Subjects
Biology
Chemistry
AP Chemistry
English
AP English Literature
Biology
Dec 11, 2025
135
5 pages
Olivia @oliviag
Ever wondered how scientists organise the millions of different living things on Earth? Classification is like nature's filing... Show more
Classification is basically sorting living things into groups based on their similarities. Think of it like organising your music library - you group songs by genre, artist, then album to find what you're looking for.
Scientists use a specific hierarchy with eight levels domain, kingdom, phylum, class, order, family, genus, and species. A helpful way to remember this order is "King Prawn Curry Or Fat Greasy Sausage"!
The most important level is species - this contains all organisms that can breed together to produce living, fertile offspring. It's the smallest and most specific group in the classification system.
Did you know? Scientists can now use DNA, RNA, and even different versions of haemoglobin to work out how closely related different organisms are - it's like doing a biological family tree!
Swedish scientist Carl Linnaeus developed the classification system we still use today. He solved a major problem - scientists in different countries were using different names for the same animals, making international research nearly impossible.
Let's look at humans as an example. We belong to Kingdom Animalia (we're animals), Phylum Chordata (we have backbones), Class Mammalia (we're mammals), Order Primates (we have primate features), Family Hominidae (we're larger primates), Genus Homo , and Species sapiens (we're intelligent).
This system helps scientists in three key ways they can identify new species, predict characteristics based on similar organisms, and trace evolutionary links between different creatures.
Fun fact When scientists discover a new species, they keep one specimen called a "holotype" that acts as the official example for that species!
Science never stops improving, and neither does our classification system. As microscopes got better and we understood more about cells and DNA, the original two-kingdom model (just animals and plants) kept getting updated.
Haeckel added protists, Chatton divided life based on whether cells had nuclei, and Whittaker recognised fungi as separate from plants. Each scientist built on previous work as new evidence emerged.
The biggest breakthrough came from Carl Woese in 1990, who developed the three-domain system we use today Bacteria (true bacteria), Archaea (primitive bacteria living in extreme environments), and Eukaryota .
Phylogenetic trees show how all life connects back to one simple bacterial cell at the very beginning of everything. The closer the branches on these trees, the more closely related the organisms are.
Think about it Every living thing on Earth - from bacteria to blue whales - evolved from the same single-celled ancestor billions of years ago!
Every organism gets a two-part scientific name called a binomial name - think of it as their official passport name that's recognised worldwide. This solves the problem of different common names in different languages.
The format is simple Genus + species = binomial name. For humans, that's Homo sapiens. Cats are Felis catus, dogs are Canis familiaris.
There are just two formatting rules to remember always write binomial names in italics, and capitalise the first letter of the genus but not the species name.
This system means a scientist in Japan and another in Brazil are talking about exactly the same organism, even though their common names might be completely different in their native languages.
Quick tip Your binomial name Homo sapiens literally means "wise human" - though that's debatable when you see some people's exam answers!
Here's where things get interesting - and slightly confusing. Remember that species are defined as organisms that can interbreed and produce fertile offspring? Well, nature sometimes throws us curveballs.
Lions and tigers can actually mate and produce babies - but these offspring (called ligers and tigons) are infertile. They can't reproduce themselves, which means lions and tigers remain separate species despite being able to interbreed.
These infertile offspring are called hybrids, and they show us that the boundaries between species aren't always crystal clear. It's one of the ongoing challenges scientists face when classifying life on Earth.
This is why classification is still evolving today - as we discover more about genetics and evolution, we sometimes need to rethink where certain organisms belong in the tree of life.
Amazing fact There are loads of hybrid animals in nature - mules , zorses , and even wholphins !
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
1
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
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
Olivia
@oliviag
Ever wondered how scientists organise the millions of different living things on Earth? Classification is like nature's filing system - it helps us understand where every creature fits and how they're all connected through evolution.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Classification is basically sorting living things into groups based on their similarities. Think of it like organising your music library - you group songs by genre, artist, then album to find what you're looking for.
Scientists use a specific hierarchy with eight levels: domain, kingdom, phylum, class, order, family, genus, and species. A helpful way to remember this order is "King Prawn Curry Or Fat Greasy Sausage"!
The most important level is species - this contains all organisms that can breed together to produce living, fertile offspring. It's the smallest and most specific group in the classification system.
Did you know? Scientists can now use DNA, RNA, and even different versions of haemoglobin to work out how closely related different organisms are - it's like doing a biological family tree!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Swedish scientist Carl Linnaeus developed the classification system we still use today. He solved a major problem - scientists in different countries were using different names for the same animals, making international research nearly impossible.
Let's look at humans as an example. We belong to Kingdom Animalia (we're animals), Phylum Chordata (we have backbones), Class Mammalia (we're mammals), Order Primates (we have primate features), Family Hominidae (we're larger primates), Genus Homo , and Species sapiens (we're intelligent).
This system helps scientists in three key ways: they can identify new species, predict characteristics based on similar organisms, and trace evolutionary links between different creatures.
Fun fact: When scientists discover a new species, they keep one specimen called a "holotype" that acts as the official example for that species!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Science never stops improving, and neither does our classification system. As microscopes got better and we understood more about cells and DNA, the original two-kingdom model (just animals and plants) kept getting updated.
Haeckel added protists, Chatton divided life based on whether cells had nuclei, and Whittaker recognised fungi as separate from plants. Each scientist built on previous work as new evidence emerged.
The biggest breakthrough came from Carl Woese in 1990, who developed the three-domain system we use today: Bacteria (true bacteria), Archaea (primitive bacteria living in extreme environments), and Eukaryota .
Phylogenetic trees show how all life connects back to one simple bacterial cell at the very beginning of everything. The closer the branches on these trees, the more closely related the organisms are.
Think about it: Every living thing on Earth - from bacteria to blue whales - evolved from the same single-celled ancestor billions of years ago!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Every organism gets a two-part scientific name called a binomial name - think of it as their official passport name that's recognised worldwide. This solves the problem of different common names in different languages.
The format is simple: Genus + species = binomial name. For humans, that's Homo sapiens. Cats are Felis catus, dogs are Canis familiaris.
There are just two formatting rules to remember: always write binomial names in italics, and capitalise the first letter of the genus but not the species name.
This system means a scientist in Japan and another in Brazil are talking about exactly the same organism, even though their common names might be completely different in their native languages.
Quick tip: Your binomial name Homo sapiens literally means "wise human" - though that's debatable when you see some people's exam answers!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Here's where things get interesting - and slightly confusing. Remember that species are defined as organisms that can interbreed and produce fertile offspring? Well, nature sometimes throws us curveballs.
Lions and tigers can actually mate and produce babies - but these offspring (called ligers and tigons) are infertile. They can't reproduce themselves, which means lions and tigers remain separate species despite being able to interbreed.
These infertile offspring are called hybrids, and they show us that the boundaries between species aren't always crystal clear. It's one of the ongoing challenges scientists face when classifying life on Earth.
This is why classification is still evolving today - as we discover more about genetics and evolution, we sometimes need to rethink where certain organisms belong in the tree of life.
Amazing fact: There are loads of hybrid animals in nature - mules , zorses , and even wholphins !
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
1
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
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
Sociology