when all the leaves change from green to red, yellow,

and orange.

But did you ever wonder why that transition happens?

Hi.

I'm Chlorophyll, the pigment that

gives leaves their characteristic green color.

I'm on a mission to find out why every year in the fall

the leaves change from this beautiful green shade

to all of those other colors.

My friend Brad is going to show us

how to find out exactly why all of those color changes happen.

But first, we need to talk about something

I like to call photosynthesis.

So let's talk about photosynthesis.

Photosynthesis is the process that plants

used to produce fruit.

To conduct photosynthesis, plants need three things.

First, they need water.

They draw water up through their roots

and bring it into their leaves.

Secondly, plants need carbon dioxide.

Third, and perhaps most important, plants need energy.

And they get that energy from sunlight.

Plants absorb sunlight through their leaves,

using several pigments.

The primary pigment, chlorophyll,

is what gives plants its green appearance.

With those three things things- water, carbon dioxide,

and sunlight, plants conduct photosynthesis,

and the output of that chemical reaction

is glucose, which is a sugar that plants need to stay alive.

A byproduct of photosynthesis, in addition to glucose,

is oxygen.

So really, if you look at it, chlorophyll

is a critical piece to the photosynthesis puzzle

because it gives plants the energy

to produce food that they need and to produce oxygen

that we need as humans.

OK.

I get it.

I get what you're saying, Brad.

I'm pretty much awesome at making food.

Well, sorry to tell you, Chlorophyll,

but you're not that special.

There are two other pigments that are in every leaf.

There's an orange-red pigment called carotene

and a yellow pigment called xanthophyll.

During the summer, when there's more light,

trees will produce more of you so that the leaves will appear

green, but there is still carotene and xanthophyll

inside each of leaf.

You can't be serious.

Absolutely, I am.

So you're saying that even a green leaf has

all these other pigments in it, but they still

look green because there's so much chlorophyll.

Yep.

Right now, even inside of you, there's all three pigments.

You just wouldn't know it.

Um.

I'm sorry.

I just don't believe you.

That doesn't even make sense.

Well, if you don't believe me, I'll take you to a laboratory,

and we'll prove it with science.

So we're in the lab.

We're going to do the chromatography experiment.

Wow.

I'm excited.

Yeah.

Me, too.

So chromatography is a process that you can use

to isolate pigments in a leaf.

It was first performed in 1901 by a man

named kills Mikhail Tsvet.

Whoa.

OK.

That guy's old.

Very old.

And that was the first time anyone

proved that there are multiple pigments in every leaf.

So we're going to recreate his famous experiment here,

using materials that you can find around your house.

Awesome.

I guess that means anybody can do it.

Absolutely.

Even people at home.

So the things you're going to need

are a pair of scissors, a ruler, three pencils, some scotch

tape, a coin for each person that's

in the experiment, a whole bunch of leaves

of all the different colors, and filter paper.

Here, we're just using basic coffee filters.

Rubbing alcohol.

Then, we're going to need glasses,

one glass for each person that's in the experiment.

So step one.

Take a piece of filter paper.

OK.

We're going to cut out long skinny strip between a half

an inch to an inch wide.

They need to be at least as long as your cups are tall.

Step two.

You want to take your ruler, and you

want to measure out a distance of about 2 centimeters

from the bottom of each of your strip

and draw a line using a pencil.

So once we have our long skinny strips,

the next step is to get pigment onto it.

You're going to start with the red leaf or a green leaf

in your case.

And you're going to set it down so that the top of the leaf

is facing up.

Put your filter paper over the top of it where

you've drawn a little line.

And then, take your coin and roll it

across the top of the filter paper.

And you should see even after sort of your first roll

that some of the pigment from the leaf

has transferred on to the filter paper.

So you want to get a lot of pigment

because the more pigment you get,

the better it's going to be when we do the experiment.

So once you've done that, since we're

using two pieces of paper, pick another leaf

and do the same thing.

So now, you should have two strips of paper

with a really bright color pigment line on each of them.

Oh, yeah.

All right.

Now that we're at that point, take your other pencils--

not the one that we were writing with, but the extra one.

We're going to use this as sort of a platform

that we're going to attach these to so

that they can rest in the cup.

So what you want to do is take them, and tape each of them.

The end that you didn't put the pigment on,

tape those to your pencil.

OK.

Ready to go.

OK.

So the next step is to test out this in your cup.

So you want to do is take it and rest it right across the top.

What you want to make sure is that the lengths

of your piece of paper, when it's completely straight,

just barely touch the bottom.

So now, we're ready to start the experiment.

All right.

Last step is to take some rubbing alcohol.

You want to put enough in to get the tips

of your paper wet but not enough so that it actually

touches your pigment.

Got it.

OK.

You ready to do the experiment?

So ready.

All right.

Let's drop it in.

Well, it's been like 15 minutes.

You want to take a look it?

See how they look?

Yeah.

I'm so ready for this.

So this one was the plain green leaf.

Yep.

And I've got a whole lot of colors

that I wasn't expecting to see.

What am I looking at here?

So you'll see the first band, the green,

is chlorophyll, which is what you'd expect.

But what's interesting is that above it,

there's a yellow line.

And that's the xanthophyll, the yellow pigment.

So even in a leaf that looked green,

there's actually a little bit of pigment

that you didn't even know was there.

The leaf that I did next to it, that the halfway

red and halfway [INAUDIBLE].

I see a lot more red in my coloring there.

That's the carotene.

Yep.

For that one, because it's starting to turn,

it wasn't masked by the green.

OK.

Well, what about yours?

So you can see in our red leaf--

Oh, wow.

--you see a whole lot of dark red.

That is really vibrant.

Yeah.

And you don't actually even see much of anything else

because it's already turned, and so the chlorophyll's been lost.

And in our other one, which was the yellow leaf,

you can see a band of yellow, the xanthophyll as we expect.

Yeah.

The yellow is quite strong.

But right underneath it, there's a band of green chlorophyll.

There is some green in there.

So even in the yellow guy, there was still

a little bit of chlorophyll.

And then, you see a little bit of red up above it, too.

Yes.

There's even a little bit of red even

though it was a yellow leaf which is pretty cool.

I mean, who knew?

Yeah.

There's just so many different colors in every leaf.

Well, thanks so much, Brad, for teaching me

about chromatography.

Yeah.

No problem.

Wasn't that cool experiment?

It was really sweet.

I mean, even with just like the simple household stuff,

we were able to prove that every leaf, regardless of its color,

has pigments of all of them.

I know.

I mean, who even knew those pigments were out there?

I know.

Right?

Well, I feel like I learned a lot today.

I learned how to do chromatography

with all these different kinds of pigments.

And I learned that, actually, fall

it's kind of a cool season.

Yeah.

No.

It is.

And probably, most importantly, I

learned that those other leaves are pretty awesome.

They really know how to have a good time.

They do.

[CHEERING]

I love the fall.

This is so much fun.

Leaves dance.

Leaves dance.

Go leaves.

Go leaves.

I could go in the wind and fly, and I can visit other places.

Chlorophyll is nice.

She's so green.

She's not as colorful as me, though.

It might be my new favorite thing.

I might start doing chromatography daily.

Well, you know, I had a good time making it.

But honestly, those leaves, they're not very professional.

It's just been a really nice friendship.

You guys want to say something about our friendship?

I love you guys.

I love you.

I love you, too.

I love you.

We like you, too, Xanthophyll.

All right.