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
6 Dec 2025
63
1 page
paige @paige_yuqp
Your circulatory and respiratory systems work together like a brilliant delivery service, keeping every cell in your body... Show more
Ever wondered what's actually flowing through your veins? Blood contains four essential components that each have specific jobs. Red blood cells are your oxygen delivery trucks, packed with haemoglobin and shaped like biconcave discs to maximise surface area. White blood cells act as your personal security team, hunting down harmful pathogens. Platelets are like tiny repair kits that help your blood clot when you get injured, whilst plasma serves as the liquid highway carrying all these components plus nutrients and waste products.
Your blood vessels form a massive network throughout your body. Arteries are the motorways carrying blood away from your heart to organs under high pressure, which is why they have thick, muscular walls. Veins bring blood back to your heart and have valves to prevent backflow. Capillaries are the tiny connecting roads where the actual exchange of oxygen, nutrients, and waste happens between your blood and tissues.
Quick Tip Remember "A for Away" - arteries carry blood away from the heart, whilst veins carry blood back to the heart.
Your heart is basically two pumps working side by side. The right side pumps blood to your lungs via the pulmonary artery, whilst the left side pumps oxygenated blood around your body through the aorta. The vena cava brings deoxygenated blood back to the right atrium, and the pulmonary vein returns oxygen-rich blood from the lungs to the left atrium.
Heart problems are surprisingly common. Coronary heart disease occurs when arteries narrow, restricting blood flow. Leaky valves don't open or close properly, making your heart less efficient. Treatments range from statins (drugs that reduce cholesterol) to stents (tiny tubes that prop arteries open) and even artificial pacemakers for hearts that don't beat regularly.
Heart transplants offer the best quality of life but come with significant risks. Mechanical valves can be inserted through your wrist using a thin tube - pretty amazing technology that saves lives daily.
Breathing might seem automatic, but it's actually a clever pressure system. When you inhale, your diaphragm contracts and moves down, increasing chest volume and decreasing pressure so air rushes in. Exhaling is the opposite - your diaphragm relaxes, volume decreases, pressure increases, and air gets forced out.
Gas exchange happens in tiny air sacs called alveoli at the end of bronchioles in your lungs. These are perfectly adapted with thin walls and huge surface area for efficient diffusion. Carbon dioxide moves out of your blood into the alveoli, whilst oxygen moves from the alveoli into your bloodstream.
Your respiratory system works from large to small trachea (windpipe) branches into bronchi, then smaller bronchioles, and finally the microscopic alveoli where the magic happens.
Plants have their own transport networks that are just as impressive as yours. Xylem vessels carry water and dissolved minerals up from the roots like a one-way elevator system. Phloem tubes transport glucose and other sugars around the plant through a process called translocation.
Transpiration is basically plants sweating - water evaporates from leaves, creating a pulling force that draws more water up through the roots and xylem. This process is affected by temperature (heat makes water evaporate faster), light intensity (opens stomata), humidity (affects concentration gradients), and wind (speeds up evaporation).
Plant tissues are organised brilliantly too. Epidermal tissue protects leaves, palisade mesophyll does most of the photosynthesis, and spongy mesophyll has air spaces for gas diffusion. Meristem tissue contains stem cells that help plants grow throughout their lives.
Remember Plants don't have hearts, but their transport systems are just as effective at moving materials where they're needed.
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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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
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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
paige
@paige_yuqp
Your circulatory and respiratory systems work together like a brilliant delivery service, keeping every cell in your body supplied with oxygen and nutrients. Understanding how blood, the heart, and lungs function will help you ace your biology exams and appreciate... Show more
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Ever wondered what's actually flowing through your veins? Blood contains four essential components that each have specific jobs. Red blood cells are your oxygen delivery trucks, packed with haemoglobin and shaped like biconcave discs to maximise surface area. White blood cells act as your personal security team, hunting down harmful pathogens. Platelets are like tiny repair kits that help your blood clot when you get injured, whilst plasma serves as the liquid highway carrying all these components plus nutrients and waste products.
Your blood vessels form a massive network throughout your body. Arteries are the motorways carrying blood away from your heart to organs under high pressure, which is why they have thick, muscular walls. Veins bring blood back to your heart and have valves to prevent backflow. Capillaries are the tiny connecting roads where the actual exchange of oxygen, nutrients, and waste happens between your blood and tissues.
Quick Tip: Remember "A for Away" - arteries carry blood away from the heart, whilst veins carry blood back to the heart.
Your heart is basically two pumps working side by side. The right side pumps blood to your lungs via the pulmonary artery, whilst the left side pumps oxygenated blood around your body through the aorta. The vena cava brings deoxygenated blood back to the right atrium, and the pulmonary vein returns oxygen-rich blood from the lungs to the left atrium.
Heart problems are surprisingly common. Coronary heart disease occurs when arteries narrow, restricting blood flow. Leaky valves don't open or close properly, making your heart less efficient. Treatments range from statins (drugs that reduce cholesterol) to stents (tiny tubes that prop arteries open) and even artificial pacemakers for hearts that don't beat regularly.
Heart transplants offer the best quality of life but come with significant risks. Mechanical valves can be inserted through your wrist using a thin tube - pretty amazing technology that saves lives daily.
Breathing might seem automatic, but it's actually a clever pressure system. When you inhale, your diaphragm contracts and moves down, increasing chest volume and decreasing pressure so air rushes in. Exhaling is the opposite - your diaphragm relaxes, volume decreases, pressure increases, and air gets forced out.
Gas exchange happens in tiny air sacs called alveoli at the end of bronchioles in your lungs. These are perfectly adapted with thin walls and huge surface area for efficient diffusion. Carbon dioxide moves out of your blood into the alveoli, whilst oxygen moves from the alveoli into your bloodstream.
Your respiratory system works from large to small: trachea (windpipe) branches into bronchi, then smaller bronchioles, and finally the microscopic alveoli where the magic happens.
Plants have their own transport networks that are just as impressive as yours. Xylem vessels carry water and dissolved minerals up from the roots like a one-way elevator system. Phloem tubes transport glucose and other sugars around the plant through a process called translocation.
Transpiration is basically plants sweating - water evaporates from leaves, creating a pulling force that draws more water up through the roots and xylem. This process is affected by temperature (heat makes water evaporate faster), light intensity (opens stomata), humidity (affects concentration gradients), and wind (speeds up evaporation).
Plant tissues are organised brilliantly too. Epidermal tissue protects leaves, palisade mesophyll does most of the photosynthesis, and spongy mesophyll has air spaces for gas diffusion. Meristem tissue contains stem cells that help plants grow throughout their lives.
Remember: Plants don't have hearts, but their transport systems are just as effective at moving materials where they're needed.
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.
1
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
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
Sociology