PAPER 1- IGCSE Computer Science
(Theory)
What is meant by data losing its value? - CORRECT ANS The more accurate and complete data is, the
more valuable it is.
If data is lost, corrupted or accidentally changed, it becomes less accurate and complete and loses value.
What is simplex data transmission? - CORRECT ANS data sent in one direction only
What is Machine code
1st Generation language? - CORRECT ANS The 1s and 0s that make up the instructions for a computer.
This is the lowest level of programming language that all programs must be converted to in order to be
executed on a computer. Computers only understand machine code.
Explain what is meant by an automatic backup. - CORRECT ANS An automatic backup:
is where a computer makes a backup made without user intervention
is where the computer automatically creates a backup at a scheduled time and date.
What is half duplex data transmission? - CORRECT ANS data sent in both directions but not at the same
time
What is Assembly language
2nd generation language? - CORRECT ANS One step up from machine code where the individual
machine code instructions are represented as simple keywords such as ADD or BRA. Requires an
assembler to turn it into machine code.
Explain how phishing and pharming trick a user into giving up personal data. - CORRECT ANS Four
answers accepted from:
- Phishing uses email that pretends to come from a person or organisation the user is familiar with.
,- The email asks the user to confirm account details by clicking on a link
- If clicked, the link directs the user to a fake website that looks like the organísation's real site, where
they can be tricked into giving up personal data.
- Pharming also uses fake websites to try to gain access to personal data.
- When a user tries to visit a genuine site they are instead directed to a fake site
- If the user enters personal data on the fake site the data is stolen and passed to criminals.
What is full duplex data transmission? - CORRECT ANS data sent in both directions simultaneously
What is High level language
3rd generation language.? - CORRECT ANS A computer programming language that is much closer to a
human language than machine code. Examples of high level languages are Python, PHP, Visual Basic and
C (although there are lots more!). Requires and interpreter or a compiler to turn it into machine code.
Explain how anti-virus software may help to prevent distributed denial of service attacks. - CORRECT
ANS Answers could include:
- Denial of service attacks occur when malware on a computer instructs the computer to send a high
volume of requests to a server
- Anti-virus software detects and removes malware from computers, removing the cause of the attack.
Give an example of simplex data transmission - CORRECT ANS data being sent from a computer to a
printer
What is a Megabyte (Mb)? - CORRECT ANS 1024 kilobytes.
Explain why computer security is more effective when anti-virus software and firewalls are used. -
CORRECT ANS Four answers accepted from:
- Malware is software that is designed to disrupt or modify a computer system.
,- It is usually accidentally downloaded from email attachments, websites and USB sticks
- Anti-virus software detects and removes malware from a computer, helping to keep the computer
safe.
- Computers communicate by sending messages. Most messages a computer sends are authorised
- Some messages are created by malware or hackers. These messages are unauthorised messages
- Firewalls monitor communications to prevent unauthorised messages from being sent, helping to keep
the computer safe.
Give an example of half duplex data transmission - CORRECT ANS a phone conversation between two
people where only one person speaks at a time
What is a Gigabyte (Gb)? - CORRECT ANS 1024 megabytes.
What is a Terabyte (Tb)? - CORRECT ANS 1024 gigabytes.
Give an example of duplex data transmission - CORRECT ANS broadband connection on a phone line
Describe how a proxy server can help keep data safe. - CORRECT ANS Two answers accepted from:
- Aproxy server is a computer that sits between a network server and the internet
- The proxy server directs traffic away from the main server by examining the traffic.
- If the traffic is authorised it is forwarded to the network server; if not, the traffic is kept away from the
network server, keeping it and the data on it safe.
Explain the difference between symmetric and asymmetric encryption. - CORRECT ANS Four answers
accepted from:
- Encryption converts data into a form that cannot be understood by anyone other than an authorised
user
- Encryption works by using a key
, - Symmetric encryption uses the same key to encrypt and decrypt data.
- Asymmetric encryption uses two separate keys which work as a pair.
- The first key is used to encrypt the data.
- The second key is used to decrypt the data.
What is serial data transmission? - CORRECT ANS when data is sent, one bit at a time, over a sing wire or
channel
What is binary? - CORRECT ANS The number system we use to represent the data stored in a digital
computer. Binary is a base 2 number system and uses the digits 1 and 0.
Describe what a protocol is and how protocols help protect data. - CORRECT ANS Two answers accepted
from:
- A protocol is a set of rules that governs communications between computers.
- Some protocols, such as secure socket layer, use asymmetric encryption to create a secure link
between one computer and another.
- This meCORRECT ANS that data can be safely transmitted between computers as anyone without the
encryption keys cannot read the data.
What is parallel data transmission? - CORRECT ANS when several bits of dots are sent down several
wires or channels at the same time
What is hexadecimal? - CORRECT ANS A base 16 number system that we use to represent the data
stored in a digital computer. Hexadecimal is used instead of binary for two reasons: 1. It it easier for
humCORRECT ANS to read than binary. 2. A single hexadecimal digit can be represented in a nibble (4
bits).
Computer security - CORRECT ANS Computer security is the protection of computers from unauthorised
access and the protection of data from loss.
(Theory)
What is meant by data losing its value? - CORRECT ANS The more accurate and complete data is, the
more valuable it is.
If data is lost, corrupted or accidentally changed, it becomes less accurate and complete and loses value.
What is simplex data transmission? - CORRECT ANS data sent in one direction only
What is Machine code
1st Generation language? - CORRECT ANS The 1s and 0s that make up the instructions for a computer.
This is the lowest level of programming language that all programs must be converted to in order to be
executed on a computer. Computers only understand machine code.
Explain what is meant by an automatic backup. - CORRECT ANS An automatic backup:
is where a computer makes a backup made without user intervention
is where the computer automatically creates a backup at a scheduled time and date.
What is half duplex data transmission? - CORRECT ANS data sent in both directions but not at the same
time
What is Assembly language
2nd generation language? - CORRECT ANS One step up from machine code where the individual
machine code instructions are represented as simple keywords such as ADD or BRA. Requires an
assembler to turn it into machine code.
Explain how phishing and pharming trick a user into giving up personal data. - CORRECT ANS Four
answers accepted from:
- Phishing uses email that pretends to come from a person or organisation the user is familiar with.
,- The email asks the user to confirm account details by clicking on a link
- If clicked, the link directs the user to a fake website that looks like the organísation's real site, where
they can be tricked into giving up personal data.
- Pharming also uses fake websites to try to gain access to personal data.
- When a user tries to visit a genuine site they are instead directed to a fake site
- If the user enters personal data on the fake site the data is stolen and passed to criminals.
What is full duplex data transmission? - CORRECT ANS data sent in both directions simultaneously
What is High level language
3rd generation language.? - CORRECT ANS A computer programming language that is much closer to a
human language than machine code. Examples of high level languages are Python, PHP, Visual Basic and
C (although there are lots more!). Requires and interpreter or a compiler to turn it into machine code.
Explain how anti-virus software may help to prevent distributed denial of service attacks. - CORRECT
ANS Answers could include:
- Denial of service attacks occur when malware on a computer instructs the computer to send a high
volume of requests to a server
- Anti-virus software detects and removes malware from computers, removing the cause of the attack.
Give an example of simplex data transmission - CORRECT ANS data being sent from a computer to a
printer
What is a Megabyte (Mb)? - CORRECT ANS 1024 kilobytes.
Explain why computer security is more effective when anti-virus software and firewalls are used. -
CORRECT ANS Four answers accepted from:
- Malware is software that is designed to disrupt or modify a computer system.
,- It is usually accidentally downloaded from email attachments, websites and USB sticks
- Anti-virus software detects and removes malware from a computer, helping to keep the computer
safe.
- Computers communicate by sending messages. Most messages a computer sends are authorised
- Some messages are created by malware or hackers. These messages are unauthorised messages
- Firewalls monitor communications to prevent unauthorised messages from being sent, helping to keep
the computer safe.
Give an example of half duplex data transmission - CORRECT ANS a phone conversation between two
people where only one person speaks at a time
What is a Gigabyte (Gb)? - CORRECT ANS 1024 megabytes.
What is a Terabyte (Tb)? - CORRECT ANS 1024 gigabytes.
Give an example of duplex data transmission - CORRECT ANS broadband connection on a phone line
Describe how a proxy server can help keep data safe. - CORRECT ANS Two answers accepted from:
- Aproxy server is a computer that sits between a network server and the internet
- The proxy server directs traffic away from the main server by examining the traffic.
- If the traffic is authorised it is forwarded to the network server; if not, the traffic is kept away from the
network server, keeping it and the data on it safe.
Explain the difference between symmetric and asymmetric encryption. - CORRECT ANS Four answers
accepted from:
- Encryption converts data into a form that cannot be understood by anyone other than an authorised
user
- Encryption works by using a key
, - Symmetric encryption uses the same key to encrypt and decrypt data.
- Asymmetric encryption uses two separate keys which work as a pair.
- The first key is used to encrypt the data.
- The second key is used to decrypt the data.
What is serial data transmission? - CORRECT ANS when data is sent, one bit at a time, over a sing wire or
channel
What is binary? - CORRECT ANS The number system we use to represent the data stored in a digital
computer. Binary is a base 2 number system and uses the digits 1 and 0.
Describe what a protocol is and how protocols help protect data. - CORRECT ANS Two answers accepted
from:
- A protocol is a set of rules that governs communications between computers.
- Some protocols, such as secure socket layer, use asymmetric encryption to create a secure link
between one computer and another.
- This meCORRECT ANS that data can be safely transmitted between computers as anyone without the
encryption keys cannot read the data.
What is parallel data transmission? - CORRECT ANS when several bits of dots are sent down several
wires or channels at the same time
What is hexadecimal? - CORRECT ANS A base 16 number system that we use to represent the data
stored in a digital computer. Hexadecimal is used instead of binary for two reasons: 1. It it easier for
humCORRECT ANS to read than binary. 2. A single hexadecimal digit can be represented in a nibble (4
bits).
Computer security - CORRECT ANS Computer security is the protection of computers from unauthorised
access and the protection of data from loss.
