Information Technology 9626/11 October/November 2024: question paper and mark scheme

Mark scheme

1(a) THREE marks available 3 Max TWO marks: • To prepare a data storage medium for initial use (1) • The purpose of low-level formatting is to prepare the disk surface to receive data/allow the user to save data/files (1) • High-level formatting creates a file system on the disk (1) • Allows the operating system to use the disk space to store and access files (1). Max TWO marks: • Low-level formatting divides the disk surface into tracks/sectors/cylinders (1) • Write heads magnetise the disk areas (1) • Tracks are numbered starting from 0 (1) • A gap is left between tracks (1) • Each track is organised into numbered sectors, starting at 1 and separated by gaps (1) 1(b) THREE marks available: 3 • Identifies Lossless and identifies Lossy compression (1) Max TWO marks • Reduces the overall number of bits/bytes (in a file)//reduces file size (1) • To increase available storage space on a hard drive (1) • File compression programs remove redundancy (1) Max TWO Marks • A lossless file compression program uses codes to represent repeated Information (1) • Lossless compression removes meta data (1) 1(c) THREE marks available: 3 Max TWO marks: • It speeds up the access time to a file (1). • To create larger regions of (contiguous) free space (1) Max TWO marks: • Organises the contents of the disk into the smallest number of contiguous regions/fragments (1) • The data blocks of a file/defragmented files are moved around to bring whole/all the parts of a file together (1)

Mark scheme

2(a) THREE from: 3 • Mainframes have peripheral processors that deal with all input and output operations (1st) • this leaves the CPU to concentrate on the processing of data (1) Volume of Input (Max 1) • Mainframe computers deal with a very high level of input (1) Volume of Output (Max 1) • Mainframe computers deal with a very high level of output (1) Throughput (Max 1) • This refers to how many processes can be carried out per day (1) • Mainframes can carry out many transactions per day//have a fast rate of processing (1) • Throughput is a discrete mainframe characteristic. (1) 2(b) THREE from: 3 • Mainframe computers are more secure than other types of computer systems (1) • Mainframe has many layers of security (1) • Uses different levels of access (1st) • depends on a user’s level of security as to which sets of data they can access (1) • Data that is transmitted and data within the system are encrypted//mainframe computers use encryption to protect data (1) System is continually monitored for unauthorised access attempts (1)

Mark scheme

3 SIX from: 6 • MIS is used in decision making (1) • MIS is used to coordinate/control data in a business. (1) • MIS software can provide past, present and predictive (TWO FROM) information (1) • MIS software can be used with project management (1) • MIS system may be based on a database (1st) • which can be queried (1) • Can be used to gather/analyse/assess information (1st) • e.g. personnel/sales/inventory/production/employee performance (1) • MIS software could be used to create reports. (1) • By comparing reports to previous reports, trends can be identified (1) • Can produce graphs/charts (1)

Mark scheme

4(a)(i) ONE mark: 1 • Each record in one table relates to only one record in another table (1). 4(a)(ii) ONE from: 1 • Each record in one table can relate to many records in another table (1) 4(b) THREE from: 3 • Need to create a link table (1) • Is created using two one-to-many relationships (1) • Each primary key must exist as a foreign key (1st) • in the link table (1) (Only award once) • The primary key(s) link(s) to the foreign key(s) (1st) • in the link table (1) (only award once) • Not possible to create a single many-to-many relationship (1) • Only a theoretical type of relationship//cannot exist (1).

Mark scheme

5(a) THREE marks available: 3 Max TWO • Data is collected for a specific purpose/task (1) • Provides original data/first hand data (1) Max TWO e.g. • Observation could be used, by the scientist going to the farmland and looking (1) • Questionnaires could be distributed amongst farmers/3rd party linked to scenario (1) • Interviews could be carried out with farmers/3rd party linked to scenario (1) • Data logging/sensors could be used to gather pollution data (1). 5(b) THREE marks available: 3 Max TWO • An indirect data source is when data is obtained from a third party/is second hand (1) • Means data that was collected for a particular reason but is then used for another purpose (award concept of data being used for a different purpose) (1) Max TWO • Could collect data from local government agencies (1) • Could use information presented in scientific journals (1)

Mark scheme

6 FOUR from: 4 • Verification is checking that data has been copied correctly from the data source (1) • Validation is checking that the data entered is reasonable/sensible/follows rules (1) • Verification will not pick up the fact that the original data might be invalid (1) • Verification would pick up a transposition error/most validation checks (except a check digit) would not (1) • Neither validation nor verification on their own will pick up all errors//need both to cover all possible errors. (1)

Mark scheme

7 EIGHT marks available 8 e.g. Benefits max 6 • Compilation process only needs to be done once (1) • Once the program is already compiled into machine language, there is no translation software that the user has to keep up to date (1) • Compiled software can run faster than interpreted software (1) • Compiling a program is a much quicker process than interpreting the code (1) • Compilers compile the code all at once/interpreters converts the code line by line (1) • Do not need to share source code (1) • Compilers also improve security for programmers (1st) by making it much harder to copy the code (1) Drawbacks max 6 • Can only be used on the operating system it was compiled upon (1) • Only produces error list once whole process has been completed (1) • It is slow/more difficult to debug the program (1) • The whole program needs to be compiled again after an error is corrected (1) • It uses up more memory than an interpreter as the whole program has to be loaded (1) • Once compiled, any changes to the original high-level code will require the program to be compiled again (1).

Mark scheme

8(a) THREE marks available 3 e.g. • Motion sensor detects movement (1) • Infrared sensor to detect heat (1) • Sound sensor to detect level of sound/unexpected sound (may exemplify) (1) • Pressure sensor (placed under a rug/carpet) to detect increase in weight by burglar standing on it (1) • Light sensor to detect a break in a light beam. (1) 8(b) THREE from: 3 • Microprocessor may be programmed to have (a range of) acceptable levels (1) • If sensor is activated/sensor readings are outside the expected levels/range (1) • Data is sent from sensor to Analogue to Digital Converter (ADC) (1) • ADC converts the data to digital (1st) – so can be understood by the microprocessor (1) • It sets off an audible alarm sounds/activates lights/alerts police or alarm company or key holder. (1)

Mark scheme

9 EIGHT marks available 8 EIGHT from: Pros max SIX: • Computers never forget to take readings (1) • They take readings constantly (accept 24/7) (1) • No need for human intervention to take readings (1) • The readings are more accurate//can detect readings that humans may not (1) • Readings of several variables can be taken simultaneously (1) • Computers can take readings in dangerous areas for humans to be (1) • Transmission of data can be in real time (not quicker) (1) • Data can be stored for later collection to save electrical power/to reduce human impact (1) Cons max 6: • The monitoring equipment will have to be placed by humans (1) • Sensors/computers have to be repaired/maintained by humans (1) • Environment can affect the signal (1) • Geographical events can affect or move the equipment (1) • The presence/maintaining of the system can affect pollution itself (1) • Humans still have to plan/decide where to place sensors and which sensors to use/which variables to monitor. (1) Conclusion • Valid conclusion based on points made (1)

Mark scheme

10 EIGHT from: 8 Max five if only first points • Knowledge base comprises a database of facts and a rules base (1st) – It is the information used to make the decision (1) – Database of facts gathered from experts (1) • Rules base is a set of rules/statements (1st) – usually of the form IF . . . THEN//description of IF …THEN in practice in context (outcomes based on what is seen/observed/measured) (1) • The shell includes the user interface, explanation system, inference engine and knowledge base editor (THREE FROM) (1) • Inference engine is the reasoning part of the system (1st) – That uses forward chaining or backward chaining (1) • User interface is how the computer interacts with the user, (1st) – displays questions/information (1) – enables the user to type in answers to the questions (1) • Knowledge base editing software/knowledge base editor enables the knowledge engineer to edit rules and facts (1) • Explanation system explains to a user the chain of reasoning used to arrive at a particular conclusion. (1)

Mark scheme

11 FOUR from: 4 • Identifies Lossless and identifies Lossy compression (1) Max 3 for Lossless: • Does not reduce the quality of the audio file (1) • Audio file can be recreated exactly as it was when first created (1) • Algorithms used to perform this compression mainly look for repeating patterns (1) Max 3 for Lossy: • Reduces quality of the audio file (1) • Creates smaller file sizes than lossless compression (1) • The data that is removed can never be replaced (1) • Some lossy compression software will remove frequencies that are outside the range of human hearing. (1)