Subjects
Maths
Chemistry
Biology
English Language
History
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
Show all topics
Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
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
Show all topics
Biology
9 Dec 2025
82
4 pages
hannah @hannah_qhgof
Your body faces constant attacks from harmful microorganisms called pathogens that cause communicable diseases. Understanding how these diseases... Show more
Pathogens are nasty microorganisms that invade your body and make you ill. They come in four main types, each with their own sneaky ways of causing trouble.
Bacteria multiply incredibly fast inside you and pump out toxins that damage your cells and tissues. Meanwhile, viruses are even more devious - they hijack your cells' machinery to make copies of themselves, then burst the cell open to release new viruses everywhere.
Protists are single-celled parasites that often hitch rides on vectors (like mosquitoes) to reach new hosts. Fungi can be single-celled or made of thread-like structures called hyphae that penetrate skin and plant surfaces, spreading through spores.
Quick Tip Remember that pathogens spread through dirty water, air droplets from coughs and sneezes, and direct contact with contaminated surfaces.
Measles spreads through droplets when infected people cough or sneeze, causing red rashes and fever. It can be deadly if it leads to pneumonia, but most people get vaccinated as children to prevent it.
HIV spreads through sexual contact or sharing needles, initially causing flu-like symptoms before attacking your immune system. Antiretroviral drugs can control it during the symptom-free years, but late-stage HIV becomes AIDS.
The tobacco mosaic virus affects plants, creating mosaic patterns on leaves that reduce photosynthesis and stunt growth. This shows how diseases don't just affect humans - they impact the entire ecosystem.
Remember Vaccination is your best defence against viral diseases since antibiotics don't work on viruses.
Rose black spot is a fungal disease causing purple-black spots on rose leaves, which then yellow and drop off. It spreads through water and wind, but you can treat it with fungicides and removing affected leaves.
Malaria comes from protists carried by mosquitoes. When mosquitoes bite infected animals, they pick up the protist and inject it into their next victim, causing recurring fever episodes. Prevention focuses on mosquito nets and insecticides.
Salmonella bacteria cause food poisoning with fever, cramps, and vomiting from their toxins. Gonorrhoea is a sexually transmitted bacterial disease causing painful urination and discharge - now harder to treat due to antibiotic resistance.
Key Point Each pathogen type requires different treatment approaches, so identifying the cause is crucial for effective treatment.
Your body has brilliant built-in defences that work 24/7 to keep pathogens out. Your skin acts like a fortress wall, whilst your nose produces mucus to trap particles and your stomach's hydrochloric acid destroys swallowed pathogens.
Your immune system uses white blood cells as microscopic soldiers. They engulf pathogens through phagocytosis, produce antibodies that lock onto invaders, and create antitoxins to neutralise bacterial poisons.
Vaccination works by introducing dead or inactive pathogens, training your immune system to recognise real threats. It's prevented countless epidemics, though some people worry about rare side effects like swelling or fever.
Prevention beats cure every time - wash your hands regularly, destroy vector breeding sites, isolate infected individuals, and get vaccinated when recommended.
Top Tip Your immune system has an amazing memory - once it learns to fight a pathogen, it remembers how to defeat it quickly next time.
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.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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
hannah
@hannah_qhgof
Your body faces constant attacks from harmful microorganisms called pathogens that cause communicable diseases. Understanding how these diseases spread and how your immune system fights back is crucial for protecting yourself and others from infections.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Pathogens are nasty microorganisms that invade your body and make you ill. They come in four main types, each with their own sneaky ways of causing trouble.
Bacteria multiply incredibly fast inside you and pump out toxins that damage your cells and tissues. Meanwhile, viruses are even more devious - they hijack your cells' machinery to make copies of themselves, then burst the cell open to release new viruses everywhere.
Protists are single-celled parasites that often hitch rides on vectors (like mosquitoes) to reach new hosts. Fungi can be single-celled or made of thread-like structures called hyphae that penetrate skin and plant surfaces, spreading through spores.
Quick Tip: Remember that pathogens spread through dirty water, air droplets from coughs and sneezes, and direct contact with contaminated surfaces.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Measles spreads through droplets when infected people cough or sneeze, causing red rashes and fever. It can be deadly if it leads to pneumonia, but most people get vaccinated as children to prevent it.
HIV spreads through sexual contact or sharing needles, initially causing flu-like symptoms before attacking your immune system. Antiretroviral drugs can control it during the symptom-free years, but late-stage HIV becomes AIDS.
The tobacco mosaic virus affects plants, creating mosaic patterns on leaves that reduce photosynthesis and stunt growth. This shows how diseases don't just affect humans - they impact the entire ecosystem.
Remember: Vaccination is your best defence against viral diseases since antibiotics don't work on viruses.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Rose black spot is a fungal disease causing purple-black spots on rose leaves, which then yellow and drop off. It spreads through water and wind, but you can treat it with fungicides and removing affected leaves.
Malaria comes from protists carried by mosquitoes. When mosquitoes bite infected animals, they pick up the protist and inject it into their next victim, causing recurring fever episodes. Prevention focuses on mosquito nets and insecticides.
Salmonella bacteria cause food poisoning with fever, cramps, and vomiting from their toxins. Gonorrhoea is a sexually transmitted bacterial disease causing painful urination and discharge - now harder to treat due to antibiotic resistance.
Key Point: Each pathogen type requires different treatment approaches, so identifying the cause is crucial for effective treatment.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Your body has brilliant built-in defences that work 24/7 to keep pathogens out. Your skin acts like a fortress wall, whilst your nose produces mucus to trap particles and your stomach's hydrochloric acid destroys swallowed pathogens.
Your immune system uses white blood cells as microscopic soldiers. They engulf pathogens through phagocytosis, produce antibodies that lock onto invaders, and create antitoxins to neutralise bacterial poisons.
Vaccination works by introducing dead or inactive pathogens, training your immune system to recognise real threats. It's prevented countless epidemics, though some people worry about rare side effects like swelling or fever.
Prevention beats cure every time - wash your hands regularly, destroy vector breeding sites, isolate infected individuals, and get vaccinated when recommended.
Top Tip: Your immune system has an amazing memory - once it learns to fight a pathogen, it remembers how to defeat it quickly next time.
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.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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
Sociology