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
5 Dec 2025
136
4 pages
Olivia Churcher @oliviachurcher
Reproduction involves the creation of specialised cells called gametes, fertilisation, and subsequent development. Understanding how our bodies produce... Show more
Gametes are sex cells produced through meiosis in specialised organs. Males produce sperm in the testes, while females produce ova (eggs) in the ovaries. These specialised cells are essential for sexual reproduction.
The male reproductive system features seminiferous tubules where sperm production occurs and interstitial cells that produce testosterone. Supporting structures like the prostate gland and seminal vesicles secrete fluids that help maintain sperm mobility and viability as they travel through the sperm duct.
Female ova develop in the ovaries, protected by fluid-filled sacs called follicles. These follicles not only protect the developing eggs but also release important hormones like oestrogen and progesterone that regulate the reproductive cycle.
💡 Remember this Fertilisation occurs when sperm and egg nuclei fuse to form a diploid zygote. In humans, this process happens in the oviduct (fallopian tube), not in the uterus where the embryo will later develop.
Puberty begins when the hypothalamus releases hormones that stimulate the pituitary gland to produce FSH (Follicle Stimulating Hormone) and LH (Luteinising Hormone). These hormones trigger the development of reproductive systems and the production of sex hormones.
In males, FSH stimulates sperm production while ICSH (Interstitial Cell Stimulating Hormone) triggers testosterone production. Testosterone then further promotes sperm production and activates the prostate gland and seminal vesicles, creating a feedback loop that maintains fertility.
The female menstrual cycle (approximately 28 days) is controlled by a complex interplay of hormones. During the follicular phase, FSH stimulates follicle development and oestrogen production. The LH surge triggers ovulation around day 14, and the follicle transforms into a corpus luteum, which secretes progesterone during the luteal phase.
🔍 Understanding hormone graphs When looking at menstrual cycle hormone graphs, notice how FSH and LH peak just before ovulation, while progesterone rises after ovulation. If pregnancy doesn't occur, progesterone levels fall, leading to menstruation as the endometrium sheds.
Understanding fertility allows us to either enhance it (infertility treatments) or prevent conception (contraception). While women experience cyclical fertility with specific fertile windows, men produce sperm continuously, resulting in constant fertility.
Infertility treatments include various approaches. Ovulation stimulation uses drugs that prevent negative feedback on FSH secretion or mimic FSH/LH action. In vitro fertilisation (IVF) involves removing eggs, fertilising them in a lab, and implanting the embryos. For men with sperm issues, intra-cytoplasmic sperm injection (ICSI) directly injects sperm into eggs.
Contraception methods fall into physical and chemical categories. Physical methods include barrier methods (condoms, diaphragms), IUDs (preventing implantation), and sterilisation procedures. Chemical methods like the combined pill mimic hormone feedback to prevent ovulation, while the progesterone-only pill thickens cervical mucus to block sperm.
🧠 Quick fact Identifying the fertile window is possible through natural signs—body temperature rises by about 0.5°C and cervical mucus becomes thin and watery during ovulation, which is useful knowledge whether trying to conceive or avoid pregnancy!
Screening techniques help monitor the health of both mother and developing baby throughout pregnancy and after birth. These tests identify potential issues early, allowing for appropriate interventions.
Antenatal screening includes ultrasound scans at different stages—a dating scan establishes the due date, while an anomaly scan checks for physical abnormalities. Blood and urine tests track marker chemicals, with atypical results potentially indicating medical conditions. For diagnostic certainty, amniocentesis and chorionic villus sampling (CVS) can be performed, though they carry some miscarriage risk.
Postnatal screening tests newborns for metabolic disorders like phenylketonuria (PKU), a condition where phenylalanine can't be converted to tyrosine due to a mutation. Early detection allows dietary management to prevent complications.
🧬 Genetic inheritance patterns Understanding inheritance patterns helps predict the likelihood of genetic conditions. Autosomal recessive traits require two carrier parents, dominant traits appear in every generation, and sex-linked disorders affect males more frequently than females since males have only one X chromosome.
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
Olivia Churcher
@oliviachurcher
Reproduction involves the creation of specialised cells called gametes, fertilisation, and subsequent development. Understanding how our bodies produce these cells, regulate fertility, and screen for potential issues is essential for grasping human reproduction biology. This summary covers the key concepts... Show more
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Gametes are sex cells produced through meiosis in specialised organs. Males produce sperm in the testes, while females produce ova (eggs) in the ovaries. These specialised cells are essential for sexual reproduction.
The male reproductive system features seminiferous tubules where sperm production occurs and interstitial cells that produce testosterone. Supporting structures like the prostate gland and seminal vesicles secrete fluids that help maintain sperm mobility and viability as they travel through the sperm duct.
Female ova develop in the ovaries, protected by fluid-filled sacs called follicles. These follicles not only protect the developing eggs but also release important hormones like oestrogen and progesterone that regulate the reproductive cycle.
💡 Remember this: Fertilisation occurs when sperm and egg nuclei fuse to form a diploid zygote. In humans, this process happens in the oviduct (fallopian tube), not in the uterus where the embryo will later develop.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Puberty begins when the hypothalamus releases hormones that stimulate the pituitary gland to produce FSH (Follicle Stimulating Hormone) and LH (Luteinising Hormone). These hormones trigger the development of reproductive systems and the production of sex hormones.
In males, FSH stimulates sperm production while ICSH (Interstitial Cell Stimulating Hormone) triggers testosterone production. Testosterone then further promotes sperm production and activates the prostate gland and seminal vesicles, creating a feedback loop that maintains fertility.
The female menstrual cycle (approximately 28 days) is controlled by a complex interplay of hormones. During the follicular phase, FSH stimulates follicle development and oestrogen production. The LH surge triggers ovulation around day 14, and the follicle transforms into a corpus luteum, which secretes progesterone during the luteal phase.
🔍 Understanding hormone graphs: When looking at menstrual cycle hormone graphs, notice how FSH and LH peak just before ovulation, while progesterone rises after ovulation. If pregnancy doesn't occur, progesterone levels fall, leading to menstruation as the endometrium sheds.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Understanding fertility allows us to either enhance it (infertility treatments) or prevent conception (contraception). While women experience cyclical fertility with specific fertile windows, men produce sperm continuously, resulting in constant fertility.
Infertility treatments include various approaches. Ovulation stimulation uses drugs that prevent negative feedback on FSH secretion or mimic FSH/LH action. In vitro fertilisation (IVF) involves removing eggs, fertilising them in a lab, and implanting the embryos. For men with sperm issues, intra-cytoplasmic sperm injection (ICSI) directly injects sperm into eggs.
Contraception methods fall into physical and chemical categories. Physical methods include barrier methods (condoms, diaphragms), IUDs (preventing implantation), and sterilisation procedures. Chemical methods like the combined pill mimic hormone feedback to prevent ovulation, while the progesterone-only pill thickens cervical mucus to block sperm.
🧠 Quick fact: Identifying the fertile window is possible through natural signs—body temperature rises by about 0.5°C and cervical mucus becomes thin and watery during ovulation, which is useful knowledge whether trying to conceive or avoid pregnancy!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Screening techniques help monitor the health of both mother and developing baby throughout pregnancy and after birth. These tests identify potential issues early, allowing for appropriate interventions.
Antenatal screening includes ultrasound scans at different stages—a dating scan establishes the due date, while an anomaly scan checks for physical abnormalities. Blood and urine tests track marker chemicals, with atypical results potentially indicating medical conditions. For diagnostic certainty, amniocentesis and chorionic villus sampling (CVS) can be performed, though they carry some miscarriage risk.
Postnatal screening tests newborns for metabolic disorders like phenylketonuria (PKU), a condition where phenylalanine can't be converted to tyrosine due to a mutation. Early detection allows dietary management to prevent complications.
🧬 Genetic inheritance patterns: Understanding inheritance patterns helps predict the likelihood of genetic conditions. Autosomal recessive traits require two carrier parents, dominant traits appear in every generation, and sex-linked disorders affect males more frequently than females since males have only one X chromosome.
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.
4
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