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Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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1l the quest for political stability: germany, 1871-1991
Britain & the wider world: 1745 -1901
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
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26 Nov 2025
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Harry
@harry_s0nw9
Computer software is everywhere in our daily lives, from the... Show more











This topic covers the essential software concepts you'll need to master for A Level Computer Science. You'll explore everything from the apps you use daily to the behind-the-scenes programs that keep computers running smoothly.
The six key areas include application software (like Word or Photoshop), utility software (programs that maintain your computer), and open source vs closed source software (understanding who can see and modify the code). You'll also learn about translators that convert programming code into language computers understand.
Finally, you'll discover how compilation stages work and the role of libraries, linkers and loaders in bringing software to life. These concepts connect directly to programming tasks you'll encounter in coursework and exams.
Quick Tip: Each section builds on the previous one, so understanding application types will help you grasp how they're created and maintained.

Application software is basically any program designed to help you complete specific tasks - think of it as software that directly benefits you as a user. From writing essays in Word to editing photos in Photoshop, these programs make your digital life possible.
The most common types include word processors for creating documents, database management software for organising data, and web browsers for surfing the internet. You'll also encounter graphics manipulation tools, spreadsheet software, and presentation programs in your daily studies.
Some applications focus on system protection, like antivirus software, whilst others help with creativity, such as video editing programs. Integrated Development Environments (IDEs) are special applications that help programmers write and test code.
When exam questions ask you to recommend software, always read the scenario carefully, identify what tasks need completing, then explain how specific features of your chosen application will solve the problem.
Exam Success: Always link application features directly to user needs - don't just name the software, explain why it's perfect for the job.

The key application categories you'll encounter include email clients for managing messages across different providers, video editing software for creating films, and virtualisation software for running multiple operating systems on one machine. Each serves distinct purposes in modern computing.
For exam success, follow this three-step approach: carefully read scenarios to identify specific user tasks, recall multiple software applications with relevant features, then clearly explain how each application's capabilities meet the scenario's requirements.
Consider the banking example - a new bank needs to write letters and store customer data. A word processor provides document creation and formatting features, whilst a database management system offers secure data storage and retrieval capabilities.
Always connect application features directly to user needs rather than just naming software. This demonstrates your understanding of how technology solves real-world problems.
Pro Tip: Practice identifying user tasks from scenarios - this skill transfers to coursework projects where you'll need to choose appropriate software solutions.

Utility software works behind the scenes to keep your computer running efficiently - think of it as the maintenance crew for your system. Unlike application software that helps you complete tasks, utilities support the operating system itself.
Disk defragmentation reorganises files on hard drives to improve access speed by putting related data together and eliminating gaps. File management utilities help you organise, search, and move files around your system efficiently.
Device drivers act as translators between your hardware and operating system, ensuring components like printers and graphics cards work properly. System cleanup tools remove temporary files and unnecessary data that can slow down your computer.
Security utilities protect against viruses, malware, and other threats by monitoring system activities and blocking suspicious behaviour. Most operating systems include basic utilities, though you can install additional tools for enhanced functionality.
Remember: Modern SSDs don't require defragmentation like traditional hard drives - this is a common exam trick question!

Software development follows two main approaches that affect how you can use and modify programs. Open source software allows anyone to view, modify, and distribute the source code - like having access to a recipe that you can adapt and share.
Closed source software keeps the code secret and proprietary, similar to a restaurant's secret recipe that customers can't see or change. Examples include Linux (open source) versus Windows (closed source), or Apache web server versus Adobe Photoshop.
For creators, open source offers collaboration benefits and faster innovation but less control over the final product. Closed source provides greater control and revenue opportunities but requires handling all development responsibilities internally.
Users benefit from open source through cost savings, customisation options, and transparency about how programs work. Closed source typically offers better technical support, polished interfaces, and guaranteed compatibility but at higher costs.
Exam Focus: Questions often ask you to compare benefits and drawbacks for both creators and users - make sure you can discuss both perspectives clearly.

Translators are essential programs that convert human-readable code into language computers can execute. Think of them as interpreters at international conferences - they bridge the communication gap between programmers and machines.
Interpreters work line-by-line, reading and executing code immediately. This makes debugging easier since you can test small sections quickly, but overall execution runs slower because translation happens during runtime.
Compilers translate entire programs at once before execution begins. This creates faster-running programs and doesn't require the translator during execution, but initial compilation takes longer and debugging can be more challenging.
Assemblers specifically handle assembly language - a low-level programming language that's closer to machine code than high-level languages like Python or Java. They occupy a unique position in the translation hierarchy.
Key Insight: Choose interpreters for development and testing phases, compilers for final program distribution - each serves different purposes in software creation.




Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Harry
@harry_s0nw9
Computer software is everywhere in our daily lives, from the apps on your phone to the programs that help websites run. Understanding how software works and gets created is crucial for anyone studying Computer Science, as it forms the foundation... Show more

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This topic covers the essential software concepts you'll need to master for A Level Computer Science. You'll explore everything from the apps you use daily to the behind-the-scenes programs that keep computers running smoothly.
The six key areas include application software (like Word or Photoshop), utility software (programs that maintain your computer), and open source vs closed source software (understanding who can see and modify the code). You'll also learn about translators that convert programming code into language computers understand.
Finally, you'll discover how compilation stages work and the role of libraries, linkers and loaders in bringing software to life. These concepts connect directly to programming tasks you'll encounter in coursework and exams.
Quick Tip: Each section builds on the previous one, so understanding application types will help you grasp how they're created and maintained.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Application software is basically any program designed to help you complete specific tasks - think of it as software that directly benefits you as a user. From writing essays in Word to editing photos in Photoshop, these programs make your digital life possible.
The most common types include word processors for creating documents, database management software for organising data, and web browsers for surfing the internet. You'll also encounter graphics manipulation tools, spreadsheet software, and presentation programs in your daily studies.
Some applications focus on system protection, like antivirus software, whilst others help with creativity, such as video editing programs. Integrated Development Environments (IDEs) are special applications that help programmers write and test code.
When exam questions ask you to recommend software, always read the scenario carefully, identify what tasks need completing, then explain how specific features of your chosen application will solve the problem.
Exam Success: Always link application features directly to user needs - don't just name the software, explain why it's perfect for the job.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The key application categories you'll encounter include email clients for managing messages across different providers, video editing software for creating films, and virtualisation software for running multiple operating systems on one machine. Each serves distinct purposes in modern computing.
For exam success, follow this three-step approach: carefully read scenarios to identify specific user tasks, recall multiple software applications with relevant features, then clearly explain how each application's capabilities meet the scenario's requirements.
Consider the banking example - a new bank needs to write letters and store customer data. A word processor provides document creation and formatting features, whilst a database management system offers secure data storage and retrieval capabilities.
Always connect application features directly to user needs rather than just naming software. This demonstrates your understanding of how technology solves real-world problems.
Pro Tip: Practice identifying user tasks from scenarios - this skill transfers to coursework projects where you'll need to choose appropriate software solutions.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Utility software works behind the scenes to keep your computer running efficiently - think of it as the maintenance crew for your system. Unlike application software that helps you complete tasks, utilities support the operating system itself.
Disk defragmentation reorganises files on hard drives to improve access speed by putting related data together and eliminating gaps. File management utilities help you organise, search, and move files around your system efficiently.
Device drivers act as translators between your hardware and operating system, ensuring components like printers and graphics cards work properly. System cleanup tools remove temporary files and unnecessary data that can slow down your computer.
Security utilities protect against viruses, malware, and other threats by monitoring system activities and blocking suspicious behaviour. Most operating systems include basic utilities, though you can install additional tools for enhanced functionality.
Remember: Modern SSDs don't require defragmentation like traditional hard drives - this is a common exam trick question!

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Software development follows two main approaches that affect how you can use and modify programs. Open source software allows anyone to view, modify, and distribute the source code - like having access to a recipe that you can adapt and share.
Closed source software keeps the code secret and proprietary, similar to a restaurant's secret recipe that customers can't see or change. Examples include Linux (open source) versus Windows (closed source), or Apache web server versus Adobe Photoshop.
For creators, open source offers collaboration benefits and faster innovation but less control over the final product. Closed source provides greater control and revenue opportunities but requires handling all development responsibilities internally.
Users benefit from open source through cost savings, customisation options, and transparency about how programs work. Closed source typically offers better technical support, polished interfaces, and guaranteed compatibility but at higher costs.
Exam Focus: Questions often ask you to compare benefits and drawbacks for both creators and users - make sure you can discuss both perspectives clearly.

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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Translators are essential programs that convert human-readable code into language computers can execute. Think of them as interpreters at international conferences - they bridge the communication gap between programmers and machines.
Interpreters work line-by-line, reading and executing code immediately. This makes debugging easier since you can test small sections quickly, but overall execution runs slower because translation happens during runtime.
Compilers translate entire programs at once before execution begins. This creates faster-running programs and doesn't require the translator during execution, but initial compilation takes longer and debugging can be more challenging.
Assemblers specifically handle assembly language - a low-level programming language that's closer to machine code than high-level languages like Python or Java. They occupy a unique position in the translation hierarchy.
Key Insight: Choose interpreters for development and testing phases, compilers for final program distribution - each serves different purposes in software creation.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user