T2 - MS

Question 1

Describe how transistors can be used to store a value in binary. 2

Answer 1

Transistor has two states
1 represents on, 0 represents off
Each transistor stores one bit

Question 2

Give two reasons why computer scientists use hexadecimal to represent numbers instead of binary.

Answer 2

Easier/quicker to communicate / enter /
write / read / remember
Less chance of input errors // easier to
spot errors

Question 3

Identify how many unique values can be represented by 4 bits.

Answer 3

16

Question 4

Describe how a character set is used to represent the string value stored in the variable name

Answer 4

Each character (in character set) has a
unique (binary) number/value
Each character in the string is assigned
its associated number/value

Question 5

State what is meant by the term image resolution.

Answer 5

Number of pixels (in an image)
Height and width (of an image)

Question 6

Give two ways that the file size of the image could be reduced.

Answer 6

Reduce number of pixels / resolution
Reduce number of colours

Question 7

State what is meant by the term metadata.

Answer 7

Data about data / the image/file //

properties of the file

Question 8

Identify three pieces of metadata that is often stored with an image.

Answer 8

Height
Width
Colour/bit depth
Date
Geolocation
File size
File type
Compression type
Author

Question 9

Describe how bitmap images are represented in binary. 3

Answer 9

Image made of / split up into pixels

Each pixel given a binary code…

…which represents the colour of that
pixel

Each colour is given a different/unique
binary code.

Metadata stored alongside the image

Question 10

Explain why computers represent data in binary form. 2

Answer 10

Computers consist of transistors /
switches / logic circuits / gates…
…which only have two values / on or
off / 1 or 0 / open or closed

Question 11

Describe one advantage of using lossy compression on the image that will be used on
the website.

Answer 11

File size is reduced / gets smaller //
image contains less data
..so quicker to upload / download / load
/ transfer

Question 12

Describe one disadvantage of using lossy compression on the image that will be used on
the website.

Answer 12

Quality of image is reduced (compared
to original)
…because data is lost

Question 13

Describe how an analogue sound wave is converted into digital form.

Answer 13

sound wave is sampled
… amplitude/height (of wave) is
measured
… at set/regular time intervals // by
example
Each sample/measurement is stored
as a binary number

Question 14

Describe the data that is recorded when sound is sampled. 2

Answer 14

The height / amplitude⋯
⋯as a numerical value
⋯of the wave(form)

Question 15

Describe how the file size of the sound recording could be reduced.

Answer 15

Reduce the sample rate (from 48KHz
to a lower rate)
⋯so fewer samples are taken per
second
Reduce the bit depth (from 24 bits to a
lower bit depth)
⋯so less data is used for each sample

Question 16

Define what is meant by the term sampling frequency.

Answer 16

number of samples taken per second /
per time period

Question 17

Explain why lossy compression may not be appropriate to compress all of the student’s files.

Answer 17

Data will be permanently lost // not all
data is recoverable
Text files cannot be compressed with
lossy
Teacher requires the original/high
quality image/video/sound files