Name: 植物の構造 (Plant Structure)
Uploaded: 2021-01-14T06:36:28.000Z
Duration: 13 min 37 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Hi. It's Mr. Andersen and in this podcast I'm going to talk about plant

仮定法過去

structure. So a good way to think about this is plant anatomy. If you never stood next

to a giant sequoia then you should. It dwarfs all the trees around iy. And it shows you

how huge plants can become. Just using a few simple ingredients like water, carbon dioxide

and a few nutrients from the soil it can become massive. And you can see the rings that we'll

talk about kind of near the end. And so basically everything I'm going to talk about for the

most part is going to be angiosperms. So flowering plants. And flowering plants can be broken

down into two different dicots and monocots. And so what is a cot? A cot is simply a cotyledon.

And so a cotyledon is going to be a baby plant leaf. And so here we've got two different

seed types. There's going to be a seed coat around the outside. And little endosperm in

here. But you can see this baby plant. And in this dicot you'll have two cotyledons.

One, two. But in a monocot you're only going to have one. Now the quintessential dicot

that I think of is dandelion. And a monocot I think about is grass. And so if you've ever

looked at a dandelion leaf, all the veins, which really are vascular material, it's kind

of like our circulatory system, moving water and sugar, are going to be net like. They're

going to branch out. But if we're talking about a monocot, they're going to be parallel.

So if you've ever looked at the veins in the grass, a blade of grass, it's going to be

all parallel. If you were to look at their flowers, in a dicot, they're going to have

4 to 5 or multiples of 4 to 5 on their petals. So you can see 1, 2, 3, 4, 5. So probably

a dicot. Where as if it's a monocot, they're going to be in multiples of 3. So you can

see that this one has 6 petals. And so it's going to be a monocot. And then another way

to differentiate between the two is going to be roots. A dandelion, if you've ever tried

to pull one out, they have this really big tap root system. But in monocots, like grass,

they're going to have a netlike root system. And it's going to be what makes up sod for

example and grass. And so those are the different types of angiosperms. When we talk about phytotomy

you should realize that plants live a double life. They live life underground. We call

that the root system. And then they have a life above ground. We call that the shoot

system. Within that shoot system, basically you're going to have nodes. So that would

be a node there. A node there. You could have another node there. And another node up here.

But the distance between those nodes is going to be the internodes. So that would be the

internode between the two. And so basically plants are able to grow up, but they're also

able to grow out and each of these node points. Just like use they're going to have tissues.

And so in us if we're talking about tissues, now you would think of muscular, excuse me,

muscular nervous, connective and then epithelial. But in plants there are just going to be three

types of tissues. They have dermal tissue, ground tissue and then vascular tissue. And

just like us they break that into specific types of cells. We've got the epidermis, which

is the dermal lining. And then we have periderm, which is going to be mostly when we get to

the level of bark. So it's secondary growth. Function of that is to provide protection.

So this is a cross-section of a leaf. So it's going to provide protection from the outside.

Same thing right here. You can see this in a stem. We're going to have dermal tissues

on the outside. And they also prevent water loss. So basically epidermis is the big type

of dermal tissue. Ground tissue is going to be just run of the mill cells. And so this

is going to be broken into three types. And these words are really fun to say. Parenchyma,

collenchyma, and sclerenchyma. What do they do? Basically they do the jobs of the plant.

So they're going to be the site of photosynthesis for example in the leaf. But it's going to

be metabolism, storage, growth. All of that is going to be in the ground tissue. And then

finally we have the vascular tissue. That's made up of two type. Xylem and phloem. And

they're going to move the water and the sugar. So we'll get more specific to each of these.

So let's start with the dermal tissue. Dermal tissue, for the most part is going to be epidermis.

So right here we're looking at a cross-section of a leaf. So this would be dermal tissue

on the top and on the bottom. The guard cells also make up part of that. And the guard cells,

you can see a zoomed in version of it right here. Basically what they do is they surround

the stomata, or this opening. What does the stomata do? You can see it's the hole in the

leaf. Basically it allows water to evaporate out and that water as it evaporates out is

going to carry water all the way up in the plant. But they also bring in a really important

gas. That's going to be CO2. And so plants kind of have guard cells that are doing really

good feedback. Basically if they have a lot of moisture and they can let a lot of it go

and it's really sunny they open the guard cells up. And the stomata are going to allow

a lot of water to come out, a bunch of carbon dioxide in. And so they can make a bunch of

sugars. Likewise if it's really, really hot, really, really dry, they can close up the

stomata. So they don't lose all of their water. One thing that I should mention is going to

be this real waxy covering on the epidermis. That's called the cuticle. And it's like wax.

It's that wax that you feel, that slippery stuff you feel on the outside of a leaf. And

that's going to prevent water from getting in and getting out. If we get to the ground

tissue, basic run of the mill cells are going to be parenchyma cells. The typical plant

cell is parenchyma cell. What do they do? They're going to be the site of metabolism.

Site of photosynthesis. Outside that, as a plant starts to grow we have the collenchyma.

I always remember the c and l and collenchyma stands for celery. So those are going to be

these real durable cells on the outside of celery. They provide support as it starts

to grow. And so you can see the dermis on the outside. Collenchyma cells. And then these

are going to be parenchyma cells right here. They provide support. And if you take a plant

as it grows, and just mess with it all the time, push it all the time, simulating like

wind, the collenchyma gets stronger and stronger and stronger. But it never gets as strong

as the sclerenchyma. Sclerenchyma are going to be the really durable, wooded kind of portions

of a plant as it start to grow. This is a sclerenchyma fiber that's cut in half. If

we were to look at a fiber we could find this. This is hemp. We pulled the sclerenchyma cells

out to use these fibers to make rope. It's incredibly durable. And so sclerenchyma is

going to be these big fibers that give it that really really strong, like in a branch

that grows. But we'll also have sclerenchyma cells like the core of an apple, of example

is sclerenchyma. It's protecting the seeds on the inside. Or the grit on the inside or

a pear is sclerenchyma. So that's the ground. Now we go to the vascular. Vascular is going

to be made up of two types. The xylem and the phloem. So in this we're cutting a stem

apart. This would all be xylem in here. And then level 4 right here is going to be phloem.

Basically xylem is moving water. It's going to move water from the roots to the shoots.

Phloem is going to move sugar up and down in a plant. And so on the outside we'd have

dermis. They we're going to have so sclerenchyma cells that are are giving it durable support.

So now we're going to talk about growth and then finally finish up with flowers. But this

is an old story. If you go and take a spike and hammer it into a tree. Let's say that

we put it at about 3 feet right here. And you come back in 100 years. So let's say,

make it more realistic, 40 years. And the plant, the tree now, instead of being whatever,

16 feet tall is 160 feet tall. How high is that spike going to be? Well the right answer

is that it will still be 3 feet tall. Because plants grow from the top and they grow from

the bottom. They from from the shoots and and the roots. But the middle is going to

stay the same. Now the bark is going to start to grow up. And so that tree might, the spike

might not be as far in, but just like humans we first grow up. Get much, much longer. And

they we're going to, I'll tell you this, as you get older you start to get wider and wider

and wider. And so we call this primary growth. This first growth. And how does that occur?

Well we use something called an apical meristem. Basically that's going to be a site. Right

here we're looking at a root where you have cells that keep copying themselves. We call

those undifferentiated. Think of it like a stem cell that keeps making copies of itself.

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植物の構造 (Plant Structure)

specific

eventually

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metabolism