Computer Science Component 1Understanding Computer ScienceNovember 2017 releaseIn the style of EduqasTime 1 hour 45 mins

Marks Available 100

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1. Memory is an important component in a computer.

Tick () the correct boxes below to show whether the statements apply to RAM or ROM. [3]

STATEMENT RAM ROM

Contains instructions and data for the programs

that are running.

Non -volatile

Stores programs and data to boot up the computer

2. The Central Processing Unit or CPU is an important computer part.

(a) Describe the role of the CPU in a computer. [2]

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(b) CPU’s have registers such as the Current Instruction Register and the Memory Address

register. Describe what a register is. [2]

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(c) A CPU can be RISC or CISC. Describe the difference between a RISC processor and a CISC

processor and explain where might they be used. [5]

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(d) A CPU has 6MB of cache memory. Describe the function of cache memory. [2]

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(e) Sometimes a computer might need to use virtual memory. Describe how virtual memory

works. [2]

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3. A 6th form student is going to buy a laptop to help with her studies. She has the choice of buying

one with a Solid-State Drive or a Hard Disk Drive. Discuss the suitability of both types of storage

technology for a laptop. [6]

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4. The TCP/IP protocol, on which the Internet is built, is modelled using the TCP/IP 5-layer model.

Complete the table which summarises the 5-layer model. [6]

Order in

the Model

(5 - top of

the model)

LayerProtocol /

connectionDescription

1 EthernetAllows data to be transmitted and

received.

Network Layer IP

Application LayerThe group of applications requiring

network communications.

2 Data Link Layer MAC Where the network hardware operates.

4 TCP/UDPEstablishes connection with remote host.

Divides data into packets.

5. A common way for database security to be breached is through SQL injection.

(a)

(i) Explain how SQL injection works. [2]

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(ii) How can an organisation protect itself from SQL injection? [2]

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(b) Describe one way an organisation could identify security vulnerabilities in its systems. [2]

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6.

(a) Showing your workings complete the table below, converting between denary, binary and

hexadecimal numbers as necessary. [6]

Hexadecimal Denary Binary

D416 21210 110101002

19510 110000112

1316 000100112

9E16 15810

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(b)

(i) Showing your workings, add 001110112 010101012 [2]

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(ii) Using an example of binary addition, explain the concept of overflow. [4]

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(c) Using an example demonstrate and state what effect an arithmetic shift of one place to the

right has on a byte. Then demonstrate and state what effect an arithmetic shift of two

places to the right will have on the same byte. [4]

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7. Many computers make use of utility software. Using an example of a type of utility software,

describe what utility software is and the particular function of your example. [3]

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8. The diagram below shows a representation of a bitmap image.

LBL DB G G B LBL

B G G DG G LBL

DG G DG DG G DG

B B BR LB B B

B B DB BR B B

DG G LB DB DG G

The colours are as follows

G Green

SB Sky Blue

LBL Light Blue

DG Dark Green

BR Brown

DB Dark Brown

B Blue

LB Light Brown

(a) Explain using the example how this image would be stored on a computer. [3]

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(b) State two pieces of metadata stored in image files. [2]

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(c) The image can be compressed. Discuss the difference between lossy compression and

lossless compression. [2]

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State how reducing the amount of colours in the image would have an effect on the quality and

file size of the image. [2]

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(d) An image is compressed from 360 kb to 120kb. Calculate the compression ratio. [2]

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9.

The diagram shows a computer network.

(a) What are the following components? [3]

A ……………………………………………………………………………………………….

B………………………………………………………………………………………………..

C………………………………………………………………………………………………..

(b) A small business is thinking of changing its network from a client-server network to a peer-

to-peer network. What are the benefits and drawbacks of a peer-to-peer network

compared with a client server network? [6]

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A B

C

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10. Boolean logic reflects the way the logic gates work in a computer’s CPU.

(a)

(i) Complete the following truth table. [3]

(ii) Use this truth table to simplify the expression [1]

A+A . B

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A B A A .B A+A . B

1 1

1 0

0 1

0 0

(b) Using the following identities:

simplify the Boolean expression: [3]

X=(A+B ) . A

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P .P=0

(P+Q ) .R=(P .R )+(Q .R)

P+0=P

(c) The following diagram shows a logic system.

Write down the Boolean expressions for each of the outputs Q1, Q2 and Q3 in terms of the

inputs A, B and C

Q1 = ...................................................... [1]

Q2 = ...................................................... [2]

Q3 = ...................................................... [1]

11. Programs can be written in High Level Language or Low-Level Language.

(a) Discuss the difference between a High-Level Language and a Low-Level language. [4]

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(b) Describe the situations where a Low-Level Language might be used. [2]

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12.

(a) Smartphones are often only used for two years. Identify two reasons for this. [2]

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(b) A student is thinking of replacing his computer monitor with a more energy efficient version.

Discuss the environmental impact of this. [6]

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(c) Identify how expansion of the internet access has a negative effect on the environment.

[2]

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