Plant organs | The basic structure and function of each
Summary
TLDRIn this educational video, Miss Angler delves into the intricate world of plant organs, focusing on their structure and function. She distinguishes between above-ground shoot systems, including leaves and stems, and below-ground root systems. Miss Angler explains the critical roles of dermal, vascular, and ground tissues in these organs. She details the unique adaptations of leaves for photosynthesis and the specialized structures of stems and roots for support, water absorption, and nutrient transport. The video serves as an informative guide for understanding the complex biology of plants.
Takeaways
- 🌿 The video focuses on plant organs, emphasizing the importance of understanding plant tissues before studying organs.
- 🔍 It differentiates between shoot and root systems, highlighting the distinct structures and functions of plant organs above and below ground.
- 🧪 Dermal tissues are crucial for covering and protecting plant organs, including specialized structures like stomata for gas exchange.
- 🚰 Vascular tissues, xylem and phloem, are essential for providing support, structure, and transportation of water and food within the plant.
- 🌱 Ground tissues serve as the foundational building blocks of plants, including parenchyma, collenchyma, and sclerenchyma, each with specific roles.
- 🍃 Leaves are compared to solar panels, capturing sunlight for photosynthesis, with a detailed structure including the cuticle, epidermis, mesophyll, and vascular tissues.
- 🌱 Stems are described as cylindrical structures with vascular bundles, including the epidermis, cortex, cambium, and pith, playing various roles in growth and support.
- 🌳 Roots are specialized for anchoring and absorbing water and minerals, with root hairs increasing surface area for absorption and a unique structure compared to stems.
- 💧 The video explains the significance of the endodermis and casparian strip in funneling water and minerals into the xylem for transport.
- 🌱 The cambium and pericycle are highlighted as regions responsible for lateral growth and adaptation of vascular tissues in plants.
Q & A
What are the two major systems of a plant that are mentioned in the script?
-The two major systems of a plant mentioned are the shoot system, which includes structures like leaves and stems, and the root system, which includes roots and root hairs.
What is the function of dermal tissues in plants?
-Dermal tissues are responsible for covering the outside of the plant, providing protection. They can be found on the stem, leaf, and roots, and can be specialized into structures like stomata.
How does the script differentiate between xylem and phloem?
-Xylem is responsible for transporting water from the roots up to the rest of the plant, while phloem transports food in both upward and downward directions.
What is the significance of the term 'ground tissues' as mentioned in the script?
-Ground tissues are the foundational tissues that provide support and structure to the plant. They include parenchyma, collenchyma, and sclerenchyma, and are involved in functions like storage and support.
What is the primary function of the cuticle in leaves?
-The cuticle in leaves serves as a waterproof layer that prevents water loss due to heat and allows sunlight to pass through to the upper epidermal layer.
How do Palisade cells and spongy cells differ in structure and function within leaves?
-Palisade cells are elongated and stacked closely together for efficient photosynthesis, while spongy cells are irregularly shaped and serve more as packaging tissue for water and water evaporation.
What is the role of stomata in plant leaves?
-Stomata are specialized epidermal cells that allow gases and water to enter and exit the leaf, playing a crucial role in photosynthesis and transpiration.
Why are root hairs important for plant roots?
-Root hairs increase the surface area of the roots, which is essential for absorbing more water and minerals from the soil.
What is the function of the endodermis in roots?
-The endodermis is a layer that funnels water into the root, ensuring that water moves in a specific direction towards the xylem for transport within the plant.
How does the cambium contribute to the growth of a plant stem?
-The cambium is a meristematic tissue that allows for lateral growth, enabling the stem to grow wider and thicker over time.
Outlines
🌿 Introduction to Plant Organs
Miss Angler welcomes viewers to her biology class, focusing on plant organs. She emphasizes the importance of understanding plant tissues before delving into organs. The video is structured to cover both shoot and root systems, highlighting the differences between above- and below-ground structures. The three main tissue types—dermal, vascular, and ground tissues—are introduced as essential for understanding plant organs. Dermal tissues protect the plant, vascular tissues transport water and food, and ground tissues provide structural support. The video encourages viewers to subscribe for regular updates and to watch related videos for a comprehensive understanding.
🍃 Exploring Leaf Structure and Function
The video script delves into the anatomy of leaves, comparing them to solar panels due to their role in photosynthesis. The cuticle's role in waterproofing and allowing sunlight penetration is discussed. The epidermis is highlighted as a protective layer, while the mesophyll, consisting of palisade and spongy cells, is detailed for its role in photosynthesis. Palisade cells are described as elongated for light absorption, and spongy cells as supportive packaging tissue. Vascular tissues, xylem, and phloem within leaf veins are explained for their transport functions, with xylem carrying water and phloem transporting photosynthetic products. Stomata are introduced as modified epidermal cells that regulate gas and water exchange, crucial for photosynthesis. The importance of understanding these structures for future lessons on plant transportation and support is noted.
🌱 Stem Structure and Tissue Types
The script shifts focus to dicot stem structure, distinguishing it from roots by the presence of vascular bundles. Epidermal tissue in stems is mentioned, often containing chloroplasts, and the cortex, which may include chlorenchyma for photosynthesis, is described. The vascular bundles, containing xylem and phloem, are central to stem conduction, with xylem transporting water upwards and phloem moving food downwards. The cambium's role in lateral growth and the pith, composed of parenchyma, are also covered. The importance of recognizing the correct placement of phloem and xylem in vascular bundles is emphasized for understanding plant transportation mechanisms.
🌱 Root Structure and Specialization
Roots are introduced as highly specialized, with a focus on their吸水 and anchoring functions. Root hairs, lacking a cuticle for enhanced water absorption, are detailed. The cortex, composed of ground tissues, is noted to potentially include parenchyma and collenchyma but lacks chlorenchyma due to the absence of chloroplasts. The endodermis, with its casparian strip, is highlighted for directing water flow. The script contrasts xylem and phloem positions in roots versus stems, with phloem now central and xylem peripheral. The pericycle and vascular cambium are introduced for their roles in growth and tissue transformation. The video concludes with a terminology recap, encouraging the use of precise botanical terms for better understanding and communication.
📚 Recap and Terminology Review
The final paragraph provides a recap of key terms and concepts covered in the video, including tissue types, structures like the cuticle, mesophyll, and regions in stems and roots. It emphasizes the importance of understanding these terms for effective study and communication in the field of botany. The video concludes with an invitation for viewers to engage with the content by liking and subscribing for more educational videos.
Mindmap
Keywords
💡Plant Organs
💡Dermal Tissues
💡Vascular Tissues
💡Ground Tissues
💡Mesophyll
💡Stomata
💡Epidermis
💡Cortex
💡Cambium
💡Root Hairs
💡Endodermis
Highlights
Introduction to plant organs and the importance of understanding plant tissues before studying organs.
Explanation of the shoot system, which includes structures like leaves and stems.
Discussion on the root system, focusing on roots and root hairs.
Emphasis on the differences between plant organs above and below ground.
Overview of the three main tissue types: dermal, vascular, and ground tissues.
Description of dermal tissues and their role in covering the plant's exterior.
Explanation of vascular tissues, including xylem for water and phloem for food transport.
Introduction to ground tissues, which provide the foundation for plant structures.
Detailed look at the structure and function of leaves, including the cuticle and epidermis.
Discussion on mesophyll, including palisade and spongy cells, and their roles in photosynthesis.
Explanation of vascular tissues in leaves, including veins and their transport functions.
Description of stomata as modified epidermal cells that regulate gas and water exchange.
Introduction to stem structures, highlighting the differences between monocot and dicot stems.
Detailed examination of dicot stem tissues, including epidermis, cortex, and vascular bundles.
Importance of the cambium in stem growth and its role in lateral expansion.
Overview of root structures, including root hairs and their significance for water absorption.
Explanation of the endodermis and casparian strip's role in water movement within roots.
Terminology recap for easy study and understanding of plant tissues and organs.
Transcripts
hi everybody and welcome back to miss
Angus biology class I am Miss angler in
today's video we are going to be looking
at plant organs now it is at this point
that if you are not so certain about
plant tissues you should click the video
now at the top right hand corner go
watch that video and then come back here
the reason for that is you need to know
all the plant tissues and their
functions and structure before I can
apply and show you how they make these
organs now if you are new here don't
forget to give this video a thumbs up
and make sure you are subscribed with
your notifications turned on because I
post every Tuesday and Thursday
so let's get into the video now breaking
down our plant into two major systems
the first system is above ground which
we call the shoot system this is where
we're going to go through the structures
that we see in the leaf and the stem and
then we're going to go into the root
system which of course is exclusively
The Roots as well as the outgrowth
called the root hairs now remember it's
really important that we understand that
there is a difference between a plant
organs above and below ground and
sometimes there are certain structures
or tissues that have slightly different
roles above or below ground
now before we go any further in this
section we do need to recap the three
main tissues I'm going to talk about
throughout this video and I'm going to
apply these tissue types to each of the
organs so you know how they work now
remember these are organs which means
they need to be made up of many
different tissues working together for a
common cause
so the first group of tissues that we
want to go over are going to be the
dermal tissues now you may remember the
dermal tissues as these are the tissues
that are responsible for covering the
outside of our plant we see this on the
stem the leaf and The Roots now these
dermal tissues can be specialized as we
see as our example here we can get
something like stomata which is a
special kind of dermal tissue and it is
adapted for a very specific function but
I'll get into that later the next kind
of tissue type we need to just quickly
revise over is vascular tissue now
vascular tissue comes in two kinds and
vascular tissue is either going to be
xylem for water or phloem for food it's
also important to remember that this is
what gives the plant structure and
support it's also the transportation
tissue and as we can see with the arrows
in this diagram xylem goes in one
direction from The Roots up only whereas
phloem can go both down and up because
it's transporting food
now the final group of tissues we are
going to look at is ground tissues
please don't be confused by this name it
doesn't mean that these tissues are in
the ground or underground they are
simply the building tissues or they
provide the foundation that we build our
plant off of hence ground building from
the ground up and these tissues
generally fall into three major
categories they are parenchyma calling
timer and sclerenchyma please remember
you do need to be able to draw and label
and tell the difference between these
tissues and exams and tests as well and
you also need to know the differences in
their functions based off of their
structures
now when we just quickly go over the
different variances for their functions
remember that parenchyma is the
packaging tissue so it's big cells we've
got Colin kymer which is the structural
support but not as hard and rigid
generally we see this in a stem it's
often green and filled with chloroplasts
as well and it's got thickened corners
and then finally we've got sclerenchyma
which is the very very hard connective
tissue that we have in Plants it's what
forms things like the husk of a seed or
the bark and the wood of a tree and it
has very thickened cell walls all the
way around it
now each of these tissue types are going
to be explained for each of the organs
in other words for every plant organ you
must know the dermal tissue that is
present the vascular tissue that is
present and the ground tissue that is
present and it varies from organ to
organ
so let's begin with our first organ of a
plant which is of course a leaf or
leaves now leaves are really important
because they are like our solar panels
right they are trapping the sunlight
they are absorbing it and they are using
it for photosynthesis and they've got a
lot going on inside of them each of them
having a very important function now
this is a diagram of a 3D image of a
leaf that we have cut open so we can see
it on the inside and I'm starting off
with something called the cuticle now
the cuticle is a see-through translucent
covering and it's most important
function is that it is there for
waterproofing now waterproofing is
really important because you need to
prevent water loss due to heat and
that's what the cuticle does it's also
clear which means that it allows
sunlight to move through the cuticle and
into the upper epidermal layer which we
see here and now and that brings me to
the next layer which is of course the
epidermis and the epidermal tissue if we
remember is the tissue that is
responsible for protection now
the um upper epidermal layer doesn't
necessarily have any color to it either
and it often is there as a protective
barrier the most important thing about
this also is that it is one cell layer
thick so it's not a very thick layer but
it acts as the skin or outer layer now
sitting just below that is something
called the mesophyll now the word meso
means middle okay and the mesophyll is
made out of two kinds of special cells
one is called a palisade cell the other
is called a spongy cell now we call it a
palisade cell because like a palisade
fence all of the cells are elongated
like rectangles and they sit side by
side
the spongy cells or the spongy mesophyll
are the irregular shaped cells that sit
just below it now their shapes are
really important in the way that they
are put together because it influences
of course their function so let's just
quickly speak about Palisade cells
Palisade cells are stacked the way they
are and they're stacked standing up
because you want to be able to put as
many cells next to each other as
possible now what's also really cool
about Palisade cells is that the
chloroplasts can actually move inside
the cells and so what they often do is
they accumulate near the top end of the
cell so they can be closest to the
sunlight
spongy mesophil cells which are these
cells that are lower down and on our
diagram they are these lighter green
cells that we see over here
they are more of the packaging tissue
they are a type of packaging tissue that
is used often for water and for water
evaporation but I'm going to get more
onto that in another video where I go
into the transportation and support
systems of plants the next thing that we
see inside our leaves is of course the
next group of tissue which is our
vascular tissues we have got our xylem
and we have got our flow now remember
these are running through veins in
leaves which I'm sure you've seen before
and that's what this entire structure is
over here
what are they transporting they are
transporting all the products of
photosynthesis so when we are
photosynthesizing we are taking all of
those carbohydrates and we are moving
them around to the plant and that is
moving in the flow the xylem on the
other hand is bringing water all the way
up from our roots to the leaves so that
we can use that water to photosynthesize
and that water is going into our meso
fill
now our final underside of our Leaf
again has a repetition of structures
we've got the lower dermis and the lower
cuticle this is on the underside of the
leaf but now we've got a really
important extra modified epidermal
tissue which is this over here it is the
stomata now the stomata is a modified
epithelial cell and you actually have
two cells that sit side by side and they
look sort of like jelly bean shapes and
what happens is they have really really
large vacuoles on the inside so this
little black area here is going to be my
vacuole and what we do is we fill that
vacuole up with liquid or we drain it to
make it open or closed now right now
this stomata is open whereas this
stomata would be closed
and that's how we open and close the
stomata to allow specifically gases but
also water
to leave the leaf as byproducts of
photosynthesis now all of this is going
to be even more elaborated when I move
on to transportation and support within
plants
the next structure I want to move into
is stems now there are more than one
kind of stem actually there's a monocot
stem and a dicot stem I'm specifically
going to focus in on dicot stems it
depends on the school and the curriculum
that you're doing but the majority of us
are only going to learn about a
dicotyledonous stem which is what you
see here and I automatically already
know it is a stem for a couple of
reasons one of course before we go any
further look at this shape okay this is
a cross section through a stem and we
know that stems are generally like a
cylinder right the next thing I know and
I can confirm that this is a stem is
because of these egg shaped bundles of
tissues they sometimes look like eggs or
maybe sometimes they also look like an
acorn from a um oak tree depends on how
you see it but that is the defining
thing to say this is a stem now while
they're making such a big deal about
this is because when we go onto Roots
just now well you might confuse stems
with roots so this is what it looks like
we have little bundles of tissues in a
circle around the center and that's how
I know I'm dealing with a stem now let's
go into the various tissues again every
single one of the tissues we've covered
must appear here so starting off with
the epidermis now a stem does have an
epidermis and this epidermal tissue
sometimes contains chloroplasts often it
is in the colon climber which sits just
below the epidermis and that sits inside
the cortex
now the cortex is the filling of the
stem and as I said to you now it can
contain Colin kymer now if Colin kymer
has chloroplasts in it we call it
chlorine
chymer and that's what gives a stem a
green look to it and so I want you to
imagine that this whole entire area here
where it's got that stripy green detail
that is all going to be the cortex
now sitting beyond that or as I
mentioned to you earlier these little
units
of tissue and it is made out of our
second category of tissues which is the
xylem and the flow and these are our
vascular tissues
now as it may already be very obvious
stems are conductive tissues in other
words we are moving things from the
roots and the leaves up and down and so
that's why it's really important that
these vascular bundles or this xylem and
phloem appears and so in many textbooks
we refer to these little egg shaped
structures as a vascular
bundle and that's what it is together
it's really important to everybody that
you put the phloem
on the outside
and the xylem on the inside it's really
really important so we've got the water
transportation on the inside and the
food Transportation on the outside it
will be very clear again why that is
happening once we get to transportation
in Plants now the final two things I
want to cover is this white inner ring
and it is called the cambium now cambium
is a type of tissue I didn't recap
earlier but you may remember this from
learning your other plant tissues a
cambium is a merry stem and Mary stems
remember are able to turn into things so
it means that they can change they can
differentiate and this cambium is what
is allowing the stem to grow and widen
and thicken but it can also sometimes
become Bach
and we'll get into that a little bit
more later on again once we go into more
detail into plants but the basics is
that cambium allows 4 lateral growth in
other words taking a narrow stem and
making it much wider now the final final
Final tissue we're going to go over here
is the pith the pith is all this Central
tissue that sits in the middle here it
is mostly ground tissue think things
like our parenchyma
it's quite fleshy and green
um and as plants age and change and
maybe this stem is going to become a
woody stem the Perth the cambian and the
cortex all slightly start to change
consistencies but for now I'm only
talking about Green fleshy stems so
we'll stick to the pith being made out
of parenchyma
now we're going to move on to our last
plant organ which are roots and roots
are incredibly specialized like leaves
and so it's important to know those
specialized tissues now I also want to
remind you that you do need to be able
to tell the difference between a root
and a stem and you can see here that the
root diagram is very similar to a stem
because remember a stem has those
vascular bundles of tissues going around
in a circle and then they have got the
cambium which runs through it's like an
inner circle you can see the pictures
look very very similar but the main
difference is remember those vascular
bundles they are divided into half the
top half having the phloem and the
bottom half having the xylem if we have
a look at the diagram alongside that is
actually not the case but before I get
to those let's make sure we start from
the outside and work our way in now I'm
going to start off with these routes now
root hairs are really important because
they increase the surface area that is
why we have them and we need to increase
the surface area so we can absorb more
now potentially you will be asked to
draw a root hair and this is sort of
what a root here looks like we've got
our nucleus up in the top corner and
what makes root hairs unique is that
they have a vacuole which is what I'm
drawing now
which goes the full length
of your
um root hair and the reason why you have
the vacuole there is to create a osmotic
difference in other words a difference
in water so that you're constantly
pulling water in all the time and
remember that's the main function of
roots is to Anchor but also to absorb
water and minerals now sitting just
inside of that is again the cortex layer
and the cortex layer remember is made up
of all of those ground tissues now
potentially there will be two kinds of
ground tissues here we'll have
parenchyma but we'll probably also have
Colin kymer too now a quick side note
will we ever find chlorine chymer in a
root no we will not because Roots do not
have chloroplasts because they cannot
photosynthesize because they are
underground so just keep that in mind
and actually something I want to go back
to before we go any further I forgot to
mention this about our routers our root
hairs they do not have a cuticle so on
the outside there is no cuticle now this
makes sense
because what do cuticles do cuticles
waterproof now why would you want to
make the cell that is responsible for
absorbing water waterproof the answer
you wouldn't want to do that you want
your root hairs to absorb as much water
as possible so root hairs have no
cuticle on them
now let's move in to our deeper layers
and we're going to go into the
endodermis now the endodermis is as it
suggests Endo means inside and dermis
means skin it is a layer that is very
specially functioning to funnel water in
other words cause water to flow in a
certain direction now what's not in this
diagram which we do need to know which
is found just below the endodermis or
part of the endodermis is something
called the casparin
strip
now the kasparian strip is a waterproof
layer that makes sure water gets where
it needs to go now again I'm going to
elaborate this more when we do transport
of water in Plants but essentially water
is going to go from the outside soil
into the root here through the cortex
through the endodermis around the
casparin strip and then into the xylem
and it's this casparin strip that is
waterproof but it doesn't make sense now
why there's a waterproof layer on the
inside but don't worry the upcoming
video will explain that too we then have
Sitting below that as we've mentioned
before we have our xylem
and we have our floamed Asylum there's
our phloem and you'll notice there again
in different locations the phloem is now
sitting on the center and the xylem is
in red sitting in them right right in
the middle of our diagram and along the
edges now the last and final thing that
I want to bring your attention to is
something called the pericycle and also
the vascular cambium so I'm actually
going to put these two together
um the pericycle is again where we have
growth and where we are going to affect
water movement and the vascular cambium
as we mentioned earlier cambium means it
is a merry stem it is growing
and it potentially will change the type
of tissue it started off as and so
vascular cambium is essentially a merry
stem that turns into more vascular
tissue
now as always I like to finish off my
lessons with terminology recap remember
you can use these to create flash cards
which makes studying so much easier and
you will definitely get more marks by
using the correct terminology in your
explanations now as you can see there
was a lot of terminology so let's
quickly go through them all we spoke
about the tissue types in the beginning
and we spoke about the outer layer being
called the epidermal tissue this is the
single layer of cells that sits on the
outside of a plant it's there for
protection and it is specialized in
leaves and in Roots we then spoke about
ground tissue which was that special
packaging tissue that fills up the
majority of the plant it gives its shape
but also support examples of it we'll
speak about just now but they were
things like sclerenchyma and Colin kymer
we then spoke about vascular tissue
which was the xylem and phloem they are
the ones who are transporting substances
within plants we then moved on to
specific structures like a cuticle and a
cuticle is a thin waxy waterproof layer
that we find on the outside of leaves
sometimes stems but never roots
speaking of Leaves we moved on to the
mesophyll layer which is the middle
layer of the leaf it is where we find
the specialized mesophyll Palisade cells
and the mesophyll spongy cells
speaking of that packaging tissue we
looked at also mentioning the ground
tissues parenchyma collenchyma and
sclerenchyma again if you'd like more
detail on that go and watch my plant
tissues video we then moved on to
Regions or areas that you find in stems
and roots and that one region we spoke
about a lot was the cortex the cortex is
this packaging layer it is often right
underneath the epidermal layer when we
see this in stems and Roots please don't
think cortex core that's not what it
means
we did just now mention xylem and phloem
so I'm not going to go over those again
the cambium remember cambium is a word
to describe that very unique kind of
tissue that can grow into almost
anything cambium does fall under a
non-permanent or semi-permanent tissue
it often allows for lateral growth and
plants getting wider
along with that we also spoke about the
pericycle and the pericycle is closely
related to the cambium the pericycle is
not a tissue but rather a region it's
very similar to the cortex it is an area
or a layer a name we give a layer
speaking of layers we also have the
endodermis which is the inner skin like
layer and that we find in Roots it has a
very important job of funneling water
from the outside of the root to the core
of the root and it does this through the
casparian strip which is this waterproof
waxy layer right in the middle of the
root and it funnels water into xylem
which we'll get to in more detail at a
later video we also looked at root hairs
and stomata which were specialized
epidermal cells that allowed substances
into and out of a plant
now if you like this video make sure you
give it a thumbs up and I will see you
all again soon bye
[Music]
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