AQA GCSE Computer Science Paper 2: Computing concepts June 2019 question paper 8525/2

Convert the decimal number 197 into binary.

Convert the hexadecimal number A4 into decimal.

Show your working.

What is the largest decimal number that can be represented using 5 bits?

How many bits are there in 3 MB?

Show your working.

State one advantage of using Unicode instead of using ASCII.

Which two of the following are components of a CPU?

Shade two lozenges.

A computer game is one type of application software. State two other types of application software. You must not use brand names in your answer.

Select the correct statement about secondary storage.

Shade one lozenge.

Describe how an optical disk is read.

The Huffman tree in Figure 1 was generated for the string ARE ALL STARS REAL

Part of the string ARE ALL STARS REAL was incorrectly encoded as in Figure 2 below.

Figure 2

1111000010101011 What string does this encoding represent?

What would be the correct binary encoding for the substring STAR ?

Write the correct encoding below the letters in the table.

Explain two reasons why software companies usually do not make their source code publicly available. Source code is the code they wrote to create the software.

Define the term embedded system.

Draw a simple diagram to show a star network topology containing four desktop computers.

Draw a simple diagram to show a bus network topology containing four desktop computers.

State two advantages of using a star topology instead of a bus topology.

State one disadvantage of using a star topology instead of a bus topology.

Discuss the benefits and risks of using a computer network.

Define the term network protocol.

Which two of the following are email protocols?

Shade two lozenges.

Explain why a firewall improves network security.

A company has decided to move its business online but it is concerned about making sure that only authorised users can gain access to the system. The company has set up a CAPTCHA system to check that the user is not a robot.

Explain three different electronic methods that could then be used to confirm user identity.

Penetration testing can be conducted as either black-box or white-box testing.

Explain the difference between these two types of penetration testing.

The four layers of the TCP/IP network model are shown below.

For each row in Figure 3, write the letter A, B, C or D that matches the description.

Each letter should only be used once.

A Application layer B Transport layer C Internet layer D Link layer

A virus is a specific category of malware.

Describe three other different categories of malware.

Malware 1

Malware 2

Malware 3

A burglar alarm sounds an alarm when it is armed (turned on) and the window or door is opened.

The truth table for this basic system is shown in Figure 4.

Draw the logic circuit that represents the truth table in Figure 4. You must use the correct symbols for logic gates. You may not need to use all the gates shown.

Specifications for two different devices are shown in Figure 5.

Discuss the advantages and disadvantages of Device A compared to Device B.

Your answer should explain the impact each advantage/disadvantage will have on the operation of the device.

You should assume that any aspects of the specifications not mentioned in Figure 5 are the same for both devices.