Obojživelníci jsou super zajímavá skupina zvířat, která dokáže žít jak... Show more
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Matematika
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Updated Apr 5, 2026
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Hlavní charakteristiky a znaky obojživelníků
1 / 3
Základní znaky obojživelníků
Obojživelníci jsou prostě úžasní! Jejich největší finta je, že dokáží žít částečně ve vodě a částečně na souši. Nejtypičtější představitelé jsou žáby, ropuchy a mloci.
Když se podíváš na dospělou žábu nebo ropuchu, všimneš si, že nemá ocas. To je jeden z jejich hlavních rysů. Většina z nich má hladkou kůži, jen ropuchy jsou výjimka s jejich bradavičnatou kůží.
Nejdůležitější je jejich tenká a propustná kůže, která je plná krevních cév. Tahle speciální kůže jim umožňuje dýchat nejen plícemi, ale i povrchem těla - což je docela hustý trik!
Zajímavost: Obojživelníci patří mezi nejstarší skupiny suchozemských obratlovců na Zemi.
Dýchání a termoregulace
Tady to začíná být fakt zajímavé! Dospělí obojživelníci dýchají kombinovaně - používají jak plíce, tak kůži. Jejich tenká kůže jim slouží jako druhé plíce, protože je dobře prokrvená a umožňuje výměnu plynů.
Na souši si musí kůži udržovat vlhkou pomocí slizových žláz, jinak by nemohli dýchat. Proto je často vidíš poblíž vody nebo ve vlhkých místech.
Obojživelníci jsou studenokrevní (poikilotermní), což znamená, že si nedokáží regulovat tělesnou teplotu jako my. Jejich teplota se mění podle okolí. V zimě proto upadají do zimního strnulosti - jejich metabolismus se zpomalí a čekají na teplejší dny.
Tip na zkoušku: Zapamatuj si, že obojživelníci dýchají dvěma způsoby - plícemi i kůží!
Potrava a rozmnožování
Obojživelníci jsou masožraví predátoři, kteří hrají důležitou roli v přírodě. Loví živou kořist jako jsou nahí plži, hmyz, pavouci a další drobní živočichové.
Jejich tajná zbraň je lepkavý, elastický a rychlý jazyk, kterým dokáží chytit kořist rychlostí blesku. Jsou to skuteční lovci, kteří pomáhají udržovat rovnováhu v ekosystémech.
Během období páření se z obojživelníků stávají opravdoví zpěváci. Samci vydávají charakteristické volací zvuky, kterými si lákají samice. Jejich rozmnožování často probíhá ve vodním prostředí, kde se vyvíjejí jejich vajíčka a larvy.
Díky svým jedinečným adaptacím dokáží obojživelníci přežívat v různých prostředích a jsou nepostradatelnou součástí přírody po celém světě.
Pamatuj si: Obojživelníci jsou důležití predátoři, kteří kontrolují populace hmyzu a jiných drobných živočichů.
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4.7/5
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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 Knowunity AI. 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 Knowunity AI. 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
Hlavní charakteristiky a znaky obojživelníků
Obojživelníci jsou super zajímavá skupina zvířat, která dokáže žít jak ve vodě, tak na souši. Patří mezi nejstarší suchozemské obratlovce a mají spoustu cool vlastností, které ti pomůžou pochopit, jak se dokázali přizpůsobit životu v obou prostředích.
Základní znaky obojživelníků
Obojživelníci jsou prostě úžasní! Jejich největší finta je, že dokáží žít částečně ve vodě a částečně na souši. Nejtypičtější představitelé jsou žáby, ropuchy a mloci.
Když se podíváš na dospělou žábu nebo ropuchu, všimneš si, že nemá ocas. To je jeden z jejich hlavních rysů. Většina z nich má hladkou kůži, jen ropuchy jsou výjimka s jejich bradavičnatou kůží.
Nejdůležitější je jejich tenká a propustná kůže, která je plná krevních cév. Tahle speciální kůže jim umožňuje dýchat nejen plícemi, ale i povrchem těla - což je docela hustý trik!
Zajímavost: Obojživelníci patří mezi nejstarší skupiny suchozemských obratlovců na Zemi.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Dýchání a termoregulace
Tady to začíná být fakt zajímavé! Dospělí obojživelníci dýchají kombinovaně - používají jak plíce, tak kůži. Jejich tenká kůže jim slouží jako druhé plíce, protože je dobře prokrvená a umožňuje výměnu plynů.
Na souši si musí kůži udržovat vlhkou pomocí slizových žláz, jinak by nemohli dýchat. Proto je často vidíš poblíž vody nebo ve vlhkých místech.
Obojživelníci jsou studenokrevní (poikilotermní), což znamená, že si nedokáží regulovat tělesnou teplotu jako my. Jejich teplota se mění podle okolí. V zimě proto upadají do zimního strnulosti - jejich metabolismus se zpomalí a čekají na teplejší dny.
Tip na zkoušku: Zapamatuj si, že obojživelníci dýchají dvěma způsoby - plícemi i kůží!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Potrava a rozmnožování
Obojživelníci jsou masožraví predátoři, kteří hrají důležitou roli v přírodě. Loví živou kořist jako jsou nahí plži, hmyz, pavouci a další drobní živočichové.
Jejich tajná zbraň je lepkavý, elastický a rychlý jazyk, kterým dokáží chytit kořist rychlostí blesku. Jsou to skuteční lovci, kteří pomáhají udržovat rovnováhu v ekosystémech.
Během období páření se z obojživelníků stávají opravdoví zpěváci. Samci vydávají charakteristické volací zvuky, kterými si lákají samice. Jejich rozmnožování často probíhá ve vodním prostředí, kde se vyvíjejí jejich vajíčka a larvy.
Díky svým jedinečným adaptacím dokáží obojživelníci přežívat v různých prostředích a jsou nepostradatelnou součástí přírody po celém světě.
Pamatuj si: Obojživelníci jsou důležití predátoři, kteří kontrolují populace hmyzu a jiných drobných živočichů.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
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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4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. 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 Knowunity AI. 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