Methods of data transmission - Cambridge IGCSE Computer Science (Paper 1) Exam Questions

Practise 28 exam-style questions on Methods of data transmission for Cambridge IGCSE Computer Science (Paper 1). Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

28 questions
1–6 marks each
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20 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

1 mark

Give one example of a use of simplex data transmission.

Model answer

A sensor sending temperature readings to a computer, where the computer never sends data back to the sensor.

Explanation

Simplex means data travels in one direction only, so the example must be a device that only sends or only receives. Anything involving a conversation, such as a phone call or walkie-talkie, needs data in both directions and is not simplex.

Mark scheme

1 mark
Any suitable one-way use, e.g. a keyboard sending data to a computer / a sensor sending readings to a computer or microprocessor / a television or radio broadcast / a computer sending data to a printer / a computer sending data to a monitor
the example must only need data to travel in one direction; do not accept a telephone call, video call or walkie-talkie

Question 2

2 marks

Explain why parallel data transmission is not suitable for sending data over long distances.

Model answer

Over a long distance the bits travelling along the different wires may arrive at slightly different times, which is called skew. This means the receiver may combine bits from different bytes, so the data is corrupted.

Explanation

The main reason is skew: the further the data travels, the more out of step the separate wires become. A point plus its consequence (errors in the data) earns both marks; cost and interference are also valid reasons.

Mark scheme

1 mark
The bits on the different wires may arrive at different times / out of synchronisation (skew)
max 2
1 mark
So the data may be corrupted / the receiver may read bits from the wrong byte / errors occur
expansion of the skew point
1 mark
Long cables with many wires are expensive
1 mark
There is more interference/crosstalk between the wires over a long cable

Question 3

3 marks

The diagram shows the byte 10110010 being sent from a sender to a receiver using serial transmission and using parallel transmission.

Describe how the data is sent in each method.

Model answer

In serial transmission the bits of 10110010 are sent one at a time, one after another, along a single wire. In parallel transmission all eight bits are sent at the same time, each along its own wire, so eight wires are used.

Explanation

The diagram shows the difference: one wire carrying the bits in sequence for serial, and eight wires carrying one bit each for parallel. For full marks describe both how many bits travel at once and how many wires are used.

Mark scheme

1 mark
Serial: the bits are sent one at a time / one after another
max 3
1 mark
Serial: along a single wire/channel
1 mark
Parallel: all eight bits are sent at the same time
1 mark
Parallel: each bit travels along its own wire / eight wires are used

Question 4

4 marks

Give the missing terms A to D in this description of data transmission.

In A data transmission, data is sent one bit at a time along a single wire. In B data transmission, several bits are sent at the same time along several wires, which is faster over short distances. A connection where data can only travel in one direction is called C. A connection where data can travel in both directions at the same time is called D.

Model answer

A: serial
B: parallel
C: simplex
D: full-duplex

Explanation

Serial and parallel describe how many bits are sent at once; simplex, half-duplex and full-duplex describe the direction of the data. Full-duplex is both directions at the same time, whereas half-duplex is both directions but one at a time.

Mark scheme

1 mark
A: serial
1 mark
B: parallel
1 mark
C: simplex
1 mark
D: full-duplex
do not accept 'duplex' on its own or 'half-duplex'

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