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3 questions · 5 marks
Computers manipulate binary patterns.
Convert the binary pattern 1010 0100 to denary.
Award one mark for:
164
Why: Correct: 128 + 32 + 4 = 164 (1).
37
Why: Reads the place values from the wrong end (the left-hand bit as 1), so the value is wrong.
3
Why: Counts the 1s instead of adding their place values.
Files can be compressed before they are stored.
Define the term lossless compression.
Award one mark for any of the following up to a maximum of two marks:
Allow 'the compressed file takes up less storage space' for the first mark.
The second and third bullets are two ways of making the same point: award a maximum of one mark for them, so a response that says no data is lost and that the original file can be restored, but does not say the file is smaller, scores one mark.
Do not accept descriptions of lossy compression, e.g. 'it removes data that is not needed to make the file smaller'.
Ignore reference to download/transmission times, bandwidth and streaming, as these are benefits of compression and not part of the definition.
Lossless compression reduces the size of a file without permanently removing any data, so the original file can be restored exactly.
Why: Reduces the size of a file (1) and no data is lost, so the original can be restored exactly (1); maximum of two marks reached.
It makes a file smaller so it downloads more quickly.
Why: Reduces the size of a file (1); the faster download is ignored as a benefit, not part of the definition.
It removes data that is not needed to make the file smaller.
Why: Describes lossy compression, which the do-not-accept line rules out, so the mention of making the file smaller is not credited.
A school laptop is shared by several teachers.
Describe the purpose of giving each teacher their own user account on the laptop.
Award up to two marks for a linked description such as:
Do not accept responses about the laptop running faster or having more storage because it has more accounts.
Do not accept 'so they can log in' without saying why having separate accounts helps.
Each teacher's files are stored separately, so other teachers cannot open or change their work.
Why: Separate files for each account (1) and other teachers kept out of that work (1).
So that each teacher has their own files.
Why: First point of separate files per account (1), but no development of what this achieves (0).
So the laptop runs faster because each teacher has their own account.
Why: Gives speed as a purpose of user accounts, which is not correct for user management; no creditworthy point.
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