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respiration biology notes
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Nov 25, 2025
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Comprehensive Notes on Respiration in Biology
Los
@los
1 / 5
Respiration and Aerobic Respiration
Think of respiration as your body's power station - it's the process that transfers energy from glucose in every single cell. Without it, you literally couldn't survive for seconds.
Aerobic respiration is the VIP version because it uses oxygen and happens mainly in the mitochondria (your cell's powerhouses). The equation is dead simple: glucose + oxygen → carbon dioxide + water. It's exothermic, meaning it releases energy that powers everything from muscle contractions to keeping your body temperature steady.
Your body uses this transferred energy for three main jobs: building bigger molecules from smaller ones (like making proteins), allowing muscles to contract so you can move, and maintaining your body temperature. Enzymes control every single reaction, acting like molecular managers that keep everything running smoothly.
Quick Tip: Remember that aerobic respiration is the most efficient way to get energy from glucose - think of it as the premium fuel your body prefers.
Anaerobic Respiration and Oxygen Debt
When you're sprinting or doing intense exercise, your body can't deliver oxygen fast enough to your muscles. That's when anaerobic respiration kicks in as an emergency backup system.
In your muscles, glucose breaks down without oxygen to make lactic acid. It's much less efficient than aerobic respiration because glucose isn't fully broken down, but it keeps your muscles working when oxygen runs short. The downside? Lactic acid buildup makes your muscles feel like they're on fire.
After intense exercise, you'll have an oxygen debt - basically, your body owes itself oxygen. That's why you keep breathing hard after stopping exercise. Your body needs this extra oxygen to convert the nasty lactic acid back into harmless carbon dioxide and water.
Your liver also helps out by converting lactic acid back to glucose. Meanwhile, fermentation in yeast cells works similarly, producing ethanol and carbon dioxide - which is why bread rises and alcoholic drinks exist!
Remember: Anaerobic respiration is your body's emergency generator - useful in a crisis but not sustainable long-term.
Exercise and Energy Demands
During exercise, your muscle cells work overtime and need way more energy than usual. Your body responds like a well-oiled machine - breathing rate and heart rate both increase to deliver more oxygen and glucose whilst removing carbon dioxide faster.
When you do vigorous exercise like sprinting, your body simply can't supply oxygen quickly enough. Your muscles switch to anaerobic respiration, but this creates lactic acid buildup that causes pain and muscle fatigue. Your muscles literally get tired and stop working efficiently.
The recovery period after exercise is when your body pays back the oxygen debt. Your heart rate and breathing stay elevated until all that lactic acid is sorted out. This is completely normal and shows your body is working properly to restore balance.
Fun Fact: Your heart rate increases with exercise intensity because your muscles are basically screaming "We need more fuel and oxygen, NOW!"
Investigating Exercise Effects and Metabolism Basics
You can easily measure how exercise affects your body by taking your pulse after different activities - sitting, gentle walking, jogging, and running. Plot these on a bar chart and you'll see your heart rate climbing with exercise intensity.
Metabolism is the sum of all chemical reactions happening in your cells and body. It's like having thousands of tiny factories running simultaneously, all controlled by enzymes. These reactions link together in chains, with one reaction's product becoming the next reaction's starting material.
Some reactions are endothermic and build bigger molecules from smaller ones. Your body makes starch, glycogen, and cellulose from glucose molecules, creates lipids from glycerol and fatty acids, and combines glucose with nitrates to make amino acids for proteins.
Other reactions are exothermic and break large molecules down. Respiration breaks down glucose to power everything, whilst excess protein gets broken down to make urea that you excrete in urine.
Key Point: Metabolism never stops - even when you're sleeping, thousands of chemical reactions keep you alive.
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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.
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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
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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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
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Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Comprehensive Notes on Respiration in Biology
Los
@los
Your body is like a 24/7 chemical factory, constantly transferring energy and breaking down molecules to keep you alive. Respiration is the star process that powers everything your cells do, from building muscles to keeping your heart beating.
Respiration and Aerobic Respiration
Think of respiration as your body's power station - it's the process that transfers energy from glucose in every single cell. Without it, you literally couldn't survive for seconds.
Aerobic respiration is the VIP version because it uses oxygen and happens mainly in the mitochondria (your cell's powerhouses). The equation is dead simple: glucose + oxygen → carbon dioxide + water. It's exothermic, meaning it releases energy that powers everything from muscle contractions to keeping your body temperature steady.
Your body uses this transferred energy for three main jobs: building bigger molecules from smaller ones (like making proteins), allowing muscles to contract so you can move, and maintaining your body temperature. Enzymes control every single reaction, acting like molecular managers that keep everything running smoothly.
Quick Tip: Remember that aerobic respiration is the most efficient way to get energy from glucose - think of it as the premium fuel your body prefers.
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Anaerobic Respiration and Oxygen Debt
When you're sprinting or doing intense exercise, your body can't deliver oxygen fast enough to your muscles. That's when anaerobic respiration kicks in as an emergency backup system.
In your muscles, glucose breaks down without oxygen to make lactic acid. It's much less efficient than aerobic respiration because glucose isn't fully broken down, but it keeps your muscles working when oxygen runs short. The downside? Lactic acid buildup makes your muscles feel like they're on fire.
After intense exercise, you'll have an oxygen debt - basically, your body owes itself oxygen. That's why you keep breathing hard after stopping exercise. Your body needs this extra oxygen to convert the nasty lactic acid back into harmless carbon dioxide and water.
Your liver also helps out by converting lactic acid back to glucose. Meanwhile, fermentation in yeast cells works similarly, producing ethanol and carbon dioxide - which is why bread rises and alcoholic drinks exist!
Remember: Anaerobic respiration is your body's emergency generator - useful in a crisis but not sustainable long-term.
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Exercise and Energy Demands
During exercise, your muscle cells work overtime and need way more energy than usual. Your body responds like a well-oiled machine - breathing rate and heart rate both increase to deliver more oxygen and glucose whilst removing carbon dioxide faster.
When you do vigorous exercise like sprinting, your body simply can't supply oxygen quickly enough. Your muscles switch to anaerobic respiration, but this creates lactic acid buildup that causes pain and muscle fatigue. Your muscles literally get tired and stop working efficiently.
The recovery period after exercise is when your body pays back the oxygen debt. Your heart rate and breathing stay elevated until all that lactic acid is sorted out. This is completely normal and shows your body is working properly to restore balance.
Fun Fact: Your heart rate increases with exercise intensity because your muscles are basically screaming "We need more fuel and oxygen, NOW!"
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Investigating Exercise Effects and Metabolism Basics
You can easily measure how exercise affects your body by taking your pulse after different activities - sitting, gentle walking, jogging, and running. Plot these on a bar chart and you'll see your heart rate climbing with exercise intensity.
Metabolism is the sum of all chemical reactions happening in your cells and body. It's like having thousands of tiny factories running simultaneously, all controlled by enzymes. These reactions link together in chains, with one reaction's product becoming the next reaction's starting material.
Some reactions are endothermic and build bigger molecules from smaller ones. Your body makes starch, glycogen, and cellulose from glucose molecules, creates lipids from glycerol and fatty acids, and combines glucose with nitrates to make amino acids for proteins.
Other reactions are exothermic and break large molecules down. Respiration breaks down glucose to power everything, whilst excess protein gets broken down to make urea that you excrete in urine.
Key Point: Metabolism never stops - even when you're sleeping, thousands of chemical reactions keep you alive.
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We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the 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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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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user