AQA GCSE Computer Science Paper 2: Computing concepts June 2018 question paper 8525/2

A bit pattern is shown in Figure 1.

Figure 1

10011100

Convert the bit pattern shown in Figure 1 into decimal.

Convert the bit pattern shown in Figure 1 into hexadecimal.

You should show your working.

Figure 2 shows an 8 x 8 black and white bitmap image. The image has been represented as a bit pattern with each bit representing a pixel. Row 3 has been represented as 01011010.

What is the binary representation of Row 4 in Figure 2 ?

Row 4:

The image in Figure 2 is going to be changed so that each pixel can be any one of 16 different colours.

What is the minimum number of bits that would be needed to represent the entire 16-colour image?

You should show your working.

ROM is a type of memory used in computers.

Shade two lozenges to show which statements are true about ROM.

Explain how a magnetic hard disk drive (HDD) operates.

Figure 3 shows a logic circuit.

State the type of logic gate labelled G₁ in Figure 3.

State the type of logic gate labelled G₂ in Figure 3.

State what a NOT gate does.

State three components of the CPU and describe their purpose.

Component 1:

Description:

Component 2:

Description:

Component 3:

Description:

Figure 4 shows a simplified diagram of the Fetch-Execute cycle.

Fill in the name of the missing stage in Figure 4 below.

Computer users will often store their data ‘in the cloud’. State three reasons why you might want to use cloud storage rather than local storage.

Describe one difference between system software and application software.

Describe two different functions performed by an operating system.

Function 1:

Function 2:

A student was asked to describe what software and hardware are. They gave the following answer:

‘New hardware can be installed by downloading it from the web or an installation disk whereas software requires someone to physically attach it to the computer.’

Explain two mistakes the student has made.

Explain two differences between a LAN and a WAN.

Difference 1:

Difference 2:

HTTP and HTTPS are two application layer protocols.

Explain why HTTPS is often used rather than HTTP.

The application layer and the network (internet) layer are two of the layers within the TCP/IP stack.

What are the names of the other two TCP/IP stack layers?

What is the purpose of the network (internet) layer within the TCP/IP stack?

Explain how MAC address filtering works.

Social engineering is where someone is tricked or manipulated into providing secure information or access to a secure system. Describe each of the following social engineering techniques.

Blagging:

Phishing:

Shouldering (or shoulder surfing):

The Huffman tree shown in Figure 6 was created to encode the string shown in Figure 5. The frequency of each character is shown in brackets. For example, the letter A appears five times within the string shown in Figure 5.

Figure 5

AAGHHGGSAAASG

Complete the code table below for characters G, S and H for the Huffman tree shown in Figure 6. The code for character A has already been completed.

The string shown in Figure 5 could also be encoded using ASCII. ASCII uses 7 bits to represent each character.

How many bits are saved by using Huffman coding rather than ASCII to represent the string shown in Figure 5 ?

You must show your working.

Many organisations provide free public access to a wireless network.

Explain three ethical, legal or data privacy issues that an organisation should be aware of when allowing this access.

AQATravel is a tour operator that sells holidays to places all around the world. They hold all of their customer and business data electronically. Following recent news articles about the effects of malware attacks on businesses, the management of AQATravel have been investigating how they could protect themselves against malware attacks.

Discuss four methods that AQATravel could use to prevent infections from malware and/or to minimise the damage that could be caused by malware.