Cohesion, Adhesion, & Surface Tension
Summary
TLDRThis educational script delves into the emergent properties of water, focusing on cohesion and adhesion. It explains how water molecules bond through hydrogen bonding, creating a cohesive force that allows water to stick to itself and adhere to other substances. The script further explores the significance of these properties in the biological process of transpiration in plants, illustrating how water travels from roots to leaves. Additionally, it touches on surface tension, a phenomenon where water molecules at the surface form a 'skin' due to unbalanced cohesive forces, which is crucial for various biological functions and the behavior of water in nature.
Takeaways
- π§ Cohesion is the process where water molecules stick to each other through hydrogen bonding.
- π Adhesion is the process where water molecules stick to non-water molecules, also through hydrogen bonding.
- π³ Transpiration is the process by which water is pulled up from the roots and distributed throughout a plant via the xylem.
- πΏ Xylem acts like a vascular tissue in plants, transporting water from roots to leaves and branches.
- π§π The combination of cohesion and adhesion allows water to move up the plant as a continuous column.
- π± Capillary action is a key mechanism in water transport within plants, similar to how a paper towel absorbs water.
- π¬ Surface tension is the result of water molecules at the surface being pulled inward by hydrogen bonds, forming a 'skin' on the water's surface.
- π Surface tension is biologically significant, allowing insects like water striders to walk on water and maintaining the integrity of water droplets.
- π§οΈ Raindrops and water droplets are examples of how surface tension plays a role in the natural world and the food web.
- π€ The script emphasizes the importance of understanding cohesion, adhesion, and surface tension for various biological processes and phenomena.
Q & A
What are the two main properties of water discussed in the script?
-The two main properties of water discussed are cohesion and adhesion.
What is cohesion and how does it relate to water molecules?
-Cohesion is the property where water sticks to other water molecules through hydrogen bonding, creating an attraction between the water molecules themselves.
What is adhesion and how does it differ from cohesion?
-Adhesion is when water sticks to non-water molecules, also through hydrogen bonding, but the difference is that it involves the water molecule's oxygen forming a bond with a hydrogen of another substance, not another water molecule.
Why are cohesion and adhesion important in the context of plant biology?
-Cohesion and adhesion are important in plant biology as they play a crucial role in the process of transpiration, allowing water to be pulled up from the roots and distributed throughout the plant.
Can you explain the process of transpiration in plants as described in the script?
-Transpiration is the process where water is pulled up from the roots of a plant, moves through the xylem (vascular tissue), and is eventually released through small holes called stomata on the underside of the leaves.
How does the script describe the movement of water in the xylem?
-The script describes the movement of water in the xylem as a column where water molecules cohesively bind to one another and adhere to the sides of the xylem, moving upwards due to transpiration.
What is surface tension and how does it relate to the hydrogen bonding of water molecules?
-Surface tension is the phenomenon where water molecules at the surface are held together by hydrogen bonding, creating a 'skin' effect because there are no molecules above them to counteract the downward pull of the bonds.
Why is surface tension biologically significant according to the script?
-Surface tension is biologically significant because it keeps water in droplets, which is important for various biological processes and interactions, such as insects walking on water or the formation of raindrops.
How does the script illustrate the concept of surface tension with an example?
-The script uses the example of a beaker filled with water molecules to show how the surface molecules are pulled inwards by cohesion, forming a skin on the top due to surface tension.
What role do the concepts of cohesion, adhesion, and surface tension play in the movement and behavior of water in various biological contexts?
-These concepts are fundamental to understanding how water moves within and interacts with biological systems, such as the upward movement in plants through transpiration and the formation of water droplets that insects can interact with.
What is capillary action as mentioned in the script and how does it relate to water movement in plants?
-Capillary action is the process where a liquid, like water, travels up through a narrow space against gravity, similar to how water moves up a paper towel. In plants, it's how water moves up through the roots and into the xylem due to cohesion and adhesion.
Outlines
π§ Cohesion and Adhesion in Water
The script introduces the concept of emergent properties of water, focusing on its cohesive and adhesive properties. Cohesion is the attraction between water molecules through hydrogen bonding, while adhesion is the attraction of water molecules to other substances. The video explains how these properties are crucial in the process of transpiration in plants, where water moves from roots to leaves through xylem, the plant's vascular tissue. The script discusses how water molecules stick together and to the plant tissue, facilitating the upward movement of water without a mechanical pump. It also hints at the importance of these properties in biology, setting the stage for further exploration in upcoming classes and labs.
π Exploring Surface Tension and Its Biological Significance
This paragraph delves into surface tension, another emergent property of water, which is a result of the cohesive forces between water molecules. The script describes how water molecules at the surface are pulled towards the center due to the lack of molecules above them, creating a 'skin' effect. This phenomenon is observable in everyday life, such as when water forms a bubble on a flat surface. The biological importance of surface tension is highlighted, explaining its role in maintaining water droplets, which are vital for various ecological processes and organisms, including insects that can walk on water. The script aims to clarify the concept of surface tension and its relevance in the biological context.
Mindmap
Keywords
π‘Cohesion
π‘Adhesion
π‘Transpiration
π‘Xylem
π‘Capillary Action
π‘Surface Tension
π‘Hydrogen Bonding
π‘Stomata
π‘Vascular Tissue
π‘Water Column
π‘Water Strider
Highlights
Emergent properties of water, specifically its cohesive and adhesive properties, are discussed.
Cohesion is the attraction between water molecules through hydrogen bonding.
Adhesion is the process where water sticks to non-water molecules, also via hydrogen bonding.
Transpiration in plants is a key process where water moves from roots to leaves.
Xylem, a vascular tissue in plants, functions like blood vessels to transport water.
Water exits leaves through small holes called stomata as part of transpiration.
The absence of a pump mechanism in plants is highlighted, questioning how water moves upwards.
Capillary action is described as a key process in water movement within plants.
Cohesion and adhesion are essential for the column of water to move upwards in plants.
Surface tension is explained as a result of water molecules being held together by hydrogen bonds.
The top layer of water molecules forms a 'skin' due to the lack of molecules above pulling them apart.
Biological importance of surface tension is highlighted, such as in the case of water striders.
Surface tension plays a role in keeping water in droplets, which is vital for various biological processes.
The role of hydrogen bonding in creating surface tension is emphasized.
The practical applications of cohesion, adhesion, and surface tension in biology are discussed.
The transcript concludes with an invitation for questions, indicating an interactive educational approach.
Transcripts
[Music]
so the first of the emergent properties
of water I want to talk about is um its
ability to um adhere to other molecules
or to cohesively stick to itself so
there's two words that we need to talk
about first and the words are cohesion
and adhesion um and these are almost
always going to be talked about together
but you need to know the difference
between them so the first thing you need
to know is that cohesion is when water
sticks to other water
molecules um and that that's going to be
through hydrogen bonding so I'm going to
have a water hydrogen bound to another
water um hydrogen bonded to another
water molecule so it's just the
attraction between the water molecules
uh adhesion is when water sticks to non
water molecules and it's going to happen
the same way it's also going to be
through hydrogen bonding it's just
instead of the oxygen from a water
molecule forming a hydrogen bond with a
hydrogen of another water molecule it's
between the negative side of a water
molecule with a positive side of
something else and that's really it so
in this example I'm going to have the
water um adhering to some type of plant
molecule that's not water so this is
important uh cohesion and adhesion are
are super important actually in biology
and the um
there dozens literally dozens of times
that we're going to talk about this this
year but the one that I want to talk
about is the one that we're going to be
focusing on the most in the next couple
weeks which is actually going to be
transpiration of plants so transpiration
of plants is the process where water is
pulled up from the roots um of the plant
so the water's going to move up uh
through the roots of this tree
and then it's going to be pulled up
through the xylem which is one of the
vascular tissues so just think of it as
like a blood vessel but it just carries
water in the tree and it's going to
distribute that water to all the leaves
and all the branches and throughout the
entire tree so I'm going to have my
water um coming up through the tree
through the roots and it's going to move
up and it's eventually going to exit the
leaves on the undersides of the leaves
there's these small holes called um
States and the water is actually going
to move up all the way through the tree
through trans through through
transpiration and then it's eventually
going to um to exit through the bottoms
of the leaves through those holes and
we're going to talk about that at length
um in class and we're going to do a
couple different Labs on it but
basically we need to talk about how does
the water move like because there's no
little pump in there right so let's look
at a blown up view of some of this
vascular tissue some of this xylem um so
the transpiration
of water that's what we're looking at so
I'm going to this is my zoomed in view
so let me draw my xyum with my brown
lines and then I'm going to have my
water so moving up
through the xylem I'm going to have the
water actually sticking to themselves so
the water molecules are going to
cohesively be bound to one another so as
one water molecule moves the next is
going to get pulled up right or as water
molecules get pulled up they're going to
keep shoving so the water's going to
move as a column right um the next thing
you need to know is that the water is
going to adhere to the sides of the xylm
so it's going to through hydrogen
bonding it's also going to stick to the
sides of the actual plant vascular
tissue and that's that's adhesion and so
the combination of cohesion and adhesion
what's going to happen is as that water
flows into the roots you're going to get
a column of water basically moving up
through capillary action um which is
just when you like you take a a piece of
paper towel and the water travels up
through it it's basically the same thing
but this is happening on on a grand
scale inside of all plants that's how
water gets from the roots of any plant
to the leaves of any plant so that's
cohesion and adhesion now the next thing
we want to talk about with cohesion is
going to be surface tension so surface
tension you've all seen before um it's
when water molecules are being held
together by um by the the hydrogen
bonding between them so let's look at an
example of of surface tension and let's
talk about um why it why we're talking
about the surface not just the whole
cohesive water so the molecules at the
surface at that top layer don't have any
water molecules on top of them so
instead what's happening is all of those
those those hydrogen bonds
are pulling them kind of down so the the
surface molecules are going to be pulled
in towards the center of the Water by
cohesion so let's look at a picture of
that so I've got my Beaker and I'm going
to fill it with water
molecules and uh in the center what
would happen is all of those white lines
are those are going to indicate the
hydrogen bonding everything's pulling
together right but if we look at one of
the water molecules at the surface
they're only being pulled kind of next
to each other and then down there's
nothing that's pulling it up so it kind
of forms a skin on the top and you've
seen that in real life if you take and
you put some water on your desk it'll
form a little bubble so let's fill that
in with my water molecules and we'll put
in all my cohesive forces right there
all those hydrogen bonds then what you
get is you get those are a normal
cohesion um you get these bonds that I'm
I'm looking at the top that's going to
kind of be that that surface tension and
it's still cohesion but what you're what
you're seeing is you're seeing the
actual hydrogen bonding that's leading
to the surface tension now why do we
care in biology I mean it's cool like
because you've all seen pictures of the
water Strider right well this is why we
care in biology surface tension is
biologically important because it keeps
water in droplets and water droplets are
important how water moves is important
and having water droplets do raindrops
those are all important because you know
insects other aspects of the the um the
food web they're going to depend on that
um that cohesive nature of water and on
um and on being able to walk across that
water so that's surface tension um and
uh hopefully that's pretty clear I think
everybody's seen examples of surface
tension
before so that's really all I want to
talk about on cohesion adhesion and
surface tension if you have questions
come on in
Browse More Related Video
5.0 / 5 (0 votes)