clothing/Brand, e.g. SH – Shirt, SK – Skirt Use narrower ranges for size, e.g. 25–27, 28–30 Use the bottom end of the range for size so only 2 characters are used

Mark scheme

4(a) Three max from: 3 A malicious program that replicates itself… …until it fills all of the storage space on a drive or network Exploits security holes in networks Usually a small self-contained program that invades computers on a network A worm locates a computer’s vulnerability and spreads within its connected network Worms often originate from e-mail attachments that appear to be from trusted senders Worms then spread to a user’s contacts via their e-mail account and address book. Worms can slow down a network… …by consuming bandwidth 4(b) Three from: 3 Programs that secretly record what a user does on their computer Spyware is software that is installed on a computer without the user’s knowledge Often the first indication is a noticeable reduction in processor speeds Can gather information like Web browsing habits Can capture e-mail messages Can capture a user’s personal data… …such as usernames and passwords as well as credit card information Transmits this data to a third party over the internet

Mark scheme

5 Six from: 6 Max 4 from: Bar charts show data with blocks of different heights… …with the height of the block corresponding to the quantity being represented Sales($) values would be the height of the block… …and the Months of the year would be the labels along the x axis in a bar chart Line graphs show a series of points connected by straight lines… …with the horizontal axis normally representing time In a line graph the Sales ($) would be the y axis… …The Months of the year would be along the x axis of a line graph Max 6 from: Bar charts are used for comparisons of categories of data Bar charts are better for comparing the sales of different months… …but not the trend Line graphs are better for showing trends over time… …it’s easier to see small changes on line graphs than bar charts… …although bar charts can be used to show trends… …the line in a line graph makes the overall trends very clear There would be no need to have the y axis starting at zero in this line graph… …so the trend would be more obvious A bar chart has to have the y axis starting at zero… …and so the trend for this data would be more difficult to determine Must be a proper analysis to gain full marks Max. five marks if bullets/list of points Must have expansions to be a proper analysis

Mark scheme

6(a) Six from: 6 LAN stands for local area network LAN covers a small geographic area LAN is used within a home, office, school, or group of buildings (must have at least 2) LANs have a high data transfer rate/WANs have a lower data transfer rate compared to LANs LANs use Layer 1, layer 2 and layer 3 devices One LAN can be connected to other LANs over any distance via telephone lines and radio waves A system of LANs connected in this way is called a Wide Area Network Ethernet and WiFi are the two most common technologies in use for local area networks Most LANs use a switch/hub to link the network and manage all the connected devices In businesses and schools one computer/a server may also be the central access point of a LAN 6(b) Four matched pairs from: 8 Email: electronic mail where they could write letters to each other Narinder may not be sure that her parents have received the message/it may take a long time to receive a reply/no video/audio interaction Vide-conference/call where Narinder and her parents could use laptops with cameras and microphones to speak to each other Parents receiving the call must also have video conferencing software running in order to listen/can be affected by bandwidth issues/needs a lot of planning before hand/lag due to poor internet connection VoIP: Voice Over Internet Protocol. Narinder would use a microphone connected to a computer/speak using a VoIP phone (and the software would convert it into a format that can be sent over the internet) Parents receiving the call must also have VoIP application running/installed in order to listen/can be affected by bandwidth issues Social networking sites where Narinder could post a message with pictures/video on her page/area/can update her posts Can later regret posting pictures or comments that were thought funny at the time/possible for hackers to use her photos without permission/ Parents might not be skilled social network users/ it may take a long time to receive a reply Chat rooms: Narinder could meet her parents in a chat room and chat to them by typing a message Parents might not be skilled chatters and not know how to keep conversation private/Other people apart from parents may be able to enter the room, thereby losing privacy/strangers could eavesdrop Text messaging: Narinder and her parents could send messages to each other It may take a long time to receive a reply/need to have phone switched on

Mark scheme

7 Eight from: 8 Rajvinder sends emails to every person being invited informing/reminding them of the conference/sends reminders/sends date and time of meeting Rajvinder sends log in details to members of the sales team He uploads any necessary documents for the meeting He sends a link to the website He enters his user name and password (obtained from the provider) He selects a start time/end time/time/date In the meeting area, he types an agenda He uses the software to select participants He selects an appropriate meeting space/room He selects/types in those team members who can enter the room automatically and those who have to be invited He chooses which participants can be presenters/can modify documents He limits the participation of team members/mute volume/disables messaging/disables cameras The participants click on the link to enter the conference The participants enter the password/log in The participants wait until Rajvinder allows them to enter

Mark scheme

8 Six from: 6 Advantages It is easier for users to navigate around the database using one… … especially for users who are not familiar with a particular database… …than if they had to select tools from an unfamiliar/complex tool bar The administrator of the database can prevent other users from accessing specific sections of a database… … to avoid them corrupting the data A click-based interface makes it easier for people to access specific datasets/reports/other forms… …all the user has to do is simply click on the buttons provided… …instead of selecting tools from an unfamiliar tool bar This is more useful when users are just going to use the database… …and not create new tables/forms/reports Disadvantages As a database becomes bigger, the design of a switchboard can become quite complex There is a limit to the number of buttons that can be placed on a switchboard/switchboards are restrictive… …so users may not be able to create new tables/forms/reports as easily as with a database not using one If more features are required, further switchboards need to be added increasing the complexity At least one of each required to obtain full marks Must be a proper evaluation to obtain full marks Max. five marks if bullets/list of points Must have expansions or comparisons to be a proper evaluation

Mark scheme

9(a) The transaction file must be validated 1 9(b) Eight from: 8 The computer reads the first record in the transaction file belonging to 25306 The computer reads the first record in the old master file belonging to 13487 The record from the transaction file is compared to the record from the master file If the records don’t match, the computer writes the master file record to the new master file The records don’t match so the next record of the master file is read, 25306 If it matches, the transaction is carried out/weekly pay is calculated The records match so the computer calculates the hourly rate x hours worked, 25 x 35… …using the hourly rate, 25, from the master file and the hours worked, 35, from the transaction file The processed record is written to the new master file The next record, 25376, is read from the transaction file… …then compared to next master file record, 25376 This continues until the last record from the transaction file, record 39286, is read/all the transaction file records are read After processing the last record of the transaction file, 39286, all the remaining old master file records are written to the new master file… …in this case one record, 39875

Mark scheme

10(a) Three from: 3 Testing nuclear reactions using computer models avoids safety problems such as explosions/meltdowns/environmental problems Testing nuclear reactions using computer models cuts costs as the testing company doesn’t have to pay as much money for materials Results can be obtained in a short period of time regarding reactions that take a long time in real life Re-designing computer models is cheaper than re-creating a nuclear reaction Computer model can be designed to allow for extreme conditions/natural disasters 10(b) Two from: 2 Models can’t always recreate exactly the real-world experiment Not every possible variable may be included in the model, leading to inaccurate results It costs money to hire computer experts to create the models

Mark scheme

11(a) Column B will widen to the width necessary for the largest piece of 1 text/number to fit within the cell. 11(b) The height of Row 3 will increase to the height necessary for the largest 1 piece of text/number to fit within the cell. 11(c) Set to currency, 2 decimal places and symbol set to $ (must have at least 2) 1 11(d) Limit check 1 mark 2 Checks that values in B2:B5 are greater than or equal to 0.8

Mark scheme

12(a) Three from: 3 Proprietary software is software that is owned by an individual or a company, usually the one that developed it There are almost always major restrictions on its use A software vendor delineates the specific terms of use in an end-user license agreement Its source code is almost always kept secret Usually covered by copyright, which provides a legal basis for its owner to establish exclusive rights 12(b) Two from: 2 Can be used and implemented/accessed by anyone An open-source file format can be used by both proprietary and open- source software Anyone may use them at no monetary cost for any desired purpose They can be opened by most types of software by a standards organisation