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 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.
A computer can store a maximum of 80 bits for a text message. Each character is stored using 7-bit ASCII.
State the maximum number of whole characters that can be stored in the message.
Award one mark for:
Allow 11 remainder 3.
Allow 80 ÷ 7 = 11.428... rounded down to 11.
Do not accept 11.4 or 12 (rounding up or giving a decimal answer).
Do not award an unevaluated calculation such as 80 ÷ 7 with no answer.
11
Why: Correct: 80 ÷ 7 = 11 remainder 3, so 11 whole characters can be stored (1).
11.4
Why: Near miss: gives a decimal result rather than the number of whole characters; the mark scheme does not accept 11.4.
12
Why: Rounds up to 12, but 12 characters would need 84 bits, more than the 80 available; the mark scheme does not accept 12.
A student has a large number of photographs stored on a computer.
Describe the purpose of data compression software.
Award up to two marks for a linked description such as:
Do not accept 'it compresses the files' on its own, as this repeats the question.
Do not accept responses about protecting files from malware/viruses or about deleting files.
It makes the files smaller so that they use less storage space on the computer and more of them fit on the disk.
Why: The point (1) and a linked development giving the benefit (1).
It makes files smaller.
Why: This is the point (1) but there is no development of what the smaller size leads to, so only one mark.
It protects the files from viruses so that they cannot be damaged.
Why: This describes anti-malware software, which the mark scheme does not accept; no creditworthy point is made.
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