Build a practice paper from 631 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 · 5 marks
Computers manipulate binary patterns.
Convert the binary pattern 1110 0000 to denary.
Award one mark for:
224
Why: Correct: 128 + 64 + 32 = 224 (1).
7
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.
Bitmap images are stored as a grid of pixels.
Define the term pixel.
Award one mark for any of the following up to a maximum of two marks:
Allow 'picture element' for element/part in the first two bullets, but not on its own
Allow 'bit depth' for colour depth
Do not accept 'picture element'/'pixel' on its own
Do not accept 'a group of pixels' or 'a dot' on its own; allow 'dot' only when it is described as the smallest element/area of the image
Do not accept 'single colour' on its own for the second mark; it must be linked to a binary value/number of bits
Do not accept 'lots of coloured dots' (it contradicts a single colour)
The smallest identifiable area of a bitmap image, which has one colour stored as a binary value.
Why: Smallest identifiable area (1) and single colour stored as a binary value (1)
The smallest part of a bitmap image, made of one colour.
Why: Smallest part (1); no credit for the second mark because the single colour is not linked to a binary value or number of bits
A picture element made from lots of coloured dots.
Why: 'Picture element' on its own is not accepted and 'lots of coloured dots' contradicts a single colour
Images and sound can be stored using lossy compression.
Define the term lossy compression.
Award one mark for any of the following up to a maximum of two marks:
Allow 'some data is deleted/discarded and cannot be recovered' for the second mark.
Do not award the first mark where the response also states that no data is lost.
Do not accept 'removes repeated data' (this describes lossless compression).
Lossy compression reduces the size of a file by permanently removing some data, so the original cannot be restored exactly.
Why: Reduces the size of a file (1); permanently removes some data (1); maximum two marks awarded.
It makes a file smaller.
Why: Reduces the size of a file (1); no reference to data being permanently lost.
It makes a file smaller without losing any of the data.
Why: States that no data is lost, which describes lossless compression; the first mark is not awarded.
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.