Download GCSE Computer Science Exam Questions and Solutions and more Exams Computer Science in PDF only on Docsity!
Edexcel GCSE Computer Science Exam
Question and Solution
What is a character? - Solution -A letter,number or symbol on a given character set What is a string? - Solution -A sequence of characters What is casting? - Solution -Changing the data type of a variable What is a count-controlled loop? - Solution -A loop that repeats a specific number of times (FOR loops) What is a condition controlled loop? - Solution -A loop that runs until a condition is met (WHILE loops) When would you use a variable? - Solution -When a value might need to change while the program is running When would you use a constant? - Solution -When a value would not need to change while while the program is running Why are constants useful? - Solution -Readability and easier to update What is a subprogram? - Solution -A block of code that performs a specific task What are libraries? - Solution -Collections of pre-written subprograms for specific purposes What is a local variable? - Solution -A variable that is declared inside a function or procedure so can be accessed within the subprogram
What is a global variable? - Solution -A variable that can be accessed from anywhere Do functions return a value? - Solution -Yes Do procedures return a value? - Solution -No What is an array? - Solution -A data structure with one or more elements of the same type (have a fixed length only contain elements of the same data type) What is an index? - Solution -A position within an array What is a 1D array? - Solution -An array that stores data in one direction (horizontal) What is a 2D array? - Solution -An array that stores data horizontally and vertically (indexed with two numbers) Why is it good to close files after use? - Solution -It frees up resources,prevents corruption and flushes the buffer What's does MOD do? - Solution -Gives remainder What does DIV do? - Solution -Shows how many times x goes into y (23 DIV 5 = 4) What does the Boolean operator NOT do? - Solution -The opposite of the input What does the Boolean operator OR do? - Solution -If one side is true then the output is true
Colour depth measured in bits What is included in metadata? - Solution -File name File format Colour depth Resolution What does increasing bitrate cause? - Solution -More detailed audio but more storage required What is sampling? - Solution -Recording a signal at regular intervals What is sampling frequency? - Solution -The number of samples obtained per second(Hz) What does increasing sampling frequency have? - Solution -A truer digital signal to the original but a greater file size What is bit depth? - Solution -How many bits are available for each sample What is bitrate? - Solution -Number of bits used per second What is the equation for bitrate? - Solution -Bitrate = sampling frequency(Hz)*sample size(b) What is the equation for File size? - Solution -File size = bitrate(bps) * time(s) What is lossy compression? - Solution -Some of the original data is removed and once it is decompressed it is not the same as the original
What is lossless compression? - Solution -No data is removed and the original data can be recovered when the file is decompressed What is cache? - Solution -Very fast memory in the CPU that stores copies of frequently used data What is the purpose of the CPU? - Solution -To process data and instructions To control the rest of the computer system What is the role of the ALU? - Solution -To perform arithmetic and logical operations What is the role of the CU? - Solution -Fetches, decodes and manages the execution of instructions What are registers? - Solution -Memory inside CPU used to store data needed during processing What is stored in registers? - Solution -Current instruction Result of calculations What is clock speed? - Solution -The number of instructions a single processor core can carry out per second (Hz) What is main memory? - Solution -Any memory device that is directly accessible by the CPU What are examples of volatile memory? - Solution -RAM, cache What is RAM? - Solution -Random Access Memory What is ROM? - Solution -Read Only Memory
Name 3 examples of embedded systems? - Solution -GPS MP3 Players Cameras What is the purpose of the operating system? - Solution - Manages the hardware Manages the applications installed Creates a user interface Provides a layer of security What are device drivers? - Solution -Small programs stored on the hard drive that tell the computer how to communicate with peripheral devices What is utility software? - Solution -Software which focuses on the maintenance of a part of the system What happens in a full backup? - Solution -All data is backed up whenever selected Slow to create but fast to restore What happens in an incremental backup? - Solution -Only data created after the previous back up is copied Fast to create but slow to restore What does defragging a disk do? - Solution -Reorganises data do it can be accessed faster What is antivirus software? - Solution -Finds and removes malicious software
- Contains a database of known viruses Provides real-time protection
Types of utility software - Solution -Disk fragmentation back up programmes encryption anti-virus compression software What are examples of low level programming languages? - Solution -Assembly Machine code What are examples of High-level programming languages? - Solution -Java Python What is a translator? - Solution -A program that converts code from one language to another What is an assembler? - Solution -Assembler is a software that translates assembly code into machine code Optimisation occurs What are the features of a compiler? - Solution -Converts high level code to machine code Creates machine code Can be optimised Error reports are only shown after scanning whole code Translates whole code at once
How does the operating system use scheduling to allocate processor time? - Solution -All processes are held in a queue and processes are prioritised What is penetration testing? - Solution -A simulated attack on a system to test vulnerabilities of the system What checks are carried out during a code review? - Solution - Inefficient code,logic errors, security vulnerabilities What is the best case scenario for a binary search algorithm? - Solution -Target is in the middle of the list What is the worst case scenario for a binary search algorithm? - Solution -Target item is not in the list What is a PAN? - Solution -Personal Area Network is a network within the range of an individual person E.g Bluetooth What is a LAN? - Solution -Local Area Network is network that connects devices close to each other What is a WAN? - Solution -Wide Area Network is a network over a large geographical area What happens in a client/sever network? - Solution -Every device is a client or server, clients request resources and a sever holds resources to send to the client What are the advantages of a client-server network? - Solution - Server can backup and store data centrally
What are the disadvantages of a client-server network? - Solution -Sever is expensive and difficult to run What is a peer-to-peer network? - Solution -A network in which each computer has both server and client capabilities. What factors affect network performance? - Solution -Latency, Bandwidth and Error rate What is the application layer? - Solution -Where network application operate What is the transport layer? - Solution -Sets up communication between two hosts What is the network layer? - Solution -Addresses and packages the data and then routes it What is the link layer? - Solution -Where the hardware (NIC's) and drivers operate What is Ethernet? - Solution -A standardised family of protocols Why are Ethernet cables made out of twisted copper cables? - Solution -To cancel out electromagnetic interference What are the advantages of WiFi over wired connection? - Solution -Devices can connect remotely Cheap to set up with less disruption Easy to expand network What are the disadvantages of WiFi over wired connection? - Solution -Signal quality degraded fast
When mail is downloaded from the server it is deleted from it Why are the advantages of the Bus topology? - Solution -Easy to connect peripherals Requires minimal cables If one node breaks the rest of the network is unaffected Cheap to install Why are the disadvantages of the Bus topology? - Solution - Every node on the network receives all data sent Can her many data collisions What are the advantages of the Ring topology? - Solution -Easy to install extra network devices Adding extra modes has no performance impact Why are the disadvantages of the Ring topology? - Solution -If the main cable is damaged the whole network fails Every node on the network receives all data sent All nodes must be switched on What are the advantages of the Star topology? - Solution -Failure of a node does not affect the other nodes High performance What are the disadvantages of a Star topology? - Solution -Whole network fails if the switch fails
Requires many cables so can be expensive What are the advantages of a Mesh topology? - Solution -New nodes can be added without interfering other nodes Messages should always get through due to many possible routes What are the disadvantages of a mesh network? - Solution - Require a lot of maintenance Full mesh networks can be impractical as high number of connections needed What does a firewall do? - Solution -Monitors traffic entering and leaving a network What are the advantages of cloud computing? - Solution -Data can be easily accessed with internet connection Easy to update and back up Additional storage can be added easily What are the disadvantages of cloud computing? - Solution - Vulnerable to hacking Need an Internet connection Control over data is given to external companies Name 4 security threats - Solution -Unpatched software Eavesdropping
What is open source software? - Solution -Software where the source code is made freely available. What is proprietary software? - Solution -Software that is copyrighted and is only available under licence What are the advantages of open source software? - Solution - Provides source code so it can be modified Modified versions are also freely available Can have many authors so allows many programmers to contribute and improve the software What are the disadvantages of open source software? - Solution - No guarantee it works properly Companies have to keep source code open even to competitions Support might not be readily available What are examples of open source software? - Solution -Firefox Linux Python What are the advantages of proprietary software? - Solution - Regular fixes and patches Help is readily available Product should be free of bugs What are the disadvantages of proprietary software? - Solution - Can be expensive
Software cannot be adapted to meet the needs of the user Cannot redistribute the software What are examples of proprietary software? - Solution -Windows Microsoft Office Logic music What features of an IDE which are useful when entering program code? - Solution -Adds line numbers, indentation What factors affect the file size of a bitmap image? - Solution - Resolution Colour depth How is data written to and read from flash memory? - Solution -A strong electric current is used to force electrons through a barrier and trap them on the other side What are the advantages of fibre optic cables? - Solution -Large bandwidth so good for long distances Immune to electromagnetic interference Secure for carrying sensitive data What are the disadvantages of fibre optic cables? - Solution - Expensive to install Fragile What is bandwidth? - Solution -The amount of data that can be carried at a time
