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Understanding the Calvin Benson Cycle in Photosynthesis

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Salina

12/11/2025

AP Biology

Unit 3: Calvin Benson Cycle in Photosynthesis

18

Dec 11, 2025

2 pages

Understanding the Calvin Benson Cycle in Photosynthesis

user profile picture

Salina

@alinahrestha_xngi

The Calvin-Benson Cycle is the process plants use during photosynthesis... Show more

Input
3
Coa enters one
per Cycle
Rubiso
happens 3 times
enzyme that
addas CO2+ RUBP
$
1C+5C=6C$
Phase 1: Carbon Fixation
Short lived
interme

Calvin Cycle Overview

The Calvin-Benson Cycle consists of three main phases that work together to produce sugars from carbon dioxide. It all begins when the enzyme RuBisCO captures CO₂ and attaches it to a 5-carbon molecule called RuBP (ribulose bisphosphate), creating a 6-carbon intermediate that quickly breaks down.

In Phase 1 (Carbon Fixation), CO₂ enters the cycle and combines with RuBP. This creates a short-lived intermediate that breaks down into 3-PGA 3phosphoglycerate3-phosphoglycerate, a 3-carbon molecule. For every three CO₂ molecules that enter, six 3-PGA molecules are formed.

Phase 2 (Reduction) uses energy from ATP and NADPH (produced during the light reactions) to convert 3-PGA into G3P glyceraldehyde3phosphateglyceraldehyde 3-phosphate. This requires both the phosphate from ATP and the hydrogen from NADPH to reduce the molecules. Out of six G3P molecules produced, one can exit the cycle to form glucose or other compounds.

Remember This: For every three CO₂ molecules fixed by RuBisCO, only one G3P molecule (3 carbons) can leave the cycle as product, while the remaining five G3P molecules must be recycled to regenerate RuBP.

Phase 3 (Regeneration) uses the remaining five G3P molecules and more ATP to rebuild the three original RuBP molecules, allowing the cycle to continue capturing more carbon dioxide.

Input
3
Coa enters one
per Cycle
Rubiso
happens 3 times
enzyme that
addas CO2+ RUBP
$
1C+5C=6C$
Phase 1: Carbon Fixation
Short lived
interme

Calvin Cycle Energy Flow

The Calvin Cycle is essentially a carbon-fixing factory that runs on the energy captured during the light reactions. When CO₂ combines with RuBP a5carbonmoleculea 5-carbon molecule, it initiates a series of reactions that transform carbon dioxide into usable sugar.

The pathway requires precise energy inputs at specific steps. First, ATP provides energy to convert the 3-carbon compounds 3PGA3-PGA into 1,3-bisphosphoglycerate. Then, NADPH donates high-energy electrons and hydrogen to create G3P glyceraldehyde3phosphateglyceraldehyde 3-phosphate, which is the first stable product of photosynthesis.

For every six G3P molecules produced, one can exit to form glucose a6carbonsugara 6-carbon sugar while the other five remain in the cycle. These five G3P molecules (containing 15 carbon atoms total) are rearranged using additional ATP energy to regenerate three RuBP molecules (each with 5 carbons), completing the cycle.

Pro Tip: Think of the Calvin Cycle as a carbon assembly line where for every three turns of the cycle, you get enough carbon atoms 3×CO2=3carbons3 × CO₂ = 3 carbons to build half of a glucose molecule (which requires 6 carbons total).



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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

 

AP Biology

18

Dec 11, 2025

2 pages

Understanding the Calvin Benson Cycle in Photosynthesis

user profile picture

Salina

@alinahrestha_xngi

The Calvin-Benson Cycle is the process plants use during photosynthesis to convert carbon dioxide into glucose. This critical cycle takes place in the chloroplasts and is sometimes called the "dark reactions" because it doesn't directly require light, though it depends... Show more

Input
3
Coa enters one
per Cycle
Rubiso
happens 3 times
enzyme that
addas CO2+ RUBP
$
1C+5C=6C$
Phase 1: Carbon Fixation
Short lived
interme

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

Calvin Cycle Overview

The Calvin-Benson Cycle consists of three main phases that work together to produce sugars from carbon dioxide. It all begins when the enzyme RuBisCO captures CO₂ and attaches it to a 5-carbon molecule called RuBP (ribulose bisphosphate), creating a 6-carbon intermediate that quickly breaks down.

In Phase 1 (Carbon Fixation), CO₂ enters the cycle and combines with RuBP. This creates a short-lived intermediate that breaks down into 3-PGA 3phosphoglycerate3-phosphoglycerate, a 3-carbon molecule. For every three CO₂ molecules that enter, six 3-PGA molecules are formed.

Phase 2 (Reduction) uses energy from ATP and NADPH (produced during the light reactions) to convert 3-PGA into G3P glyceraldehyde3phosphateglyceraldehyde 3-phosphate. This requires both the phosphate from ATP and the hydrogen from NADPH to reduce the molecules. Out of six G3P molecules produced, one can exit the cycle to form glucose or other compounds.

Remember This: For every three CO₂ molecules fixed by RuBisCO, only one G3P molecule (3 carbons) can leave the cycle as product, while the remaining five G3P molecules must be recycled to regenerate RuBP.

Phase 3 (Regeneration) uses the remaining five G3P molecules and more ATP to rebuild the three original RuBP molecules, allowing the cycle to continue capturing more carbon dioxide.

Input
3
Coa enters one
per Cycle
Rubiso
happens 3 times
enzyme that
addas CO2+ RUBP
$
1C+5C=6C$
Phase 1: Carbon Fixation
Short lived
interme

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

Calvin Cycle Energy Flow

The Calvin Cycle is essentially a carbon-fixing factory that runs on the energy captured during the light reactions. When CO₂ combines with RuBP a5carbonmoleculea 5-carbon molecule, it initiates a series of reactions that transform carbon dioxide into usable sugar.

The pathway requires precise energy inputs at specific steps. First, ATP provides energy to convert the 3-carbon compounds 3PGA3-PGA into 1,3-bisphosphoglycerate. Then, NADPH donates high-energy electrons and hydrogen to create G3P glyceraldehyde3phosphateglyceraldehyde 3-phosphate, which is the first stable product of photosynthesis.

For every six G3P molecules produced, one can exit to form glucose a6carbonsugara 6-carbon sugar while the other five remain in the cycle. These five G3P molecules (containing 15 carbon atoms total) are rearranged using additional ATP energy to regenerate three RuBP molecules (each with 5 carbons), completing the cycle.

Pro Tip: Think of the Calvin Cycle as a carbon assembly line where for every three turns of the cycle, you get enough carbon atoms 3×CO2=3carbons3 × CO₂ = 3 carbons to build half of a glucose molecule (which requires 6 carbons total).

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.

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

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