GCSE A451 - Files

Question 1

Describe HTML (2)

Answer 1

• HyperText Mark-up Language
• Text file containing the text to be displayed on webpage…
• Uses tags which indicate how to display it

Question 2

Explain the importance of HTML when creating web pages (2)

Answer 2

• Web browser used to understand the code in the file and display the data correctly
• It is an common standard…
• data will display correctly on all browsers
• because code conforms to the standard

Question 3

A list of file extensions include

JPG
PDF
MP3
MPEG
ZIP

Match the file extensions to these scenarios (5):

High resolution image
Sheet of paper to be printed
A video
A compression  selection of 200 files
An audio recording

Answer 3

High resolution image - JPG
Sheet of paper to be printed - PDF
A video - MPEG
A compression  selection of 200 files - ZIP
An audio recording - MP3

Question 4

Explain the importance of compressing files when transmitting them over the internet. (2)

Answer 4

• It reduces the size of the file which needs to be transmitted
• Shortens download time
• Reduces Internet traffic

Question 5

Describe the difference between lossy and lossless compression and give an example of where both would be used. (4)

Answer 5

• In lossy compression, when the data is uncompressed it is not exactly the same as the original
  -But the difference is so small that it cannot normally be noticed
• Eg music files(mp3), large resolution images for displaying on small screens.
• In lossless compression, when the data is uncompressed it is restored completely to the original file
  Eg compressed text files.

Question 6

A computer has 2 terabytes of storage.
How much is this in gigabytes? (2)
Show your working

Answer 6

• Multiply by 1024

- 2048 (GB)

Question 7

Describe how sampling is used when storing sound (2)

Answer 7

The height of the sound wave is measured
… at regular intervals
… and converted to binary.

Question 8

Explain the effect of the sampling interval on the size and quality of sound recorded (3)

Answer 8

If the interval is smaller/if you sample more often you have more data to store…
… so larger file
but the sound reproduced is closer to the original…
 …so better quality.

Question 9

State how many bytes there are in a kilobyte and gigabyte (2)

Answer 9

• 1 kilobyte = 1024 bytes

* 1 gigabyte =1024 x 1024 x 1024 bytes