Information Technology 9626/13 October/November 2023: question paper and mark scheme

Mark scheme

1 Three from: 4 • Data consists of raw figures/characters/numbers (which require processing for interpretation) (1) • Data does not have any meaning/context (1) • Information is data that has been given meaning/context (1) • Information is data that has been processed (1) One mark for any example. Example must cover BOTH data and information (1)

Mark scheme

2 Four from: 4 • File size is smaller (1) • Takes up less storage (space) (1) • Text format doesn’t need to buy a licence/software (1) • As the file size is smaller the processing time is shorter/less processing power is required (1) • Does not need to be opened by a WP package (1) • Can be opened by more applications (1) • Data can be exchanged between different computers/operating systems (1) • Word processing software has different versions and one version may not open documents produced by a different version (1)

Mark scheme

3(a) Three from: 3 • Whether a computer will repair itself if an error occurs (1) • Whether a computer can continue to operate even if one (or more) of its components has failed (1st) • without affecting the operation of the system/without downtime (award once only) (1) • Whether a computer’s operating quality can reduce, but does not fail completely (1) • Whether when a hardware component/processor fails, another takes over/elements are hot swappable (1st) • without affecting the operation of the system/without downtime (award once only) (1) • Whether computers have two different instances/installations/versions of software (1st) • if there is a problem with the first instance/installation/version, the other version is automatically run (1) • this (characteristic) does not apply to mainframes (1) 3(b) Two from: 2 • Computers generate heat/become overheated (1). • When a computer overheats, it will address this issue (1). • Overheating of mainframes and supercomputers is a problem (1st) • due to the quality and quantity of processors generating a lot of heat (1) • hence the need for cooling systems (1) • Air cooling systems have been used but uses up a lot of power/are very expensive to build and operate (1) • Water cooling systems are more cost-effective/more efficient (1) • in removing any excess heat (1) • Many data centres are now being built in cooler parts of the world (1) 3(c) Three from: 3 • The amount of data that has to be processed is very large (1st) • as countries tend to have a lot of people (1) • The amount of data is increasing (1st) • as each census produces more data (to add to what already exists)/world populations are rising (1) • All data needs to be processed in a short period of time (1st) • and mainframes have a high speed of processing data (1) • (As more data is added), more powerful machines are needed (1st) • and mainframes are easily scalable (1) • Mainframes are very reliable (1st) MAX two marks if answers are all only first marks.

Mark scheme

4(a) Three matched pairs from: 6 • Might enter an account number with 9 or 11 digits/less than/more than 10 (1st) • Length check to make sure that the account number is exactly 10 characters (1) • Might enter a wrong digit (1st) • Use a check digit which creates a new digit by performing a calculation on individual digits of the account number and appending the resulting digit (1) • Might omit one of the account numbers (1st) • Presence check would make sure account numbers are entered. (1) 4(b) Three from: 4 • A key number would be calculated (1) • All the account numbers/numbers in the account number would be added together (1st) • To create a single number (1) • The data/file would be transmitted along with the hash total/key number (1) • The hash total is recalculated once received (1) • The original hash total is compared with the new one (1) • If they do not match an error has been made (1) One from: • A control total checks fields that are used for calculations whereas a hash total is used for fields that hold information (1) • The field holds data, and will not be used for calculations (1)

Mark scheme

5(a) Two from: 2 • Two readings/measurements need to be taken (using the sensor) (1) • Can correct slope/offset errors (1) • Best used where readings are linear (1) • Reading taken at the low end of the range and the high end of the range (1) • Readings taken by a check/reference instrument/uses (previously) known readings (1) • Value for offset is calculated (1st) • by comparing to reference readings/known readings (1) 5(b) Two from: 2 • Uses many/more than two readings/measurements (from the sensor) (1) • Readings taken at a high value, a middle value and a low value (1) • Best used where readings form a curve/non linear (1) • Readings taken by a check/reference instrument/uses (previously) known readings (1) • The calibration cannot be carried out by just adding an offset value/by allowing for the slope (1) • To calibrate the sensor the algorithm needs to include ‘curve fitting’ (1) • Uses a formula to calculate the correction (1) • Uses a quadratic function such as y = ax2 + bx + c (1st) • where y is the reading from the standardised sensor/actual value x is the reading from the sensor needing calibration (1)

Mark scheme

6 Four from: 4 • Simple query is on one field (1) • Complex query is on more than one field (1) • Complex query can use Boolean operators (1) • One mark for TWO examples of Boolean operators: AND, OR, NOT (1) • Simple query use a single criterion only (1) • Complex query uses more than one criterion (1)

Mark scheme

7(a) Two from: 2 • Fade in occurs at the beginning of a sound clip when the sound gradually gets louder (1) • Fade out occurs towards/at the end of a sound clip when the sound gradually gets softer (1) • Volume stops increasing when the required sound level is reached (1) • Sound disappears altogether (1) 7(b) Two from: 2 • Lossless compression retains the quality of the original/does not reduce the quality of the audio file (1) • Data is not lost (1) • When lossless compression software sees a repeated sequence of bits it replaces the repeated sequences with a character (1st) • which indicates what is being repeated and how many times (1) 7(c) Two from: 2 • Removes some of the audio file’s data (1) • Reduces the quality of the audio file (1) • Removes sounds at very low and high frequencies (which are outside the range of human hearing) (1) • Creates smaller file sizes than lossless compression (1) • Once this data has been removed from the files it can never be replaced (1)

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8 Six from: 6 • Immediately before/after/inside count ← 0 box insert total ← 0 (1) • Immediately before/after/inside total ← total + number box insert count ← count + 1 (1) • average ← total/number should be changed to average ← total/10 (1) OR • average ← total/count (1) • yes/no should be reversed (1) OR • count=10 changed to count<10 (1) • Loop line should return to flowchart above Input number box (where drawn on the flowchart, no need to delete the original line or add arrow heads) (1) • Print/output average should be included after average ← total/10 box (1) • Stop box/end should be included at end of flowchart (1) • Add instructions to input box (1)

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9 INPUT X,Y 8 W←X/Y Z=INT(W) IF W=Z THEN PRINT/OUTPUT Y, “ (e.g.)is a factor of ”,X ELSE PRINT/OUTPUT Y, “ (e.g.)is not a factor of ”,X ENDIF Eight from: • INPUT X (1) Y (1) • Correct IF statement (1) • IF and ENDIF indented correctly (1) • Use of THEN (1) • Valid output statement (1) with both commas (1) with speech marks (1) • Use of ELSE (1) • THEN and ELSE indented correctly (1) • Valid output statement after ELSE (1) Commas between values and text in second statement text within speech marks (1) • Correct use of ENDIF (1) • No further code after ENDIF statement (1)

Mark scheme

10 Eight from: 8 • (This) custom written software is created for a defined/this purpose/running a payroll/commissioned by an individual company/business (1) • Does not need to be adapted for use (1) • (Any) settings built into the software can be changed (1st) • if the software doesn't initially meet the manager's requirements (1) • such as ability to copy software on to several devices (1) • Software will have/Programmer can ensure the software will have all the features that are required (1) • Software will be/Programmer will ensure that it is compatible with the existing system and software (1) • Custom written software will not have any unnecessary/distracting features/bloat ware (1) • The company will own the copyright of the custom written software (1st) • so can sell it to others (1) • Usually takes up less storage space than off-the-shelf software (1st) • so less expensive media/data storage costs (1) Max 6 marks for just bullet points

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11 Eight from: 8 • Weather forecasting used to involve several weather forecasters and days of calculations (1st) • today one model can manage the task (1) • Computer models help forecasters to make more reliable predictions (1) • Models can be used to predict future patterns (of weather) (1) • More complex models create more accurate forecasts (1st) • which allow forecasts further into the future (1) • Human weather forecasters are still needed to evaluate the results (1) • Weather forecasting requires the use of a lot of data (1) • To be effective models must consider many variables (1st) • such as (TWO Variables identified): atmospheric pressure, humidity, rainfall, temperature, wind speed, wind direction (1) • as well as calculations such as (ONE of): vertical air motions, temperature changes, moisture processes (1) • A lot of computing power is needed to run a computer model so supercomputers have to be/are used (1) • Supercomputers are (very) expensive (so makes the process an expensive one) (1) • Models can be used to compare current conditions with previous similar conditions/shown trends over a period of time (1) Max 6 marks for just bullet points