Subjects
Maths
Biology
Chemistry
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
1l the quest for political stability: germany, 1871-1991
Britain & the wider world: 1745 -1901
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
10
0
gmelonergan
25/11/2025
Biology
4- Natural Selection and Genetic Modification - GCSE Edexcel Biology
688
•
25 Nov 2025
•
gmelonergan
@gmelonergan_pquc
Ever wondered how humans evolved or how scientists create disease-resistant... Show more
You've probably heard of famous fossils like Lucy and Ardi - these ancient human ancestors show us how we've changed over millions of years. Scientists use Carl Linnaeus' binomial system to classify species and date rock layers to work out when these early humans lived.
Darwin's theory of evolution explains how species change over time through a simple process. When there's genetic variation in a population and environmental changes create competition, only the fittest individuals survive through natural selection. These survivors pass on their advantageous traits through inheritance, leading to evolution.
You can see this happening right now with antibiotic-resistant bacteria - they've evolved to survive medical treatments! The pentadactyl limb found in humans, bats, and whales suggests we all evolved from a common ancestor.
Quick Tip: Remember Darwin's process as "VCSIE" - Variation, Competition, Selection, Inheritance, Evolution!
Carl Woese revolutionised how we classify life by creating three domains based on cellular structure. Archaea and Bacteria both lack a nucleus, but bacteria don't have unused DNA sections. Eukaryota (including humans) have a nucleus and unused DNA sections, making our genetic code quite inefficient compared to bacteria!
Humans have been playing matchmaker with organisms for thousands of years through artificial selection. Selective breeding lets farmers choose organisms with desirable traits like disease resistance, better yield, or improved flavour to create new breeds and varieties.
Genetic engineering takes this further by directly inserting genes from one organism into another, creating GMOs (genetically modified organisms). It's like copy-pasting useful genetic code between completely different species!
Tissue culture grows identical cells in nutrient-rich solutions, starting with a callus (a blob of undifferentiated cells). Scientists use this technique to save rare plant species from extinction by growing many identical copies from just a small piece of plant tissue.
Remember: Tissue culture involves sterilising plant pieces in bleach, growing them on nutrient medium, treating with hormones, then planting in soil.
The process requires sterile conditions because you don't want harmful bacteria competing with your precious plant cells for nutrients.
Creating insulin for diabetics using bacteria is one of genetic engineering's greatest success stories. Scientists essentially turn bacteria into tiny insulin factories through a six-step process.
First, restriction endonuclease enzymes cut out the human insulin gene, leaving sticky ends - single-stranded DNA bits that act like genetic velcro. The same enzyme opens up a bacterial plasmid (a circular piece of DNA), creating matching sticky ends.
DNA ligase then glues the insulin gene into the plasmid, creating a recombinant plasmid containing DNA from two different organisms. This vector carries the new gene back into the bacterium, making it transgenic.
Key Point: The recombinant plasmid acts as a vector because it delivers foreign DNA into the host cell.
Once the transgenic bacteria reproduce asexually, you get millions of identical bacteria all churning out human insulin. This insulin can then be extracted and purified for medical use - much safer than using pig insulin!
GM organisms tackle agricultural challenges by introducing genes that make crops resistant to pests or herbicides. Instead of constantly spraying insecticides to kill crop-damaging insects, scientists can engineer plants to produce their own pest deterrents.
Fertilisers boost plant growth by providing essential mineral ions, but excess fertiliser often washes into waterways, causing pollution. This creates a balancing act between maximising crop yields and protecting the environment.
Biological control offers an eco-friendly alternative by using natural predators to control pests. Think ladybirds eating aphids - it's nature's own pest management system without harmful chemicals.
Food for Thought: Combining selective breeding, GM technology, and biological control could be the key to feeding our growing population sustainably.
These modern techniques help farmers increase food production whilst potentially reducing environmental impact. Whether through creating drought-resistant crops or using beneficial insects instead of pesticides, science is revolutionising how we grow food.
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.
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
gmelonergan
@gmelonergan_pquc
Ever wondered how humans evolved or how scientists create disease-resistant crops? This topic covers everything from Darwin's groundbreaking theories to modern genetic engineering techniques that are shaping agriculture and medicine today.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
You've probably heard of famous fossils like Lucy and Ardi - these ancient human ancestors show us how we've changed over millions of years. Scientists use Carl Linnaeus' binomial system to classify species and date rock layers to work out when these early humans lived.
Darwin's theory of evolution explains how species change over time through a simple process. When there's genetic variation in a population and environmental changes create competition, only the fittest individuals survive through natural selection. These survivors pass on their advantageous traits through inheritance, leading to evolution.
You can see this happening right now with antibiotic-resistant bacteria - they've evolved to survive medical treatments! The pentadactyl limb found in humans, bats, and whales suggests we all evolved from a common ancestor.
Quick Tip: Remember Darwin's process as "VCSIE" - Variation, Competition, Selection, Inheritance, Evolution!
Carl Woese revolutionised how we classify life by creating three domains based on cellular structure. Archaea and Bacteria both lack a nucleus, but bacteria don't have unused DNA sections. Eukaryota (including humans) have a nucleus and unused DNA sections, making our genetic code quite inefficient compared to bacteria!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Humans have been playing matchmaker with organisms for thousands of years through artificial selection. Selective breeding lets farmers choose organisms with desirable traits like disease resistance, better yield, or improved flavour to create new breeds and varieties.
Genetic engineering takes this further by directly inserting genes from one organism into another, creating GMOs (genetically modified organisms). It's like copy-pasting useful genetic code between completely different species!
Tissue culture grows identical cells in nutrient-rich solutions, starting with a callus (a blob of undifferentiated cells). Scientists use this technique to save rare plant species from extinction by growing many identical copies from just a small piece of plant tissue.
Remember: Tissue culture involves sterilising plant pieces in bleach, growing them on nutrient medium, treating with hormones, then planting in soil.
The process requires sterile conditions because you don't want harmful bacteria competing with your precious plant cells for nutrients.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Creating insulin for diabetics using bacteria is one of genetic engineering's greatest success stories. Scientists essentially turn bacteria into tiny insulin factories through a six-step process.
First, restriction endonuclease enzymes cut out the human insulin gene, leaving sticky ends - single-stranded DNA bits that act like genetic velcro. The same enzyme opens up a bacterial plasmid (a circular piece of DNA), creating matching sticky ends.
DNA ligase then glues the insulin gene into the plasmid, creating a recombinant plasmid containing DNA from two different organisms. This vector carries the new gene back into the bacterium, making it transgenic.
Key Point: The recombinant plasmid acts as a vector because it delivers foreign DNA into the host cell.
Once the transgenic bacteria reproduce asexually, you get millions of identical bacteria all churning out human insulin. This insulin can then be extracted and purified for medical use - much safer than using pig insulin!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
GM organisms tackle agricultural challenges by introducing genes that make crops resistant to pests or herbicides. Instead of constantly spraying insecticides to kill crop-damaging insects, scientists can engineer plants to produce their own pest deterrents.
Fertilisers boost plant growth by providing essential mineral ions, but excess fertiliser often washes into waterways, causing pollution. This creates a balancing act between maximising crop yields and protecting the environment.
Biological control offers an eco-friendly alternative by using natural predators to control pests. Think ladybirds eating aphids - it's nature's own pest management system without harmful chemicals.
Food for Thought: Combining selective breeding, GM technology, and biological control could be the key to feeding our growing population sustainably.
These modern techniques help farmers increase food production whilst potentially reducing environmental impact. Whether through creating drought-resistant crops or using beneficial insects instead of pesticides, science is revolutionising how we grow food.
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.
10
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the key concepts of genetic variation, natural selection, mutation, selective breeding, and genetic engineering. This summary is tailored for GCSE combined science students, providing essential insights into how these processes shape the diversity of life and influence evolution.
BiologyExplore key concepts of evolution and variation in this comprehensive study resource. Covering essential topics such as natural selection, genetic engineering, and the fossil record, this 9-page revision guide includes exam-style questions and answers to enhance your understanding. Perfect for AQA GCSE Biology students seeking to master the principles of evolution and genetic variation.
BiologyExplore the fundamentals of selective breeding, including its definition, detailed process, advantages such as improved yield and desirable traits, and disadvantages like inbreeding and health issues. This summary provides essential insights for students studying genetics and agriculture.
BiologyFull notes on topic 6, except punnet squares
BiologyExplore key concepts in genetics, inheritance, and evolution with this comprehensive summary. Understand selective breeding, cloning, genetic engineering, and the impact of mutations on species. Ideal for GCSE Biology AQA students, this resource covers essential topics like natural selection, genetic variation, and the Linnaean classification system.
BiologyExplore the fundamentals of genetic engineering, including the six key steps in gene transfer, advantages and disadvantages, and real-world applications such as insulin production and stem cell research. This summary provides essential insights for students studying biotechnology and genetics.
BiologyApp 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
