Build a practice paper from 693 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.
3 questions · 4 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.
A bitmap image has a resolution.
State what is meant by the resolution of an image.
Award one mark for any of the following:
Do not accept the number of pixels in the image on its own, without dimensions or an area, e.g. 'the total number of pixels'
Do not accept colour depth / the number of bits used per pixel / the number of colours
Do not accept file size in bytes / the amount of storage the image uses / screen size / image quality
The concentration of pixels in an area, such as the number of pixels per inch.
Why: Gives the density/concentration of pixels in an area, and pixels per inch (1)
The number of pixels in the image.
Why: A bare total pixel count is not accepted without dimensions or an area
The number of bits used to store each pixel's colour.
Why: Describes colour depth, not resolution, and colour depth is not accepted
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.
Teachers: build a paper, print it with the mark schemes at the end, and sign your school up to set your classes activities on every topic.
Fetch Decode Explain isn't affiliated with or endorsed by Pearson Edexcel.