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Triangle Congruence and Similarity Theorems
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32
โข
Dec 29, 2025
โข
Stephanie๐
@stephanie_071607
Ever wondered how life on Earth is organized, from the... Show more





Life on Earth follows an amazing pattern of organization, starting with microscopic cells and building up to our entire living planet. Each level becomes more complex as it combines elements from the level below it.
Think of it like building with LEGO blocks - you start with individual pieces, connect them to make something bigger, and eventually create entire structures. In biology, we start with cells and work our way up to the biosphere.
Understanding these levels helps us see how everything in nature is connected. Whether we're studying a single cell or an entire ecosystem, each level plays an important role in supporting life.
Fun Fact: The word "biology" comes from the Greek words "bios" (life) and "logos" (study), literally meaning "the study of life!"

The journey starts with the cell, the smallest unit of life. Cells are like tiny factories that carry out all the basic functions needed to stay alive. Every living thing on Earthโfrom bacteria to blue whalesโis made of at least one cell.
When many similar cells work together for a specific job, they form a tissue. Think of tissues like teams of specialized workers. For example, cardiac muscle tissue contains cells that all work together to help your heart pump blood.
These two levels might be too small to see with your naked eye, but they're doing incredibly important work! Your body has trillions of cells organized into different types of tissues, each with their own special function.
Remember This: The cell theory states that all living things are made of cells, cells are the basic unit of structure and function in living things, and all cells come from pre-existing cells.

When different tissues team up, they form an organ - a structure with a specific job in the body. Your heart, lungs, and stomach are all organs made of multiple tissue types working together.
Several organs working as a team create an organ system. For example, your digestive system includes your stomach, intestines, liver, and other organs that help process food.
When all organ systems work together, they create a complete organism - an individual living thing like you! Organisms can be as simple as a single-celled amoeba or as complex as a human being.
A group of the same type of organisms living in one area forms a population. For instance, all the robins in your neighborhood make up a robin population. They're the same species and can breed with each other.
Think About It: Your body has about 78 organs working together in different organ systems. What would happen if one organ stopped working properly?

When different populations live together in the same area, they form a community. The squirrels, birds, insects, and plants in a forest make up a community, interacting with each other but not with non-living things.
An ecosystem takes things further by including both living organisms (biotic factors) and their physical environment (abiotic factors). A pond ecosystem includes the fish, plants, and also the water, sunlight, and soil.
Similar ecosystems around the world are grouped into biomes. All the world's deserts form the desert biome, sharing similar climate, plants, and wildlife, even if they're on different continents.
Finally, the biosphere includes all areas on Earth where life exists - from the deepest ocean trenches to the highest mountain peaks. It's the sum of all biomes and represents the entire living world.
Cool Connection: You're connected to every level of organization! You're an organism made of organ systems, organs, tissues, and cells, living in a population, community, ecosystem, biome, and the biosphere.
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 โ 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
I think itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve 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 itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve seen! Geometry too!
Paul T
iOS user
Stephanie๐
@stephanie_071607
Ever wondered how life on Earth is organized, from the tiniest cells to our entire planet? The levels of organization in biology show us how simple cells build up to create complex life forms and eventually entire ecosystems. Let's explore... Show more

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Life on Earth follows an amazing pattern of organization, starting with microscopic cells and building up to our entire living planet. Each level becomes more complex as it combines elements from the level below it.
Think of it like building with LEGO blocks - you start with individual pieces, connect them to make something bigger, and eventually create entire structures. In biology, we start with cells and work our way up to the biosphere.
Understanding these levels helps us see how everything in nature is connected. Whether we're studying a single cell or an entire ecosystem, each level plays an important role in supporting life.
Fun Fact: The word "biology" comes from the Greek words "bios" (life) and "logos" (study), literally meaning "the study of life!"

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The journey starts with the cell, the smallest unit of life. Cells are like tiny factories that carry out all the basic functions needed to stay alive. Every living thing on Earthโfrom bacteria to blue whalesโis made of at least one cell.
When many similar cells work together for a specific job, they form a tissue. Think of tissues like teams of specialized workers. For example, cardiac muscle tissue contains cells that all work together to help your heart pump blood.
These two levels might be too small to see with your naked eye, but they're doing incredibly important work! Your body has trillions of cells organized into different types of tissues, each with their own special function.
Remember This: The cell theory states that all living things are made of cells, cells are the basic unit of structure and function in living things, and all cells come from pre-existing cells.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When different tissues team up, they form an organ - a structure with a specific job in the body. Your heart, lungs, and stomach are all organs made of multiple tissue types working together.
Several organs working as a team create an organ system. For example, your digestive system includes your stomach, intestines, liver, and other organs that help process food.
When all organ systems work together, they create a complete organism - an individual living thing like you! Organisms can be as simple as a single-celled amoeba or as complex as a human being.
A group of the same type of organisms living in one area forms a population. For instance, all the robins in your neighborhood make up a robin population. They're the same species and can breed with each other.
Think About It: Your body has about 78 organs working together in different organ systems. What would happen if one organ stopped working properly?

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When different populations live together in the same area, they form a community. The squirrels, birds, insects, and plants in a forest make up a community, interacting with each other but not with non-living things.
An ecosystem takes things further by including both living organisms (biotic factors) and their physical environment (abiotic factors). A pond ecosystem includes the fish, plants, and also the water, sunlight, and soil.
Similar ecosystems around the world are grouped into biomes. All the world's deserts form the desert biome, sharing similar climate, plants, and wildlife, even if they're on different continents.
Finally, the biosphere includes all areas on Earth where life exists - from the deepest ocean trenches to the highest mountain peaks. It's the sum of all biomes and represents the entire living world.
Cool Connection: You're connected to every level of organization! You're an organism made of organ systems, organs, tissues, and cells, living in a population, community, ecosystem, biome, and the biosphere.
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 โ all at your fingertips.
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Transform this note into: โ 50+ Practice Questions โ Interactive Flashcards โ Full Mock Exam โ Essay Outlines
Unit 6: The Human Body Module 22: Integumentary, Skeletal, and Muscular Systems Lesson 2: The Skeletal System Lesson 3: The Muscular System Biology 9A
3.6.3 Skeletal Muscles
notes about human anatomy
The basic of cell theory and pictures
Anatomy Cardiovascular System notes
Discussed here are the characteristics of living things, big ideas in biology, information and heredity, and unity and diversity of life.
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 itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve 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 itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve seen! Geometry too!
Paul T
iOS user