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Fun WJEC A Level Biology: Knowledge Organizers, Past Papers & More!

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Respiration mind map A level

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Biology

Bioenergetics

Photosynthesis

796

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11 Jul 2025

•

3 pages

Fun WJEC A Level Biology: Knowledge Organizers, Past Papers & More!

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Eliza

@3liza

Respiration and Energy Production in Cells: A Comprehensive Guide

Cellular... Show more

Universal energy carrier's ATP transfers energy for all biochemical reactions in the cells of all living organisms. ATP Synthase ADP + iP. A

Stages of Cellular Respiration

This page details the three main stages of cellular respiration: glycolysis, the link reaction, and the Krebs cycle.

  1. Glycolysis Summary: Occurs in the cytoplasm Converts 6C glucose to 3C pyruvate Net gain of two ATP Produces reduced NAD
  2. Link Reaction: Takes place in the matrix of mitochondria Converts 3C pyruvate to acetyl coenzyme A Involves decarboxylation removalofCO2removal of CO₂ and dehydrogenation removalofhydrogenremoval of hydrogen Reduces NAD
  3. Krebs Cycle: Occurs in the mitochondrial matrix Produces 1 ATP per cycle Generates FADH₂ equivalentto2ATPinETCequivalent to 2 ATP in ETC and NADH₂ equivalentto3ATPequivalent to 3 ATP Happens twice per glucose molecule

Highlight: The Krebs cycle is a key process in aerobic respiration, occurring in the mitochondrial matrix and producing significant amounts of reduced coenzymes for the electron transport chain.

The page also provides information on different types of organisms based on their respiratory requirements:

  • Aerobes: Most life forms that use oxygen to respire
  • Facultative anaerobes: Organisms that can respire for a short time without oxygen
  • Strict anaerobes: Some bacteria species that can only respire in the absence of oxygen

Vocabulary: Decarboxylation is the removal of CO₂, while dehydrogenation is the removal of hydrogen.

Universal energy carrier's ATP transfers energy for all biochemical reactions in the cells of all living organisms. ATP Synthase ADP + iP. A

The Krebs Cycle and ATP Production

This page provides a detailed diagram and explanation of the Krebs cycle, a crucial process in aerobic respiration that occurs in the mitochondrial matrix.

The Krebs cycle begins with a 4C oxaloacetate molecule and involves several steps:

  1. 2C acetyl fragment fromacetylcoenzymeAfrom acetyl coenzyme A combines with oxaloacetate to form 6C citrate
  2. Through a series of reactions, the 6C citrate is converted back to 4C oxaloacetate
  3. During this process, CO₂ is released decarboxylationdecarboxylation and hydrogen is removed dehydrogenationdehydrogenation

Highlight: The Krebs cycle produces 15 ATP per cycle, with a total of 30 ATP per glucose molecule asthecycleoccurstwiceforeachglucosemoleculeas the cycle occurs twice for each glucose molecule.

ATP production in the Krebs cycle:

  • 1 ATP produced directly through substrate-level phosphorylation
  • 4 pairs of hydrogen atoms carried by NAD eachpairgenerates3ATPintheETCeach pair generates 3 ATP in the ETC: 4 x 3 = 12 ATP
  • 1 pair of hydrogen atoms carried by FAD generates2ATPintheETCgenerates 2 ATP in the ETC: 1 x 2 = 2 ATP

Example: For each glucose molecule, the Krebs cycle occurs twice, resulting in 30 ATP 15x215 x 2 from this stage alone.

The page also summarizes the total ATP production during aerobic respiration:

  • Glycolysis: 2 ATP
  • Krebs cycle: 30 ATP
  • Total: 38 ATP per glucose molecule

Vocabulary: FAD FlavinAdenineDinucleotideFlavin Adenine Dinucleotide and NAD NicotinamideAdenineDinucleotideNicotinamide Adenine Dinucleotide are important coenzymes in the electron transport chain.

Universal energy carrier's ATP transfers energy for all biochemical reactions in the cells of all living organisms. ATP Synthase ADP + iP. A

ATP: The Universal Energy Carrier

ATP AdenosineTriphosphateAdenosine Triphosphate plays a crucial role in cellular energy transfer for all living organisms. It consists of adenine, ribose, and three phosphate groups.

Definition: ATP AdenosineTriphosphateAdenosine Triphosphate is the universal energy carrier that transfers energy for all biochemical reactions in cells.

ATP is synthesized through the process of phosphorylation, where ADP combines with inorganic phosphate. This reaction is catalyzed by ATP synthase:

ADP + iP → ATP

The reverse process, where ATP is broken down to release energy, is catalyzed by ATPase:

ATP → ADP + iP

Highlight: ATP hydrolysis releases 30.6 kJ/mol of energy, which is used for various cellular processes.

Advantages of ATP include:

  1. Solubility for easy transport
  2. Only one enzyme needed for hydrolysis
  3. Easy to hydrolyze
  4. Easily transported across membranes

The guide also introduces the concept of metabolism, which encompasses all chemical reactions in cells. These reactions are categorized into:

  1. Catabolic reactions: Breaking down large molecules
  2. Anabolic reactions: Building up large molecules

Vocabulary: Aerobes are organisms that use oxygen to respire, while anaerobes can respire without oxygen.

The electron transport chain ETCETC is a crucial part of aerobic respiration, involving the movement of electrons from higher to lower energy levels, releasing energy in the process. This energy is used to pump protons, creating an electrochemical gradient that drives ATP synthesis.



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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

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

Subjects

Biology

Bioenergetics

Photosynthesis

 

Biology

•

796

•

11 Jul 2025

•

3 pages

Fun WJEC A Level Biology: Knowledge Organizers, Past Papers & More!

user profile picture

Eliza

@3liza

Respiration and Energy Production in Cells: A Comprehensive Guide

Cellular respiration is a fundamental process in living organisms, involving the breakdown of glucose to produce ATP, the universal energy carrier. This guide covers the key stages of respiration, including glycolysis,... Show more

Universal energy carrier's ATP transfers energy for all biochemical reactions in the cells of all living organisms. ATP Synthase ADP + iP. A

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Improve your grades

Join milions of students

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Stages of Cellular Respiration

This page details the three main stages of cellular respiration: glycolysis, the link reaction, and the Krebs cycle.

  1. Glycolysis Summary: Occurs in the cytoplasm Converts 6C glucose to 3C pyruvate Net gain of two ATP Produces reduced NAD
  2. Link Reaction: Takes place in the matrix of mitochondria Converts 3C pyruvate to acetyl coenzyme A Involves decarboxylation removalofCO2removal of CO₂ and dehydrogenation removalofhydrogenremoval of hydrogen Reduces NAD
  3. Krebs Cycle: Occurs in the mitochondrial matrix Produces 1 ATP per cycle Generates FADH₂ equivalentto2ATPinETCequivalent to 2 ATP in ETC and NADH₂ equivalentto3ATPequivalent to 3 ATP Happens twice per glucose molecule

Highlight: The Krebs cycle is a key process in aerobic respiration, occurring in the mitochondrial matrix and producing significant amounts of reduced coenzymes for the electron transport chain.

The page also provides information on different types of organisms based on their respiratory requirements:

  • Aerobes: Most life forms that use oxygen to respire
  • Facultative anaerobes: Organisms that can respire for a short time without oxygen
  • Strict anaerobes: Some bacteria species that can only respire in the absence of oxygen

Vocabulary: Decarboxylation is the removal of CO₂, while dehydrogenation is the removal of hydrogen.

Universal energy carrier's ATP transfers energy for all biochemical reactions in the cells of all living organisms. ATP Synthase ADP + iP. A

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

The Krebs Cycle and ATP Production

This page provides a detailed diagram and explanation of the Krebs cycle, a crucial process in aerobic respiration that occurs in the mitochondrial matrix.

The Krebs cycle begins with a 4C oxaloacetate molecule and involves several steps:

  1. 2C acetyl fragment fromacetylcoenzymeAfrom acetyl coenzyme A combines with oxaloacetate to form 6C citrate
  2. Through a series of reactions, the 6C citrate is converted back to 4C oxaloacetate
  3. During this process, CO₂ is released decarboxylationdecarboxylation and hydrogen is removed dehydrogenationdehydrogenation

Highlight: The Krebs cycle produces 15 ATP per cycle, with a total of 30 ATP per glucose molecule asthecycleoccurstwiceforeachglucosemoleculeas the cycle occurs twice for each glucose molecule.

ATP production in the Krebs cycle:

  • 1 ATP produced directly through substrate-level phosphorylation
  • 4 pairs of hydrogen atoms carried by NAD eachpairgenerates3ATPintheETCeach pair generates 3 ATP in the ETC: 4 x 3 = 12 ATP
  • 1 pair of hydrogen atoms carried by FAD generates2ATPintheETCgenerates 2 ATP in the ETC: 1 x 2 = 2 ATP

Example: For each glucose molecule, the Krebs cycle occurs twice, resulting in 30 ATP 15x215 x 2 from this stage alone.

The page also summarizes the total ATP production during aerobic respiration:

  • Glycolysis: 2 ATP
  • Krebs cycle: 30 ATP
  • Total: 38 ATP per glucose molecule

Vocabulary: FAD FlavinAdenineDinucleotideFlavin Adenine Dinucleotide and NAD NicotinamideAdenineDinucleotideNicotinamide Adenine Dinucleotide are important coenzymes in the electron transport chain.

Universal energy carrier's ATP transfers energy for all biochemical reactions in the cells of all living organisms. ATP Synthase ADP + iP. A

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

ATP: The Universal Energy Carrier

ATP AdenosineTriphosphateAdenosine Triphosphate plays a crucial role in cellular energy transfer for all living organisms. It consists of adenine, ribose, and three phosphate groups.

Definition: ATP AdenosineTriphosphateAdenosine Triphosphate is the universal energy carrier that transfers energy for all biochemical reactions in cells.

ATP is synthesized through the process of phosphorylation, where ADP combines with inorganic phosphate. This reaction is catalyzed by ATP synthase:

ADP + iP → ATP

The reverse process, where ATP is broken down to release energy, is catalyzed by ATPase:

ATP → ADP + iP

Highlight: ATP hydrolysis releases 30.6 kJ/mol of energy, which is used for various cellular processes.

Advantages of ATP include:

  1. Solubility for easy transport
  2. Only one enzyme needed for hydrolysis
  3. Easy to hydrolyze
  4. Easily transported across membranes

The guide also introduces the concept of metabolism, which encompasses all chemical reactions in cells. These reactions are categorized into:

  1. Catabolic reactions: Breaking down large molecules
  2. Anabolic reactions: Building up large molecules

Vocabulary: Aerobes are organisms that use oxygen to respire, while anaerobes can respire without oxygen.

The electron transport chain ETCETC is a crucial part of aerobic respiration, involving the movement of electrons from higher to lower energy levels, releasing energy in the process. This energy is used to pump protons, creating an electrochemical gradient that drives ATP synthesis.

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.

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