Ch13 : Data representation

Multiple Choice

What is the defined list of characters recognised by a computer’s hardware and software called?

• ASCII code

• Character set

• Interchangeable

• Data stream

Multiple Choice

Why is it important for computers to use a standard code like ASCII for representing text?

• To ensure data can be exchanged between different computers and manufacturers

• To make computers faster

• To reduce the size of the keyboard

• To improve the graphics quality

Multiple Choice

ASCII stands for:
 

• a) American Standard Code for Information Interchange

• b) Advanced Symbol Chart for Integrated Input

•  c) Automatic System Coding Interface

• d) Analogue Signal Code Interpretation

Multiple Choice

ASCII is mainly used to:
     

• a) Store images

• b) Represent characters in binary form

• c) Measure sound

• d) Convert signals

Multiple Choice

How many bits were originally used in the ASCII code, and how many characters could be represented?

• 7 bits, 128 characters

• 8 bits, 256 characters

• 6 bits, 64 characters

• 5 bits, 32 characters

Multiple Choice

ASCII is a character-encoding scheme that uses a numeric value to represent each character. For example, the uppercase letter “G” is represented by the decimal (base 10) value 71. A partial list of characters and their corresponding ASCII values are shown in the table above.

ASCII characters can also be represented by binary numbers. According to ASCII character encoding, which of the following letters is represented by the binary (base 2) number 1010100?

• N

• P

• T

• W

Multiple Choice

Which of the following ASCII code ranges represent upper-case alphabetic characters, lower-case alphabetic characters, and numeric characters 0 to 9?

• 65-90 for upper-case, 97-122 for lower-case, 48-57 for numeric

• 48-57 for upper-case, 65-90 for lower-case, 97-122 for numeric

• 97-122 for upper-case, 65-90 for lower-case, 48-57 for numeric

• 65-90 for upper-case, 48-57 for lower-case, 97-122 for numeric

Match

Match each term to its correct definition:

• The encrypted version of a message created using a key

• Changing encoded information back into readable form

• Changing information into a code so it cannot be read by everyone

• Changing information into a different form so it can be read by a computer

• The person for whom the message is intended

Cipher

Decrypt

Encrypt

Encode

Intended recipient

• Cipher

• Decrypt

• Encrypt

• Encode

• Intended recipient

Multiple Choice

What is the answer?

• 01001110

• 01111000

• 10011100

• 01000111

Multiple Choice

What is the answer?

• A

• B

• C

• D

Multiple Choice

What would ord('c') return?

• a) ‘c’

•  b) 100

• c) 99

•  d) ‘d’

Multiple Choice

What would chr(100) return?

• a) 100

• b) ‘d’

• c) 99

• d) ‘c’

Multiple Choice

What does the ord() function do?

• a) Returns a random number

•  b) Converts binary to hexadecimal

•  c) Returns the denary (ASCII) code of a character

• d) Encrypts a message

Multiple Choice

Which Python functions are used to convert a character to its ASCII code and vice versa?

• ord() and chr()

• ascii() and code()

• char() and num()

• asc() and dec()

Multiple Choice

What is the purpose of the ord() function in the pseudocode shown?

• To convert a character to its denary code

• To convert a number to a character

• To display a string on the screen

• To receive input from the keyboard

Multiple Choice

How does the chr() function help in building up a string from user input according to the algorithm shown?

• It converts denary codes to characters and appends them to a string

• It converts characters to denary codes

• It sorts the string alphabetically

• It removes spaces from the string

Drag and Drop

To turn information into a code so that it cannot be read by everyone​

Placeholder

To change encoded information back to its original form​

Placeholder

To change information into a different form so a computer can read it​

Placeholder

The person that the message is written for​

Placeholder

Drag these tiles and drop them in the correct blank above

Encrypt

Decrypt

Encode

Intended recipient

Multiple Choice

What is the purpose of the ord() function in pseudocode?

• a) It returns the next character in the alphabet.

• b) It converts a number into a character.

• c) It takes a character as a parameter and returns its denary (ASCII) code.

• d) It prints text to the screen.

Multiple Select

Which of the following are reasons for the development of the extended ASCII code (Choose three answers)?

• Need for more characters to support foreign languages

• Need for more mathematical symbols

• To reduce the number of printable characters

• To accommodate special symbols for drawing pictures

Multiple Choice

Unicode can represent more characters than ASCII.

• True

• False

Multiple Choice

What problem did the Unicode Consortium aim to solve, and how does Unicode address this problem?

• It aimed to solve the problem of limited color depth in images by introducing more colors.

• It aimed to solve the problem of multiple versions of ASCII by developing a universal standard for text representation.

• It aimed to solve the problem of image resolution by increasing the number of pixels per inch.

• It aimed to solve the problem of file size by compressing text files.

Multiple Choice

Why was Unicode developed?

• To replace binary code

• To provide a universal character set for all languages

• To improve internet speed

• To reduce file sizes

Multiple Select

Select three answers:

• All of the major languages/symbols/characters can be represented by Unicode because it uses a minimum of 16 bits/more bits/32 bits/65536 characters

• Unicode can represent all/more characters/any language whereas ASCII can only represent English/Latin/128 characters/doesn’t have enough characters

• Unicode can represent all characters because it uses 16 bits/2 bytes /more bits instead of 8 bits/1 byte

• Unicode uses fewer bits than ASCII, and Unicode is faster to type than ASCII.

Multiple Choice

Image resolution refers to:

• The number of colours

• The file format

• The number of pixels (width × height)

• The bit depth

Multiple Select

Which of the following statements about pixels and resolution is/are correct (choose three answers) ?

• A pixel is the smallest single point of color in a graphic image.

• Resolution refers to the number of pixels per inch when an image is displayed.

• Higher resolution means fewer pixels per square inch.

• Lower resolution images show less detail.

Multiple Choice

If 1 bit is used to represent each pixel, how many different colors can be displayed in the image?

• 1

• 2

• 8

• 256

Multiple Choice

Which formula is used to calculate the file size of a bitmap image?

• Width × Height × Colour depth

• Width + Height + Colour depth

• Width × Height ÷ Colour depth

• Width + Height × Colour depth

Multiple Choice

Which characteristics of a sound wave determine its loudness and pitch?

• Amplitude and frequency

• Wavelength and speed

• Amplitude and wavelength

• Frequency and speed

Multiple Choice

What does analogue recording represent?

• a) Changes in binary code

•  b) Continuous changes in air pressure caused by sound waves

• c) Data stored as 1s and 0s

•  d) Voltage changes represented in bits

Multiple Choice

The changes in voltage in analogue recording are directly:

• Opposite to air pressure

• Proportional to the changes in air pressure

• Random to air pressure

• Unrelated to air movement

Multiple Choice

What causes a speaker’s diaphragm to vibrate in analogue playback?

• Voltage reduction

• Amplified voltage changes

• Sound compression

• Quantised bits

Multiple Choice

What term means increasing the strength of a sound?

• Sampling

• Amplification

• Quantisation

• Resolution

Multiple Choice

Which medium is mentioned as an example of analogue sound storage?

• Compact disc

• Flash drive

• Vinyl record

• SD card

Multiple Select

Which of the following statements are true about digital recording?

• Digital recordings use a series of sound 'snapshots' called samples.

• Continuous change can be represented by a digital stream.

• Sound data must be represented as streams of 1s and 0s.

• Sampling is the process of taking measurements of a sound wave at regular intervals.

Multiple Choice

What does each vertical line in the sound wave diagram represent?
 

• One waveform

• One sample of the sound

• One bit

• One frequency

Multiple Choice

Digital sound recordings can be easily edited, copied, and shared on different digital media.

• True

• False

Multiple Choice

Which of the following is not an advantage of digital sound recording compared to analogue recording?

• a) It is easily copied.

• b) It can be edited using computer equipment.

• c) It does not physically deteriorate with use.

• d) It always has higher accuracy than analogue recording.

Multiple Choice

The number of bits used per sample is called:

• Sampling rate

• Resolution rate

• Bit depth (or sample resolution)

• File rate

Match

Match the following

• Can be easily copied or transferred between digital devices

• To get worse over time, though digital files do not physically do this

• The degree of similarity between the original sound and the recorded sound

• Converts digital sound data back into an analogue wave

• Converts sound waves into a digital stream of 1s and 0s

Portable

Deteriorate

Fidelity

Digital-to-Analogue Converter (DAC)

Analogue-to-Digital Recorder (ADR)

• Portable

• Deteriorate

• Fidelity

• Digital-to-Analogue Converter (DAC)

• Analogue-to-Digital Recorder (ADR)

Multiple Choice

File size of a sound file depends on:

• Sampling rate, bit depth, and duration

• Screen resolution

• Character encoding

• File extension

Multiple Choice

What is the purpose of using an industry standard like ASCII code in computers?

• To ensure data can be exchanged between different computers and manufacturers

• To increase the speed of data processing

• To reduce the size of computer hardware

• To improve the quality of images displayed

Match

Match the following

• Assigning binary values to sampled signals

• Number of samples per second

• Number of bits used for each sound sample

• Measuring the amplitude of an analogue signal at regular intervals

Quantisation

Sample rate

Sample resolution

Sampling

• Quantisation

• Sample rate

• Sample resolution

• Sampling

Drag and Drop

Number of bits used to represent each colour​

Placeholder

Smallest element of a bitmap image​

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Image made up of a grid of pixels​

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Image described using mathematical shapes​

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Drag these tiles and drop them in the correct blank above

Colour Depth

Pixel

Bitmap image

Vector image

Dropdown

Data that varies continuously​ ​

Select answer

Data represented by discrete binary values​

Select answer

Character encoding for English letters and symbols​

Select answer

Extended character encoding for global languages​

Select answer