Biology is organized from the very small to the very large which would be the biosphere.

And so each of these different levels is called a system. And a system is separated from its

surroundings using a boundary. And so an example, non-biological example, if we have a city

that would be a system. Inside that we have a school. Inside that we have a classroom.

And so it's kind of like these Russian dolls, with the larger ones enveloping the small

ones. And so as we move through these hierarchy of life, one term that I want you to keep

in the back of your head is emergent properties. In other words, with each level, as we get

to a level, there's going to be a property or properties that show up that weren't there

on the level before. And so let me give you an example. This right here is a soldier.

This would be a termite protecting the mound. But each of these termites inside are an individual

system of their own. They're working together in a system of a colony. And they're actually

farming a little fungus that grows within the termite mound. And if we even look at

a larger scale, this right here is a termite cathedral. Now a termite cathedral is so big

that it faces a major problem. Carbon dioxide is going to build up on the inside of these

as they're all doing cellular respiration. And so they could all asphyxiate if there

wasn't some way to remove that. And so they're designed so that as the wind blows, there's

ventilation. We can actually sweep that carbon dioxide away and new oxygen in its place.

Now you might think, wow, smart termite. How did they figure that out? Well basically think

of it as 80 different termite cathedrals that are a little bit smaller. And in some of those

all the termites die. Well their genes would die with them. And those that have any kind

of a ventilation are going to be able to survive. And so we get emergent property showing up.

So here it is. Your hierarchy of life from atom all the way to biosphere. And as you

get good at biology you'll just simply memorize these. Let's start with the first one, which

is not really biology at all, this is an atom. This is an important atom called carbon because

it has four valence electrons and so it's very good at bonding. If we go to the next

level, that would be the molecule. And so here's carbon again. But it's bonded to two

oxygen molecules. And so now it's carbon dioxide. What would be an emergent property? Well that

would be the idea that it's more stable. It's actually formed and it's sharing these electrons

and so it's now bonded. And so that would be something that we find in molecules. Go

to the next level, we have what are called macromolecules or large molecules. The four

different types remember are carbohydrates, proteins, lipids and nucleic acids. An emergent

property in them is that they're built up of monomers. So repeating blocks. And they

eventually show what's called polymerization. Next if we go, we get to the level of the

organelle. These are going to be the tiny organs inside cells. This right here would

be the plasma membrane. It's made up of macromolecules. It's made up of this phosphate group on the

top. And it gives it this emergent property. The ability to separate the outside and the

inside of a cell. Speaking of cells this would be a red blood cell. A red blood cell is going

to have that plasma membrane inside it, but it's also going to have the hemoglobin protein

that I just showed just a second ago. And so now it's emergent property is that it can

move around and it can actually grab oxygen and then move that to different parts in the

body. Next we go to the level of a tissue. A tissue is made up of a bunch of cells that

are working together. This is actually a muscle cell. You can see that there are some striations

in it. And we look down here we can see these intercalated disks and so we know that this

is cardiac muscle. And so it does a specific function, which is contract, to beat your

heart. But it also can receive nerve signals. And so that nervous signal can kind of wash

it across it. Okay. When you have a bunch of tissues that are organized and working

together we have what's called an organ. And this one is called the heart. Now this is

going to have all four different types of tissues inside it. It's going to have muscle

tissue, nervous tissue, connective tissue. It's going to have epithelial tissue on the

inside. And so all those tissues are working together with a single purpose. That heart

is sitting inside what's called an organ system. And so this would be the circulatory system.

Here we have our red blood cell. But we also have the heart and all of these arteries and

veins and they're working together to move that red blood cell around your body. Next

we have an organism. This is called an elk. An elk is made up of a number of organ systems

that are working together. Organisms are organized into a population. So this would be all of

the elk that are living in one area at a time. Once we get a number of different organisms

living in one area at one time, now we have all these intraspecies interactions between

you know bull elk and cow elk. And so basically this would be an emergent property we find

at the level of the population. Next we have all of these different populations interacting

together. And so this would be a community. It's all biotic at this point. So they're

all living things. But we're going to have, this looks like predation right here. This

would be predation. We're going to have, you know, competition. We're going to have parasitism.

And so we have all these interactions between different populations at the level of a community.

Next we go to the level of the ecosystem. I happen to live right here. Right on the

border of one of the greatest ecosystems in the world, the Greater Yellowstone Ecosystem.

What have we added when we get to the level of an ecosystem? Now we're adding abiotic

material. So we're adding water. We're adding chemistry. We're adding light. And all of

these things go together to form an ecosystem. Interesting, where do we put this boundary?

Well basically they discovered the Greater Yellowstone Ecosystem the way they figured

out the boundaries. They looked at wherever grizzly bears are found and we said this is

going to be that ecosystem. Now we go to the level of a biome. A biome is going to be ecosystems

that have similar climate. So they're going to have the same temperature and they're going

to have the same precipitation throughout the year. And so tropical rain forest or desert.

Or this would be a northwestern coniferous forest. Or the tundra. Or the taiga. And so

these are all types of biomes. And the biomes together form what's called the biosphere.

And the biosphere on our planet is wherever we find life. And that goes from deep in the

ocean to high in the atmosphere. And that is the hierarchy of life. So I hope that's

helpful.