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Computer Science
Paper 1
| Question | Answer |
|---|---|
| What is the purpose of the CPU, and what does it stand for? | Executes instructions in order to run programs - Central Processing Unit |
| What is the function of the Arithmetic Logic Unit (ALU)? | Performs calculations and logical operations |
| What is the function of the Control Unit (CU)? | Controls the operation of the fetch-execute cycle and sends commands to other components |
| What is the role of cache? | Stores frequently used data and instructions |
| What is the role of the Memory Address Register (MAR)? | Stores the address of the data to be fetched from or the address where the data is to be stored. |
| What is the role of the Memory Data Register (MDR)? | Stores the data that is being fetched from or written to memory. |
| What is the function of the Program Counter (PC)? | Stores the address of the next instruction to be fetched from memory |
| What is the function of the Accumulator? | Stores the results of calculations or operations carried out by the ALU |
| What are the first 3 steps to the fetch-execute cycle? | - The address of the next instruction to be fetched is transferred from the PC to the MAR - Instruction fetched from memory and copied into MDR - PC is incremented and instruction decoded by the CU |
| What are the last 2 steps to the fetch-execute cycle? | - Decoded instruction is executed by the CPU or ALU - Process repeats for the next instruction so that CPU continuously performs |
| When it comes to the clock, what happens with every tick? | The CPU fetches and executes one instruction |
| What happens the greater the clock speed gets? | The faster the CPU can execute instructions, improving performance |
| What happens if cache size was larger? | Increases amount of frequently used data that can be stored, improving performance |
| What are cores? | Individual processing units within the CPU |
| What does having more cores improve performance and make it faster? | More instructions can be processed at once allowing the CPU to handle more tasks simultaneously |
| What is an embedded system? | A computer system designed to perform specific functions within a larger electronic system |
| Give 2 features of embedded systems. | Minimal or no UI, optimized for efficiency and reliability |
| Give 2 examples of embedded systems. | Washing machines and traffic lights |
| Why do we need primary storage? | Provides fast access to data and instructions currently in use by the CPU |
| What does primary storage usually consist of? | RAM and ROM |
| What is RAM and what does it consist of, is it volatile or non-volatile? | Random Access Memory - Holds the data and instructions the computer is currently working with, like the OS, documents and running applications. It is volatile (lost when turned off) |
| What is ROM and what does it consist of, is it volatile or non-volatile? | Read Only Memory - Stores firmware for the computer to boot up and operate (cannot be written to) and it's non-volatile |
| What is Virtual Memory and when is it used? | It allows the system to use part of the Secondary Storage. When extra programs need to be run but the RAM is full, unnecessary data is moved to virtual memory, creating more space in RAM |
| Give 1 benefit and 1 disadvantage of Virtual Memory. | -Allows more programs to be run -Process of swapping between VM and RAM takes longer than RAM alone |
| Why is secondary storage needed? | So data/files can be stored on a long term basis using non-volatile storage |
| Give an example of a SSD. | Flash drive |
| Give an example of optical | CD |
| Give an example of magnetic | HDD |
| Give the capacity of HDD, SDD and Optical. (In order best to worst) | - Very high capacity(HDD) - Relatively low (SDD) - Very low (Optical) |
| Give the read/write speeds of HDD, SDD and Optical. (In order best to worst) | - Very high (SSD) - Good (HDD) - Relatively low (Optical) |
| Give the portability of HDD, SDD and Optical. (In order best to worst) | - Light, rarely damaged (SSD) - Light, can be scratched (Optical) - Heavy and easily damaged (HDD) |
| Give the durability of HDD, SDD and Optical. (In order best to worst) | - No moving parts, very durable (SSD) - Moving parts, prone to damage (HDD) - Easily scratched and damaged (Optical) |
| Give the reliability of HDD, SDD and Optical. (In order best to worst) | - Very reliable (SSD) - Fairly, degrades over time (HDD) - Less, damage affects data easily (Optical) |
| Give the cost (per GB) of HDD, SDD and Optical. (In order best to worst) | - Cheap (HDD) - Cheap per disk, expensive by GB (Optical) - Expensive (SSD) |
| What is a HDD good for? | Desktop PCs and Servers |
| What is a SSD good for? | Laptops, phones, tablets |
| What is Optical good for? | Sharing and distributing small volumes of data |
| Give the formula for sound file size. | Sample rate x duration (s) x bit depth |
| Give the formula for image file size. | Colour depth x image height (px) x image width (px) |
| Give the formula for text file size. | Bits per character x number of characters |
| What is character encoding? | The process of converting characters in to binary |
| In ASCIII "A" is 65, so what would "B" be? | 66 |
| What is the number of characters limited by? | The number of bits available |
| In bits, how is ASCII represented? | 8 bits |
| Why does Unicode have a larger number of characters? | Each character can be represented between 8 and 32 bits |
| What is colour depth? | Number of bits assigned to each pixel |
| If a colour depth of 2 was used, how do we work out that 4 colours can be represented | 2(to the power of colour depth) |
| What is resolution? | The number of pixels within an image |
| What is image metadata? (give 2 examples) | Data about the image (file format, resolution) |
| If the image resolution or/and colour depth increase how does this affect the image (2) | Higher quality and file size |
| How should an analogue sound be stored in a computer? | In binary |
| What is sample rate and what unit is it measured in? | Number of sound samples per second (Hz) |
| What is bit depth in sound? | Number of bits available to store each sample |
| If sample rate and/or bit depth increase how does this affect playback quality and file size? | Increases both |
| Why do we compress data? (2) | Save storage space and speed up file transfer |
| Give 2 benefits of lossy compression. | Smaller file size, faster to send/store |
| Give 2 bad things about lossy compression. | Loss of quality, irreversible |
| Give 2 benefits of lossless compression. | No data lost, reversible |
| Give 1 bad thing about lossless compression. | Less reduction in size compared to lossy |
| Give 2 features of a LAN. | Covers small geographical area, often owned and managed by a single person or organisation |
| Give 2 examples where a LAN might be used. | School, Office |
| Give 2 features of a WAN. | Covers a large geographical area, often under collective ownership |
| Give 2 examples of a WAN. | The internet, a global company |
| What is bandwidth? | The maximum amount of data that can be transmitted over a network within a given time |
| How does having a higher bandwidth affect the performance of a network? | Allows faster data transfer and better overall performance |
| How does having a higher number of devices on a network affect performance? | As having more devices means the available bandwidth must be shared, slowing things down |
| How does a client-server network work? | Servers are powerful computers that control the network and provide services and resources to clients, we use the client devices and they send requests to the servers |
| How does a peer-to-peer network work? | Every computer has equal status and can act as the client and server sending and requesting resources |
| What do Wireless Access Points do? | Use radio transceivers to allow devices to connect wirelessly to a network |
| What do Routers do and allow? | Connect 2 or more networks together, they allow LAN to be connected to the Internet |
| What is the role of a switch? | Connects each device on a network, receives data packets from all clients and responsible for sending packets to the correct device |
| What is the role of the Network Interface Card? (NIC) | Hardware components in devices that allow them to connect to networks |
| What is transmission media? | Physical or wireless methods to carry data around the network. e.g (Ethernet cables, radiowaves) |
| What is the internet? | A network of smaller computer networks |
| How does the Domain Name System work (DNS)? (3) | -URL entered -DNS server is checked for entered URL -Corresponding IP is returned |
| What is hosting? | The process of storing a website's files on a server and making it accessible to users over the internet |
| What is a web server and how are clients related to this? | It stores and provides access to web pages. A client will send a request and the web server will send the data (web page) |
| Give 2 advantages of the cloud | -Accessible anywhere -No need to manage or upgrade hardware |
| Give 2 disadvantages of the cloud | -Paid subscription -Requires internet connection |
| What is a star topology? | Each client has its own direct connection to the central switch |
| Give 2 advantages of a star topology. | -Easy to add and remove clients -If one cable fails, it doesn't affect the rest of the network |
| Give 2 disadvantages of a star topology. | -If central switch fails, all communication stops -Expensive |
| What is a mesh topology? | Each device is connected directly to multiple other devices in the network |
| Give 2 advantages of a mesh topology. | -Data can be transferred quickly using shortest available path -Data can take an alt route if one device fails |
| Give a disadvantage of a mesh topology. | -Requires a lot of cabling and network ports |
| Give 2 advantages of wired ethernet connection. | -Faster and more reliable connection -More secure |
| Give 2 disadvantages of wired ethernet connection | -Less convenient -Harder to set up and expand |
| Give 2 advantages of wireless connection (e.g WiFi and Bluetooth) | -More flexible and convenient -Easier and cheaper to install |
| Give 2 disadvantages of wireless connection (e.g WiFi and Bluetooth) | -Slower and less reliable than wired -Less secure |
| What is encryption? | Method of converting data into a coded format that only people with the decryption key can read |
| What is IP addressing? | A system used for uniquely identifying devices on a network |
| What is the format of an IPv6 address? | 8 groups of 4 hexadecimal digits separated by colons |
| What is a MAC address? | Unique identifier permanentley assigned to a devices NIC during manufacture |
| What is the format of a MAC address? | Separated in colons and its a 12 digit hexadecimal number |
| What are MAC addresses crucial for? | Identifying devices on a local network and ensuring data is delivered to the correct device |
| What are communication protocols? | A set of rules for transferring data |
| What is the role of the TCP in the TCP/IP protocol? | Ensures data sent over a network arrives completely and in the correct order |
| What is the role of the IP in the TCP/IP protocol? | Responsible for routing and addressing data packets across networks |
| What is HTTP used for? | Transferring web pages and other content between web servers and browsers |
| How is HTTPS different? | It encrypts data being transferred between web servers and browsers |
| What is FTP used for? | Transfer files between computers over a network such as the internet |
| What does POP allow? | Users to access their emails stored on a remote email server |
| What does IMAP allow? | Users to access and manage their emails stored on a remote email server |
| What is SMTP used for? | Sending emails from one email server to another across the internet |
| What are layers? | What network communication is organised into, different protocols operate at each layer |
| Give 2 benefits of layers. | -Each is self-contained so can be developed independent -Troubleshooting is easier |
| What is a computer virus? | A type of malware that attaches to a program or file and spreads when opened |
| What are 3 things a virus can do? | -Corrupt/delete data -Slow systems -Make them unusable |
| What is a trojan? | A malicious program that disguises itself as legit software |
| What can a trojan do? | Create backdoors allowing hackers to control the system, steal data or install more malware |
| What is spyware? | Gathers information about a users activity such as keystrokes, login details or browsing habits |
| What does spyware do? | Send this info to the hacker |
| What is social engineering? | Manipulating people to give sensitive info |
| What is phishing? | A type of social engineering, done in emails that looks official, provides a link to give details and is fake |
| What is a brute-force attack? | Trying every combination to find a user's username and password, usually done with automated software |
| What is a DOS attack used for? | Overwhelm a website or online service with massive amounts of traffic making it slow or inaccessible |
| When does Data Interception and theft occur? | When cybercriminals capture data being transmitted over an unsecured network, often looking for unencrypted data |
| What happens in SQL injection? | Specially crafted SQL code is entered into an input field, if the website doesn't properly check this it is run |
| What is penetration testing? | Attempting to gain access to resources without username and passwords, to find problems before a hacker can |
| What does anti-malware software do? | Scans files by comparing them to a known database of malware, it then tells the user |
| What do firewalls do? | Scans incoming and outgoing traffic comparing it to a criteria. It will block data based on a set of security rules |
| What are user access levels used for? | To control what data and features different users can access within a system (used at schools) |
| What are some examples of physical security? | CCTV, locks on doors or keycard entry to prevent unauthorised access to hardware |
| What does a UI allow and what are the 2 types? | The user to interact with the computer: GUI and Command line |
| What does a GUI allow? | Users to interact with visible icons and menus |
| What does a command line interface allow? | Users to interact by typing commands |
| What does the OS do with memory management? | Allocates sections of computer's memory into applications. |
| How does the OS make multitasking possible? | It rapidly switches between tasks, giving each program a small slice of the processor's time |
| Give 2 examples of peripherals. | Keyboards, printers |
| How do peripherals work? | Data is transferred between the device and processor using drivers (translator between OS and hardware) |
| What does user management allow? | Multiple accounts, different accounts with different access and different files for each account |
| Give 2 examples of security within user management | Strong password or lock account after too many failed attempts |
| Give 3 key features within file management. | Creating files, naming files and placing them in folders |
| What is the purpose of defragmentation? | Improve the efficiency of the system by putting all the pieces of each file together and grouping related files close to each other |
| What are 2 other examples of utility software? | Encryption software and data compression software |
| Give an example of a cultural issue. | In other countries people wouldn't like being pictures in public and having them posted |
| Give 2 environmental issues. | E-waste when devices are thrown away and lead and mercury in computers that are damaging if not disposed properly |
| What is 1 good thing for the environment about emails? | Reduces use of paper |
| What is a privacy issue? | People won't like governments and security services having access to private data |
| How do governments and security services argue for this? | That it protects citizens from terrorism and other threats |
| What does the data protection act 2018 govern? | How organisations can use the personal information of individuals |
| In this act, anyone who uses data must make sure it... (2) | -Is secured safely -Used fairly and lawfully |
| Give 2 rights people have in this act. | -The right to be informed how their data is used -The right to have their personal data erased |
| What does the Computer Misuse Act 1990 aim to do? | Prevent unauthorised access to or modification of data |
| What does the Copyright Designs and Patents Act 1988 do? | Protects peoples original work from being copied or used without their permission |
| What is open source software? | Software made freely for anyone to use, distribute or edit |
| Give 2 advantages of open source. | -Made freely for anyone to use -Often supported by a large community |
| Give 1 disadvantage of open source | -Doesn't usually have official customer support |
| Give 2 advantages of Proprietary software | -Usually well-tested and reliable -Customer support often provided |
| Give 2 disadvantages of Proprietary software | -Must be paid for -User relies on company for updates |
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