How did everything get started? A nice simple explanation of a complex theory

A cool comparison of the scale of everything in the Universe.

Population, community and ecosystem

With so many organisms on Earth, living things are bound to interact with one another. Symbiosis is a close relationship between two species. One type of interaction between two species is called mutualism. An example of mutualism exists between honey bees and flowers. Flowers provide nectar to the bees. The bees use the sugar rich liquid to make honey. As the bees fly from flower to flower tiny grains of pollen get stuck to the bee. The bee moves the pollen without even knowing it. The pollination is necessary for flowers to reproduce. In this relationship both species benefit. The bee gets nectar and the flower gets pollinated. Another relationship is called commensalism. This interaction takes place when sharks and remora live together. The remora use sucking disks on their heads to attach themselves to sharks. The sharks are powerful swimmers and do not even notice the remora and are neither helped nor harmed. However the remora benefit from this relationship. The fish get a free ride and protection. They also feed on scraps left over by the shark. In commensalism one species benefits and the other is neither helped nor harmed. The last type of symbiotic relationship is called parasitism. An example of this relationship exists between humans and mosquitoes. The insects land on and take the blood from humans. The mosquito benefits as it uses the blood for energy. The human or host is harmed in this relationship as blood is needed and the human could become infected with disease. In parasitism one species benefits and the other is harmed.

This newest science animation is about genes, DNA and Chromosomes. There is SO much more to say about this subject, but I decided to start off with the basics, and I will definitely make another animation on this subject again. Don't hesitate to comment if you it turns out I made an mistake somewhere, or if you want to tell me something else! Animation: Chaja Hogeweg (www.chajahogeweg.com) Voice-over: Adam Janka Software: Adobe After Effects, Adobe Photoshop, Adobe Illustrator, Toonboom Harmony More of this? https://www.youtube.com/watch?v=k71vEXjaPuQ&feature=youtu.be

What are Isotopes? Find out in this video from the Properties of Matter chapter. 00:00:02,590 -- 00:00:07,319 In a previous video we learnt about Isotopes. Here are a few more examples. 00:00:07,319 -- 00:00:14,319 There are two isotopic forms of Chlorine: Chlorine 35 and Chlorine 37. Remember isotopes 00:00:16,910 -- 00:00:21,869 have the SAME number of protons, but a different number of neutrons. So how 00:00:21,869 -- 00:00:27,090 many neutrons are in each of these isotopic forms of Chlorine? 00:00:27,090 -- 00:00:30,980 Remember: Mass Number = Number of Protons + Number of 00:00:30,980 -- 00:00:34,030 Neutrons. And the number of protons for each isotope forms 00:00:34,030 -- 00:00:39,960 of elements is the same, so we can rearrange this formula to calculate the number of neutrons 00:00:39,960 -- 00:00:44,969 in each form. Neutrons = Mass Number - Protons 00:00:44,969 -- 00:00:51,969 When we look at Chlorine on the periodic table it has an atomic number of 17, therefore it 00:00:55,149 -- 00:00:59,860 has 17 protons. So Chlorine-35 has a mass of 35. 00:00:59,860 -- 00:01:04,480 Neutrons = Mass Number - Protons = 35 -17 00:01:04,480 -- 00:01:06,909 = 18 18 neutrons 00:01:06,909 -- 00:01:13,909 So Chlorine-37 has a mass of 37. Neutrons = Mass Number - Protons 00:01:15,360 -- 00:01:18,929 = 37 -17 = 20 00:01:18,929 -- 00:01:24,590 20 neutrons. So Chlorine-35 has 18 neutrons and Chlorine 00:01:24,590 -- 00:01:25,999 37 has 20 neutrons. 00:01:25,999 -- 00:01:32,999 Another example of an isotope is Lithium. Lithium has two stable isotopic forms. 00:01:33,340 -- 00:01:38,619 The atomic number of Lithium is 3, therefore it has 3 protons. 00:01:38,619 -- 00:01:43,450 The isotopes of Lithium have 3 neutrons and 4 neutrons respectively. 00:01:43,450 -- 00:01:48,729 How do we calculate each of the isotopes mass number? 00:01:48,729 -- 00:01:52,349 Remember, Mass Number = Number of Protons + Number of 00:01:52,349 -- 00:01:56,209 Neutrons. So for one isotopic form the mass number would 00:01:56,209 -- 00:02:00,059 be: 3 + 3 = 6 00:02:00,059 -- 00:02:04,489 So we would have Li-6 And for the other form, the mass number would 00:02:04,489 -- 00:02:05,599 be 3+4 = 7 00:02:05,599 -- 00:02:09,580 So we would have Li- 7 Want to learn more? Visit: www.fuseschool.org This video is distributed under a Creative Commons License: Attribution-NonCommercial-NoDerivs CC BY-NC-ND

'The Journey of the Digestive System' by National Geographic

The mechanisms of evolution explained in one video.

A great video about life in the womb

Hank brings us the story of the electron and describes how reality is a kind of music, discussing electron shells and orbitals, electron configurations, ionization and electron affinities, and how all these things can be understood via the periodic table. Crash Course on the internet! http://www.facebook.com/YouTubeCrashCourse http://www.twitter.com/TheCrashCourse http://TheCrashCourse.tumblr.com Table of Contents Snobby Scientists 00:43 Great Dane/Bohr Model 01:57 Electrons as Music 04:13 Electron Shells and Orbitals 04:44 Electron Configurations 05:54 Ionization and Electron Affinities 08:17 Periodic Table 10:18 Support CrashCourse on Subbable: http://subbable.com/crashcourse

Hank gives us a tour of the most important table ever, including the life story of the obsessive man who championed it, Dmitri Mendeleev. The periodic table of elements is a concise, information-dense catalog of all of the different sorts of atoms in the universe, and it has a wealth of information to tell us if we can learn to read it. Like Crash Course? http://www.facebook.com/YouTubeCrashCourse Follow Crash Course! http://www.twitter.com/TheCrashCourse Tumbl Crash Course: http://thecrashcourse.tumblr.com Table of Contents Dmitri Mendeleev - 0:45 Mendeleev's Organization of the Periodic Table - 2:31 Relationships in the Periodic Table - 5:03 Why Mendeleev Stood Out from his Colleagues - 7:09 How the Periodic Table Could be Improved - 8:28 More info. about the cylindrical periodic table of elements: http://www.av8n.com/physics/periodic-table.htm Support CrashCourse on Subbable: http://subbable.com/crashcourse

A bell can be heard ringing within a bell jar. The bell jar is connected to a vacuum pump and the air is slowly removed. Once a vacuum has been achieved the pumped is turned off and air is allowed to slowly re-enter the bell jar.

Hank talks about the last major way humans are impacting the environment in this penultimate episode of Crash Course Ecology. Pollution takes many forms - from the simplest piece of litter to the more complex endocrine distruptors - and ultimately, humans are responsible for it all.

Hank talks about the last major way humans are impacting the environment in this penultimate episode of Crash Course Ecology. Pollution takes many forms - from the simplest piece of litter to the more complex endocrine distruptors - and ultimately, humans are responsible for it all.