O-LevelComputer ScienceData Transmission2210/12 · May/June 2024 · Q27 Marks

Data can be transmitted from one device to another.

(a)Tick (✔) one box to show which of the terms is not a method for transmitting data. A serial B simplex C parallel D parity[1]
(b)Data is broken down into smaller units to be transmitted from one device to another. Give the name of the unit that data is broken down into.[1]
(c)(i)Data is often encrypted when it is transmitted from one device to another. Explain how data is encrypted using symmetric encryption.[4]
(c)(ii)Give the purpose of encryption.[1]

Mark scheme

Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.

[1] D
[1] Packet
[4] Data is encrypted and decrypted using the same key (1 mark) Any three from: • Plain text is encrypted into cipher text // cipher text is decrypted into plain text • Data is encrypted using an algorithm ... • ... that uses a key • The key can be generated using an algorithm • The key is transmitted to the receiver
[1] Any one from: To help keep the data secure To make the data meaningless

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Topic: Data Transmission, O-Level Computer Science (syllabus 2210). Structured question, 7 marks.
Source: O-Level Computer Science, May/June 2024 Paper 1 Variant 2, question 2.

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