WorksheetsiGCSE Computer Science: Data Compression and Encryption
Total questions: 18
Worksheet time: 13mins
Which of these are recognised types of file compression? (select all that apply)
lossless
lossy
superchannel
standard
redundant
What are the main reasons to compress data? (select all that apply)
To reduce secondary storage space
To maximise the available RAM memory
To speed up network transmission times
To optimise the data
To reduce packet congestion on networks
Which of these are recognised lossless compression algorithms? (select all that apply)
RLE
LZ-77 (dictionary coder)
Caesar cipher
Merges sort
What is the correct Run-length encoding for the data: cccmmmmmsssssdcccccc
3c5m5s1d6c
c3m5s5d1c6
cmsdc35516
cccmmmmmsssssdcccccc
Which of these image file formats support lossless compression techniques? (select all that apply)
JPG
PNG
GIF
BMP
SVG
Which of these audio file formats support lossy compression?
FLAC
MP3
WAV
OggPCM
WMA
What is the correct order of memory storage units from smallest to largest?
KiB MB MiB GB TiB
KiB MiB MB TiB GB
MB MiB KB GB TiB
KB GB MB MiB TiB
What is the name of the lossy compression algorithm used in JPG image compression?
Discrete Cosine Transform
Abstract Sinusoidal Mutation
Run-length encoding
LZ-77
On which of these data strings would you expect a dictionary-based lossless compression algorithm like LZ-77 to achieve the highest compression ratio?
This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop. This is an endless loop.
lpumf yxidt mgcwo aiyfj nqyuj znhja vjacx vewcf jmxgy suqwj dvnzq zcops gpsbz rgxox sxypw mvvun cxxda dfixa burli sitbh ljprx uqehk aggap btnep ispxx zmuus ndbyd hwplq zbwgd pznkr zkdbp ssedo
Grumpy wizards make toxic brew for the evil Queen and Jack
Old MacDonald had a farm
E-I-E-I-O
And on his farm he had a cow
E-I-E-I-O
With a moo-moo here
And a moo-moo there
Here a moo, there a moo
Everywhere a moo-moo
Old MacDonald had a farm
E-I-E-I-O
On which piece of data would you expect the run-length encoding algorithm to achieve the highest compression ratio?
Nellie the Elephant packed her trunk
And said goodbye to the circus
Off she went with a trumpety-trump
Trump, trump, trump
Computer Science is great Computer Science is great Computer Science is great Computer Science is great Computer Science is great Computer Science is great Computer Science is great
What type of modelling is being exploited in mp3 audio lossy compression?
psychological
psychokinetic
physiological
psychoacoustic
Asymmetric encryption is when ...
a message is encrypted and decrypted using two different keys: a public one and a private one
only one message can be encrypted at a time
An encrypted message is received, but there is no requirement to return an encrypted message
There is no key available to decrypt an encrypted message that has been received
Which of these encryption algorithms do you need to know about for iGCSE Computer Science? (select all that apply)
Caesar
Pigpen
Vigenère
Rail-fence
Vernam
Which is a Caesar cipher?
Which is a Vigenère cipher?
Which is a Pigpen cipher?
Which is a rail-fence cipher?
Select all the statements that are true about the Caesar cipher
It was first used by Roman Emperor Julius Caesar
It is a very secure form of encryption
It does not provide much information 'leakage' for a cryptographer
It can be easily cracked using frequency analysis techniques
It is an example of a substitution cipher
