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3 Dec 2025
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Biology: Understanding Infection and Immune Response
flo
@flo_effins
1 / 3
Pathogens and How They Spread
Pathogens are nasty microorganisms that sneak into your body and make you ill. Think of them as four main troublemakers: bacteria, viruses, protists and fungi.
These disease-causing agents are surprisingly sneaky about getting around. Water can carry pathogens like cholera if it's contaminated - that's why you shouldn't drink from dodgy sources. Air is another highway for pathogens, especially when someone coughs or sneezes near you (hello, flu season!).
Direct contact is probably the most common way you'll encounter pathogens. Touching contaminated surfaces or sharing towels can spread things like athlete's foot fungus. This is why washing your hands is so important!
Key Point: Pathogens spread through water, air, and direct contact - knowing this helps you avoid getting sick!
Some serious viral diseases you should know about include measles (causes that distinctive red rash), HIV (attacks your immune system), and tobacco mosaic virus (affects plants by creating spotted leaves that can't photosynthesise properly).
Bacterial, Fungal and Protist Diseases
Bacterial diseases can really ruin your day, but the good news is they're often treatable. Salmonella is that food poisoning bug that gives you fever, stomach cramps and makes you feel absolutely dreadful - all thanks to the toxins bacteria produce.
Gonorrhoea is a sexually transmitted bacterial infection that causes painful symptoms but can be sorted with antibiotics. This shows why bacterial diseases are often easier to treat than viral ones.
Fungal diseases like rose black spot might not affect you directly, but they're brilliant examples for exams. This fungus creates dark spots on rose leaves, reducing photosynthesis and weakening the plant.
Remember: Bacteria can be treated with antibiotics, but viruses cannot - this is a common exam question!
Malaria is caused by a protist and spread by mosquitoes. It causes recurring fever episodes and can be prevented by controlling mosquito breeding areas. Understanding how different types of pathogens cause disease will help you ace those biology questions.
Your Body's Defence System
Your body is basically a fortress with multiple layers of protection - and it's more impressive than any castle! Your skin acts as the first barrier, whilst hairs and mucus in your nose trap particles before they can cause trouble.
Your trachea and bronchi are lined with tiny hairs called cilia that sweep mucus (and trapped pathogens) away from your lungs. Meanwhile, your stomach produces hydrochloric acid that's strong enough to kill most pathogens that dare to enter.
When pathogens do get through, your white blood cells spring into action. They can literally engulf and digest foreign invaders through phagocytosis - imagine tiny Pac-Men gobbling up the bad guys!
Exam Tip: Remember that antibodies are specific to each pathogen - they won't work against different invaders!
White blood cells also produce antibodies - special proteins that lock onto specific pathogens so other immune cells can destroy them. They even make antitoxins to neutralise the poisonous substances bacteria produce. Your immune system truly is incredible!
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Most popular content: Adaptive Immune Response
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Students love us — and so will you.
4.9/5
App Store
4.8/5
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
Biology: Understanding Infection and Immune Response
flo
@flo_effins
Your body is constantly under attack from invisible enemies called pathogens - but don't worry, you've got an incredible defence system! Understanding how diseases spread and how your body fights back is crucial for staying healthy and doing well in... Show more
Pathogens and How They Spread
Pathogens are nasty microorganisms that sneak into your body and make you ill. Think of them as four main troublemakers: bacteria, viruses, protists and fungi.
These disease-causing agents are surprisingly sneaky about getting around. Water can carry pathogens like cholera if it's contaminated - that's why you shouldn't drink from dodgy sources. Air is another highway for pathogens, especially when someone coughs or sneezes near you (hello, flu season!).
Direct contact is probably the most common way you'll encounter pathogens. Touching contaminated surfaces or sharing towels can spread things like athlete's foot fungus. This is why washing your hands is so important!
Key Point: Pathogens spread through water, air, and direct contact - knowing this helps you avoid getting sick!
Some serious viral diseases you should know about include measles (causes that distinctive red rash), HIV (attacks your immune system), and tobacco mosaic virus (affects plants by creating spotted leaves that can't photosynthesise properly).
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Bacterial, Fungal and Protist Diseases
Bacterial diseases can really ruin your day, but the good news is they're often treatable. Salmonella is that food poisoning bug that gives you fever, stomach cramps and makes you feel absolutely dreadful - all thanks to the toxins bacteria produce.
Gonorrhoea is a sexually transmitted bacterial infection that causes painful symptoms but can be sorted with antibiotics. This shows why bacterial diseases are often easier to treat than viral ones.
Fungal diseases like rose black spot might not affect you directly, but they're brilliant examples for exams. This fungus creates dark spots on rose leaves, reducing photosynthesis and weakening the plant.
Remember: Bacteria can be treated with antibiotics, but viruses cannot - this is a common exam question!
Malaria is caused by a protist and spread by mosquitoes. It causes recurring fever episodes and can be prevented by controlling mosquito breeding areas. Understanding how different types of pathogens cause disease will help you ace those biology questions.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Your Body's Defence System
Your body is basically a fortress with multiple layers of protection - and it's more impressive than any castle! Your skin acts as the first barrier, whilst hairs and mucus in your nose trap particles before they can cause trouble.
Your trachea and bronchi are lined with tiny hairs called cilia that sweep mucus (and trapped pathogens) away from your lungs. Meanwhile, your stomach produces hydrochloric acid that's strong enough to kill most pathogens that dare to enter.
When pathogens do get through, your white blood cells spring into action. They can literally engulf and digest foreign invaders through phagocytosis - imagine tiny Pac-Men gobbling up the bad guys!
Exam Tip: Remember that antibodies are specific to each pathogen - they won't work against different invaders!
White blood cells also produce antibodies - special proteins that lock onto specific pathogens so other immune cells can destroy them. They even make antitoxins to neutralise the poisonous substances bacteria produce. Your immune system truly is incredible!
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
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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Most popular content: Adaptive Immune Response
Most popular content in Biology
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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