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23 Dec 2025
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Comprehensive Meiosis Study Notes for OCR A-Level Biology
Diah Diamond
@diahdiamond
Meiosis: The Ultimate Cell Division
Meiosis is fundamentally different from mitosis because it's designed to reduce chromosome number by half. While your body cells have 46 chromosomes , meiosis creates gametes with just 23 chromosomes .
What makes meiosis unique is that it involves two consecutive divisions: meiosis I and meiosis II. Each division follows the familiar stages you know from mitosis - prophase, metaphase, anaphase, and telophase - but with some crucial differences that create genetic diversity.
The entire process transforms one diploid cell into four haploid gametes, each genetically unique. This genetic shuffling is essential for sexual reproduction in both plants and animals, ensuring that offspring aren't exact copies of their parents.
Key Point: Meiosis creates genetic diversity through two special processes - crossing over and independent assortment - that don't happen in mitosis.
Meiosis I: The Reduction Division
Prophase I is where the real magic happens. Homologous chromosomes pair up side by side, and crossing over occurs when non-sister chromatids swap genetic material. These crossing points are called chiasmata, and they're crucial for creating genetic variation.
During metaphase I, homologous pairs line up along the cell's equator. Here's the key difference from mitosis: independent assortment means maternal and paternal chromosomes position themselves randomly, creating countless possible combinations.
Anaphase I separates whole chromosomes (not sister chromatids like in mitosis), pulling homologous pairs to opposite poles. The centromeres don't divide - this is crucial to remember.
Telophase I and cytokinesis complete the first division, creating two haploid cells. In animals, the cell membrane pinches inward, while plant cells form new cell walls using vesicles from the Golgi apparatus.
Meiosis II: The Separation Division
Meiosis II resembles mitosis but starts with haploid cells. Importantly, there's no interphase between meiosis I and II, so DNA isn't replicated again.
The stages proceed quickly: chromosomes line up individually in metaphase II, then centromeres finally divide in anaphase II, separating sister chromatids to opposite poles.
After telophase II and cytokinesis, you end up with four genetically unique haploid cells from one original diploid cell. These become eggs, sperm, or spores depending on the organism.
Remember: Meiosis I reduces chromosome number (reduction division), while meiosis II separates chromatids (separation division) - just like mitosis but in haploid cells.
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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.
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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.
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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.
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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
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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
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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
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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
Comprehensive Meiosis Study Notes for OCR A-Level Biology
Diah Diamond
@diahdiamond
Think of meiosis as nature's way of shuffling the genetic deck of cards before creating new life. This special type of cell division is what makes sexual reproduction possible, turning your diploid cells (with paired chromosomes) into haploid gametes (eggs... Show more
Meiosis: The Ultimate Cell Division
Meiosis is fundamentally different from mitosis because it's designed to reduce chromosome number by half. While your body cells have 46 chromosomes , meiosis creates gametes with just 23 chromosomes .
What makes meiosis unique is that it involves two consecutive divisions: meiosis I and meiosis II. Each division follows the familiar stages you know from mitosis - prophase, metaphase, anaphase, and telophase - but with some crucial differences that create genetic diversity.
The entire process transforms one diploid cell into four haploid gametes, each genetically unique. This genetic shuffling is essential for sexual reproduction in both plants and animals, ensuring that offspring aren't exact copies of their parents.
Key Point: Meiosis creates genetic diversity through two special processes - crossing over and independent assortment - that don't happen in mitosis.
Meiosis I: The Reduction Division
Prophase I is where the real magic happens. Homologous chromosomes pair up side by side, and crossing over occurs when non-sister chromatids swap genetic material. These crossing points are called chiasmata, and they're crucial for creating genetic variation.
During metaphase I, homologous pairs line up along the cell's equator. Here's the key difference from mitosis: independent assortment means maternal and paternal chromosomes position themselves randomly, creating countless possible combinations.
Anaphase I separates whole chromosomes (not sister chromatids like in mitosis), pulling homologous pairs to opposite poles. The centromeres don't divide - this is crucial to remember.
Telophase I and cytokinesis complete the first division, creating two haploid cells. In animals, the cell membrane pinches inward, while plant cells form new cell walls using vesicles from the Golgi apparatus.
Meiosis II: The Separation Division
Meiosis II resembles mitosis but starts with haploid cells. Importantly, there's no interphase between meiosis I and II, so DNA isn't replicated again.
The stages proceed quickly: chromosomes line up individually in metaphase II, then centromeres finally divide in anaphase II, separating sister chromatids to opposite poles.
After telophase II and cytokinesis, you end up with four genetically unique haploid cells from one original diploid cell. These become eggs, sperm, or spores depending on the organism.
Remember: Meiosis I reduces chromosome number (reduction division), while meiosis II separates chromatids (separation division) - just like mitosis but in haploid cells.
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?
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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